Abstract:
A device having a first stimulation unit that generates electrical first stimuli suppressing a pathological synchronous activity of neurons in the brain and/or spinal cord of a patient upon administering the same to the brain and/or spinal cord of the patient, a second stimulation unit that generates optical and/or acoustic and/or tactile and/or vibratory second stimuli, and a controller that controls the first and the second stimulation units. The generation of the first and second stimuli optionally occurs in a first or in a second operating mode, and the controller actuates the first and the second stimulation units such that in the first operating mode the generation of at least 60% of the second stimuli is chronologically coupled to the generation of the first stimuli, and in the second operating mode the generation of at least 60% of the second stimuli is carried out without generating the first stimuli.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage of PCT/EP2009/007452, filed on Oct. 16, 2009, which claims the benefit of German Application No. 10 2008 052 078.0, filed on Oct. 17, 2008, all of which are incorporated by reference herein. 
     BACKGROUND 
     In the case of patients with neurological or psychiatric diseases, e.g. Parkinson&#39;s disease, essential tremor, dystonia, obsessive disorders, nerve cell networks exhibit pathological (abnormal) activity, e.g. excessively synchronous activity, in circumscribed regions of the brain, e.g. in the thalamus and the basal ganglia. In this case, a large number of neurons synchronously form action potentials, i.e. the involved neurons fire excessively synchronously. By contrast, in healthy individuals the neurons fire in a qualitatively different fashion in these regions of the brain, e.g. in an uncorrelated fashion. 
     In the case of Parkinson&#39;s disease, the pathologically (abnormally) synchronous activity changes the neuronal activity in other regions of the brain, e.g. in areas of the cerebral cortex such as the primary motor cortex. Here, the pathologically synchronous activity in the region of the thalamus and the basal ganglia impresses its rhythm onto the areas of e.g. the cerebral cortex, and so, ultimately, the muscles controlled by these areas develop a pathological activity, for example rhythmic trembling (tremor). 
     Neurological and psychiatric diseases with excessively pronounced neuronal synchronization are currently treated by electrical brain stimulation if medicinal therapy fails. 
     SUMMARY 
     A device having a first stimulation unit that generates electrical first stimuli suppressing a pathological synchronous activity of neurons in the brain and/or spinal cord of a patient upon administering the same to the brain and/or spinal cord of the patient, a second stimulation unit that generates optical and/or acoustic and/or tactile and/or vibratory second stimuli, and a controller that controls the first and the second stimulation units. The generation of the first and second stimuli optionally occurs in a first or in a second operating mode, and the controller actuates the first and the second stimulation units such that in the first operating mode the generation of at least 60% of the second stimuli is chronologically coupled to the generation of the first stimuli, and in the second operating mode the generation of at least 60% of the second stimuli is carried out without generating the first stimuli. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following text, the system and method will be explained in more detail in an exemplary fashion with the aid of the drawings, in which: 
         FIG. 1  shows a schematic illustration of a device  100  for conditioned desynchronizing stimulation as per an exemplary embodiment, during operation; 
         FIGS. 2A and 2B  show schematic illustrations of two different modes of operation of the device  100 ; 
         FIG. 3  shows a schematic illustration of a device  300  for conditioned desynchronizing stimulation as per a further exemplary embodiment, during operation; 
         FIG. 4  shows a schematic illustration of an exemplary embodiment of a stimulation electrode  14 ; 
         FIG. 5  shows a schematic illustration of the device  100  with the stimulation electrode  14 , during operation; 
         FIG. 6  shows a schematic illustration of specific electrical stimuli that are applied by means of a plurality of stimulation contact surfaces; 
         FIG. 7  shows a schematic illustration of sequences of electrical pulse trains, which are applied by means of a plurality of stimulation contact surfaces; 
         FIG. 8  shows a schematic illustration of an electrical pulse train; 
         FIG. 9  shows a schematic illustration of a variation of the stimulation shown in  FIG. 6 ; 
         FIG. 10  shows a schematic illustration of a further variation of the stimulation shown in  FIG. 6 ; 
         FIG. 11  shows a schematic illustration of the device  100  for conditioned desynchronizing stimulation as per an exemplary embodiment, during operation; 
         FIGS. 12A and 12B  show schematic illustrations of an exemplary embodiment of a stimulation unit for producing and applying non-specific optical stimuli, acoustic stimuli, tactile stimuli and vibration stimuli; and 
         FIG. 13  shows a schematic illustration of a further exemplary embodiment of a stimulation unit for producing and applying acoustic stimuli. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates a device  100  for conditioned desynchronizing stimulation. The device  100  consists of a control unit  10 , a first stimulation unit  11  and a second stimulation unit  12 . The first stimulation unit  11  produces electrical first stimuli  21  and the second stimulation unit produces sensory second stimuli  22 . The sensory second stimuli  22  are one or more stimuli from the group of optical stimuli, acoustic stimuli, tactile stimuli and vibration stimuli. The control unit  10  serves to control the two stimulation units  11  and  12  by means of control signals  23  and  24 . 
