DE102009051276A1 - In-vivo stimulation probe - Google Patents

Abstract

Described is a measuring probe and a system for the targeted optical in vivo stimulation of nerve cells and for the electrical measurement of nerve cell impulses. The measuring probe comprises at least one measuring needle for automatically controlled, in-vivo motor introduction into a vertebrate brain, wherein the needle has at least one electrical sensor for contacting at least one nerve cell of the brain in order to measure its activity. In addition, the measuring probe comprises at least one light source with whose emitted light the at least one nerve cell can be optically stimulated.

Description

The invention relates to an in vivo usable stimulation probe which preferably stimulates nerve cells with light in vivo and electrically measures the response of the stimulated nerve cell.

Background of the invention

The measurement of single nerve cell activity in intact animals is an important method to study a correlation of nerve cell activity with the behavior or cognitive performance of the animal. Such studies were z. B. extensively performed to investigate the behavior of nerve cells of the hippocampus in spatial navigation tasks. However, previous experimental arrangements have a number of significant disadvantages. The ability to stimulate defined nerve cell populations has so far mostly been given only by direct electrical stimulation. The ability to perform such stimulations as well as measurements has not yet been implemented telemetrically. This limits the experiments to be carried out because the test set attached to the head of the test animal must be connected to a cable with amplifier and analysis unit. Previous experimental setups are also relatively heavy, which limits the free movement of the experimental animals and makes use in small rodents (eg mice) problematic.

A branch of neuroscience that has only been established for a few years now allows the highly networked structures in the brain to be specifically investigated and influenced using a new method: optogenetics. By means of optogenetic methods, individual cell types within the nervous system can be manipulated extremely precisely, whereby the function of individual elements in complex neuronal circuits can be specifically investigated. In principle, nerve cells (neurons) are provided by genetic engineering with the genes for light sensor proteins, which make it possible to activate or inhibit the neurons by irradiation with light. In this way it is possible to selectively equip special cell groups in the complex neural networks in the brain with a proverbial switch and to control their activity by means of light.

In a publication ( Zhang et al., J. Neural Eng. 6 (2009) 055007 (13pp) an electrode for optogenetic applications has been described. In this application, an electrode tip was generated, through which both light applied and electrical signals can be measured. This application consists of a tapered optical fiber with a small aperture at the tip caused by gold plating. Through this aperture, an illumination in the near-field can be made. The measurement of electrical signals takes place via the gold coating. The electrode fibers can also be arranged as an array. However, in the described form, this application does not permit i) the measurement of single cell signals of multiple neurons in the exposed region, ii) the measurement of signals in vivo, and iii) not the telemetric measurement of signals in vertebrates.

It is an object of the invention to provide an improved apparatus, system and method for targeted optical in vivo stimulation of nerve cells and for electrical measurement of nerve cell pulses of the stimulated nerve cells.

This object is solved by the features of the independent claims. The dependent claims relate to preferred embodiments of the invention.

SUMMARY OF THE INVENTION

The invention provides a measuring probe, in particular a stimulation measuring probe, and a method for the targeted optical in vivo stimulation of at least one nerve cell, preferably several nerve cells. With the probe according to the invention, the nerve cell pulses of the optically stimulated nerve cells can be measured electrically. The measuring probe preferably has at least one (measuring) needle which is suitable for being introduced in vivo into a brain of a vertebrate or mammal. In order to measure electrical nerve cell pulses and thus the activity of at least one nerve cell, the measuring needle has at least one electrical sensor or measuring contact, which serves for contacting with the nerve cell to be measured. In addition, the measuring probe preferably has at least one light source with whose emitted light the at least one nerve cell can be optically stimulated. The light source is not limited to a specific wavelength. Preferably, however, light from the visible range is used or from the area adjacent to the visible light. According to another preferred embodiment, the light may be monochromatic or approximately monochromatic.

The at least one sensor or measuring contact is preferably attached to the (pointed) or distal end of the measuring needle in order to bring the sensor or measuring contact directly into contact with the at least one nerve cell and to derive the electrical impulses of the nerve cell (s). The at least one light source can for example, also be attached directly to the electrical sensor on the needle tip. According to a further preferred embodiment, the measuring probe may alternatively or additionally comprise optical means for directing the light emitted by a light source remote from the at least one measuring contact to the nerve cell. For example, optical fibers may be used alone or in combination with lenses for light conduction.

The measuring probe according to the invention is preferably designed so that the emitted light can substantially illuminate and thus optically stimulate the nerve cell to be derived from the electrical contact, and / or optically stimulate at least one nerve cell adjacent to the nerve cell, which can be derived with the electrical contact.

