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Definitions

• compositions comprising non-human animal cells expressing stabilized step function opsin (SSFO) proteins on their plasma membranes and methods of using the same to selectively depolarize neurons residing in microcircuits of the pre-frontal cortex to affect one or more social behaviors, communications, and/or conditioned behaviors in the non-human animal.
• SSFO stabilized step function opsin
• Optogenetics is the combination of genetic and optical methods used to control specific events in targeted cells of living tissue, even within freely moving mammals and other animals, with the temporal precision (millisecond-timescale) needed to keep pace with functioning intact biological systems.
• the hallmark of optogenetics is the introduction of fast light-activated channel proteins to the plasma membranes of target neuronal cells that allow temporally precise manipulation of neuronal membrane potential while maintaining cell-type resolution through the use of specific targeting mechanisms.
• microbial opsins which can be used to investigate the function of neural systems are the
• channelrhodopsins (ChR2, ChRl, VChRl, and SFOs) used to promote depolarization in response to light.
• channelrhodopsins ChoR2, ChRl, VChRl, and SFOs
• SFOs also has the potential to address the hardware challenge, since the orders-of-magnitude greater light sensitivity characteristic of SFOs could in theory allow non- brain penetrating light delivery, and the persistent action of the bistable SFOs after light-off could allow hardware-free behavioral testing.
• the known SFOs C128A,S,T and D156A are not stable enough to produce constant photocurrent after a single light flash over the many minutes required for complex behavioral testing.
• animal cells non-human animals, brain slices comprising cells expressing stabilized step Junction opsin proteins on their plasma membranes and methods of using the same to selectively depolarize neurons residing in microcircuits of the prefrontal cortex.
• non-human animals comprising a first light- activated cation channel protein expressed in neurons of the pre-frontal cortex of the animal, wherein the protein is capable of inducing depolarizing current in the neurons by light and exhibits rapid step-like activation in response to a single pulse of light having a first wavelength and deactivation in response to a pulse of light having a second wavelength, wherein the depolarizing current in the neurons is maintained for at least about ten minutes; and wherein the activation of the protein in the pre-frontal cortex neurons induces changes in social behaviors, communications, and/or conditioned behaviors in the animal.
• a brain slice comprising neurons of the pre-frontal cortex, wherein a light-activated protein is expressed in the neurons of the pre-frontal cortex, wherein the protein is capable of inducing depolarizing current in the neurons by light and exhibits rapid step-like activation in response to a single pulse of light having a first wavelength and deactivation in response to a pulse of light having a second
• a method for identifying a chemical compound that inhibits the depolarization of excitatory or inhibitory neurons in the prefrontal cortex of a non-human animal comprising: (a) depolarizing excitatory or inhibitory neurons in the prefrontal cortex of a non-human animal comprising a first light-activated protein cation channel protein expressed on the cell membrane of the neurons of the prefrontal cortex of the animal, wherein the protein is capable of mediating a depolarizing current in the neurons when the neurons are illuminated with light, wherein the protein exhibits rapid step-like activation in response to a single pulse of light having a first wavelength and deactivation in response to a pulse of light having a second wavelength; wherein the depolarizing current in the neurons is maintained for at least about ten minutes; wherein the protein comprises the amino acid sequence of ChR2, ChRl, VChRl, or VChR2 with amino acid substitutions
• a method for identifying a chemical compound that restores a social behavior, communication, and/or conditioned behavior in a non-human animal comprising: (a) depolarizing excitatory neurons in the prefrontal cortex of a non-human animal comprising a light-activated protein cation channel protein expressed on the cell membrane of the neurons, wherein the protein is capable of inducing a depolarizing current in the neurons when the neurons are illuminated with light, wherein the protein exhibits rapid step-like activation in response to a single pulse of light having a first wavelength and deactivation in response to a pulse of light having a second wavelength; wherein the depolarizing current in the neurons is maintained for at least about ten minutes; and wherein the protein comprises the amino acid sequence of ChR2, ChRl , VChRl , or VChR2 with amino acid substitutions at amino acid residues corresponding to CI 28 and D 156 of the amino acid sequence of ChR2, wherein depolarizing the excitatory neuron inhibit
• the present disclosure relates to optical control over nervous system disorders (such as disorders associated with social dysfunction), as described herein. While the present disclosure is not necessarily limited in these contexts, various aspects of the disclosure may be appreciated through a discussion of examples using these and other contexts.
• Various embodiments of the present disclosure relate to an optogenetic system or method that correlates temporal, spatio and/or cell-type control over a neural circuit with measurable metrics. For instance, various metrics or symptoms might be associated with a neurological disorder (such as a neurological disorder exhibiting various symptoms of social dysfunction).
• the optogenetic system targets a neural circuit within a
• the optogenetic system involves monitoring the subject/patient for the metrics or symptoms associated with the neurological disorder. In this manner, the optogenetic system can provide detailed information about the neural circuit, its function and/or the neurological disorder.
• particular embodiments relate to studying and probing disorders.
• Other embodiments relate to the identification and/or study of phenotypes and endophenotypes.
• Still other embodiments relate to the identification of treatment targets.
• aspects of the present disclosure are directed toward the artificial inducement of disorder/disease states on a fast-temporal time scale. These aspects allow for study of disease states in otherwise healthy animals. This can be particularly useful for diseases that are poorly understood and otherwise difficult to accurately model in live animals. For instance, it can be difficult to test and/or study disease states due to the lack of available animals exhibiting the disease state. Moreover, certain embodiments allow for reversible disease states, which can be particularly useful for establishing baseline/control points for testing and/or for testing the effects of a treatment on the same animal when exhibiting the disease state and when not exhibiting the disease state. Various other possibilities exist, some of which are discussed in more detail herein.
• aspects of the present disclosure are directed to using an artificially induced disorder/disease state for the study of disease states in otherwise healthy animals. This can be particularly useful for diseases that are poorly understood and otherwise difficult to accurately model in living animals. For instance, it can be difficult to test and/or study disease states due to the lack of available animals exhibiting the disease state. Moreover, certain embodiments allow for reversible disease states, which can be particularly useful in establishing baseline/control points for testing and/or for testing the effects of a treatment on the same animal when exhibiting the disease state and when not exhibiting the disease state.
• Certain aspects of the present disclosure are directed to a method that includes modifying (e.g., elevating or lowering) an excitation/inhibition (E/I) balance in a targeted neural circuit in a prefrontal cortex of a subject/patient. For instance, the E/I balance is changed to a level that preserves the responsiveness of the targeted neural circuit to intrinsic electrical activity while symptoms of a disorder are temporally increased. While the E/I balance is changed, a stimulus is introduce to the subject/patient and the symptoms of the disorder are monitored.
• the subject can be a test animal that is healthy, or an animal model of a disorder.
• the result of the manipulation is either a transient recapitulation of disease symptoms (in an otherwise healthy animal) or alleviation of symptoms (in an animal model of a neurological disorder).
• the monitoring of the symptoms also includes assessing the efficacy of the stimulus in mitigating the symptoms of the disorder.
• FIG. 1 Kinetic and absorbance properties of a fully stabilized SFO.
• FIG. 2 depicts Stable step-modulation of neural activity in multiple cell types in vitro and in vivo,
• Gray horizontal bars indicate light pulses and trace colors indicate wavelength of light used in each light pulse; summary spectra (right) for measurements of activation and deactivation of ChR2(C128S/D156A) are shown.
• Starred example trace is plotted below the instantaneous spike -rate heat maps calculated with 2s moving average.
• Each heat-map line represents one sweep at indicated depth (3 sweeps at each site); 470 nm activation pulse and 561 nm deactivation pulses are indicated by blue and green bars, respectively,
• Instantaneous spike -rate heat maps are shown for activity of isolated single units indicated as Neuron 1 and Neuron 2; waveforms of indicated units are plotted next to corresponding traces.
• Graph shows average c--fos positive cell counts in mPFC of CaMKIIa-SSFO, and PV::Cre/DIO- SSFO animals
• CaMKIIa-SSFO mice showed a significant reduction in social exploration
• mice were reconditioned without optical stimulation and freezing was evaluated 24h later. All mice showed similar freezing behavior in the absence of light, (f) Open-field exploration is indistinguishable in CaMKIIa-SSFO (blue) and CaMKIIa-EYFP (gray) control mice, before (Test 1) and after (Test light activation.
• FIG. 4 depicts SSFO activation in pyramidal cells increases network activity and impairs information transmission through principal neurons
• (a) Whole cell recording from a layer 2/3 pyramidal neuron expressing SSFO in a prefrontal cortical slice from a mouse injected with AAV5-CaMKIl -SSFO-EYFP. Activation with 470 nm light triggered depolarization of the recorded cell.
• Inset compares expanded 2s periods pre-activation (1), post-activation (2) and post-deactivation (3).
• FIG. 5 depicts impaired cellular information processing in elevated but not reduced cellular E/I balance
• Asterisks indicate the significance of the difference in magnitude of the change in mutual information for CaMKIIct::SSFO vs. PV::SSFO.
• (i) Same as in (g), but with varying input sEPSC rate bins. Here the time bin width was kept constant at 125 ms.
• (j) Same as in (h), but with varying input sEPSC rate bins. All bar graphs depict mean ⁇ s.e.m. (* p ⁇ 0.05; ** p O.01).
• FIG. 6 depicts elevated cellular E/I balance in mPFC drives baseline gamma rhythmicity in freely-moving, socially impaired mice
• CMO Implantable chronic multisite optrode
• Arrowheads indicate wire termination sites; arrow shows cleaved end of fiberoptic connector,
• Electrolytic lesions mark the sites from which recordings were taken in a mouse expressing CaMKIIa::SSFO.
• FIG. 7 depicts locomoter behavior in a novel open field behavioral test,
• (a) Open- field behavior of mice expressing CaMKIIa::SSFO in mPFC pre-activation (dark gray bars; 2.5 min) and post-activation (light gray bars; 2.5 min) with 1 s 473 nm light. Track length, % time in center, and % time in the periphery are shown (n 3 mice). A yellow light pulse was applied after the second 2.5 min period to deactivate SSFO.
• FIG. 8 depicts increase in power at gamma frequency under high light density, (a) voltage clamp experiment with corresponding spectra for IPSCs recorded at OmV and for EPSCs at -60 mV (b) Change in power of synaptic activity within the indicated frequency bins recorded in mPFC pyramidal neurons during a 20s pulse of 560 nm light at the indicated light power densities. Power differences are shown between baseline (pre-light) period to light-on period when voltage clamping the cells to - 60 mV or 0 mV, or in current clamp (CC) mode. Strongest gamma-modulation is evident at the highest light power density, and is strongest in 0 mV and CC recordings, (c) Relative gamma power for the three light powers in the three recording configurations from (b).
• FIG. 9 depicts inhibition of PFC excitatory or inhibitory cells,
• FIG. 10 depicts combinatorial optogenetics in behaving mammals: rescue of elevated E/I-balance social behavior, (a) Action spectra of SSFO and C1V1-E122T/E162T (C1V1). Vertical lines indicate stimulation wavelengths used in the experiments, (b)
• FIG. 12 depicts a flow diagram for testing of a disease model, consistent with various 10 embodiments of the present disclosure.
• FIG. 13 depicts a model for assessing treatments of various nervous system disorders, consistent with an embodiment of the present disclosure.