     The device  100  can in particular be used for the treatment of neurological or psychiatric diseases, e.g. Parkinson&#39;s disease, essential tremor, dystonia, epilepsy, tremor as a result of multiple sclerosis or other pathological tremor, depression, motor disturbance, cerebellar diseases, obsessive disorders, Tourette&#39;s syndrome, functional disorders after a stroke, spasticity, tinnitus, sleep disorders, schizophrenia, substance dependencies, personality disorders, attention-deficit disorder, attention-deficit hyperactivity disorder, pathological gambling, neuroses, bulimia, burnout syndrome, fibromyalgia, migraine, cluster headache, general headache, neuralgia, ataxia, tic disorder or hypertonia, but also for the treatment of other diseases. 
     The aforementioned diseases can be caused by a disorder in the bioelectric communication of neural networks, which are connected in specific circuits. Herein, a neuron population continuously generates abnormal (pathological) neuronal activity and possibly an abnormal connectivity (network structure) associated therewith. In the process, a large number of neurons form action potentials at the same time, i.e. the involved neurons fire in an overly synchronous fashion. Additionally, the sick neuron population exhibits an oscillatory neuronal activity, i.e. the neurons fire rhythmically. In the case of neurological or psychiatric diseases, the average frequency of the abnormal (pathological) rhythmic activity of the affected neural networks lies approximately in the region of 1 to 30 Hz, but it can also lie outside of this range. By contrast, the neurons fire qualitatively differently in healthy humans, e.g. in an uncorrelated fashion. 
     In  FIG. 1 , the device  100  is illustrated in its intended operational state. During operation, the electrical first stimuli  21  are applied to the brain  29  and/or spinal cord  29  of a patient. At least one neuron population  30  in the brain  29  or spinal cord  29  of the patient has an pathologically synchronized neuronal activity as described above. In order to produce and apply the first stimuli  21 , the first stimulation unit  10  can contain a generator unit  13  and at least one stimulation electrode  14 . The generator unit  13  produces the first stimuli  21 , which are transmitted to the stimulation electrode  14  by means of suitable connection lines. The stimulation electrode  14  has been placed into the brain  29  or into the region of the spinal cord  29  of the patient by surgery such that the first stimuli  21  are administered to the pathologically active neuron population  30 , or at least to regions of the brain  29  or spinal cord  29  from where the first stimuli  21  are transmitted to the pathologically active neuron population  30  via the nervous system. The first stimuli  21  are embodied such that they suppress the pathologically synchronous activity of the neuron population  30  or even lead to a desynchronization of the neuron population  30 . Since the first stimuli  21  are therapeutically effective electrical stimuli, they are also referred to as “specific” stimuli. 
     The second stimulation unit  12  produces optical, acoustic, tactile and/or vibratory second stimuli  22 . The optical and/or acoustic second stimuli  22  are taken in by the eyes and ears, respectively, of the patient and are transmitted to the nervous system. The tactile second stimuli  22  can be pressure and/or touch stimuli, which are recorded by receptors situated in the skin of the patient. More particularly, these receptors include Merkel cells and Ruffini endings, which act as pressure receptors and, more particularly, as intensity detectors, and also Meissner&#39;s corpuscles and hair follicle receptors, which act as touch sensors and, more particularly, as velocity detectors. In contrast to the tactile second stimuli  22  relating to the surface sensitivity of the skin, the vibratory second stimuli  22  are predominately directed at the depth sensitivity. The vibratory second stimuli  22  can be recorded by receptors situated in the skin, the muscles, the subcutaneous tissue and/or the tendons of the patient. Pacinian corpuscles are mentioned in an exemplary fashion as receptors for the vibratory second stimuli  22 ; they impart vibration sensations and accelerations. 