The measuring probe also preferably has at least one of the following components: a signal preamplifier for amplifying the electrical nerve cell signals detected by the electrical sensor, a microactuator for moving the measuring needle relative to the nerve cell, an electrical circuit for preprocessing the amplified electrical signals and an electrical circuit for targeted Driving the light source.

The microactuator is used for positioning or fine positioning of the measuring needle within the brain. A microactuator according to the invention can be, for example, as a microelectromotor, a piezomotor, a pneumatic / hydraulic drive or an actuator based on shape memory metals, wherein a transmission is preferably present for transmitting an actuator movement to the needle, preferably a planetary gear. The microactuator preferably allows a (translational) movement of the measuring needle relative to the brain of preferably up to 5 mm, the relative movement preferably having an accuracy of about 5 μm.

An electrical circuit provided on the measuring probe preferably has a device for preprocessing. For example, it is advantageous if the analog nerve cell signals derived with the measuring sensors are already preprocessed within the measuring probe with an analog-to-digital converter (ADC). In addition, pre-amplifier can be arranged on the probe.

The measuring probe according to the invention has at least one, preferably a plurality of electrical sensors at the front end of the measuring needle. For digital processing, it may also be advantageous if the probe has 2 ⁿ sensors, where n can be any integer between 1 and 16.

The measuring probe according to the invention is preferably adapted in its dimensions to the object to be measured. To implant the probe into a small vertebrate animal, the measuring needle is preferably at least 2 mm long, and preferably at least 4 to 5 mm long. The diameter of the measuring needle is preferably between 100 .mu.m and 400 .mu.m, preferably at about 250 .mu.m. If a light source is mounted remotely from the measuring needle on the measuring sensor and the light emitted by the light source is passed to the measuring sensors, the diameter of the optical waveguide should also be made thin, preferably about 60 microns to 300 microns, for example 110 microns.

According to the invention, the light can be emitted by any suitable light source. Due to the preferred small dimensions, however, it is preferred to use as the light source a photodiode or an LED, which preferably emits light in the wavelength range between 300 nm and 650 nm.

The measuring probe according to the invention is preferably intended for small vertebrates or mammals, wherein the vertebrate is preferably a mouse, rat, guinea pig or cat. In particular, the dimensions and weight of the probe are designed to allow for in vivo introduction into a mouse, rat, guinea pig or cat brain, and the probe is small enough from mice, rats, guinea pigs, or both Cat to be born. For example, the probe can weigh between 0.5 g and 10 g. The length of the probe is preferably 10-30 mm. The diameter of the measuring probe is preferably between 4-10 mm.

The invention also relates to a system for optogenetic in vivo examination of nerve cells, which in addition to the measuring probe according to the invention also has a, preferably external (stationary) processing station separate from the measuring probe. The processing station serves to process the signals measured and preferably preprocessed by the measuring probe and / or to control the measuring probe.

In order for the measuring probe to be able to communicate with the processing station, the measuring probe preferably has a transmitter or transceiver in order to transmit the signals from the measuring probe, preferably digitally and preferably wirelessly, to the processing station. Communication between the measuring probe and the processing station can be unidirectional or bidirectional. For wireless communication, for example, light, ultrasound and / or a radio frequency can be used as the carrier medium. Such a system thus allows a very elegant one telemetric measurement (telemetering) of signals in vertebrates.

The system according to the invention may additionally have a measuring probe additional module, which is designed separately from the measuring probe, but is electrically connected to the measuring probe and can be carried by the living vertebrate as a "backpack" on its back. This additional module can have at least one of the following components: an electrical energy source for the electrical power supply of the measuring probe, a microcontroller for (pre-) processing of the signals emitted by the measuring probe, a storage medium for (intermediate) storage of the signals emitted by the measuring probe. In addition, it may be advantageous if the processing station communicates with the measuring probe via the measuring probe additional module, i. H. the wireless communication takes place between the processing station and the probe add-on module (backpack).

The invention also includes individual features in the figures, even though they are shown there in connection with other features and / or are not mentioned above or below.

The invention also includes embodiments with any combination of features mentioned or shown above or below various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Show it:

1a a perspective view of a component of a measuring probe according to the invention;

1b an enlarged view of the needle tip of the probe according to the invention the 1a ;

2 schematically preferred electronic components or functions of a system according to the invention with a measuring probe, a backpack and a processing station for a telemetric measurement;

3 schematic representation of the preferred movement units according to the invention;

4 a perspective view of a probe according to the invention di attached to a skull of a vertebrate; and

5 a photographic view of individual components of the probe according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

According to the invention, an electrical in vivo measurement is combined with an optogenetic stimulation. Optogenetic approaches allow the manipulation of the activities of specified subsets of neurons in an in vivo system. In particular, according to the invention, the use of the in vivo optogenetic measuring probe can be used to study the function or the behavior of neurons in the case of pathological behavior such as epileptic seizures.

