MEDICAL DEVICE FOR STIMULATING NEURONS OF A PATIENT TO SUPPRESS A PATHOLOGICALLY SYNCHRONOUS NEURONAL ACTIVITY

Abstract

A medical device (10) is provided for stimulating neurons of a patient (12) to suppress a pathologically synchronous activity of the neurons, comprising a stimulation unit (14) configured for selectively generating acoustic stimuli to be administered to the patient (12), and a control unit (20) for actuating the stimulation unit (14) to generate a plurality of stimuli of different frequencies, wherein the control unit (20) is configured to determine a target frequency range within a patient's hearing range in dependence on a patient's auditory perception; and to select the plurality of stimuli such that the frequencies of the different stimuli are within the determined frequency range and correspond to tone frequencies of a musical scale spanning at least one octave.

Claims

1. A medical device for stimulating neurons of a patient to suppress a pathologically synchronous activity of the neurons, comprising: a stimulation unit configured for selectively generating acoustic stimuli to be administered to the patient; and a control unit for actuating the stimulation unit to generate a plurality of stimuli of different frequencies, wherein the control unit is configured to determine a target frequency range within a hearing range of the patient in dependence on an auditory perception of the patient and to select the plurality of stimuli such that the frequencies of the plurality of stimuli are within the target frequency range and correspond to tone frequencies of a musical scale spanning at least one octave.

2. The medical device according to claim 1, wherein the control unit (20) is configured to determine the target frequency range in dependence on a subjective evaluation of the auditory perception of the patient.

3. The medical device according to claim 1, wherein the control unit is configured to determine the target frequency range in dependence on an evaluation of at least one frequency-dependent characteristic of the auditory perception of the patient.

4. The medical device according to claim 1, wherein the control unit is configured to determine the target frequency range in dependence on at least one of an audiogram determination procedure, a psychoacoustic tinnitus spectrum determination procedure, a procedure for determining auditory hallucinations, a similarity measure procedure, or a procedure for determining pleasantness or unpleasantness of different tones experienced by the patient.

5. The medical device according to claim 1, wherein the musical scale comprises a pitch pattern consisting of a plurality of pitches per octave.

6. The medical device according to claim 1, wherein the musical scale is a pentatonic scale.

7. The medical device according to claim 1, wherein the control unit is configured to select the frequencies of the plurality of stimuli from a set of frequencies defined as:
F={f.sub.i,j|i is an integer; 1i5; j is an integer; and 1jJ}, wherein F refers to the set of frequencies; i indicates one of five different pitches of one octave; J refers to a total number of octaves; j indicates one of the J total number of octaves; f.sub.i,j refers to one frequency in the set of frequencies, and wherein the frequencies in the set of frequencies are calculated according to at least one of the following equations: $f_{1,j}=2^{j-1}{f}_0,$ $f_{2,j}=2^{j-1}\frac{9}{8}{f}_0,$ $f_{3,j}=2^{j-1}\frac{5}{4}{f}_0,$ $f_{4,j}=2^{j-1}\frac{3}{2}{f}_0,$ $f_{5,j}=2^{j-1}\frac{5}{3}{f}_0,$ wherein f.sub.0 refers to a basic frequency.

8. The medical device according to claim 1, wherein the control unit is configured to define for each one of the plurality of stimuli a frequency and an amplitude, and wherein the control unit is configured to determine the amplitude of a stimulus in dependence on the frequency of the stimulus.

9. The medical device according to claim 1, wherein the control unit is configured to actuate the stimulation unit to variedly generate the plurality of stimuli.

10. The medical device according to claim 1, wherein the control unit is configured to actuate the stimulation unit to subsequently generate different compound stimuli, each of which is constituted by at least one of the plurality of stimuli.

11. The medical device according to claim 10, wherein the control unit is configured for selectively and intermittently actuating the stimulation unit in a sequence of subsequent actuation periods, wherein one compound stimuli is allocated to each actuation period.

12. The medical device according to claim 1, wherein the control unit is configured to vary a set of stimuli comprising the plurality of stimuli during operation of the medical device.

13. The medical device according to claim 1, wherein the control unit is configured to determine for each stimulus of the plurality of stimuli, an occurrence probability coefficient, and wherein the control unit is configured to control actuation of the stimulation unit in dependence on the occurrence probability coefficients.

