KR101069153B1 - Optical Brain Response Monitoring Device For Closed-loop Deep Brain Stimulation - Google Patents

Abstract

An optical brain response monitoring apparatus for a closed cardiovascular stimulation system, comprising: a stimulator for injecting electrical stimulation into brain tissue; A light source unit for injecting an optical signal into the brain tissue to monitor the response of the brain tissue according to the stimulus; A photo detector detecting an optical signal emitted from the brain tissue and converting the detected optical signal into an electrical signal; An analyzer configured to analyze the converted electrical signal to generate optical brain response data; And a control unit generating a control signal according to an analysis result of the analysis unit to control the stimulation unit, wherein the analysis unit analyzes brain activity by measuring a change in optical properties of brain tissue in an electrical signal, and changes in the optical properties. Disclosed is a brain response monitoring apparatus for measuring the physical quantity change of the light signal emitted from the brain tissue.

Cardiac stimulation, Brain response monitoring, Light signal

Description

Optical Brain Response Monitoring Device For Closed-loop Deep Brain Stimulation}

The present invention relates to a brain response monitoring device for injecting electrical stimulation into the brain tissue and monitoring the response result by optical observation method, which can be measured for a long time using an optical observation method. The present invention relates to a brain response monitoring device without stimulus noise.

Deep brain stimulation (DBS) refers to a technique for restoring the motor function of a patient suffering from a movement disorder by electrical stimulation of the deep brain. For example, the motor function of Parkinson's disease or hydration can be restored through electrical stimulation. Recently, the application to the mental disorders such as chronic pain, depression as well as physical disorders has been expanded.

In recent years, a closed-loop DBS has been studied, which simultaneously measures the brain response caused by cardiac brain stimulation and changes the stimulation conditions according to the brain response. This is to enable more efficient and safe cardio brain stimulation in consideration of brain response to the stimulus. In order to measure the brain response, a conventional microelectrode was inserted into the brain. However, closed-loop DBS using measuring electrodes was not suitable for the following reasons.

The DBS should repeat the stimulus and measurement for a long time. When the measurement electrode used in the related art is inserted into the brain tissue for a long time, the performance of the electrode that detects an electrical signal is degraded by cellular or fibrous encapsulation of the conductor portion of the electrode. In addition, the silicon-based monitoring electrode is not flexible, and when inserted into the brain tissue, the electrode may be broken or the brain tissue may be damaged. When the brain tissue response to the electrical stimulation is observed through the electrical signal, the distortion of the signal due to the input electrical signal is inevitable, and thus the accuracy of the measurement is reduced. Commonly referred to as stimulus artifact. Therefore, there is a need for the development of a new closed-loop DBS equipped with a brain response monitoring device that can overcome such problems.

The present invention has been proposed to overcome the prior art as described above, in the brain response monitoring device, using the optical observation method to observe the response of the brain tissue to the stimulus signal to control the stimulus signal is input again, It provides a brain response monitoring device for the type cardio brain stimulation system.

Brain response monitoring apparatus according to an embodiment of the present invention for achieving the above object, the stimulator for injecting electrical stimulation to the brain tissue; A light source unit for injecting an optical signal into the brain tissue to monitor the response of the brain tissue according to the stimulus; A photo detector detecting an optical signal emitted from the brain tissue and converting the detected optical signal into an electrical signal; An analyzer configured to analyze the converted electrical signal to generate optical brain response data; And a control unit generating a control signal according to an analysis result of the analysis unit to control the stimulation unit, wherein the analysis unit analyzes brain activity by measuring a change in optical properties of brain tissue in an electrical signal, and changes in the optical properties. Is measured by the change in physical quantity of the optical signal emitted from the brain tissue.

According to the present invention, by improving the problem of the monitoring method using the electrode used in the prior art, it is possible to monitor the brain response for a long time. In addition, since there is no stimulus noise generated by the monitoring method through the electrode, precise measurement is possible, thereby optimizing the electric stimulation conditions or the stimulus position. By monitoring the response to stimuli in real time, the activation of new basic clinical studies through brain stimulation is also expected.