The measuring probe according to the invention is designed as a novel lightweight in-vivo measuring probe, with which in free-moving vertebrates (mice) an electrical measurement of nerve currents in response to a targeted light stimulation can be performed. According to the invention, a plurality of electronic components are combined to form a measuring probe according to the invention, wherein the measuring probe itself is fastened on the upper side of the skull and the vertebrate is only slightly limited in its movement.

1 shows a main component of a measuring probe according to the invention 42 with a measuring needle designed as a microneedle 10 , which is introduced to measure nerve cell currents in a vertebrate brain. At the distal end of the measuring needle 10 , ie in the vicinity of the needle tip, there is at least one electrical sensor or measuring contact 11 for deriving electrical signals of nerve cells. In the illustrated embodiment, 16 measuring contacts are shown.

At the proximal end of the probe or the measuring needle 10 Bond pads are for contacting electronic circuit elements 30 and a light source in the form of a photodiode 20 which are arranged on a circuit board. That of the photodiode 20 emitted light is transmitted through an optical fiber 40 directed to the needle tip of the measuring needle and in the vicinity of the electrical measuring contacts of the optical waveguide 40 emitted. The measuring needle may preferably be produced by microtechnological / thin-film technology (MST, M (O) EMS).

The measuring needle is preferably embedded in a circuit board to which the electronic components for the operation of the measuring probe and the mechanical and optical actuators are bonded. The measuring probe preferably has a housing in which an actuator (motor) and / or a preamplifier are arranged. Preferably, the housing of the probe is fixed to the skull of the experimental animal appropriate. With the help of the actuator, the measuring needle can be moved relative to the skull of the vertebrate, whereby an accurate and / or later positioning of the measuring contacts within the brain is possible. With the help of an integrated signal preamplifier, the electrical signals of the nerve cells derived from the measuring contacts can already be preprocessed within the measuring probe.

Since the measuring probe according to the invention is attached to the skull of the test animal, the dimensions and weight should be as low as possible. However, further components for supplying energy to the measuring probe and / or for data transmission can likewise be carried by the vertebrate. According to the invention, these further components are preferably carried in a probe addition module, preferably in the form of a "backpack", which is designed separately from the measuring probe, from the vertebrate. Preferably, the "backpack" contains at least one of the following components: battery, microcontroller, analog-to-digital converter, memory and transmitter or transceiver. The "backpack" is preferably connected via thin cables with the measuring probe according to the invention. The "backpack" can also be implanted "encapsulated" under the skin.

2 schematically shows the individual components of a system according to the invention with a probe and a separate backpack, preferably the probe and / or the backpack are worn by the vertebrate. In addition, the system according to the invention preferably has an external processing station, which has a communication unit for communication with the measuring probe or the backpack. Preferably, the communication unit is in communication with a computer (personal computer, PC) on which software for data analysis (analysis software) and / or for control (control software) of the measuring probe is provided.

3 schematically the individual components of another preferred embodiment of a system according to the invention. In this embodiment, the probe according to the invention is attached to a "helmet", wherein essential components can not be attached directly to the probe according to the invention on the helmet, such as a motor and / or the probe with the board and the measuring needle and / or at least one preamplifier, optional with multiplexer. A light source, for example in the form of an LED, can either be mounted directly on the measuring probe board or on the helmet of the measuring probe.

Preferably, unidirectional or bi-directional data exchange takes place between the "helmet" (and its components) and the backpack according to the invention, which is preferably carried by the living test animal, via at least one wire line. The backpack preferably has an energy source and / or a processing device (for example in the form of a microcontroller) and / or a radio transmission device, preferably with an antenna.

Between the backpack according to the invention and the workstation according to the invention, which is preferably located away from the test animal, a unidirectional or bidirectional data exchange preferably takes place wirelessly.

4 shows a perspective view of a probe according to the invention which is attached to a skull of a vertebrate. The housing of the measuring probe according to the invention is shown with an electric motor, which causes a translational movement of the measuring needle relative to the skull and thus allows a displacement of the measuring needle within the brain. Finally, the shows 5 individual components of a measuring probe according to the invention. The housing 43 the probe is placed over a pedestal 45 attached to the head of the vertebrate. The motor is preferably on the housing 43 , for example by means of the retaining clip 44 , detachably fastened. The motor 50 is with the circuit board 31 connected in such a way that the measuring needle 10 when motor is operated via a thread shown together with the circuit board 31 relative to the housing 43 is displaceable. In other words, by the engine 50 can the measuring needle 10 be moved relative to the housing in or within the brain of the experimental animal.