14. The medical device according to claim 13, wherein the control unit is configured: to determine the individual occurrence probability coefficients in dependence on the frequency of their associated stimulus; or to determine individual occurrence probability coefficients in dependence on a value of the frequency-dependent characteristic of the auditory perception of the patient related to its associated stimulus.

15. A method comprising using the medical device of claim 1 to treat a pathologically synchronous activity of neurons of the patient.

16. The medical device of claim 3, wherein the at least one frequency-dependent characteristic is at least one of an auditory threshold, a contribution to a tinnitus sensation of the patient, a similarity to auditory hallucinations perceived by the patient, or a degree of pleasantness or unpleasantness experienced by the patient.

17. The medical device according to claim 5, wherein the pitch pattern defines an ascending interval pattern between pitches which repeats among octaves.

18. The medical device according to claim 6, wherein the musical scale is an anhemitonic scale or major pentatonic scale.

19. The medical device according to claim 12, wherein the control unit is configured to vary the set of stimuli after a predetermined period of time or in dependence on an input or feedback of the patient.

20. The medical device according to claim 10, wherein the control unit is configured to: determine for each compound stimulus, an occurrence probability coefficient, wherein the control unit is configured to: determine individual occurrence probability coefficients in dependence on the frequencies of stimuli comprised in an associated compound stimuli; or to determine individual occurrence probability coefficients in dependence on a value of a frequency-dependent characteristic of the auditory perception of the patient related to its associated compound stimuli; and control actuation of the stimulation unit in dependence on the occurrence probability coefficients.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0092] The present disclosure will be more readily appreciated by reference to the following detailed description when being considered in connection with the accompanying drawings in which:

[0093] FIG. 1 is a schematic view of a medical device in a state in which therapeutic treatment is provided to a patient;

[0094] FIG. 2 shows a flow diagram depicting a use of the medical device shown in FIG. 1 for performing therapeutic treatment;

[0095] FIG. 3 shows a schematic diagram depicting an evaluation function determined by the medical device depicted in FIG. 1; and

[0096] FIG. 4 shows a schematic actuation sequence according to which a stimulation unit of the medical device depicted in FIG. 1 is operated.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0097] In the following, the invention will be explained in more detail with reference to the accompanying Figures. In the Figures, like elements are denoted by identical reference numerals and repeated description thereof may be omitted in order to avoid redundancies.

[0098] FIG. 1 depicts a medical device 10 for stimulating neurons of a patient 12 which is used to treat a pathologically synchronous activity of the neurons of the patient 12. In other words, the medical device 10 is intended to be used for the treatment of neurological or psychiatric disorders or diseases caused by a pathologically synchronous neuronal activity.

[0099] The medical device 10 is a non-invasive therapeutic device which, for acting upon the patient 12, comprises a stimulation unit 14 configured for selectively generating acoustic stimuli to be administered to the patient 12. Specifically, the stimulation unit 14 is provided in the form of earphones or in-ear phones, also referred to as earbuds, comprising a first acoustic source 16 and the second acoustic source 18 provided in the form of loudspeaker drivers which are attachable to the patient's ear canal, as can be gathered from FIG. 1. In one configuration, the stimulation unit 14 may be provided in the form of earphones having a case that fits behind the ear and ear buds attachable to the patient's ear canal. The case may accommodate electronics and may be connected to an ear mould accommodating the ear buds by a clear tube that wraps around the top of a patient's ear. Alternatively, the stimulation unit may be provided in the form of headphones which are attachable to the patient's ears. Each one of the first and the second acoustic source 16, 18 is configured to generate acoustic stimuli, in particular sound stimuli in the form of sound waves or tones, of a desired characteristic, i.e. of desired frequency and a desired amplitude, also referred to as loudness and intensity.

[0100] The medical device 10 further comprises a control unit 20 for actuating the stimulation unit 14 to generate a plurality of stimuli of different frequencies. In other words, the operation of the stimulation unit 14 is controlled by means of the control unit 20. The control unit 20 is communicatively connected to the stimulation unit 14 as indicated by dashed lines in FIG. 1 so as to transmit control signals to the stimulation unit 14. For doing so, the control unit 20 may be connected to the stimulation unit 14 via a signal line or wirelessly.