• This invention provides, inter alia, animal cells, non-human animals, and brain slices comprising cells expressing stabilized step function opsin proteins on their plasma membranes, and methods of using the stabilized step function opsin proteins to selectively depolarize excitatory or inhibitory neurons residing in the same microcircuit in the prefrontal cortex.
• the step function opsins, or SFOs are ChR2 light-activated cation channel proteins that can induce prolonged stable excitable states in neurons upon exposure to blue light and then be reversed upon exposure to green or yellow light.
• the SFOs were developed to implement bistable changes in excitability of targeted populations operating on timescales up to 4 orders of magnitude longer than that of wild type (wt) ChR2 for more stable state modulation (SFOs: up to 10-100 seconds). While these opsin genes delivered a new kind of optogenetic control complementary to that of conventional channelrhodopsins designed to control individual action potentials, the timescale was still not suitable for evaluating prolonged and complex mammalian behaviors over many minutes.
• SSFO stabilized step function opsin
• brain slices from non-human animals containing cortical excitatory or inhibitory neurons expressing the stabilized step function opsin proteins disclosed herein can be used to search for chemical compounds which can selectively inhibit the
• cortical neurons may be responsible for or involved with the social and cognitive behavioral defects associated with neurological disorders such as schizophrenia and/or autism spectrum disorder.
• an “animal” can be a vertebrate, such as any common laboratory model organism, or a mammal. Mammals include, but are not limited to, humans and non-human primates, farm animals, sport animals, pets, mice, rats, and other rodents.
• amino acid substitution or “mutation” as used herein means that at least one amino acid component of a defined amino acid sequence is altered or substituted with another amino acid leading to the protein encoded by that amino acid sequence having altered activity or expression levels within a cell.
• ChR2-C1208 channelrhodopsin-2 (ChR2) and bacteriorhodopsin (BR), in which similar mutations led to moderate slowing of the photocycle.
• ChR2 channelrhodopsin-2
• BR bacteriorhodopsin
• T90 the BR homolog of ChR2-C128, is hydrogen- bonded to Dl 15 of BR; these two amino acids are thought to work in concert to stabilize the all- trans conformation of the retinal chromophore, and ChR2-D156 is the homolog of BR Dl 15. If C128 and D156 modulate ChR2 closure solely via their presumptive shared hydrogen bond, then a combination mutation of these two residues would not be expected to generate significantly greater effects on channel kinetics than either mutation alone.
• the invention includes proteins comprising substituted or mutated amino acid sequences, wherein the mutant protein retains the characteristic light-activatable nature of the precursor SFO protein but may also possess altered properties in some specific aspects.
• mutant light-activated SFO proteins described herein may exhibit an increased level of expression both within an animal cell or on the animal cell plasma membrane; an increased level of sustained photocurrents in response to a first wavelength of light; a faster but less complete deactivation when exposed to a second wavelength of light; and/or a combination of traits whereby the SFO protein possess the properties of low desensitization, fast deactivation, and/or strong expression in animal cells.
• Light-activated SFO proteins comprising amino acid substitutions or mutations include those in which one or more amino acid residues have undergone an amino acid substitution while retaining the ability to respond to light and the ability to control the polarization state of a plasma membrane.
• light-activated proteins comprising amino acid substitutions or mutations can be made by substituting one or more amino acids into the amino acid sequence corresponding to SEQ ID NO: 1 , SEQ ID NO:2, SEQ ID NO:
• the invention includes proteins comprising altered amino acid sequences in comparison with the amino acid sequence in SEQ ID NO:l, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:4, wherein the altered light-activated stabilized step function opsin protein retains the characteristic light-activated nature and/or the ability to regulate ion flow across plasma membranes of the protein with the amino acid sequence represented in SEQ ID NO:l, SEQ ID NO:2, SEQ ID NO:3, or SEQ ID NO:4 but may have altered properties in some specific aspects.
• Amino acid substitutions in a native protein sequence may be conservative or non- conservative and such substituted amino acid residues may or may not be one encoded by the genetic code.
• the standard twenty amino acid "alphabet" is divided into chemical families based on chemical properties of their side chains.
• amino acids with basic side chains e.g., lysine, arginine, histidine
• acidic side chains e.g., aspartic acid, glutamic acid
• uncharged polar side chains e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine
• nonpolar side chains e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan
• beta-branched side chains e.g., threonine, valine, isoleucine
• side chains having aromatic groups e.g., tyrosine, phenylalanine, tryptophan, histidine.
• a “conservative amino acid substitution” is one in which the amino acid residue is replaced with an amino acid residue having a chemically similar side chain (i.e., replacing an amino acid possessing a basic side chain with another amino acid with a basic side chain).
• a “non-conservative amino acid substitution” is one in which the amino acid residue is replaced with an amino acid residue having a chemically different side chain (i.e., replacing an amino acid having a basic side chain with an amino acid having an aromatic side chain).
• the amino acid substitutions may be conservative or non-conservative. Additionally, the amino acid substitutions may be located in the SFO retinal binding pocket, in one or more of the SFO intracellular loop domains, and/or in both the retinal binding pocket or the intracellular loop domains.
• the SFO protein can have a mutation at amino acid residue C 128 of SEQ ID NO: 1. In some embodiments, the SFO protein can have a mutation at amino acid residue D 156 of SEQ ID NO: 1.
• a light-activated SSFO protein expressed on a cell plasma membrane capable of mediating a depolarizing current in the cell when the cell is illuminated with light, wherein the protein exhibits rapid step-like activation in response to a single pulse of light having a first wavelength and deactivation in response to a pulse of light having a second wavelength; wherein the depolarizing current in the cell is maintained for up to about five, about ten, about fifteen, or about twenty minutes.
• the protein comprises the amino acid sequence of ChR2, ChRl, VChRl, or VChR2 with amino acid substitutions at amino acid residues corresponding to CI 28 and D156 of the amino acid sequence of ChR2 (See, e.g., Figure IB of International Patent Application Publication No. WO 2009/131837, which is incorporated by reference herein, illustrating conservation of amino acid residues corresponding to C128 and D156 of the amino acid sequence of ChR2 between several species of channelrhopsin cation channels; see also Kianianmomeni et al., Plant Physiol., 2009, 151:347-356, which is incorporated by reference herein in its entirety).
• the light-activated SSFO protein can comprise an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the sequence shown in SEQ ID NO:l without the signal peptide sequence. In other embodiments, the light-activated SSFO protein can comprise an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the sequence shown in SEQ ID NO:l.
• the light-activated SSFO protein can comprise an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the sequence shown in SEQ ID NO:2. In other embodiments, the light-activated SSFO protein can comprise an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the sequence shown in SEQ ID NO:3.
• the light-activated SSFO protein can comprise an amino acid sequence at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the sequence shown in SEQ ID NO:4.
• the signal peptide sequence in the SSFO proteins is deleted or substituted with a signal peptide sequence from a different protein.
• the substitution at amino acid residues corresponding to CI 28 and D156 of the amino acid sequence of ChR2 are conservative amino acid substitutions.
• the substitution at amino acid residues corresponding to CI 28 and D156 of the amino acid sequence of ChR2 are non-conservative amino acid substitutions.
• the substitution at the amino acid residue corresponding to CI 28 of the amino acid sequence of ChR2 is a substitution to serine.
• the substitution at the amino acid residue corresponding to D 156 of the amino acid sequence of ChR2 is a substitution to a non-acidic amino acid.
• the substitution at the amino acid residue corresponding to D 156 of the amino acid sequence of ChR2 is a substitution to alanine.
• the protein can further comprise a C-terminal fluorescent protein.
• the C-terminal fluorescent protein can be enhanced yellow fluorescent protein (EYFP), green fluorescent protein (GFP), cyan fluorescent protein (CFP), or red fluorescent protein (RFP).
• the second light-activated protein can be capable of mediating a hyperpolarizing current in the cell when the cell is illuminated with light.
• the second light-activated protein can be NpHR, eNpHR2.0, eNpHR3.0, eNpHR3.1, GtR3, or a C1V1 chimeric protein as described in International Patent Application No: PCT/US2011/028893 and U.S. Provisional Patent Application Nos: 61/410,736 and 61/410,744, the disclosure of each of which is incorporated by reference herein in their entirety.
• the CI VI chimeric protein comprises a light-activated protein expressed on the cell membrane, wherein the protein is a chimeric protein derived from VChRl from Volvox carteri and ChRl from Chlamydomonas reinhardti, wherein the protein comprises the amino acid sequence of VChRl having at least the first and second transmembrane helices replaced by the first and second transmembrane helices of ChRl; is responsive to light; and is capable of mediating a depolarizing current in the cell when the cell is illuminated with light.
• the protein further comprises a replacement within the intracellular loop domain located between the second and third transmembrane helices of the chimeric light responsive protein, wherein at least a portion of the intracellular loop domain is replaced by the corresponding portion from the ChRl .
• the portion of the intracellular loop domain of the CI VI chimeric protein is replaced with the corresponding portion from the ChRl extending to amino acid residue A145 of the ChRl.
• the C1V1 chimeric protein further comprises a replacement within the third transmembrane helix of the chimeric light responsive protein, wherein at least a portion of the third transmembrane helix is replaced by the corresponding sequence of ChRl .
• the portion of the intracellular loop domain of the CI VI chimeric protein is replaced with the corresponding portion from the ChRl extending to amino acid residue Wl 63 of the ChRl .
• the light having a first wavelength can be blue light. In other embodiments, said light having a first wavelength can be about 445 nm. In another embodiment, said light having a second wavelength can be green light or yellow light. In other embodiments, said light having a second wavelength can be about 590 nm. In other embodiments, said light having a second wavelength can be between about 390-400 nm, inclusive, as well as every number within this range.
• the light-activated stabilized step function opsin proteins described herein can be activated by light pulses that can have a duration for any of about 1 millisecond (ms), about 2 ms, about 3, ms, about 4, ms, about 5 ms, about 6 ms, about 7 ms, about 8 ms, about 9 ms, about 10 ms, about 15 ms, about 20 ms, about 25 ms, about 30 ms, about 35 ms, about 40 ms, about 45 ms, about 50 ms, about 60 ms, about 70 ms, about 80 ms, about 90 ms, about 100 ms, about 200 ms, about 300 ms, about 400 ms, about 500 ms, about 600 ms, about 700 ms, about 800 ms, about 900 ms, about 1 sec, about 1.25 sec, about 1.5 sec, or about 2 sec, inclusive, including any times in between these numbers
• the light-activated stabilized step function opsin proteins described herein can be activated by light pulses that can have a light power density of any of about 1 ⁇ mm " , about 2 ⁇ mm “ 2 , about 3 ⁇ 2 , about 4 ⁇ W mm " 2
• ⁇ mm “ about 5 ⁇ mm “2 , about 6 ⁇ mm “2 , about 7 ⁇ mm “2 , about 8 ⁇ W mm “2 , about 9 ⁇ mm “2 , about 10 ⁇ mm “2 , about 11 ⁇ W mm “2 , about 12 ⁇ mm “2 , about 13 ⁇ mm “2 , about 14 ⁇ mm “2 , about 15 ⁇ mm '2 , about 16 ⁇ mm '2 , about 17 ⁇ mm '2 , about 18 ⁇ mm '2 , about 19 mm " , or about 20 ⁇ mm “ , inclusive, including any values between these numbers.