     The second stimuli  22  can be consciously perceived by the patient and, more particularly, are not unpleasant for the patient. Applied on their own (i.e. without the interaction with the first stimuli  21  in the learning phase, as described below), the sensory second stimuli  22  do not have, or hardly have, a desynchronizing effect or a coincidence-rate-decreasing effect on the abnormally (pathologically) synchronous neuronal activity of the neuron population  30 . The second stimuli  22  applied by the second stimulation unit  12  are therefore also referred to as “non-specific” stimuli. 
     In order to apply the first and second stimuli  21  and  22 , the device  100  can be operated in two different modes of operation. By way of example, the respective mode of operation can be prescribed or can be selected by the control unit  10 . The control unit  10  actuates the two stimulation units  11  and  12  in accordance with the selected mode of operation. 
     In a first mode of operation, which is also referred to as a learning phase, the non-specific second stimuli  22  are at least partly administered to the patient such that they are coupled closely in time to the application of the specific first stimuli  21 , i.e. the first and second stimuli  21  and  22  are at least partly administered in pairs in the first mode of operation. This conditions the nervous system of the patient, i.e. said nervous system learns to react to the non-specific second stimuli  22  as it does to the specific first stimuli  21 , even if the specific first stimuli  21  are not being applied. This is exploited by virtue of the fact that in the second mode of operation, which is the actual stimulation phase, the first and second stimuli  21  and  22  are not always administered in pairs; rather, non-specific second stimuli  22  are also applied on their own between such pairs of first and second stimuli  21  and  22 . Since the second stimuli  22  also achieve therapeutic effects as a result of the conditioning of the nervous system of the patient achieved in the first mode of operation, i.e. in the learning phase, the necessary current input into the tissue of the patient required for the therapy is lowered in the second mode of operation, i.e. in the actual stimulation phase. Compared to conventional electrical brain stimulation, the current input can be reduced by e.g. up to a factor of 10 or more by means of the device  100 . 
     An advantage of the significantly reduced current input is that there is a significant reduction in the probability of side effects occurring. This is because as the amount of applied stimulation current increases, there is an increase in the probability of stimulating not only the target area but also adjoining areas as well. This leads to a number of side effects, which are known to a person skilled in the art and in part are very unpleasant for the patient. 
     A further advantage of the reduced current input over a conventional stimulation method is that the reduced current input for stimulation purposes goes hand in hand with significantly reduced energy requirements of the generator unit, which is usually implanted into the patient. Since the dimensions of the battery decisively determine the dimensions of the generator unit, this allows the design of a smaller generator unit. The patient is much more comfortable with this, inter alia for cosmetic reasons. Moreover, there is a reduced risk of infection in the generator pouch, which correlates with the dimensions of the generator unit. Depending on the dimensions of the generator unit, the risk of infection in currently utilized generator units is approximately 5%; that is to say approximately 5% of patients develop an infection in the generator pouch, i.e. the tissue surrounding the generator unit, after the generator unit was implanted. As a result of the significant reduction in the current input, the generator dimensions can ultimately be e.g. minimized such that the entire generator unit can be placed into the hole drilled into the cranial bones. 
       FIGS. 2A and 2B  illustrate, in the form of a graph and in an exemplary fashion, the differences in the application of the first and second stimuli  21  and  22  in the first and the second mode of operation. In  FIG. 2A , first time intervals Δt 1  and second time intervals Δt 2  are plotted, one above the other, against time t, during which time intervals the first stimuli  21  and the second stimuli  22  are generated and administered to the patient in the first mode of operation. The time intervals Δt 1  and Δt 2  are respectively represented by rectangles.  FIG. 2A  shows that, in the first mode of operation, the production and application of the non-specific second stimuli  22  is coupled to the production and application of the specific first stimuli  21 . The time intervals Δt 1  and Δt 2  occur in pairs during the learning phase. As a result of the paired application of the stimuli  21  and  22 , the brain  29  and/or spinal cord  29  of the patient is conditioned, i.e. once the learning phase has passed (e.g. already after two or more paired time intervals Δt 1  and Δt 2 ), even a non-specific second stimulus  22 , which is applied without an additional specific first stimulus  21 , causes a therapeutic effect like a specific first stimulus  21 . Prior to this learning phase, a non-specific second stimulus  22  would not have caused a therapeutic effect. 