[0101] Specifically, the control unit 20 is provided in the form of or as a part of a mobile device, such as a smart phone or tablet computer, having a display unit 22 in the form of a touch screen providing an interface for the patient 12 or a medical personnel supervising the therapeutic treatment. For providing the therapeutic treatment, a corresponding application installed on the mobile device may be executed. In a further development, an additional device may be provided which may be for exclusive use of the medical personnel. The additional device may be connected to the control unit 20 and may have further or different functionalities, such as downloading or inspecting the archive of entries. The additional device may be a mobile or stationary device and may be configured to receive feedback information from the medical personnel.

[0102] The display unit 22 is configured to provide visual information to the patient 12 or the medical personnel. Further, the display unit 22, by being provided in the form of a touch screen, is configured for receiving input or feedback information inputted by the patient 12 or the medical personnel via the touch screen. In this way, an interface for interaction between the medical device 10 and a user is provided by the touch screen which enables, on the one hand, to provide the user with information about the therapeutic treatment and, on the other hand, to provide the medical device 10 with information, in particular feedback information, from the user inputted via the touchscreen.

[0103] In the following, with reference to FIG. 2, the use of the medical device 10 to treat a pathologically synchronous activity of neurons of the patient 12 is described.

[0104] The general procedure performed by the medical device 10 is differentiated between an initializing procedure 24 and a treatment procedure 26. The initializing procedure 22 is intended to define a set S of different stimuli constituting a plurality of stimuli of different frequencies which are to be administered to the patient 12 by the stimulation unit 14. This procedure is performed by the control unit 20 together with the stimulation unit 14 and the display unit 22. Thereafter, in the treatment procedure 26, the control unit 20 actuates the stimulation unit 14 such that individual stimuli and/or a combination of individual stimuli of the plurality of stimuli S are successively generated, i.e. in an actuation sequence AS one after another.

[0105] In the initializing procedure 24, the control unit 20 selects the plurality of stimuli S so as to suppress or to contribute to the suppression of the pathologically synchronous neuronal activity upon being administered to the patient 12. To that end, the plurality of stimuli S is selected such that at least a part of the plurality of stimuli S activates the neuronal population affected by the pathologically synchronous activity when being administered to the patient 10.

[0106] Upon performing the initializing procedure 24, in a first step S1, the control unit 20 determines a target frequency range or set R.sub.target within a patient's hearing range in dependence on a patient's auditory perception. Thereafter, in step S2, the control unit 20 selects the plurality of stimuli S such that the frequency of each stimuli comprised in the set S of plurality of stimuli is within the determined frequency range R.sub.target and corresponds to a tone frequency of a musical scale spanning at least one octave.

[0107] In the following, an embodiment is described in which the medical device 10 is used to treat tinnitus.

[0108] As set forth above, in the first step S1, the control unit 20 determines the target frequency range R.sub.target which refers to a set or range from which individual stimuli of the plurality of stimuli S are selected. This is performed in dependence on a subjective evaluation of the patient's auditory perception, i.e. based on an assessment evaluated or performed by the patient. To that end, at least one frequency-dependent characteristic of the patient's auditory perception is evaluated by the patient 12. In other words, the control unit 20 is configured to determine the target frequency range in dependence on a subjective evaluation of at least one frequency-dependent characteristic of the patient's auditory perception. In the shown configuration, the frequency-dependent characteristic refers to an amount of contribution of a tone to a patient's overall tinnitus sensation. In other words, the frequency-dependent characteristic indicates how a frequency of a tone contributes to a patient's overall tinnitus sensation. For doing so, the control unit 20 performs an evaluation procedure according to sub-steps S1.1 to S1.3 which, in the shown configuration, is a psychoacoustic tinnitus spectrum determination procedure.

[0109] In a first sub-step S1.1, the control unit 20 is configured to administer a plurality of test tones to the patient 12, i.e. acoustic stimuli at a predefined frequency and a pre-defined loudness. This is performed by means of the stimulation unit 14. In this sub-step, the control unit 20 selects a set of different frequencies which are associated to the different test tones. In the shown configuration, the control unit 20 selects frequencies which correspond to a pentatonic scale, in particular a major pentatonic scale. For doing so, the control unit 20, at first, selects a basic frequency f.sub.0, for example 100 Hz or 400 Hz, and a number I of octaves which should be covered by the test tones. Specifically, the number of octaves may be two, three, four or more than four. Then, the control unit selects a predetermined number of frequencies, for example all frequencies, from the following set of frequencies F:

F={f.sub.i,j|i and 1i5; j and 1jJ}(28)

wherein i indicates one of five different pitches or tones of one octave; J refers to the total number of octaves; j indicates one of the J different octaves; f.sub.i,j refers to one frequency comprised in the set of frequencies, and wherein the frequencies comprised in the set of frequencies F are calculated according to the following equations:

[00006]$\begin{array}{cc}{f}_{1,j}=2^{j-1}{f}_0,& \left(29\right)\end{array}$$\begin{array}{cc}{f}_{2,j}=2^{j-1}\frac{9}{8}{f}_0,& \left(30\right)\end{array}$$\begin{array}{cc}{f}_{3,j}=2^{j-1}\frac{5}{4}{f}_0,& \left(31\right)\end{array}$$\begin{array}{cc}{f}_{4,j}=2^{j-1}\frac{3}{2}{f}_0,& \left(32\right)\end{array}$$\begin{array}{cc}{f}_{5,j}=2^{j-1}\frac{5}{3}{f}_0,& \left(33\right)\end{array}$

[0110] The test tones associated to the thus selected frequencies are administered one after the other to the patient 12 in a sequence. The sequence of the test tones may be defined such that the test tones are generated according to their ascending or descending frequencies or according to any other order or according to an arbitrary order.

[0111] In sub-step S1.2, for each test tone administered, the patient 12 evaluates or scores the characteristic which is associated to the patient's subjective perception of the corresponding test tone. That is, the patient 12 evaluates a contribution of the test tone to its overall tinnitus sensation. For doing so, the patient or the medical personnel inputs feedback information via the display unit 22, wherein the feedback information indicates and quantifies the patient's subjective perception of the corresponding test tone.

[0112] Based on this feedback information, in sub-step S1.3, the control unit 20 is configured to generate a set E of data points DP.sub.1, . . . ,G, each of which associates a quantified characteristic to a frequency of the corresponding test tone or sound. This set E of data points DP.sub.1, . . . ,G, constitutes an evaluation function and may be expressed according to equation (1). The set E of data points DP.sub.1, . . . ,G, is illustrated in the diagram shown in FIG. 3, wherein the abscissa of the diagram depicts the frequency of the patient's hearing range and the ordinate of the diagram depicts the quantified amount of the characteristic, i.e. the amount of contribution to the patient's overall tinnitus sensation.

[0113] Optionally, the control unit 20 may be configured to estimate further data points in order to supplement the evaluation function with further data points which go beyond the determined set E. Specifically, this step may be performed so as to obtain an evaluation function in the form of a continuous function E(v) as depicted in FIG. 3 by a dashed line. For doing so, interpolation and extrapolation techniques may be applied.

[0114] Further, in sub-step 1.4, the control unit 20 determines the target frequency range in dependence on the determined evaluation function E. At first, the control unit 20 determines a maximum scoring h.sub.E, i.e. a maximum value of the quantified characteristic, within the hearing range. Then, based on the determined maximum scoring h.sub.E, the control unit 20 is configured to determine a threshold value h.sup.th according to above equation (2), wherein the factor c is set to equal 0.25, but may also attain different pre-set values.

[0115] Based on the threshold value h.sub.th, the control unit 20 then determines the target frequency range R.sub.target by, at first, identifying frequency intervals I.sub.1, . . . ,H in which the associated values of the evaluation function E(v) are equal to or exceed the threshold value h.sub.th. These intervals I.sub.1, . . . ,H constitute the target frequency range R.sub.target which can be expressed according to the above equations (3) and (4).

[0116] According to an alternative configuration, the medical device 10 may be configured to determine the target frequency range in dependence on an evaluation of a further or alternative frequency-dependent characteristic of the patient's auditory perception. For example, the further or alternative frequency-dependent characteristic may be at least one of an auditory threshold, a similarity to auditory hallucinations perceived by the patient, and a degree of pleasantness or unpleasantness experienced by the patient. Accordingly, the medical device 10, in particular the control unit 20, may be configured to determine the target frequency range in dependence on at least one of an audiogram determination procedure; a psychoacoustic tinnitus spectrum determination procedure; a procedure for determining or evaluating auditory hallucinations; a similarity measure procedure; and a procedure for determining pleasantness and/or unpleasantness of different tones.