• the light-activated proteins can be activated by light pulses that can have a light power density of any of about 1 mW mm “2 , about 2 mW mm “2 , about 3 mW mm “2 , about 4 mW mm “2 , about 5 mW mm “2 , about 6 mW mm “2 , about 7 mW mm “2 , about 8 mW mm “ 2 , about 9 mW mm “ 2 , about 10 mW mm “ 2 , about 11 mW mm “ 2 , about 12 mW mm “ 2 , about 13 mW mm “2 , about 14 mW mm “2 , about 15 mW mm “2 , about 16 mW mm “2 , about 17 mW mm “2 , about 18 mW mm “2 , about 19 mW mm “2 , about 20 mW mm “2 , about 21 mW
• the light-activated stabilized step function opsin proteins described herein can maintain a sustained photocurrent for about 20 minutes. In other embodiments, the light-activated stabilized step function opsin proteins described herein can maintain a sustained photocurrent for any of about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26 27, 28, 29, or 30 minutes, inclusive, including for any times in between these numbers. In other embodiments, the photocycle progression of any of the light-activated stabilized step function opsin proteins described herein is completely blocked after the protein is illuminated with said single pulse of light having a first wavelength.
• the cell can be an animal cell.
• the animal cell can be a neuronal cell, a cardiac cell, or a stem cell.
• the animal cell can be a neuronal cell.
• the animal cells comprise neurons that effect social behavior when depolarized.
• the neuronal cell is a neuron that changes innate social behavior and/or conditioned behavior when depolarized.
• the animal cells comprise neurons that give rise to the social and cognitive defects in autism and/or schizophrenia when depolarized.
• the neuronal cell can be an excitatory neuron located in the pre-frontal cortex of a non-human animal.
• the excitatory neuron can be a pyramidal neuron.
• the neuronal cell can be an inhibitory neuron located in the pre-frontal cortex of a non-human animal.
• the inhibitory neuron can be a parvalbumin neuron.
• the inhibitory and excitatory neurons can be in a living non-human animal.
• the cells can be neurons in a living brain slice from a non-human animal.
• the brain slices are coronal brain slices. In some embodiments, the brain slices are from the pre-frontal cortex of a non-human animal. In other embodiments, the brain slices comprise neurons that effect social behavior when depolarized. In some embodiments, the brain slices comprise neurons that change innate social behavior and/or conditioned behavior when depolarized. In other embodiments, the brain slices comprise neurons that give rise to the social and cognitive defects in autism and/or schizophrenia when depolarized.
• the stabilized step function opsin proteins described herein may be modified by the addition of one or more amino acid sequence motifs which enhance transport to the plasma membranes of mammalian cells.
• Light-activated opsin proteins are derived from evolutionarily simpler organisms and therefore may not be expressed or tolerated by mammalian cells or may exhibit impaired subcellular localization when expressed at high levels in mammalian cells. Consequently, in some embodiments, the stabilized step function opsin proteins described herein may be fused to one or more amino acid sequence motifs selected from the group consisting of a signal peptide, an endoplasmic reticulum (ER) export signal, a membrane trafficking signal, and an N-terminal golgi export signal.
• ER endoplasmic reticulum
• the one or more amino acid sequence motifs which enhance the light-activated stabilized step function opsin proteins transport to the plasma membranes of mammalian cells can be fused to the N-terminus, the C-terminus, or to both the N- and C-terminal ends of the light-activated protein.
• the light-activated protein and the one or more amino acid sequence motifs may be separated by a linker.
• the stabilized step function opsin protein is modified by the addition of a trafficking signal (ts) which enhances transport of the protein to the cell plasma membrane.
• ts trafficking signal
• the trafficking signal is derived from the amino acid sequence of the human inward rectifier potassium channel Kj r 2.1.
• the trafficking signal comprises the amino acid sequence KSRITSEGEYIPLDQIDINV.
• the light-activated stabilized step function opsin protein is modified by the addition of a signal peptide (e.g., which enhances transport to the plasma membrane).
• the signal peptide may be fused to the C-terminus of the core amino acid sequence or may be fused to the N- terminus of the core amino acid sequence.
• the signal peptide is linked to the core amino acid sequence by a linker.
• the linker can comprise any of 5, 10, 20, 30, 40, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 400, or 500 amino acids in length.
• the signal peptide comprises the amino acid sequence MDYGGALSAVGRELLFVTNPVVVNGSVLVPEDQCYCAGWIESRGTNG.
• the light-activated stabilized step function opsin protein is modified by the addition of an endoplasmic reticulum (ER) export signal.
• the ER export signal may be fused to the C-terminus of the core amino acid sequence or may be fused to the N-terminus of the core amino acid sequence.
• the ER export signal is linked to the core amino acid sequence by a linker.
• the linker can comprise any of 5, 10, 20, 30, 40, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 400, or 500 amino acids in length.
• the ER export signal comprises the amino acid sequence FXYENE, where X can be any amino acid.
• the ER export signal comprises the amino acid sequence VXXSL, where X can be any amino acid.
• the ER export signal comprises the amino acid sequence FCYENEV.
• the cells comprising the light activated chimeric proteins disclosed herein.
• the cells are animal cells.
• the animal cells comprise the protein corresponding to SEQ ID NO: 1.
• the animal cells comprise the stabilized step function opsin proteins disclosed herein.
• the animal cell can be a neuronal cell.
• the animal cells are from the pre-frontal cortex of a non-human animal.
• the animal cells comprise neurons that effect social behavior when depolarized.
• the neuronal cell is a neuron that changes innate social behavior and/or conditioned behavior when depolarized.
• the animal cells comprise neurons that give rise to the social and cognitive defects in autism and/or schizophrenia when depolarized.
• the neuronal cell can be an excitatory neuron located in the pre-frontal cortex of a non-human animal.
• the excitatory neuron can be a pyramidal neuron.
• the neuronal cell can be an inhibitory neuron located in the pre-frontal cortex of a non-human animal.
• the inhibitory neuron can be a parvalbumin neuron.
• non-human animals comprising the proteins disclosed herein.
• the non-human animals comprise the protein corresponding to SEQ ID NO:l.
• the animals comprise the stabilized step function opsin proteins disclosed herein.
• the animals comprising the stabilized step function opsin proteins disclosed herein are transgenically expressing said stabilized step function opsin proteins.
• the animals comprising the stabilized step function opsin proteins described herein have been virally transfected with a vector carrying the stabilized step function opsin proteins such as, but not limited to, an adenoviral vector.
• the animals comprising the stabilized step function opsin proteins disclosed herein exhibit changes in behavior when said stabilized step function opsin proteins are depolarized by activation with light. In other embodiments, the animals comprising the stabilized step function opsin proteins disclosed herein exhibit changes in innate and learned social behaviors when said stabilized step function opsin proteins are depolarized by activation with light. In other embodiments, the animals comprising the stabilized step function opsin proteins disclosed herein exhibit changes in conditioned behaviors when said stabilized step function opsin proteins are depolarized by activation with light.
• the brain slices are from non-human animals transgenically expressing the stabilized step function opsin proteins described herein.
• the brain slices are from non-human animals that have been virally transfected with a vector carrying said stabilized step function opsin proteins such as, but not limited to, an adenoviral vector.
• the brain slices are coronal brain slices.
• the brain slices are from the prefrontal cortex of a non-human animal.
• the brain slices comprise neurons that effect social behavior when depolarized.
• the brain slices comprise neurons that change innate social behavior and/or conditioned behavior when depolarized. In other embodiments, the brain slices comprise neurons that give rise to the social and cognitive defects in autism and/or schizophrenia when depolarized. In some embodiments, the brain slices are any of about 100 ⁇ , about 150 ⁇ , about 200 ⁇ , about 250 ⁇ , about 300 ⁇ , about 350 ⁇ , about 400 ⁇ , about 450 ⁇ , or about 500 ⁇ thick, inclusive, including any thicknesses in between these numbers.
• isolated polynucleotides that encode stabilized step function opsin proteins that have at least one activity of a step function opsin protein.
• the disclosure provides isolated, synthetic, or recombinant polynucleotides comprising a nucleic acid sequence having at least about 70%, e.g., at least about 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%; 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%, or complete (100%) sequence identity to the nucleic acid of SEQ ID NO:2 over a region of at least about 10, e.g., at least about 15, 20, 25, 30, 35, 40, 45, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800
• the disclosure specifically provides a polynucleotide comprising a nucleic acid sequence encoding a stabilized step function opsin protein and/or a mutant variant thereof.
• the disclosure provides an isolated polynucleotide molecule, wherein the polynucleotide molecule encodes a protein comprising an amino acid sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to the amino acid sequence of SEQ ID NO: 1.
• the disclosure also provides an isolated
• polynucleotide molecule wherein the polynucleotide molecule encodes a protein comprising an amino acid sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to the amino acid sequence of SEQ ID NO:2.
• the disclosure moreover provides an isolated polynucleotide molecule, wherein the polynucleotide molecule encodes a protein comprising an amino acid sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to the amino acid sequence of SEQ ID NO:3.
• the disclosure additionally provides an isolated polynucleotide molecule, wherein the polynucleotide molecule encodes a protein comprising an amino acid sequence with at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to the amino acid sequence of SEQ ID NO:4.
• the disclosure also provides expression cassettes and/or vectors comprising the above-described nucleic acids.
• the nucleic acid encoding a stabilized step function opsin protein of the disclosure is operably linked to a promoter.
• Promoters are well known in the art. Any promoter that functions in the host cell can be used for expression of SSFO and/or any variant thereof of the present disclosure. Initiation control regions or promoters, which are useful to drive expression of a SSFO protein or variant thereof in a specific animal cell are numerous and familiar to those skilled in the art. Virtually any promoter capable of driving these nucleic acids can be used.
• a human calmodulin-dependent protein kinase II alpha (CaMKIIa) promoter may be used.
• an elongation factor la (EF-la) promoter in conjunction with a Cre-inducible recombinant AAV vector can be used with parvalbumin-Cre transgenic mice to target expression SSFO proteins to inhibitory neurons.
• vectors comprising the polynucleotides disclosed herein encoding a stabilized step function opsin proteins or any variant thereof.
• the vectors that can be administered according to the present invention also include vectors comprising a polynucleotide which encodes an RNA (e.g., an mRNA) that when transcribed from the polynucleotides of the vector will result in the accumulation of light-activated stabilized step function opsin proteins on the plasma membranes of target animal cells.
• Vectors which may be used include, without limitation, lentiviral, HSV, adenoviral, and andeno-associated viral (AAV) vectors.
• Lentiviruses include, but are not limited to HIV-1, HIV-2, SIV, FIV and EIAV. Lentiviruses may be pseudotyped with the envelope proteins of other viruses, including, but not limited to VS V, rabies, Mo-ML V, baculovirus and Ebola. Such vectors may be prepared using standard methods in the art.
• the vector is a recombinant AAV vector.
• AAV vectors are
• DNA viruses of relatively small size that can integrate, in a stable and sitespecific manner, into the genome of the cells that they infect. They are able to infect a wide spectrum of cells without inducing any effects on cellular growth, morphology or differentiation, and they do not appear to be involved in human pathologies.
• the AAV genome has been cloned, sequenced and characterized. It encompasses approximately 4700 bases and contains an inverted terminal repeat (ITR) region of approximately 145 bases at each end, which serves as an origin of replication for the virus.