     The duration of the time intervals Δt 1 , during which the specific first stimuli  21  are applied, lies e.g. between 30 minutes and 6 hours, but it can also lie outside of this range. The duration of the time intervals Δt 2 , during which the non-specific second stimuli  22  are applied, lies e.g. between 10 minutes and 6 hours, but it can also lie outside of this range. By way of example, the time intervals Δt 1  overlap with the respectively associated time intervals Δt 2  in the first mode of operation. This overlap Δt 12  equals e.g. at least 10% or 20% or 30% or 40% or 50% or 60% or 70% or 80% or at least 90% or even 100% of the respective time interval Δt 2 . In the case of time intervals Δt 1  and Δt 2 , which are associated with one another, the time interval Δt 2  can start first, as illustrated in  FIG. 2A ; however, alternatively, the time interval Δt 1  can also start first. There are pauses between successive pairs of first and second stimuli  21  and  22 , the length of which pauses Δt Pause  can lie e.g. between 3 hours and 24 hours. The lengths of the time intervals Δt 1  and Δt 2  and the overlap periods Δt 12 , and also the stimulation pauses Δt Pause  can be varied during a stimulation phase. The duration of the learning phase, i.e. the time during which the device is operated in the first mode of operation, can be prescribed and can, for example, comprise a prescribed number of paired time intervals Δt 1  and Δt 2 . 
     The following text describes examples of the application of the first and second stimuli  21  and  22  during the learning phase. According to one example, the first stimuli  21  and second stimuli  22  can be applied for a time interval Δt 1  of 6 hours and a time interval Δt 2  of 6.25 hours, respectively, with the time interval Δt 2  starting 15 minutes before the time interval Δt 1 , and both time intervals Δt 1  and Δt 2  therefore end at the same time. This process could be repeated after a pause Δt Pause  of e.g. 6 hours. In order to achieve rapid learning or conditioning of the nervous system, the number of learning events, i.e. the paired administration of first and second stimuli  21  and  22 , could be increased further compared to the preceding example. Thus, the time intervals Δt 1  and Δt 2  could be reduced e.g. to 3 and 3.125 hours respectively, with the time interval Δt 2  starting 7.5 minutes before the time interval Δt 1 . The coupled stimulation could be carried out again after a pause Δt Pause  of e.g. 3 hours. 
     A learning effect can possibly already set in after two applications of first and second stimuli  21  and  22  coupled together. In order to design a conditioning of the nervous system that is as robust as possible and be able to use the conditioning for as long as possible during the actual stimulation phase, it is possible to carry out e.g. 10 to 50 pair applications during the learning phase, i.e. during the first mode of operation. 
     During the learning phase, it is not necessary for each time interval Δt 2  to be associated with a time interval Δt 1 . By way of example, a time interval Δt 1  or Δt 2  can be inserted after a certain number of coupled-together time intervals Δt 1  and Δt 2 , which inserted time interval is not coupled to an associated time interval Δt 2  or Δt 1  and during which merely first stimuli  21  or second stimuli  22  are produced and applied. By way of example, at least 50% or 60% or 70% or 80% or 90% or even 100% of time intervals Δt 2  can be coupled to an associated time interval Δt 1  in the first mode of operation. Furthermore, at least 50% or 60% or 70% or 80% or 90% or even 100% of time intervals Δt 1  can be coupled to an associated time interval Δt 2  in the first mode of operation. 
     The actual stimulation phase follows the learning phase carried out in the first mode of operation. To this end, the control unit  10  switches into the second mode of operation.  FIG. 2B  plots, one above the other and in an exemplary fashion, the time intervals Δt 1  and Δt 2  over time t, during which time intervals the first stimuli  21  or the second stimuli  22  are produced and applied in the second mode of operation. 