[0117] In the next step S2 of the initializing procedure 24, the control unit 20 determines the set S of plurality of stimuli based on the target frequency range R.sub.target and a musical scale which, in the shown configuration, is a pentatonic scale, i.e. a major pentatonic scale. Specifically, in this step, the control unit 20 selects the plurality of stimuli S such that the frequencies of the different stimuli of the set S are within the determined frequency range R.sub.target and correspond to tone frequencies of a major pentatonic scale spanning at least one octave, for example two or three or four or five or more octaves.

[0118] For doing so, the control unit 20 determines a basic frequency f.sub.0 in sub-step S2.1 and based thereupon, in sub-step S2.2, determines a set of frequencies F constituting a major pentatonic scale according to the above equations (28) to (33). Then, in sub-step S2.3, the control unit selects those frequencies of the set of frequencies F constituting the pentatonic scale which lie within the target frequency range R.sub.target determined in step S1. Each of the selected frequencies is then associated to one individual stimuli thereby forming the plurality of stimuli S.

[0119] Based on the selected frequencies associated to individual stimuli, the control unit 20 determines an amplitude, i.e. a loudness level, for each stimuli of the plurality of stimuli S in dependence on the corresponding frequency. Specifically, this may be performed by applying a loudness match procedure. In such a procedure, neighboring tones may be pairwise administered to the patient and their loudness level stepwise adjusted based on a user feedback such that loudness of the different selected stimuli are perceived as equal or substantially equal by the patient 12. As a result, the set S of plurality of stimuli is determined, wherein each stimulus s comprised in the set S of the plurality of stimuli is defined by a frequency f and an amplitude A as expressed by above equations (14) and (15).

[0120] After the set S of plurality of stimuli is defined, the medical device 10 is operated according to the treatment procedure 26. During this procedure, the medical device 10 is operated such that the stimulation unit 14 variedly generates the plurality of stimuli. Specifically, the control unit 14 is configured for actuating the stimulation unit to successively generate different compound stimuli each of which is constituted by or consists of at least one of the plurality of stimuli S.

[0121] FIG. 4 exemplary depicts an actuation sequence AS according to which the stimulation unit 14 is actuated by the control unit 20. As can be gathered from FIG. 4, the control unit 20 may be configured for selectively and intermittently actuate the stimulation unit 14 in a sequence of subsequent actuation periods TA, wherein to each actuation period TA one compound stimuli C is allocated. In other words, during the actuation periods TA, the stimulation unit 14 is actuated so as to generate the compound stimulus C associated thereto.

[0122] The control unit 20 may be configured for actuating the stimulation unit 14 such that subsequent compound stimuli C are generated directly one after the other, i.e. without a pause interval therebetween. Preferably, the control unit 14 is configured for actuating the stimulation unit 14 such that between subsequent compound stimuli C, i.e. between subsequent actuation periods TA, a resting period TR is scheduled during which no stimuli or no compound stimuli C are generated by the stimulation unit 14. The duration of the actuating periods TA and the resting periods TR may be of the same length or may vary among the actuation sequence AS.

[0123] In a first step S3 of the treatment procedure 26, the control unit 20 is configured to determine a plurality of weighting factors .sub.1, . . . ,P, which indicate the occurrence probability of compound stimuli of the different orders in the actuation sequence AS. In other words, the weighting factors .sub.1, . . . ,P, indicates how often compound stimuli of a specific order are to be applied during the treatment. Compound stimuli having an order of 1 are constituted by one individual stimuli. By contrast, compound stimuli having an order of 2 are constituted by two individual stimuli which are administered simultaneously to the patient 12. Accordingly, compound stimuli having an order of P are constituted by a number of P different individual stimuli which are administered simultaneously to the patient 12. The highest order P may be limited to, for example, a number of three or four. According to another configuration, the highest order P may be limited to, for example, a number of six, seven or a higher number. By defining varying weighting factors .sub.p for the different orders of the stimuli, the application of specific orders of compound stimuli may be promoted for relatively higher values of the corresponding weighting factor or lowered for relatively lower values of the corresponding weighting factor.

[0124] According to one configuration, the step S3 of determining the weighting factors .sub.1, . . . ,P may be performed in dependence on an input of the patient 12. For example, on the display unit 22, a plurality of sliders may be presented to the patient 12, each of which is associated to one weighting factor of a specific order. In this way, the patient 12 may manipulate the individual sliders so as to adjust and set the different weighting factors .sub.1, . . . ,P.