• ITR inverted terminal repeat
• the remainder of the genome is divided into two essential regions that carry the encapsidation functions: the left-hand part of the genome, that contains the rep gene involved in viral replication and expression of the viral genes; and the right-hand part of the genome, that contains the cap gene encoding the capsid proteins of the virus.
• AAV vectors may be prepared using standard methods in the art.
• Adeno-associated viruses of any serotype are suitable (see, e.g., Blacklow, pp. 165-174 of "Parvoviruses and Human Disease” J. R. Pattison, ed. (1988); Rose, Comprehensive Virology 3:1, 1974; P. Tattersall "The Evolution of Parvovirus Taxonomy” in Parvoviruses (JR Kerr, SF Cotmore. ME Bloom, RM Linden, CR Parrish, Eds.) p5-14, Hudder Arnold, London, UK (2006); and DE Bowles, JE Rabinowitz, RJ Samulski "The Genus Dependovirus” (JR Kerr, SF
• the replication defective recombinant AAVs according to the invention can be prepared by co-transfecting a plasmid containing the nucleic acid sequence of interest flanked by two AAV inverted terminal repeat (ITR) regions, and a plasmid carrying the AAV encapsidation genes (rep and cap genes), into a cell line that is infected with a human helper virus (for example an adenovirus).
• ITR inverted terminal repeat
• rep and cap genes AAV encapsidation genes
• the vector(s) for use in the methods of the invention are encapsidated into a virus particle (e.g. AAV virus particle including, but not limited to, AAV1, AAV2, AAV3, AAV4, AAV5,AAV6, AAV7, AAV8, AAV9, AAV10, AAV11, AAV 12, AAV13, AAV 14, AAV15, and AAV 16).
• a virus particle e.g. AAV virus particle including, but not limited to, AAV1, AAV2, AAV3, AAV4, AAV5,AAV6, AAV7, AAV8, AAV9, AAV10, AAV11, AAV 12, AAV13, AAV 14, AAV15, and AAV 16.
• the invention includes a recombinant virus particle (recombinant because it contains a recombinant polynucleotide) comprising any of the vectors described herein. Methods of producing such particles are known in the art and are described in US Patent No. 6,596,535.
• one or more vectors may be administered to neural cells, heart cells, or stem cells. If more than one vector is used, it is understood that they may be administered at the same or at different times to the animal cells.
• a method for depolarizing excitatory or inhibitory neurons residing in a microcircuit by expressing in those neurons the light-activated stabilized step function opsin proteins described herein In some aspects, there is a provided a method for using the stabilized step function opsin proteins described herein by activating proteins with light.
• the stabilized step function opsin proteins disclosed herein can be expressed in an
• method for using the stabilized step function opsin proteins disclosed herein can be in a living non-human animal or in a living brain slice from a non-human animal.
• a method for identifying a chemical compound that inhibits the depolarization of excitatory neurons in the prefrontal cortex of a non-human animal there is provided a method for identifying a chemical compound that restores an innate social behavior and/or communication in a non-human animal.
• the proteins can be activated with light having a first wavelength that can be blue light. In other embodiments, said light having a first wavelength can be about 445 nm.
• the stabilized step function opsin proteins disclosed herein can be deactivated with light having a second wavelength.
• said light having a second wavelength can be green light or yellow light.
• said light having a second wavelength can be about 590 nm.
• said light having a second wavelength can be between about 390-400 nm, inclusive, as well as every number within this range.
• the stabilized step function opsin proteins can be activated by light pulses that can have a duration for any of about 1 millisecond (ms), about 2 ms, about 3, ms, about 4, ms, about 5 ms, about 6 ms, about 7 ms, about 8 ms, about 9 ms, about 10 ms, about 15 ms, about 20 ms, about 25 ms, about 30 ms, about 35 ms, about 40 ms, about 45 ms, about 50 ms, about 60 ms, about 70 ms, about 80 ms, about 90 ms, about 100 ms, about 200 ms, about 300 ms, about 400 ms, about 500 ms, about 600 ms, about 700 ms, about 800 ms, about 900 ms, about 1 sec, about 1.25 sec, about 1.5 sec, or about 2 sec, inclusive, including any times in between these numbers.
• ms millisecond
• the stabilized step function opsin proteins can be activated by light pulses that can have a light power density of any of about 1 ⁇ mm “2 , about 2 ⁇ mm “2 , about 3 ⁇ mm “2 , about 4 ⁇ mm “2 , about 5 ⁇ mm “2 , about 6 ⁇ mm “ , about 7 ⁇ mm , about 8 jiW mm , about 9
• the light-activated stabilized step function opsin proteins can be activated by light pulses that can have a light power density of any of about 1 mW mm “ , about 2 mW mm “2 , about 3 mW mm “2 , about 4 mW mm “2 , about 5 mW mm “2 , about 6 mW mm “2 , about 7 mW mm “2 , about 8 mW mm “2 , about 9 mW mm “2 , about 10 mW mm “2 , about 11 mW mm “2 , about 12 mW mm “2 , about 13 mW mm “2 , about 14 mW mm “2 , about 15 mW mm “ 2 , about 16 mW mm “ 2 , about 17 mW mm “ 2 , about 18 mW mm “ 2 , about 19 m
• the light-activated stabilized step function opsin proteins of the methods described herein can maintain a sustained photocurrent for about 10 minutes or longer. In other embodiments, the light-activated stabilized step function opsin proteins described herein can maintain a sustained photocurrent for any of about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26 27, 28, 29, or 30 minutes, inclusive, including for any times in between these numbers. In other embodiments, the methods provided herein comprise completely blocking the photocycle progression of any of the light- activated stabilized step function opsin proteins described herein after the protein is illuminated with a single pulse of light having a first wavelength.
• the animal cell can be a neuronal cell, a cardiac cell, or a stem cell.
• the animal cell can be a neuronal cell.
• the neuronal cell can be an excitatory neuron located in the prefrontal cortex of a non-human animal.
• the excitatory neuron can be a pyramidal neuron.
• the animal cells comprise neurons that effect social behavior when depolarized.
• the neuronal cell is a neuron that changes innate social behavior and/or conditioned behavior when depolarized.
• the animal cells comprise neurons that give rise to the social and cognitive defects in autism and/or schizophrenia when depolarized.
• the neuronal cell can be an inhibitory neuron located in the pre-frontal cortex of a non-human animal.
• the inhibitory neuron can be a parvalbumin neuron.
• the inhibitory and excitatory neurons can be in a living non-human animal. In other embodiments, the inhibitory and excitatory neurons can be in a brain slice from a non-human animal.
• a method for identifying a chemical compound that inhibits the depolarization of excitatory or inhibitory neurons in the prefrontal cortex of a non-human animal comprising: (a) depolarizing an excitatory or inhibitory neuron in the prefrontal cortex of a non-human animal or a living tissue slice from a non-human animal comprising a light-activated protein cation channel expressed on the cell membrane capable of mediating a depolarizing current in the cell when the cell is illuminated with light, wherein the protein exhibits rapid step-like activation in response to a single pulse of light having a first wavelength and deactivation in response to a pulse of light having a second wavelength; wherein the depolarizing current in the cell is maintained for up to about twenty minutes; and wherein the protein comprises the amino acid sequence of ChR2, ChRl, VChRl, or VChR2 with amino acid substitutions at amino acid residues
• the proteins can be activated with light having a first wavelength that can be blue light.
• said light having a first wavelength can be about 445 nm.
• said light having a second wavelength can be green light or yellow light.
• said light having a second wavelength can be about 590 nm.
• said light having a second wavelength can be between about 390-400 nm, inclusive, as well as every number within this range.
• the chemical compound can be a member of a combinatorial chemical library.
• the light-activated stabilized step function opsin proteins can be activated by light pulses that can have a duration for any of about 1 millisecond (ms), about 2 ms, about 3, ms, about 4, ms, about 5 ms, about 6 ms, about 7 ms, about 8 ms, about 9 ms, about 10 ms, about 15 ms, about 20 ms, about 25 ms, about 30 ms, about 35 ms, about 40 ms, about 45 ms, about 50 ms, about 60 ms, about 70 ms, about 80 ms, about 90 ms, about 100 ms, about 200 ms, about 300 ms, about 400 ms, about 500 ms, about 600 ms, about 700 ms, about 800 ms, about 900 ms, about 1 sec, about 1.25 sec, about 1.5 sec, or about 2 sec, inclusive, including any times in between
• the light-activated stabilized step function opsin proteins can be activated by light pulses that can have a light power density of any of about 1 ⁇ mm “ , about 2 mm “ , about 3 ⁇ 7 mm “ , about 4 ⁇ mm “ , about 5 ⁇ mm “ , about 6 ⁇ W mm “ , about 7 ⁇ mm “ , about 8 ⁇ W mm “ , about 9 ⁇ mm “2 , about 10 ⁇ mm “2 , about 11 ⁇ mm “2 , about 12 ⁇ mm “2 , about 13 ⁇ W mm “ 2 , about 14 ⁇ ⁇ "2 , about 15 ⁇ "2 , about 16 ⁇ ⁇ “2 , about 17 ⁇ ⁇ 2 , about 18 mm “ 2 , about 19 2 2 2
• the light-activated stabilized step function opsin proteins can be activated by light pulses that can have a light power density of any of about 1 mW mm- “2 , about 2 mW mm “2 , about 3 mW mm “2 , about 4 mW mm “2 , about 5 mW mm “2 , about 6 mW mm “2 , about 7 mW mm “2 , about 8 mW mm “2 , about 9 mW mm “2 , about 10 mW mm “2 , about 11 mW mm “2 , about 12 mW mm “2 , about 13 mW mm “2 , about 14 mW mm '2 , about 15 mW mm “2 , about 16 mW mm “2 , about 17 mW mm- 2 , about 18 mW mm '2 , about 15 mW mm “2 , about 16 mW mm “2
• the animal cell can be a neuronal cell, a cardiac cell, or a stem cell.
• the animal cell can be a neuronal cell.
• the neuronal cell can be an excitatory neuron located in the prefrontal cortex of a non-human animal.
• the excitatory neuron can be a pyramidal neuron.
• the neuronal cell can be an inhibitory neuron located in the pre-frontal cortex of a non-human animal.
• the inhibitory neuron can be a parvalbumin neuron.
• the inhibitory and excitatory neurons can be in a living non-human animal.
• the inhibitory and excitatory neurons can be in a brain slice from a non-human animal.
• the brain slices comprise neurons that effect social behavior when depolarized.
• the neuronal cell is a neuron that changes innate social behavior and/or conditioned behavior when depolarized.
• the brain slices comprise neurons that give rise to the social and cognitive defects in autism and/or schizophrenia when depolarized.
• a chemical compound that restores one or more social behaviors, communications, and/or conditioned behaviors in the non-human animal comprising: (a) depolarizing an excitatory neuron in the prefrontal cortex of a non-human animal comprising a light-activated protein cation channel expressed on the cell membrane capable of mediating a depolarizing current in the cell when the cell is illuminated with light, wherein the protein exhibits rapid step-like activation in response to a single pulse of light having a first wavelength and deactivation in response to a pulse of light having a second wavelength; wherein the depolarizing current in the cell is maintained for up to about twenty minutes; and wherein the protein comprises the amino acid sequence of ChR2, ChRl, VChRl, or VChR2 with amino acid substitutions at amino acid residues corresponding to C128 and D156 of the amino acid sequence of ChR2, wherein
• the depolarizing the excitatory neuron inhibits one or more one or more social behaviors, communications, and/or conditioned behaviors in the non-human animal; (b) administering a chemical compound to the non-human animal; and (c) determining if the administration of the chemical compound to the non-human animal restores said one or more social behaviors, communications, and/or conditioned behaviors in the non-human animal.