     During the actual stimulation phase, use is made of the fact that non-specific second stimuli  22  also have a therapeutic effect as a result of the conditioning of the nervous system of the patient achieved during the learning phase. To this end, unlike the learning phase, it is not predominately pairs consisting of first and second stimuli  21  and  22  that are applied; rather, it is only second stimuli  22  that are also repeatedly applied during a time interval Δt 2 , which second stimuli are not coupled to the application of a first stimulus  21 . By way of example, at least 10% or 20% or 30% or 40% or 50% or 60% or 70% or 80% or 90% of the time intervals Δt 2  are not associated with a time interval Δt 1  in the second mode of operation, i.e., overall, the number of time intervals Δt 1  in the second mode of operation is lower than the number of second time intervals Δt 2 . According to one embodiment, time intervals Δt 1  that are not coupled to a time interval Δt 2  can also, on occasion, be inserted during the second mode of operation. According to a further embodiment, provision can e.g. also be made for none of the time intervals Δt 2  to be associated with a time interval Δt 1  in the second mode of operation. 
     The pairs “P” consisting of specific and non-specific stimuli  21  and  22 , and the individually applied non-specific stimuli “U” can be administered in e.g. periodic sequences during the second mode of operation, e.g. in the following sequence: P-P-U-U-U-P-P-U-U-U-P-P-U-U-U- . . . . The temporal pattern, according to which the non-specific second stimuli  22  occur alone, can however also be deterministic or stochastic or a deterministic-stochastic mixture; for example, the following sequence may be selected: P-P-U-U-U-P-P-U-U-U-U-U-P-P-U-U-U-P-P-U-U-P-P-U-U-U-U-U-P-P-U-U-U- . . . . 
     The stimulation effect achieved by means of the device  100  can for example be monitored with the aid of a measuring unit. A device  300  containing such a measuring unit  15  is illustrated schematically in  FIG. 3 . The remaining components of the device  300  are identical to the device  100  shown in  FIG. 1 . The measuring unit  15  records one or more measurement signals  25 , measured on the patient; converts these measurement signals into electrical signals  26  where necessary; and transmits said signals to the control unit  10 . In particular, the measuring unit  15  can measure the neuronal activity in the stimulated target area, i.e. e.g. the neuronal activity in the neuron population  30  illustrated schematically in  FIG. 3 , or it can measure the neuronal activity of an area connected to the neuron population  30 . 
     The measuring unit  15  in the form of one or more sensors can be implanted into the body of the patient. By way of example, deep brain electrodes, subdural or epidural brain electrodes, subcutaneous EEG electrodes and subdural or epidural spinal cord electrodes can serve as invasive sensors. Moreover, electrodes to be attached to peripheral nerves can also be used as sensors. By way of example, the invasive sensor can be the same electrode  14  that is also used to apply the first stimuli  21 . 
     The measurement signals  25  can be recorded in the pauses between the administration of the specific first stimuli  21 , but more particularly also when only the non-specific second stimuli  22  are being administered. Provided that the neuronal activity of the target population  30  is measured, the amplitude of the pathological oscillations can be established in typical frequency ranges of the local field potentials, that is to say e.g. the integrated power in the beta-wave region of between 10 and 30 Hz in the case of akinetic patients with Parkinson&#39;s disease. This amplitude drops in the case of an effective stimulation. If the stimulation effect of the solely applied non-specific second stimuli  22  drops off during the second mode of operation and the measured amplitude exceeds a prescribed threshold, the next learning phase in the first mode of operation can take place. This can again be followed by the actual stimulation in the second mode of operation. 
     The medical practitioner can set an individual threshold for each patient. Alternatively, typical values can be selected as a default setting for the threshold, e.g. the mean value of the amplitude plus twice the standard deviation in regions of the frequency spectrum without frequency peaks and above e.g. 70 Hz. 
     In addition to the invasive sensors or as an alternative thereto, use can also be made of one or more non-invasive sensors such as electroencephalography (EEG) electrodes, magnetoencephalography (MEG) sensors and electromyography (EMG) electrodes. Furthermore, an accelerometer, for example, can measure the pathological oscillatory activity in the tremor frequency region or hypokinesia (in the sense of a reduction of overall movement). If a prescribed value of the tremor activity is exceeded or a value drops below a critical value of the mean hourly activity (outside of nighttime hours), this initiates e.g. the next learning phase in the first mode of operation. 