In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted to clarify the gist of the present invention.

In the present specification, the light signal refers to light injected from the light source to the light path part or transmitted from the light path part to the light detection part.

In the present specification, the optical properties of brain tissue refer to transmittance, reflectance, transmission spectrum, reflection spectrum, absorption spectrum, Raman scattering, 2 It refers to all optical physical quantities that appear in the process of brain tissue interacting with light, such as 2nd-order correlation or intensity correlation, and backscattering.

In the present specification, the physical quantity of an optical signal refers to the physical properties of light that can be measured, such as intensity of light, polarization direction, and phase in the case of modulated light.

1 is a brain response monitoring device 100 according to the present invention, the stimulator 10 for providing electrical stimulation to the brain tissue; A light source unit 20 incident an optical signal to brain tissue to monitor a response according to the stimulus; A photo detector 30 for detecting an optical signal emitted from the brain tissue and converting the detected optical signal into an electrical signal; An analysis unit 40 analyzing the converted electrical signal to generate optical brain response data; And a controller 50 generating a control signal according to an analysis result of the analyzer and controlling the stimulus.

Stimulator 10 generates electrical stimulation that is injected into the deep brain. Electrical stimulation stimulates brain tissue to induce the desired response. For example, an electrical stimulus is injected into a specific area of the brain to induce a reaction that causes the hydration patient to no longer shake his hand. This reaction is observed by the light source and the photodetector described later, and can be observed by the light-tissue interaction. Optical-tissue interaction means that the optical signal reacts with the brain tissue so that the optical property change of the brain tissue is reflected in the optical signal.

The magnetic pole part is controlled by the control part mentioned later. The magnetic pole unit receives the electrical stimulation conditions set by the controller to generate the electrical stimulation corresponding thereto.

The magnetic pole unit includes a communication unit providing a communication function for receiving a control signal from the control unit; A stimulation circuit unit generating an electrical stimulation according to a control signal received from the control unit; And an electrode unit for transmitting the electrical stimulation to the brain tissue. The stimulus circuit unit generates a stimulus signal by adjusting the magnitude, frequency, etc. of the stimulus signal according to a control signal of the controller. The relationship between the stimulus signal and the brain tissue's response is analyzed by injecting electrical stimulation into the brain tissue and observing the brain tissue's response to it.

The light source unit 20 receives an optical signal. An optical signal is incident to allow the stimulus to observe the brain tissue's response to the stimulus signal. The optical observation method is applied without observing the reaction of the brain tissue through the electrode used in the prior art. In order to implement an optical observation method, a light source unit for providing an optical signal is provided.

An optical observation method is to observe the response of brain tissue using optical properties. The brain tissue generates a corresponding neural signal before a particular thought or action, and the optical properties of the brain tissue may change when the neural signal occurs. The change in the optical properties of the brain tissue can be measured by the change in the physical quantity of the optical signal incident on the brain tissue.

Various kinds of light sources can be used for the light source unit. The light source unit may include a laser, a modulator, an optical filter, or a polarization filter. Although the optical signal itself injected from the light source may be used, the above-mentioned components are added in addition to the light source in order to obtain an effective result for measuring the neural signal. In particular, the modulator may be an optical modulator that modulates an optical signal using an electro-optic effect or an acoustic optical modulator that modulates an optical signal using an acoustic-optic effect. In addition, a method using wavelength division modulation, time division modulation, or the like can also be used.

The photo detector 30 detects an optical signal emitted from the brain tissue, converts the information contained therein into an electrical signal, and transmits the information to the analyzer 40. The information contained in the optical signal includes the intensity or polarization angle of the optical signal.

The light detector may include an optical filter or a polarization filter when the light source includes an optical filter or a polarization filter. You will need to include the same components. In addition, when modulating and injecting an optical signal in the light source unit, a demodulator for demodulating the modulated optical signal should be included.