• the social behavior is an innate social behavior and is selected from the group consisting of: allogrooming, resident-intruder aggression, isolation-induced fighting, sexual behavior, parental behavior, social recognition, and auditory communication.
• the behavior is a conditioned behavior, such as, but not limited to, a conditioned fear response.
• the non-human animal is not constrained by any hardware during steps (b) through (c).
• the hardware is a light source attached to a fiber optic cable. In other embodiments, the non-human animal is separated from hardware
• the animal cell is located on the surface of a biological tissue.
• the tissue is neural tissue or brain tissue.
• the chemical compound can be a member of a combinatorial chemical library.
• the non-human animals of the methods provided herein comprise the protein corresponding to SEQ ID NO:l. In other embodiments, the animals comprise the stabilized step function opsin proteins disclosed herein. In some
• the animals comprising the stabilized step function opsin proteins disclosed herein are transgenically expressing said stabilized step function opsin proteins.
• the animals comprising the stabilized step function opsin proteins described herein have been virally transfected with a vector carrying the stabilized step function opsin proteins such as, but not limited to, an adenoviral vector or an andeno-associated viral vector.
• the animals comprising the stabilized step function opsin proteins disclosed herein exhibit changes in behavior when said stabilized step function opsin proteins are depolarized by activation with light.
• the animals comprising the stabilized step function opsin proteins disclosed herein exhibit changes in innate and learned social behaviors when said stabilized step function opsin proteins are depolarized by activation with light. In other embodiments, the animals comprising the stabilized step function opsin proteins disclosed herein exhibit changes in conditioned behaviors when said stabilized step function opsin proteins are depolarized by activation with light.
• the present disclosure is believed to be useful for optical control over nervous system disorders.
• Specific applications of the present invention relate to optogenetic systems or methods that correlate temporal, spatio, and/or cell-type control over a neural circuit with measurable metrics.
• the following discussion summarizes such previous developments to provide a solid understanding of the foundation and underlying teachings from which implementation details and modifications might he drawn including those found in Yizhar et ah, Nature, 2011, 477(7363): 71 -8, the disclosure of which in incorporated by reference herein in its entirety. It is in this context that the following discussion is provided and with the teachings in the references incorporated herein by reference. While the present invention is not necessarily limited to such applications, various aspects of the invention may be appreciated through a discussion of various examples using this context.
• Various embodiments of the present disclosure relate to an optogenetic system or method that correlates temporal control over a neural circuit with measurable metrics. For instance, various metrics or symptoms might be associated with a neurological disorder exhibiting various symptoms of social dysfunction.
• the optogenetic system targets a neural circuit within a subject/patient for selective control thereof.
• the optogenetic system involves monitoring the subject/patient for the metrics or symptoms associated with the neurological disorder. In this manner, the optogenetic system can provide detailed information about the neural circuit, its function and/or the neurological disorder.
• FIG.12 depicts a flow diagram for testing of a disease model, consistent with various embodiments of the present disclosure.
• the disease models can be for one or more central nervous system (CNS) disorders.
• the models can include various disorders, diseases or even general characteristics of patients (e.g., mood, memory, locomotion or social behavior).
• CNS targets are identified.
• the CNS targets include the properties of the stimulus to be provided as part of assessing, testing or otherwise related to the disease model.
• targets can be spatial targets, cell type targets, temporal targets and combinations thereof.
• the properties of the targets 106-118 can then be used to select a particular opsin from the optogenetic toolkit 120.
• the optogenetic toolkit 120 includes a variety of different opsins, which can be aligned with one or more of the properties 106-118.
• opsins are discussed herein.
• the selected opsin(s) 122 can be those opsins that most closely match the CNS target(s) and/or stimulus properties.
• a desired target may be the modification of excitation/inhibition (E/I) balance within a portion of the brain over an extended period of time.
• E/I excitation/inhibition
• the selected opsin(s) are expressed in a target CNS location/cell-type 124.
• the disease module is then tested 126, e.g., through optical stimulus of the expressed opsin(s).
• Embodiments of the present disclosure are directed toward control over the cellular excitation/inhibition (E/I) balance within neocortical microcircuitry.
• E/I balance control can be particularly useful for modeling and/or treatment of social and cognitive deficits ⁇ e.g., autism and schizophrenia) that are linked to elevations in excitation.
• Embodiments of the present disclosure are directed toward the use of opsins for providing a mechanism for inducing an elevated cellular E/I balance with specific spatial and temporal control. This can include expression of light-sensitive opsins in excitatory neurons linked with one or more severe neuropsychiatric diseases.
• Various embodiments relate to tools and methods for controlling the E/I balance in freely moving mammals, which can be particularly useful for exploring underlying circuit physiology mechanisms.
• Particular aspects of the present disclosure relate to increasing the excitability of excitatory neurons, relative to the excitability of inhibitory neurons with selective spatial control. This can be particularly useful for increasing the susceptibility of the excitatory neurons to intrinsic stimulus and thereby preserving natural firing patterns. In some implementations, this excitation is reversible.
• Certain embodiments are directed toward the use of ion channels that are optically controllable. When expressed in a neuron, the ion channels are designed to increase the susceptibility of the neurons to intrinsic stimulus to maintain the increased susceptibility for extended periods of time.
• Embodiments of the present disclosure relate to SSFOs
• the increased susceptibility can be maintained from many minutes after optical stimulus is applied.
• Various embodiments are directed toward treatments, modeling and other aspects that relate to the discovery that impairments in specific social interaction and cognition behaviors in freely moving mice can be induced from targeted elevation in the E/l balance.
• Still other embodiments of the present disclosure are directed toward treatments, modeling and other aspects that relate to the discovery that the dominant circuit-level effect of the behaviorally significant E/I balance intervention is a specific elevation in baseline gamma-band (around 40-60 Hz) recurrent synaptic excitation, analogous to the elevated gamma rhythms seen at baseline in autism and schizophrenia, with concomitant quantitative impairment in microcircuit information transmission.
• Embodiments of the present disclosure relate to the use of opsins to drive E/I elevations and monitor gamma oscillations in cortical slices. Particular embodiments are directed toward the use of CI VI (discussed in more detail herein) and its variants, which can be particularly useful for driving E/I elevations and monitoring gamma oscillations in cortical slices, with 1) high potency to enable dose-response tests; 2) low desensitization to allow for step-like changes in E/I balance; and 3) red-shifted excitation to allow separable driving of different populations within the same preparation.
• CI VI discussed in more detail herein
• Embodiments of the present disclosure relate to control over elevated (or lowered) cellular E/I balance. This can be particularly useful for studying, testing and treatment relating to medication-unresponsive social and cognitive impairment in neurological disorders, such as autism and schizophrenia. Particular aspects relate to studying and distinguishing the long term effects on the development and maturation of the circuit relative to the immediate effects of E/I abnormalities with regard to the function of the neural circuits involved. Other aspects are directed toward the confirmation of elevated cellular E/l balance as a core component of cognitive defects observed in the various disease models and patients (human or otherwise). Particular embodiments provide timing and specificity sufficient for testing the elevated cellular E/I balance hypothesis in the mammalian brain (e.g., the prefrontal cortex), and identified circuit-physiology manifestations.
• mammalian brain e.g., the prefrontal cortex
• a particular aspect relates to the use of the double-mutant SSFO (discussed in more detail herein), which can be particularly useful for providing stable circuit modulation for time periods that are sufficient for temporally precise and complex behavioral experiments.
• the modulation and behavioral experiments circuit modulation can span several minutes in the absence of ongoing light activation, external fiber optic attachments and/or optical-hardware brain penetration (e.g., using a light delivery device entirely external to the brain).
• Particular implementations use a property of photon integration, which can facilitate activation of cells with low light intensity (e.g., in the low- gm/mm 2 ). This activation can occur with relatively deep penetration of light into brain tissue (e.g., 3mm or more relative to the light source).
• SSFO activation in excitatory (but not inhibitory) neurons can be used to produce profound and reversible impairments in social and cognitive function. In certain implementations, the impairments can be produced with little, if any, motor
• Embodiments of the present disclosure also relate to the use of SSFO for in vitro probing of changes in circuit properties.
• SSFO's can be used to elevate cellular E/I balance and to measure the transfer functions of pyramidal neurons.
• PYR cells expressing CI VI- E162T spiked in response to 2 ms 561 run light pulses, while the same stimulation paradigm reliably evoked excitatory postsynaptic potentials (EPSPs) in non-expressing cells within the same slices.
• ESPs excitatory postsynaptic potentials
• Particular embodiments of the present disclosure are directed toward the use of SSFO gene product to selectively favor excitation of one neural population over another.
• the selective favoring of the targeted population can be configured to prevent the SSFOs from overriding intrinsic excitation inputs to the targeted population. In this manner, the targeted population would not be driven with coordinated spikes directly caused by the opsins. Rather, the targeted population would exhibit an increased sensitivity to native inputs, which can be sparse and asynchronous.
• Embodiments of the present disclosure are directed toward the use of SFOs to address various the hardware challenges. For instance, the significant increase in light sensitivity (e.g., orders-of-magnitude greater) can facilitate the use alternative light delivery mechanisms, and hardware-free behavioral testing.
• the significant increase in light sensitivity e.g., orders-of-magnitude greater
• the use alternative light delivery mechanisms e.g., hardware-free behavioral testing.
• aspects of certain embodiments of the present disclosure are directed toward identification and modification of specific portions of light-gated channels. These modifications involve identifying key portions of the channels.
• the channels can be identified using high resolution imaging of the tertiary structure of the channel.
• ChR2 is a rhodopsin derived from the unicellular green algae
• rhodopsin is a protein that comprises at least two building blocks, an opsin protein, and a covalently bound cofactor, usually retinal (retinaldehyde).
• the rhodopsin ChR2 is derived from the opsin Channelopsin-2 (Chop2), originally named Chlamyopsin-4 (Cop4) in the
• Chlamydomonas genome Chlamydomonas genome. The temporal properties of one depolarizing
• channelrhodopsin, ChR2 include fast kinetics of activation and deactivation, affording generation of precisely timed action potential trains. For applications seeking long timescale activation, it has been discovered that the normally fast off-kinetics of the channelrhodopsins can be slowed. For example, certain implementations of channelrhodopsins apply lmW/mm 2 light for virtually the entire time in which depolarization is desired, which can be less than desirable.
• VChRl Volvox channelrhodopsin
• Embodiments of the present disclosure include relatively minor amino acid variants of the naturally occurring sequences.
• the variants are greater than about 75% homologous to the protein sequence of the naturally occurring sequences.
• the homology is greater than about 80%.
• Yet other variants have homology greater than about 85%, greater than 90%, or even as high as about 93% to about 95% or about 98%.
• Homology in this context means sequence similarity or identity, with identity being preferred. This homology can be determined using standard techniques known in the sequence analysis.
• compositions of embodiments of the present disclosure include the protein and nucleic acid sequences provided herein, including variants which are more than about 50% homologous to the provided sequence, more than about 55% homologous to the provided sequence, more than about 60% homologous to the provided sequence, more than about 65%
• homologous to the provided sequence more than about 70% homologous to the provided sequence, more than about 75% homologous to the provided sequence, more than about 80% homologous to the provided sequence, more than about 85%
• homologous to the provided sequence more than about 90% homologous to the provided sequence, or more than about 95% homologous to the provided sequence.