[0125] In a next step S4, the control unit 20 determines for each stimulus s of the plurality of stimuli S and for each compound stimulus C an occurrence probability coefficient w. Specifically, the occurrence probability coefficients w are determined as a function of the frequencies of stimuli comprised in the associated compound stimuli C. More specifically, the occurrence probability coefficients w are determined as a function of a value of the frequency-dependent characteristic of the patient's auditory perception related to its associated stimulus or compound stimuli C. In the shown configuration, the occurrence probability coefficients w may be calculated according to above equations (22) to (27). Alternatively or additionally, the control unit may be configured to calculate the occurrence probability coefficients variedly over time, e.g. by employing an exponential distribution process and/or a Markov process and/or any other suitable stochastic or deterministic or combined stochastic-deterministic process.

[0126] Then, in step S5, the control unit 20 is configured to control actuation of the stimulation unit 14 in dependence on the determined occurrence probability coefficients. Specifically, the control unit 20 is configured to select for each actuation period one compound stimuli C as given by the occurrence probability coefficients w.

[0127] According to one configuration, the control unit 20 may be configured to operate the stimulation unit 14 in a first operating mode in which exclusively or predominantly compound stimuli of the first order are generated. In other words, in this operating mode, the weighting factors which do not correspond to the first order are set equal to zero, whereas the weighting factor .sub.1 corresponding to the first order is set greater than zero. Then, after a predetermined period of time, the control unit 20 may be configured to determine whether the patient 12 responds to the provided therapy, e.g. by determining whether the tinnitus loudness has decreased by a predetermined factor, e.g. by 25% or 50%. For example, this determination may be based on a feedback provided by the patient 12. If the control unit 20 determines that the patient 12 does not respond to the provided therapy, the control unit 20 is configured to operate the stimulation unit 14 in a second operating mode in which compound stimuli of the first and second order are generated. For doing so, the control unit may go to step S3 to set the weighting factors .sub.1,2 of the first and the second order to be greater than 0. Thereafter, steps S4 and S5 are performed. Optionally, again, after a predetermined period of time, the control unit 20 determines whether the patient 12 responses to the provided therapy. If the control unit 20 determines that the patient 12 does not respond to the provided therapy, the control unit 20 is configured to operate the stimulation unit 14 in a third operating mode in which compound stimuli of the first, the second and the third and/or fourth order are generated. For doing so, the control unit may go to step S3 to set the weighting factors .sub.1-4 of the first, the second and the third and/or fourth order to be greater than 0. Thereafter, steps S4 and S5 are performed.

[0128] According to a further configuration, the control unit 20 is configured to vary the set S of stimuli constituting the plurality of stimuli during operation of the medical device 10. This may be performed after a predetermined period of time, for example after a few minutes, or in dependence on an input or feedback of the patient 12. For doing so, the control unit 20 is configured to go from step S5 to step S2.1 to vary the basic frequency f.sub.0. Thereafter, steps S2.2 to S.5 are executed.

[0129] In the shown configuration, the stimulation unit 14 is configured to provide acoustic stimuli in the form of sound stimuli. Alternatively or additionally, the stimulation unit may be configured to generate acoustic stimuli in the form of at least one of vibratory stimuli, electric stimuli and optoacoustic laser stimuli, e.g. which may be provided to the inner ear of the patient to be perceived by the hearing or auditory sense of the patient.

[0130] Specifically, the stimulation unit may comprise at least one vibrator which conducts vibratory stimuli to the inner ear via bone condition. These vibratory stimuli may exhibit the same frequency features as the sound stimuli described above. Further, the stimulation unit may be equipped with at least one means configured to deliver electric stimuli, in particular transtympanal electric stimuli. Specifically, for delivering transtympanal electric stimuli to the promontory, a needle electrode through the tympanic membrane may be used. The electric stimuli may be provided in pulses having a modulation rate at a desired frequency. The frequency of the modulation rate may exhibit the same frequency features as the sound stimuli described above. Further, the stimulation unit may be equipped with at least one means configured to deliver optoacoustic laser stimuli, for example, with a laser pulse rate of e.g. 32 kHz or 50 kHz and a laser modulation rate at a desired frequency as given by the frequencies described above.

[0131] It will be obvious for a person skilled in the art that these embodiments and items only depict examples of a plurality of possibilities. Hence, the embodiments shown here should not be understood to form a limitation of these features and configurations. Any possible combination and configuration of the described features can be chosen according to the scope of the invention.