     It is also feasible to use two thresholds for controlling the two modes of operation. By way of example, two thresholds A L  and A S  can be prescribed and used for a comparison with the amplitude of the pathological neuronal activity in the neuron population  30 , which amplitude was measured by the measuring unit  15 . The threshold A L  can be greater than the threshold A S  and constitute the more approximate of the two thresholds. If the amplitude of the beta-wave activity exceeds the value A L , a switch is carried out from the second mode of operation into the first mode of operation and a renewed learning phase is carried out. 
     Should the amplitude of the beta-wave activity exceed the more precise threshold A S  during the second mode of operation, the device  300  remains in the actual stimulation phase rather than switching into the first mode of operation, but there is an increased application of pairs “P” of specific first stimuli  21  and non-specific second stimuli  22 . By way of example, to this end, a subsequence only consisting of non-specific stimuli “U” (-U-U-U-U-U-) can be skipped, and a jump is made to the next section in the sequence that has pairs “P” of specific and non-specific stimuli  21  and  22 . Provided that, for example, a certain percentage of the second stimuli  22  are specified to be applied together with first stimuli  21  in the second mode of operation, this percentage of pairs “P” can be increased by a certain percentage when the threshold A S  is exceeded. By way of example, 30% of the second stimuli  22  are applied as pairs “P” together with first stimuli  21  in the second mode of operation. When the threshold A S  is exceeded, this percentage can, for example, be increased by 20% to 50%. As soon as the amplitude of the beta-wave activity thereafter drops below a further prescribed threshold it is possible to return again to the e.g. 30% provided in the second mode of operation. 
     The transition from the second into the first mode of operation can also be controlled by the patient by means of an external patient programming instrument. That is to say the patient has the option of pushing a button on a small, handy external instrument if the therapy seems insufficient, i.e. if e.g. the tremor or hypokinesia are too pronounced. Following a predefined mode, the control unit  10  then switches into the first mode of operation from the second mode of operation, i.e. it switches back into a new learning phase. Here, the predefined mode means that this switch over into the first mode of operation is already initiated by the first push of the button by the patient. However, the device  100  or  300  can also be set up by a medical practitioner such that the switch over into the first mode of operation is only brought about after a button is pushed a few times in a predefined time interval, e.g. after the button was pushed 3 times in half an hour. 
     In order to monitor the therapy, the device  100  or  300  registers the number of times the button is pushed, and the times associated therewith. This information can be read by the medical practitioner by means of an external programming instrument intended for the medical practitioner. 
     Provision can furthermore be made for there to be a switch back into the first mode of operation, i.e. the learning phase, from the second mode of operation after a predefined period of time. This switching mode does not necessarily require therapy monitoring with the aid of the measuring unit  15 , i.e. this switching mode can be implemented both in the device  100  and in the device  300 . 
     In order to generate the non-specific second stimuli  22 , the second stimulation unit  12  can contain e.g. a loudspeaker, a light source (or image source) and/or a vibrator. In general, the second stimuli  22  should be strong enough to be consciously perceived by the patient. However, they should not be perceived as e.g. unpleasantly strong or irritating or even distracting. By way of example, a buzzer sound, a humming sound or a melody are options for acoustic second stimuli  22  produced by the loudspeaker during the time intervals Δt 2 . Provided that optical signals are intended to be used as second stimuli  22 , these can be e.g. abstract or object-like, patterns, which either are static or change in time during the time intervals Δt 2 , e.g. a flower blowing in the wind, a fish swimming in water, a flying bird, a rising sun, etc. Tactile stimuli or vibration stimuli can be vibrations at frequencies that can be perceived by the patient and are produced by a mechanical vibrator during the time intervals Δt 2 . Perceptible vibration stimuli can have frequencies in the region of between 10 and 160 Hz or above, whereas tactile stimuli have significantly lower frequencies, which are e.g. lower than 1 Hz. Use can also be made of mixtures of tactile and vibratory stimuli. The tactile and/or vibratory stimuli can e.g. be selected for comfort by the patient him/herself. The vibrator can also be used to exert a light, pleasantly massaging effect on the skin of the patient during the time intervals Δt 2 . 