The invention also includes the exact or exact terms, features, numerical values or ranges, etc. when, above or below, these terms, features, numerical values or ranges are used in conjunction with terms such as, for example: B. "about, about, to, essentially, in general, at least, at least", etc. were called (ie "about 3" should also "3" or "substantially radially" should also include "radial"). The term "or" also means "and / or".

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Zhang et al., J. Neural Eng. 6 (2009) 055007 (13pp) [0004]

Claims (15)

Measuring probe ( 42 ) for the targeted optical in vivo stimulation of nerve cells and for the electrical measurement of nerve cell pulses, the probe comprising: at least one measuring needle ( 10 ) for in vivo introduction into a brain of a vertebrate, wherein at the needle ( 10 ) at least one electrical sensor ( 11 ) for contacting with at least one nerve cell of the brain in order to measure its activity, and at least one light source ( 20 ), with whose emitted light the at least one nerve cell can be optically stimulated. Measuring probe according to claim 1, wherein the light source ( 20 ) directly on or adjacent to the electrical sensor ( 11 ) near or at the top of the needle ( 10 ) or the measuring probe ( 42 ) optical means ( 40 ) to receive the light from the light source ( 20 ) to the nerve cell or tip of the needle. Measuring probe according to claim 2, wherein the emitted light is substantially i) that with the at least one electrical contact ( 11 ) can be optically stimulated and / or inhibited, and / or ii) optically stimulates and / or inhibits at least one nerve cell adjacent to the nerve cell which is in contact with the at least one electrical contact ( 11 ) is derivable. Measuring probe according to one of the preceding claims, wherein the measuring probe ( 42 ) at least one of the following components: a signal preamplifier for amplifying the electrical signals detected by the electrical sensor, a microactuator ( 50 ) for moving the measuring needle ( 10 ) relative to the nerve cell, an electrical circuit for preprocessing the amplified electrical signals and an electrical circuit for selectively controlling the light source ( 20 ). Measuring probe according to claim 4, wherein the microactuator ( 50 i) a microelectromotor, a piezomotor, a pneumatic / hydraulic drive or an actuator based on shape memory metals, preferably a gear is present for transmitting the actuator movement to the needle, preferably a planetary gear and / or a thread and ii) the microactuator preferably allows a (translational) movement of the measuring needle relative to the brain of up to 10 mm, wherein the relative movement preferably has an accuracy of about 5 microns. A measuring probe according to claim 4, wherein said pre-processing electrical circuit comprises an analog-to-digital converter (ADC). Measuring probe according to one of the preceding claims, wherein the measuring needle has at least one, preferably a plurality of electrical measuring pickups, preferably at or in the vicinity of the tip of the needle. Measuring probe according to one of the preceding claims, wherein i) the measuring needle ( 10 ) is at least 2 mm long, and is preferably at least 4 to 5 mm long, ii) the diameter of the measuring needle ( 10 ) is preferably between 100 μm and 400 μm, preferably about 250 μm, and iii) the diameter of the optical waveguide ( 40 ) according to claim 2 is preferably about 60 microns to 300 microns, preferably 110 microns. Measuring probe according to one of the preceding claims, wherein the at least one light source ( 20 ) is at least one photodiode or an LED, which preferably emits light in the wavelength range between 300 nm and 650 nm. Measuring probe according to one of the preceding claims, wherein the vertebrate is preferably a mouse, rat, guinea pig or cat and the measuring needle ( 10 ) is suitable for in vivo introduction into, in particular, a mouse, rat, guinea pig or cat brain and is small enough to be carried by the mouse, rat, guinea pig or cat, with the measuring probe ( 42 i) preferably weighs between 0.5 g and 10 g, and / or ii) is preferably 10-30 mm long and / or iii) preferably has a diameter of 4-10 mm. Measuring probe according to one of the preceding claims, wherein ... System for optogenetic in vivo examination of nerve cells with: a measuring probe according to any one of the preceding claims, wherein the measuring probe can be carried by the living vertebrate, and an external processing station for processing the signals measured by the measuring probe and preferably preprocessed. The system of claim 12, wherein the probe comprises a transceiver for transmitting the signals from the probe, preferably digitally and wirelessly, to the processing station, preferably by means of light, ultrasound and / or radio. A system according to claim 12 or 13, wherein the system additionally comprises a probe attachment module which may be carried by the live mammal separately from the probe, but electrically connected (also subcutaneously). The system of claim 14, wherein the add-on module comprises at least one of the following components: an electrical energy source for supplying electrical power to the probe, a microcontroller for processing the signals delivered by the probe, a storage medium for storing the signals delivered by the probe.

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