• stimulation of a target cell is generally used to describe modification of properties of the cell.
• the stimulus of a target cell may result in a change in the properties of the cell membrane that can lead to the
• the target cell is a neuron and the stimulus affects the transmission of impulses by facilitating or inhibiting the generation of impulses (action potentials) by the neuron.
• impulses action potentials
• Embodiments of the present disclosure are directed towards implementation of bistable changes in excitability of targeted populations.
• This includes, but is not necessarily limited to, the double-mutant ChR2-C128S/D156A.
• This double-mutant ChR2-C128S/D156A has been found to be well-tolerated in cultured hippocampal neurons and preserved the essential SFO properties of rapid step-like activation with single brief pulses of blue light, and deactivation with green or yellow light.
• the activation spectrum of ChR2-C128S/D156A peaks at 445nm.
• a second deactivation peak was found at 390-400nm, with faster but less complete deactivation by comparison with the 590 nm deactivation peak.
• Other embodiments are directed toward a similar mutation in VChRl.
• the mutation in VChRl could be provided at C123S/D151A, to provide a red- shifted photocurrent with slow kinetics comparable to ChR2.
• the double-mutant gene is referred to as SSFO (for stabilized step-function opsin) gene.
• SSFO is also used as shorthand for the active protein. Both residues likely are involved in ChR2 channel closure (gating), and both mutations likely stabilize the open state configuration of the channel.
• aspects of the present disclosure relate to the discovery that SSFO may be completely blocked in photocycle progression, and may therefore represent the maximal stability possible with photocycle engineering. For instance, in contrast to ChR2- C128X and ChR2-D156A, the SSFO photocycle does not appear to access additional inactive deprotonated side products which likely split off the photocycle at later photocycle stages not reached in this mutant, in turn making the SSFO even more reliable for repeated use in vivo than the parental single mutations.
• Embodiments of the present disclosure are directed toward the sensitivity of the SSFO to light. For instance, channelrhodopsins with slow decay constants effectively act as photon integrators. This can be particularly useful for more-sensitive, less- invasive approaches to optogenetic circuit modulation, still with readily titratable action on the target neuronal population via modulation of light pulse length. It has been discovered that, even at extraordinarily low light intensities (as low as 8
• Example embodiments of the present disclosure relate to the use of a hybrid ChRl/VChRl chimera that contains no ChR2 sequence at all, is derived from two opsins genes that do not express well individually, and is herein referred to as CI VI .
• Embodiments of the present disclosure also relate to improvements of the membrane targeting of VChRl through the addition of a membrane trafficking signal derived from the Ki r 2.1 channel. Confocal images from cultured neurons expressing VChRI-EYFP revealed a large proportion of intracellular protein compared with ChR2; therefore, membrane trafficking signal derived from the Ki r 2.1 channel was used to improve the membrane targeting of VChRl.
• VChRl-ts-EYFP Membrane targeting of this VChRl-ts-EYFP was slightly enhanced compared with VChRI-EYFP; however, mean photocurrents recorded from cultured hippocampal neurons expressing VChRlts-EYFP were only slightly larger than those of VChRl-EYFP.
• embodiments of the present disclosure relate VChRl modified by exchanging helices with corresponding helices from other ChRs.
• robust improvement has been discovered in two chimeras where helices 1 and 2 were replaced with the homologous segments from ChRl. It was discovered that whether splice sites were in the intracellular loop between helices 2 and 3 (at ChRl residue Alal45) or within helix 3 (at ChRl residue Trpl63), the resulting chimeras were both robustly expressed and showed similarly enhanced photocurrent and spectral properties. This result was unexpected as ChRl is only weakly expressed and poorly integrated into membranes of most mammalian host cells. The resulting hybrid ChRlIVChRl chimera is herein referred to as CI VI.
• C1V1-EYFP exhibits surprisingly improved average fluorescence compared with VChRl-EYFP.
• Whole cell photocurrents in neurons expressing CI VI were much larger than those of VChRl-EYFP and VChRlts-EYFP, and ionic selectivity was similar to that of ChR2 and VChRl.
• opsins with fast decay constants This property can be particularly useful for providing precise control over spiking, e.g., in order to interfere minimally with intrinsic conductance, trigger single spikes per light pulse and/or minimize plateau potentials during light pulse trains.
• Experimental results suggest that the light-evoked photocurrents recorded in ClVl-ts- EYFP decayed with a time constant similar to that of VChRl. Aspects of the present disclosure are therefore directed toward modifications in the chromophore region to improve photocycle kinetics, reduced inactivation and/or possible further red-shifted absorption.
• ChETA mutation E162T is directed toward a corresponding ChETA mutation E162T, which experiments suggest provides an accelerated photocycle (e.g., almost 3-fold); reference can be made to Gunaydin, et ah, Ultrafast optogenetic control, Nat Neurosci, 2010, and which is fully incorporated herein by reference. Surprisingly, this mutation was shown to shift the action spectrum hypsochromic to 530 nm, whereas analogous mutations in ChR2 or other microbial rhodopsins have caused a red-shift.
• Another embodiment is directed toward a mutation of glutamate-122 to threonine (CI VI- E122T). Experimental tests showed that CI V1-E122T is inactivated only by 26% compared to 46% inactivation of ChR2; in addition, the spectrum was further red- shifted to 546 nm.
• Another embodiment of the present disclosure is directed toward a double mutant of CI VI including both E122T and E162T mutations. Experimental tests have shown that the inactivation of the current was even lower than in the E122T mutant and the photocycle was faster compared to E162T. This suggests that multiple useful properties of the individual mutations were conserved together in the double mutant.
• Embodiments of the present disclosure include the expression of various light- responsive opsins in neurons.
• Experimental tests of CI VI opsin genes in neurons were carried out by generating lentiviral vectors encoding CIVl-ts-EYFP and various point mutation combinations discussed herein.
• the opsins were then expressed in cultured hippocampal neurons and recorded whole-cell photocurrents under identical stimulation conditions (2ms pulses, 542nm light, 5.5 mW/mm ). Photocurrents in cells expressing CI VI, C1V1-E162T and CI V1-E122T E162T were all robust and trended larger than photocurrents of ChR2-H134R.
• the experiments also included a comparison of integrated somatic YFP fluorescence and photocurrents from cells expressing CI VI- E122T E162T and from cells expressing ChR2- H134R.
• C1V1- E122T E162T cells showed stronger photocurrents than ChR2-H134R cells at equivalent fluorescence levels. This suggests that CI VI could possess a higher unitary conductance compared with ChR2-H134R.
• the test results suggest that the kinetics of CI V1-E122T were slower than those of CI V1-E122T E162T and that cells expressing CI VI- E122T responded more strongly to red light (630nm) than cells expressing the double mutant. This can be particularly useful for generating optogenetic spiking in response to red-light.
• inhibitory and/or excitatory neurons residing within the same microcircuit are be targeted with the introduction of various opsins.
• Experimental tests were performed by separately expressed CI VI- E122T E162T and ChR2-H134R under the CaMKIIa promoter in cultured hippocampal neurons.
• Cells expressing C1V1-E122T/E162T spiked in response to 2 ms green light pulses (560nm) but not violet light pulses (405nm).
• Various embodiments of the present disclosure relate to independent activation of two neuronal populations within living brain slices. Experimental tests were performed by CaMKIIa-ClVl-E122T/E162Tts-eYFP and EFla-DIO-ChR2-H134R- EYFP in mPFC of PV::Cre mice. In non-expressing PYR cells, 405 nm light pulses triggered robust and fast inhibitory postsynaptic currents due to direct activation of PV cells, while 561 nm light pulses triggered only the expected long-latency polysynaptic IPSCs arising from CIVl-expressing pyramidal cell drive of local inhibitory neurons.
• excitation of independent cellular elements can be performed in vivo.
• Experimental tests were performed using optrode recordings.
• 5Hz violet light pulses to activate ChR2 in PV cells
• 5 Hz green light pulses to activate CI VI in excitatory pyramidal neurons
• the test results suggest that when violet and green light pulses were separated by 100 ms, responses to green light pulses were not affected by the violet pulses.
• delays between violet and green pulses were reduced, green light-induced events became more readily inhibited until being effectively/completely abolished when light pulses were presented simultaneously.
• various embodiments of the present disclosure relate to an optogenetic system or method that correlates temporal, spatio and/or cell-type control over a neural circuit with measurable metrics. Consistent with the other embodiments discussed herein, particular embodiments relate to studying and probing disorders. A non-exhaustive list of example embodiments and experimental results consistent with such embodiments is provided in Yizhar et al., Nature, 2011, 477(7363):171-8, the disclosure of which in incorporated by reference herein in its entirety. The references listed therein may assist in providing general information regarding a variety of fields that may relate to one or more embodiments of the present disclosure, and further may provide specific information regarding the application of one or more such
• the present disclosure is believed to be useful as it relates to control over nervous system disorders, such as disorders associated with social dysfunction, as described herein.
• Specific applications of the present invention relate to optogenetic systems or methods that correlate temporal, spatio and/or cell-type-specific control over a neural circuit with measurable metrics.
• the following discussion summarizes such previous developments to provide a solid understanding of the foundation and underlying teachings from which implementation details and modifications might be drawn, including those found in the attached Appendix. It is in this context that the following discussion is provided and with the teachings in the references incorporated herein by reference. While the present invention is not necessarily limited to such applications, various aspects of the invention may be appreciated through a discussion of various examples using this context.
• FIG. 13 depicts a model for assessing stimuli and/or potential treatments for various nervous system disorders.
• Baseline observations 220 are taken 202 of behavior and/or cellular response for a subject/patient.
• a target cell population is chosen and modified to express a light-responsive molecule.
• the target cell population is selected to provide control over the ⁇ balance in the prefrontal cortex of a subject's brain, as discussed in more detail herein.
• the exci ion/inhibition ⁇ / ⁇ ) balance within the target cell population can then modified 204 (e.g., elevated or lowered) by exposing the modified target cell population to light.
• the light can be provided within a predetermined range based on absorption characteristics of the light-responsive molecule.
• Observations 220 of behavior and/or cellular response of the subject are again taken. These observations provide a reference point for how the subject acts under no stimuli or treatment.
• a stimulus and/or potential treatment is chosen 206 for the subject.
• stimuli and treatments include pharmacological/ drugs 208, behavioral 210 and/or electrical stimulus 212.
• the stimuli/treatments can then be assessed 214 by observing the subject's behavior in response to the treatment and/or the target cell population's behavior in response to the treatment. Based on the observations, a determination can be made regarding the need for additional stimulus or treatment 216, or the desire to test additional and/or different treatments.
• the observations 220 from various treatments can be compared 218 to each other as well as the baseline observation and the observations of behavior after E/I elevation. The comparison of the observations 220 can be used to assess the efficacy of various potential treatments.
• the elevation of the ⁇ / ⁇ balance results in social and cognitive deficits as compared to the behaviors during baseline observations.
• the purposeful and controlled elevation of the ⁇ / ⁇ balance allows for the testing of potential treatments in mammalian test subjects such as mice that do not otherwise exhibit symptoms of the disease being modeled.
• aspects of the present disclosure relate to assessing the effect of various stimuli on symptoms of neurological diseases.