     The non-specific second stimuli  22  can be continuously administered to the patient from the beginning to the end of a respective time interval Δt 2 . Alternatively, there may also be pauses in the application during the time intervals Δt 2 ; by way of example, during the time intervals Δt 2 , the second stimuli  22  can be administered during certain time intervals interspersed by application pauses. These time patterns can also be varied, e.g. stochastically or deterministically or in a mixed stochastic-deterministic fashion. Provision can be made for the second stimuli  22  to be applied over at least 60% or 70% or 80% or 90% of the duration of each time interval Δt 2 . 
     Desynchronizing electrical stimulation signals, or electrical stimulation signals that at least reduce the coincidence rate of the pathological neurons, are used as specific first stimuli  21 . The stimulation electrode  14 , by means of which the first stimuli  21  are transmitted to the brain  29  or spinal cord  29  of the patient, can for example have one or two or more stimulation contact surfaces, which are in contact with the tissue of the brain  29  or spinal cord  29  after implantation and are used to apply the electrical first stimuli  21 . 
       FIG. 4  illustrates a stimulation electrode  14  in an exemplary and schematic fashion. The stimulation electrode  14  consists of an insulated electrode shaft  50  and at least one stimulation contact surface, for example two or more stimulation contact surfaces, which has/have been introduced into the electrode shaft  50 . In the present example, the stimulation electrode  14  contains four stimulation contact surfaces  51 ,  52 ,  53  and  54 . The electrode shaft  50  and the stimulation contact surfaces  51  to  54  can be made of a biocompatible material. Furthermore, the stimulation contact surfaces  51  to  54  are electrically conductive (e.g. they are produced from a metal) and are in direct electrical contact with the nerve tissue after implantation. In the present exemplary embodiment, each of the stimulation contact surfaces  51  to  54  can be actuated via its own lead  55 , and the recorded measurement signals can be transported away via the leads  55 . Alternatively, two or more stimulation contact surfaces  51  to  54  can also be connected to the same lead  55 . 
     In  FIG. 4 , the stimulation contact surfaces  51  to  54  are arranged in rows and columns. Furthermore, the stimulation contact surfaces  51  to  54  are embodied as rectangles. These embodiments should merely be understood as being exemplary. As an alternative to these embodiments, the stimulation electrode  14  can contain any number N (N=1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, of stimulation contact surfaces, which can be arranged in an arbitrary fashion with respect to one another and can have arbitrary shapes. 
     In addition to the stimulation contact surfaces  51  to  54 , the electrode  14  can have a reference electrode  56 , the surface of which can be greater than those of the stimulation contact surfaces  51  to  54 . The reference electrode  56  is used to produce a reference potential during the stimulation of the nerve tissue. Alternatively, one of the stimulation contact surfaces  51  to  54  can also be used for this purpose. That is to say there can be either unipolar stimulation between an individual stimulation contact surface  51  to  54  and the reference electrode  56  (or the housing of the generator unit  13 ) or bipolar stimulation between various stimulation contact surfaces  51  to  54 . 
     In addition to its function as a stimulation electrode, the electrode  14  can also be used as a measuring unit  15  within the device  300 . In this case, measurement signals are recorded by at least one of the contact surfaces  51  to  54 . 
     The stimulation contact surfaces  51  to  54  can be connected to the generator unit  13  via cables or by telemetric connections. 
     The plurality of stimulation contact surfaces  51  to  54  allow separate stimulation of different regions of the brain  29  or spinal cord  29  by the individual stimulation contact surfaces  51  to  54 . By way of example, each of the stimulation contact surfaces  51  to  54  can for this purpose be connected to the generator unit  13  by means of its own connection line  55 . This allows the generator unit  13  to produce particular first stimuli  21  for each individual stimulation contact surface  51  to  54 . The stimulation contact surfaces  51  to  54  can be implanted into the patient such that the first stimuli  21 , which are applied to the tissue, are transmitted via nerves to different target areas situated in the brain  29  and/or spinal cord  29 . It follows that the device  100  or  300  can stimulate different target areas in the brain  29  and/or spinal cord  29  with possibly different and/or time-offset first stimuli  21  during the same period of stimulation Δt 1 . 