The detection of the light signal emitted from the brain tissue by the photodetector is by photo-tissue interaction. Photo-tissue interactions are divided into several categories. In the device according to the invention, the near-infrared spectrum of absorption and scattering, Raman scattering, birefringence or optical activity and second-order correlation Use

According to the four light-tissue interactions listed above, the light source portion and the photodetector portion use a scalp contact type probe. This is to transmit an optical signal to the brain tissue and to detect the optical signal emitted from the brain tissue. It's easy because you don't need to implant it inside your body.

The analyzer 40 analyzes brain activity using the electrical signal converted by the photodetector, and transmits data of the analysis result to the controller.

The analysis unit analyzes nerve signals by measuring changes in optical properties of brain tissue in response to the electrical stimulation. When the neural signal is generated, the optical properties of the brain tissue are changed, and thus the neural signal can be analyzed by using the emitted light signal while reflecting this. Neural signals in brain tissue are measured by changes in physical quantities of light signals emitted from brain tissue. The result of the neural signal analysis may be stored as data of the electrical signal. This data is referred to herein as optical brain response data.

By analyzing the neural signals, you can map the types of thoughts or actions that correspond to each neural signal. When an accident or action occurs, a specific neural signal is generated before that, so that the corresponding neural signal data analyzed above can be mapped with the type of thought or action. The analysis unit may further include a database storing the mapped data. This database can be updated continuously.

Brain activity analysis is about recognizing specific nerve signals (causing thoughts or actions). For example, in order to move a finger, a nerve signal for moving a finger is generated, and the signal reaches a muscle moving a finger along the nerve to move the finger. In the example above, the 'neural signal' is related to the 'movement of the finger'. By mapping these correlations one-to-one, one can judge a particular neural signal in a change in the optical properties of the brain tissue in response to an electrical stimulus, and determine the behavior associated with that neural signal in that particular neural signal. This series of tasks corresponds to brain activity analysis.

The controller 50 receives the optical brain response data from the analyzer to set the electrical stimulation conditions of the stimulator. The control unit calculates a correlation between the optical brain response data measured by the analysis unit and the electrical stimulation provided by the stimulation unit, and controls the stimulation unit by setting the electrical stimulation conditions according to the calculation result. The control unit may be implanted in the body. In addition, the controller may control the light source intensity, frequency, and the like of the light source unit.

As mentioned above, when the analysis unit maps a specific neural signal and a specific behavior or thought, the controller calculates a correlation between the neural signal, the behavior, the thought, and the electrical stimulation, and controls the electrode part by the correlation.

 For example, the controller collects optical brain response data according to a specific electrical stimulus of the subject. The optical brain response data is extracted by the analysis unit from the change amount data of the intensity or polarization angle of the optical signal received from the photodetector. Here, the characteristics of the brain response according to each electrical stimulation are mapped one-to-one with the input electrical stimulation, and it is determined whether the response of the brain tissue to the initially inputted stimulus signal is consistent with that predicted. The mapping can be performed through an algorithm that infers the relationship between the physical quantity change characteristic of the optical signal and the electrical stimulus.

In this step, it is possible to connect each electrical stimulus and brain activity by mapping the electrical stimulus to the location and the physical characteristics of the signal and the neural signals related thereto.

If the brain tissue's response matches what was initially predicted, it will output a control signal to continue inputting the same electrical stimulus. On the other hand, if the response does not match that expected, the control signal will be output to input different electrical stimuli. Whether the 'match' is set differently for each embodiment, the degree can be adjusted. This does not mean a perfect match or disagreement. For example, a method of determining whether the similarity is within a threshold by calculating a correspondence relationship between the data and the electrical stimulus as a similarity may be used.

2 is a brain response monitoring apparatus 200 according to the present invention, which is located between the light source and the photodetector in the brain response monitoring apparatus of FIG. 1, is implanted in the body, and transmits the incident optical signal to brain tissue. The brain response monitoring device further includes a light path unit 60 for transmitting an optical signal emitted from the brain tissue to the light detection unit. The brain response monitoring device further including a light path part uses reflection or backscattering during light-tissue interaction. The light path unit may include an optical fiber.