• modification of the E/I balance in the prefrontal cortex of a subject's brain results in the symptoms similar to those of various neurological disorders, such as autism and schizophrenia.
• the neural circuit identified as effecting E/I balance is manipulated using one or more techniques including pharmacological, electrical, magnetic, surgical and optogenetic methods. The effect of the manipulation of the symptoms displayed is monitored.
• the manipulation of pyramidal neurons and parvalbumin-expressing inhibitory interneurons is used to model disease states, and to identify new treatments for known diseases.
• the E I balance in the prefrontal cortex is elevated (or lowered) and then a potential treatment is administered to the subject.
• the effect of the treatment on either the observed symptoms or on the neural circuit (or both) can be monitored.
• the information obtained from monitoring the symptoms and/or the neural circuit can be used to provide a better understanding of the neural pathways causing the observed symptoms.
• the information may also be used to determine the efficacy of the potential treatment. Based on the efficacy, or lack thereof, of the potential treatment, modifications can be made resulting in a new potential treatment to be tested.
• a stimulus is provided to a subject that exhibits symptoms of a neural disease such as schizophrenia or autism, for example.
• the stimulus can be pharmacological, electrical, magnetic, surgical, optogenetic or behavioral, for example.
• control over the neural circuit can include inhibition or excitation, which can each include coordinated firing, and/or modified susceptibility to external circuit inputs.
• inhibition can be accomplished using a light-responsive opsin, such as an ion pump (e.g., NpHR and NpHR variants).
• ion pump e.g., NpHR and NpHR variants
• excitation can be accomplished using a light-responsive opsin, such as an ion channel (e.g., ChR2 and ChR2 variants).
• ion channels can cause the membrane potential to move toward and/or past the threshold voltage, thereby exciting or encouraging action potentials.
• a light- responsive opsin can be used to
• Example 1 Creation and characterization of the stabilized step function opsin
• ChR2(D156A) and SSFO were generated by introducing point mutations into the pLentiCaMKII -ChR2-EYFP-WPRE vector using site-directed mutagenesis (Quikchange II XL; Stratagene).
• the membrane trafficking signal was derived from the Kir2.1 channel. Mutations were confirmed by sequencing the coding sequence and splice sites.
• opsin-EYFP fusions along with the CaMKII promoter were subcloned into a modified version of the pAAV2-MCS vector.
• Cre dependent opsin expression was achieved by cloning the opsin-EYFP cassette in the reverse orientation between pairs of incompatible lox sites (loxP and lox2722) to generate a doublefloxed inverted open reading frame (D10) under the control of the elongation factor la (EF- l ) promoter. All constructs are available from the Deisseroth Lab (www.optogenetics.org).
• ChR dodecylmaltoside.
• a Ni-NTA resin Qiagen
• ChR was eluted with 500 mM imidazole. Fractions that contained the protein were pooled, desalted (Float-a-lyzer, Roth) and concentrated
• ChR2 mutants C128S, D156A, and the double mutant 128S/156A were generated and purified from Pichia pastoris to first measure intrinsic open-state stability in the absence of potentially confounding cellular properties. Absorption spectra showed expected rapid changes in response to brief light delivery that largely recovered within 3 minutes for the single mutants C128S (FIG. IB, F) and D156A (FIG. 1C, G). However, in contrast to both single mutants, the double mutant C128S D156A showed remarkably complete stability of the activated state, with essentially no detectable return to the dark state even after 30 minutes (FIG. ID, H).
• FIG. IE The unique stability of the double mutant CI 28S/D 156A is further illustrated by continuous monochromatic absorbance measurements of all three mutants over 35 minutes of recording (FIG. 1H).
• Example 2 Validation of activation in neurons and in vivo
• the double mutant therefore appeared to have markedly distinct and near-optimal stability on the mammalian behavioral timescale, but with potentially reduced crucial capability for redshifted light deactivation; all of these issues required validation in neurons and in vivo.
• Electrophysiological recordings from individual neurons identified by fluorescent protein expression were obtained in Tyrode media ([mM] 150 NaCl, 4 KCl, 2 MgCl 2 , 2 MgCl 2 , 10 D-glucose, 10 HEPES, pH 7.35 with NaOH) using a standard internal solution ([mM] 130 KGluconate, 10 KC 1 , 10 HEPES, 10 EGTA, 2 MgCl 2 , pH 7.3 with KOH) in 3-5 ⁇ glass pipettes.
• Band pass filters (Semrock) had 20 nm bandwidth, and were adjusted with additional neutral density filters (ThorLabs) to equalize light power output across the spectrum. While handling cells or tissues expressing SSFO, care was taken to minimize light exposure to prevent activation by ambient light. Before each experiment, a 20s pulse of 590 nm light was applied to convert all of the SSFO channels to the dark state and prevent run-down of photocurrents. For acquisition of SSFO activation and deactivation spectra, cultured neurons in voltage clamp mode were recorded. For recording activation spectra, a 1 s pulse of varying wavelength was applied, followed by a 10 s 590 nm pulse.
• Deactivation spectra were acquired by first applying a 1 s 470 nm pulse to activate SSFO, followed by a 10 s pulse of varying wavelength. Net activation or deactivation was calculated by dividing the photocurrent change after the first or second pulse, respectively, by the maximum photocurrent change induced by the peak wavelength for that cell. Negative values in deactivation spectra resulted from traces in which, for example, a 10 s 470nm pulse led to a slight increase in photocurrent rather than deactivate the channels. This could be the result of the relatively wide (20 nm) band-pass filter width used for these recordings with the
• Sutter DG-4 Intermediate wavelengths (between 470nm and 520nm) are expected to have a mixed effect on the channel population for the same reasons.
• opsins Both Lentiviral- and AAV-mediated gene delivery were used for heterologous expression of opsins in mice. Indicated opsins were driven by either Human calmodulin- dependent protein kinase II alpha (CaMKIIa) promoter to target cortical excitatory neurons or Elongation Factor la (EF-la) in conjunction with a Cre-inducible cassette and followed by the Woodchuck hepatitis virus posttranscriptional regulatory element (WPRE). Cre- inducible recombinant AAV vector was produced by the University of North Carolina Vector Core (Chapel Hill, NC, USA) and used in conjunction with parvalbumin::Cre transgenic mice to target parvalbumin positive interneurons.
• CaMKIIa Human calmodulin- dependent protein kinase II alpha
• EF-la Elongation Factor la
• WPRE Woodchuck hepatitis virus posttranscriptional regulatory element
• SSFO-eYFP was inserted in the reverse orientation between pairs of incompatible lox sites (loxP and lox2722).
• AAV constructs were subcloned into a modified version of the pAAV2-MCS, serotyped with AAV5 coat proteins and packaged by the viral vector core at the University of North Carolina.
• the final viral concentration of AAV vectors was 1*10 12 genome copies (gc)/mL.
• Lentiviral constructs were generated as reported. All constructs are available from the Deisseroth Lab (www.optogenetics.org). Stereotactic viral injections were carried out under protocols approved by Stanford University.
• mice kept under isoflurane anesthesia were arranged in a stereotactic frame (Kopf Instruments) and leveled using bregma and lambda skull landmarks. Craniotomies were performed so as to cause minimal damage to cortical tissue.
• Infralimbic prefrontal cortex (IL; from bregma: 1.8mm anterior, 0.35mm lateral, -2.85mm ventral) was targeted using a 1 OuL syringe and 35g beveled needle (Word Precision Instruments). Virus was infused at a rate of 0.11 lL/min.
• Subjects injected with virus for behavioral studies were additionally implanted with a chronic fiber optic coupling device to facilitate light delivery either with or without an attached penetrating cerebral fiber for local delivery to target cortical region as noted (Doric Lenses, Canada).
• Penetrating fibers were stereotactically inserted to a depth of -2.5mm from the same anterior and lateral coordinates and affixed using adhesive luting cement (C&B MetaBond) prior to adhesive closure of the scalp (Vetbond, 3M). Animals were
• Deactivation was also possible with 390 nm light, at a faster rate than yellow light due to the substantial presence of the P390 species, but was also incomplete due to the residual absorption of the dark state at this wavelength (FIG. 1A). Moreover, following deactivation with 390 nm light, reactivation with 470 nm was less effective than following 590 nm deactivation, pointing to a likely photochemical inactivation with UV light due to trapping in a deprotonated/desensitized isoform that is not reached after redshifted-light deactivation (illustrated in FIG. IE), and again supporting the use of yellow light deactivation to potentially enhance spectral separation.
• Figure 2C shows a typical long whole-cell recording with both blue light activation and yellow light deactivation in the setting of incoming asynchronous synaptic activity.
• the double-mutant gene is referred to as SSFO (for stabilized step- function opsin) gene, and for simplicity use SSFO as shorthand for the protein as well.
• SSFO stabilized step- function opsin
• Channelrhodopsins with such slow decay constants could enable the transduced cell to act as a photon integrator, with effective light sensitivity (i.e. photocurrent amplitude per photon absorbed by the cell) scaling with T 0ff.
• SSFO- eYFP in PV::Cre transgenic mice was expressed using a double-floxed inverted open reading frame (DIO) virus; in these mice, SSFO was only expressed in the GABAergic Cre- positive parvalbumin neurons.
• DIO verted open reading frame
• recordings were made at progressively more ventral sites in mice injected with AAV5-CaMKIIa::SSFO-EYFP in medial prefrontal cortex (mPFC), using an advancing two-laser optrode (FIG. 2E) and a blue/green activation/deactivation laser protocol (FIG. 2F-G).
• Multiunit activity in mPFC of these mice was significantly and stably increased only in the transduced region, in response to a 1 s pulse of 473 nm light (95 mW mm “ 2 , corresponding to 10 mW mm “ 2 at the electrode tip). This increased activity was effectively terminated with a 2s 561 nm light pulse (112 mW mm “2 ; FIG. 2F).
• Significant increases in multiunit spike rate (Hz) were restricted to mPFC (FIG. 2) and no significant reductions in spike rate were observed in any of the recording sites following blue light stimulation.
• SSFO was used to examine the effects of elevated cellular E/I balance on behavior and circuit dynamics in freely moving mice (FIG. 3).
• SSFO was expressed either in prefrontal cortical excitatory neurons using the excitatory neuron-specific CaMKIIa promoter, or in inhibitory parvalbumin (PV)- expressing neurons using a double-floxed, inverted open-reading-frame (DIO) virus in conjunction with PV::Cre transgenic mice (FIG. 3J-L).
• Virus was injected in mPFC as described above, followed by a chronic fiber-optic implant that projected past the skull immediately dorsal to mPFC for light delivery (FIG. 3A, B).
• the times of the sEPSCs within the 500 ms segment were randomly selected from a uniform distribution extending across the entire segment, simulating excitatory input from a population of unsynchronized neurons. Empirically, these stimulation parameters reliably drove pyramidal neurons at firing rates from 0 - 30 Hz. In conditions marked as baseline, a 10 sec pulse of 590 nm light was delivered to completely inactivate the opsin before running the sEPSC protocol. In conditions where the opsin was activated, a 1 sec pulse of 470 nm light preceded the sEPSC protocol.
• the joint distribution of sEPSC rate and spike rate was estimated by binning in time, sEPSC rate, and spike rate and building a joint histogram.
• Time bins were 125 ms wide, and sEPSC rate was divided into 10 equally spaced bins from 0 to 500 Hz, although the mutual information results were consistent across a wide range of binning parameters.