The optical path section should be used for a long time to measure changes in the optical properties of brain tissue. Therefore, it should not be affected by the environment inside the cell. In a conventional method of detecting an electrical signal using an electrode, a phenomenon in which an exposed portion of the electrode is wrapped in a tissue occurs, and thus the electrode needs to be replaced, which causes a problem in measuring nerve signals for a long time. Accordingly, the optical property change measurement method was changed from the electrical signal extraction method to the optical signal detection method to enable a long time measurement.

In addition, since the light path part needs to transmit the optical signal reacted with the brain tissue to the light detector, the light path part may include a beam splitter when implementing the light path part as one path.

The optical path unit may include an optical isolator to prevent the optical signal from traveling in the reverse direction of the designed travel. If the optical isolator is provided, the optical signal measurement at the photodetector will be easy since the optical signal in the opposite direction is blocked.

The light path unit may be implemented by a polarization maintaining optical fiber when the polarization filter is used in the light source unit. By using the polarized optical signal, one more variable of the optical property change can be obtained, which is advantageous for measuring the physical quantity change of the optical signal.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

3 shows a brain response monitoring apparatus according to an embodiment of the present invention. In the present embodiment, the light source unit and the light detection unit exist outside the body. The light source and the photodetector use a scalp contact probe. The control unit transmits a control signal to the stimulation unit according to the initially set environment. The magnetic pole unit includes a communication unit providing a communication function with the control unit; A stimulation circuit unit for generating an electrical stimulation according to a control signal received from a processor; And it may include an electrode unit for transmitting the electrical stimulation to the brain tissue. The stimulus unit receives the control signal, generates an electrical stimulation corresponding to the control signal, and transmits the electrical stimulus to the brain tissue through the electrode unit.

Brain tissue responds to electrical stimuli delivered to brain tissue. Brain tissue responses can be detected by optical observation methods. In the prior art, another electrode was used to detect an electrical signal.

The photodetector collects the optical signal. This is to analyze the neural signal of brain tissue by changing the physical quantity of the collected optical signal. The optical signal collected by the photodetector is converted into an electrical signal and transmitted to the analyzer. The analysis unit analyzes the change in the optical properties of the brain tissue using the received electrical signal. The change in the optical properties of the brain tissue may be measured by the change in physical quantity of the optical signal. Changes in the optical properties of brain tissues indicate that neural signals are generated in the brain tissues.

The analyzer transmits the optical brain response data recorded with the change in the physical quantity of the optical signal to the controller. The control unit controls the electrical stimulation of the stimulation unit using the received data. The controller may determine whether the data correspond to the initially input electrical stimulus, and if not, generate a control signal for changing the electrical stimulus and transmit the generated control signal to the magnetic pole. If the data match, a control signal for maintaining the electrical stimulation may be generated and transmitted to the stimulation unit. Whether or not 'match' can be adjusted in the range as mentioned above, for example, can be determined by calculating the similarity value.

As described above, while repeating this embodiment, it is possible to implement a brain response monitoring device for a closed cardiac brain stimulation system to adjust the electrical stimulation to generate the desired nerve signal.

4 shows a brain response monitoring apparatus according to an embodiment of the present invention. According to the present embodiment, the brain response monitoring device includes a light path unit positioned between the light source unit and the light detection unit. The optical path unit is implanted in the body, and transmits an optical signal incident to the light source to the brain tissue, and transmits an optical signal emitted from the brain tissue to the photodetector. The light path unit may include an optical fiber.

The optical fiber is implemented in the optical path part to take advantage of the optical properties of brain tissue. Based on the fact that the optical properties of brain tissues change when a neural signal is generated, nerve signals are measured by observing changes in the optical properties of brain tissues using reflection or backscattering of the optical signals.

The control unit transmits a control signal to the stimulation unit according to the initially set environment. The magnetic pole portion is a communication unit; Stimulation circuitry; And an electrode unit. The stimulus unit receives the control signal, generates an electrical stimulus corresponding to the control signal, and transmits the electrical stimulus to the brain tissue through the electrode unit.

Brain tissue responds to electrical stimuli delivered to brain tissue. Brain tissue responses can be detected by optical observation methods. In the prior art, another electrode was used to detect an electrical signal. In an embodiment of the present invention, since the response of the brain tissue is detected by measuring a change in optical properties of the brain tissue, the light source unit injects an optical signal for this purpose. The optical signal injected by the light source unit is transmitted to the brain tissue through the optical path unit. The brain tissue responds by electrical stimulation of the electrode part, and the optical properties of the brain tissue that change during the reaction change and release the physical quantity of the injected optical signal, which is transmitted to the light detector through the light path unit. The process of changing the physical quantity of the optical signal injected into the brain tissue corresponds to the light-tissue interaction.

In this embodiment, the implementation method of the light path part varies depending on whether reflection or backscattering is used among the light-tissue interactions.

When detecting an optical signal due to reflection, an optical path portion having one path is used. The path that receives the optical signal from the light source unit and transmits it to the brain tissue and the path that transmits the optical signal emitted from the brain tissue to the photodetector is the same path. According to this, since the entrance of the path through which the optical signal is incident and the exit of the path through which the optical signal is detected, the optical signal input and output can be separated using a beam splitter.

When detecting an optical signal by backscattering, two paths of optical paths are used. And a first path for receiving an optical signal from the light source unit and transmitting the optical signal to the brain tissue, and a second path for transmitting the optical signal emitted from the brain tissue to the photodetector.

The photodetector detects the light signal emitted from the brain tissue from the light path unit and converts the light signal into an electrical signal. The photodetector transfers the electrical signal to the analyzer. The analysis unit analyzes the change in the physical quantity of the optical signal in the electrical signal received from the photodetector, analyzes the change in the optical properties of the brain tissue from the change in the physical quantity of the optical signal, and analyzes the neural signal in the change of the optical properties of the brain tissue. . In addition, it may proceed from the analyzed nerve signal to the brain activity analysis process for analyzing a specific thought or action corresponding to the nerve signal.

The control unit controls the stimulation unit based on the analysis result. The control unit may control the stimulation unit by calculating a correlation between the data and the electrical stimulation injected by the stimulation unit using the optical brain response data generated by analyzing the analysis unit.

5 is a diagram illustrating a process of controlling the stimulation unit by the control unit. The control unit generates a control signal for controlling the electrical stimulation of the magnetic pole portion and transmits it to the magnetic pole portion. The value of the initial control signal is set to an arbitrary value, and may be changed by input depending on the response of the brain tissue to be obtained. The controller may control a light source intensity, a frequency, and the like of the light source unit.

The optical signal injected from the light source unit is transmitted to the photodetector after detecting the brain tissue. The photo detector converts the physical quantity change of the optical signal into an electrical signal and transmits the electrical signal to the analyzer. The analysis unit extracts the optical property change of the brain tissue from the electrical signal to generate optical brain response data and transmits it to the controller.

The control unit receives the optical brain response data, and searches and determines a database that has previously set whether the control signal and the brain response of the data match. 'Match' means whether the similarity between the control signal and the data is within a threshold. This threshold can be changed depending on the setting. Through this, it is possible to determine whether the control of the controller is properly performed by first comparing the control signal input to induce a specific response of the brain tissue with the optical brain response data indicated by the electrical stimulation.

For example, when the similarity between the control signal and the optical brain response data is out of the threshold value, the controller modifies the control signal and transmits the control signal to the stimulator. If the similarity between the control signal and the optical brain response data is within the threshold, the result is stored in the database. Since judging similarity takes into account some error, the brain response predicted by the control signal and the monitored optical brain response data are not exactly the same. Thus, the database can be updated continuously. The mapping table of control signal to optical brain response data is stored and the control process is terminated.

The present invention described above is limited to the above-described embodiments and the accompanying drawings as various changes and modifications can be made within the scope without departing from the technical spirit of the present invention for those skilled in the art. It doesn't happen.

1 is a view showing a brain response monitoring device according to the present invention.

FIG. 2 is a diagram illustrating a brain response monitoring apparatus including a light path unit in the brain response monitoring apparatus of FIG. 1.

3 is a view showing the operation of the brain response monitoring apparatus according to an embodiment of the present invention.