• Spike rate was binned using the smallest meaningful bin width given the time bin width ⁇ e.g. 8 Hz bin width for 125 ms time bins).
• the input-output transfer function for each neuron was quantified by computing the dynamic range and saturation point of each neuron, treating the baseline and opsin-activated conditions separately.
• Dynamic range was defined as the difference between maximal and minimal output spiking rate across the range of input sEPSC rates.
• Saturation point was defined as the lowest input sEPSC rate which drove the neuron at 90% of its maximal output spike rate within that condition.
• a reduced saturation point cannot result from a multiplicative reduction in gain or dynamic range, but instead indicates that the input-output function becomes flatter at higher input sEPSC rates.
• mice undergoing behavioral experiments were acclimated to a 12-hour reverse light/dark cycle. Prior to behavioral testing, animals were allowed to acclimate to the room in which experiments were to be conducted for at least 1 hour before the experiments started.
• the fear conditioning apparatus consisted of a square conditioning cage (18x18x30 cm) with a grid floor wired to a shock generator and a scrambler, surrounded by an acoustic chamber (Coulburn instruments, PA, USA). The apparatus was modified to enable light delivery during training and/or testing. To induce fear-conditioning mice were placed in the cage for 120 seconds, and then a pure tone (2.9 kHz) was played for 20 sec, followed by a 2 sec foot-shock (0.5 mA). This procedure was then repeated, and immediate freezing behavior was monitored for an additional 30 sec after the delivery of the second shock before the mice were returned to their home cage. Fear conditioning was assessed 24 hours later by a continuous measurement of freezing (complete immobility), the dominant behavioral fear response.
• the three-chamber social test was conducted.
• the test mice were introduced into the center chamber of the three-chambered apparatus and allowed to acclimate for 10 minutes with the doors to the two side chambers closed. Light pulses were applied at the beginning and end of the 10 minute acclimation period.
• a novel conspecific male mouse was introduced to the "social" chamber, inside a wire mesh cup (Galaxy Pencil/Utility cup, Spectrum Diversified Designs).
• a wire mesh cup Gaxy Pencil/Utility cup, Spectrum Diversified Designs.
• an identical empty cup was placed in the other (non-social) chamber.
• the designations of the social and non-social chambers were randomly chosen in each test to prevent chamber bias.
• the novel object exploration experiment was performed in the same three-chamber apparatus used for the social behavior tests, and using the same general method. Mice were placed in the center chamber with the doors to both side chambers closed. Light pulses were delivered during the 10 minute acclimation period, after which the doors were opened and the mice were allowed to explore the entire apparatus. In place of the wire mesh cups, novel objects were presented at random in either of the two end-chambers. Exploration of the novel objects was scored over a period of 10 minutes for each mouse as the time in which the mouse spent actively exploring the object. Objects used were either plastic balls, cubes or porcelain figurines, all of approximately similar size. Objects were thoroughly cleaned between tests to prevent odor traces.
• the open-field chamber (50 x 50 cm) was divided into a central field (center, 23 x 23 cm) and an outer field (periphery). Individual mice were placed in the periphery of the field and the paths of the animals were recorded by a video camera. The total distance traveled was analyzed using the Viewer2 software (BiObserve, Fort Lee, NJ). The open field test for each mouse consisted of a 5-min session divided into two 2.5 minute segments, with a 2 s 473 nm light pulse delivered between the two segments. Track length, velocity and % time in the center were scored for each mouse and averaged across mice for each condition
• the elevated plus maze was made of plastic and consisted of two light gray open arms (30 x 5 cm), two black enclosed arms (30 x 5 x 30 cm) extending from a central platform (5 5 x 5 cm) 31 at 90 degrees in the form of a plus.
• the maze was placed 30 cm above the floor.
• a 2 s 473 nm light pulse was delivered when the mouse was in the home cage.
• the fiberoptic connector was detached and the mice were individually placed in the center of the maze for a test duration of 15 minutes.
• Video tracking software (Viewerll, BiObserve, Fort Lee, NJ) was used to track mouse location. All measurements displayed were relative to the entire mouse body.
• CMO chronic multisite optrode
• IFL implantable fiberoptic lightguide
• the four-wire bundle was back-fed into a 250 gm-diameter guide tube into which the fiberoptic cable was inserted.
• the wires were connected using gold pins to a Mill-Max connector, to which a stainless steel ground wire was also connected.
• the device was implanted stereotactically following virus injection (see above) such that the fiber tip only extended past the skull but not into brain tissue.
• the ground wire was inserted through a small craniotomy above cerebellum. Mice were allowed to recover for two weeks before experiments began. To record neural activity during behavior, the mice were first acclimated over several days to the attachment of the headstage and the fiberoptic cable. The mice were allowed to explore the home cage with the headstage attached for 1-2 hours each day.
• Wavelet power spectrograms of LFP recordings were analyzed as described above by sampling the power spectrum every 2 s for the duration of the recording. Power was calculated between 2 Hz and 120 Hz with a bin width of 2 Hz.
• the effects of SSFO activation were recorded using a protocol of 2 minutes baseline recording, followed by a 1 s 473 nm pulse at an irradiance of 56 mW mm " at the fiber tip. Following the blue pulse, activity was recorded for 2 minutes, followed by a 30 s deactivating light pulse at a wavelength of 594 nm light with similar intensity. Activity was then recorded for 2 additional minutes. For each mouse this protocol was repeated at least 4 times, and power spectra for each of the three periods (pre-activation, post-activation and post-deactivation) were averaged across the 4 repetitions.
• Nuclear localization of c-fos was determined using rabbit anti-c-fos (Calbiochem) on animals that had undergone 1 s 473 nm light stimulation 90 minutes prior to perfusion; parvalbumin targeting was confirmed using colocalization of mouse anti-parvalbumin (Sigma Aldrich) and fluorescent protein. Stained slices were visualized on a Leica SP5 confocal microscope. To calculate average fluorescence in different anatomical sub- regions, histology images were analyzed using ImageJ. Individual subregion images were thresholded at a fixed threshold level. Mean fluorescence above threshold was calculated and averaged per region between mice. c ⁇ fos counts were performed using standardized landmarks to identify regions and were anonymized prior to counting.
• FIG. 3D-G Three groups of animals to behavioral testing FIG. 3D-G) CaMKIIa::SSFO mice, PV::SSFO mice, and control mice (either injected with AAV5-CaMKIIa-eYFP virus or not injected with virus). Two to four weeks after surgery, conditioned learning and
• mice 6 PV::SSFO mice; p > 0.1 ; unpaired t-test).
• the same mice were next subjected to a conditioning protocol performed immediately following delivery of a 1 s 470 nm light pulse. Twenty-four hours later, responses to the conditioned tone and context were assessed in order to evaluate the extent to which the mice learned to associate the conditioned and unconditioned stimuli while under the altered E/I states.
• the elevated E/I (CaMKIIa::SSFO) animals showed no conditioned responses (to either context: p ⁇ 0.0005 or tone: p ⁇ 0.05, compared with controls; two-sided /-test).
• CaMKIIa::SSFO mice and n 6 CaMKIIa::YFP mice; FIG. 3F and FIG. 3N).
• Example 4 Elevation but not reduction of cellular E/I leads to quantitative reduction in information processing
• Acute 300 pm coronal slices isolated from 8-9 week old wild-type C57BL/6J or PV::Cre mice previously injected with virus were obtained in ice-cold sucrose cutting solution ([mM] 11 D-glucose, 234 sucrose, 2.5 KC1, 1.25 NaH 2 P0 4 , 10 MgS0 4 , 0.5 CaCl 2 , 26 NaHC0 3 ) using a Vibratome (Leica).
• Slices were recovered in oxygenated Artificial Cerebrospinal Fluid (ACSF; [mM] 124 NaCl, 3 KC1, 1.3 MgCl 2 , 2.4 CaCl 2 , 1.25
• ACSF Artificial Cerebrospinal Fluid
• Illumination power density was 12 mW mm "2 at 500 nm with a standard EYFP filter set. Quantification of fluorescence was done with ImageJ software by marking a region containing the soma and proximal neuritis and calculating for each cell the total integrated pixel intensity in that region, rather than average fluorescence, since photocurrents are likely to be related to the total number of membrane-bound channels rather than average channel expression per area. Photon flux calculations for SSFO integration properties were done by calculating the photon flux through the microscope objective at each light power, and then dividing to reach the photon flux across the cell membrane, based on the capacitance of individual patched cells.
• CrystalLaser 10 mW solid state laser diode sources coupled to the optrode.
• Electrophysiological recordings were initiated at the Cg/PL boundary (1.8mm anterior, 0.35 mm lateral, -2.0 mm ventral) after lowering isoflurane anesthesia to a constant level of 1%. Optrode was lowered ventrally in— 0.1 mm steps. Events were isolated using a custom algorithm in Matlab (Math Works) with the threshold set above baseline noise (25 to 40 ⁇ ). Heatmap images were generated in Matlab from an unweighted moving average of 2s with 200ms steps. Moving average value was reset at the onset of external manipulations (beginning of sweep, initiation of light pulses).
• Spectral analysis of responses to SSFO in both expressing and non-expressing cells revealed that this increased activity displayed a broad spectral range with a peak above 20 Hz (FIG. 4A-B).
• pyramidal cells in slices expressing SSFO in PV cells showed a robust reduction in synaptic activity and a reduction in power at low frequencies (FIG. 4C), consistent with the increased activity of PV cells after activation with SSFO (FIG. 4D).
• CaMKIIa::SSFO or CaMKIIa::EYFP virus were injected and implanted fiberoptic connectors extending only past the skull (FIG. 6A), without entering the cortical surface (FIG. 6B).
• Elevated cellular E/I balance during conditioning showed no effect on freezing responses to footshock (indicating intact sensory perception of the aversive unconditioned stimulus; FIG. 6D), but showed a marked and fully reversible effect on contextual (p ⁇ 0.005; unpaired t-test with unequal variance) and auditory conditioning (p ⁇ 0.005; unpaired t-test with unequal variance; FIG. 6D).
• social behavior was also impaired in mice receiving noninvasive light stimulation prior to testing (p ⁇ 0.005; unpaired t-test; FIG. 6E), demonstrating the opportunity afforded by the extreme light sensitivity of the SSFO.
• CMO chronic multisite optrode
• C1V1 is a chimeric light-sensitive protein derived from the VChRl cation channel from Volvox carteri and the ChRl cation channel from Chlamydomonas Reinhardti.
• CI VI and its variants permits the experimental manipulation of cortical E/I elevations and the monitoring of gamma oscillations in cortical slices with high potency (thus allowing enable dose-response tests), low desensitization (thus permitting inducement of step-like changes in E/I balance), and red-shifted excitation (to permit separable drive of different populations within the same neural circuit).
• CI VI variant with the highest potency to enable the most reliable dose-response was selected.
• mice in the same paradigm were tested with novel juvenile mice, while delivering pulsed laser light at 590 nm to activate only CI VI -El 22T/E162T in the PV cells in the SSFO/C1 VI mice (FIG. 10B).
• SSFO was activated with a 2s 470 nm light pulse during the pre-test habituation period (FIG. 10B).
• CI VI variants were utilized, to independently modulate both excitatory neurons (using SSFO) and inhibitory PV neurons (using a CI VI variant).
• SSFO excitatory neurons
• inhibitory PV neurons using a CI VI variant.

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