4 is a view showing the operation of the brain response monitoring apparatus according to another embodiment of the present invention.

5 is a flowchart illustrating an operation of the controller of the brain response monitoring apparatus according to the present invention.

Claims (19)

In the optical brain response monitoring device for a closed cardiac brain stimulation system, Stimulator for injecting electrical stimulation to the brain tissue; A light source unit for injecting an optical signal into the brain tissue to monitor the response of the brain tissue according to the stimulus; A photo detector detecting an optical signal emitted from the brain tissue and converting the detected optical signal into an electrical signal; An optical path unit positioned between the light source unit and the photodetector unit and implanted in the body to transmit the incident optical signal to brain tissue, and to transmit the optical signal emitted from the brain tissue to the photodetector unit; An analyzer configured to analyze the converted electrical signal and generate optical brain response data; And A control unit generating a control signal according to an analysis result of the analysis unit to control the stimulation unit; The analysis unit analyzes the brain activity by measuring the change in the optical properties of the brain tissue in the electrical signal, the change in the optical properties is measured by the change in the physical quantity of the optical signal emitted from the brain tissue, The light path unit brain response monitoring device, characterized in that it comprises an optical fiber. The method of claim 1, The analysis unit, Brain response monitoring device further comprises a database storing a correspondence between the change in the optical properties of the brain tissue and brain activity. The method of claim 1, The analysis unit, Brain response monitoring device characterized in that for analyzing the brain activity by measuring the near-infrared absorption rate by the hemoglobin concentration of the optical signal. The method of claim 1, The analysis unit, Brain response monitoring device characterized in that for analyzing the brain activity by measuring the near infrared absorption and scattering spectrum of the optical signal. The method of claim 1, The analysis unit, Brain response monitoring device characterized in that for analyzing the brain activity by measuring the Raman scattering spectrum of the optical signal. The method of claim 1, The analysis unit, Brain response monitoring device characterized in that for analyzing the brain activity by measuring the birefringence or optical activity of the optical signal. The method of claim 1, The analysis unit, Brain response monitoring device characterized in that for analyzing the brain activity by measuring the second correlation value of the optical signal. The method of claim 1, The control unit, The response unit calculates a corresponding relationship between the optical brain response data analyzing the electrical signal and the electrical stimulation provided by the stimulation unit, and sets the electrical stimulation conditions of the stimulation unit to control the stimulation unit. Monitoring device. The method of claim 1, The control unit, And a database storing a correspondence relationship between the optical brain response data and an electrical stimulus. The method of claim 1, The controller is a brain response monitoring device, characterized in that implanted in the body. The method of claim 1, The magnetic pole portion, A communication unit providing a communication function with the control unit; A stimulation circuit unit generating an electrical signal according to the control signal received from the control unit; And Brain response monitoring device comprising an electrode unit for transmitting the electrical signal to the brain tissue. The method of claim 1, The stimulation unit brain response monitoring device, characterized in that for receiving an input condition of the electrical stimulation from the control unit. The method of claim 1, The light source unit and the light detection unit, Brain response monitoring device, characterized in that the scalp contact probe. delete delete The method of claim 1, The optical signal emitted from the brain tissue is due to reflection, the analysis unit brain response monitoring device, characterized in that for analyzing the brain activity by measuring the physical quantity change of the reflected optical signal. The method of claim 16, The light path unit, And a light splitter separating the incident optical signal and the emitted optical signal, The beam splitter separates the incident optical signal in a different direction according to the incident direction, and transmits the optical signal transmitted from the light source unit to the optical path and the optical signal emitted from the brain tissue passing through the optical path unit to the photodetector. Brain response monitoring device, characterized in that. The method of claim 1, The optical signal emitted from the brain tissue is due to backscattering, and the analysis unit measures the brain activity by measuring a change in physical quantity of the backscattered optical signal to analyze the brain activity. The method of claim 18, The light path unit, A first optical path through which the optical signal incident from the light source unit is transmitted; And And a second optical path through which the emitted optical signal is transmitted to the photodetector.

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