     The plurality of stimulation contact surfaces  51  to  54  afford the possibility of not only stimulating different regions of the brain  29  and/or spinal cord  29 , but also of using other forms of stimulation than would be possible if e.g. only a single stimulation contact surface were used. According to one embodiment, the stimulation electrode  14  administers first stimuli  21  to the neuron population  30  with an pathologically synchronous and oscillatory activity, which stimuli bring about a resetting, a so-called reset, of the phase of the neuronal activity of the stimulated neurons in the neuron population  30 . The reset sets the phase of the stimulated neurons to a certain phase value, e.g. 0°, independently of the current phase value. Hence the phase of the neuronal activity of the pathological neuron population  30  is controlled by means of a targeted stimulation. Furthermore, the plurality of stimulation contact surfaces  51  to  54  allow the stimulation of the pathological neuron population  30  at different sites. This affords the possibility of resetting the phase of the neuronal activity of the pathological neuron population  30  at different times at the different stimulation sites. As a result, this subdivides the pathological neuron population  30 , the neurons of which were previously active in a synchronous fashion and with the same frequency and phase, into a plurality of subpopulations, which are illustrated schematically in  FIG. 5  and are denoted by the reference signs  31 ,  32 ,  33 , and  34 . Within one of the subpopulations  31  to  34 , the neurons are still synchronous and also still fire with the same pathological frequency after the phase has been reset, but each of the subpopulations  31  to  34  has the phase in respect of its neuronal activity that was imposed on it by the stimulation stimulus. This means that after the resetting of their phases, the neuronal activities of the individual subpopulations  31  to  34  still have an approximately sinusoidal profile with the same pathological frequency, but have different phases. 
     By way of example, the stimulation contact surfaces  51  to  54  can be placed onto or in the brain tissue or spinal-cord tissue  29  of the patient such that the first stimuli  21  applied by the stimulation contact surface  51  stimulate the subpopulation  31  and reset the neuronal phase thereof, and the first stimuli  21  applied by the stimulation contact surface  52  stimulate the subpopulation  52  and reset the neuronal phase thereof. The same holds true for the stimulation contact surfaces  53  and  54  with respect to the subpopulations  33  and  34 . 
     Due to the pathological interaction between the neurons, the state with at least two subpopulations, which state was generated by the stimulation, is unstable and the entire neuron population  30  quickly approaches a state of complete desynchronization, in which the neurons fire in an uncorrelated fashion. The desired state, i.e. the complete desynchronization, thus is not available immediately after the application of the stimulation signals via the stimulation electrode  14 , but usually sets in within a few periods or even within less than one period of the pathological activity. 
     A theory for explaining the stimulation success is based on the fact that the ultimately desired desynchronization is only made possible by the pathologically increased interaction between the neurons. Hereby, a self-organization process is utilized, which is responsible for the pathological synchronization. The same process brings about a desynchronization following a subdivision of an entire population  30  into subpopulations  31  to  34  with different phases. In contrast to this, there would not be desynchronization without an pathologically increased interaction between the neurons. 
     Moreover, the electrical stimulation with the device  100  or  300  can obtain a restructuring of the connectivity of the dysfunctional neural networks and so long-lasting therapeutic effects can be brought about. The obtained synaptic reorganization is of great importance for the effective treatment of neurological or psychiatric disorders. 
     If differently embodied stimulation signals were used instead of the stimulation signals that can control the phases of the stimulated neurons, e.g. high-frequency, continuously applied high-frequency pulse trains, the above-described, long-lasting therapeutic effects could typically not be attained, and this would result in stimulation that requires continuous and comparatively high-current stimulation. In contrast to this, the stimulation forms described here only require little energy to be introduced into the neuron system from the outside in order to obtain a therapeutic effect. As a result of the relatively low energy input into the body of the patient and the often very quickly obtained stimulation results, the device  100  or  300  can significantly reduce dysesthesia and paresthesia (painful sensations) that often go hand in hand with an electrical nerve stimulation. 
     Different approaches can be taken for obtaining a desynchronization of the entire neuron population  30  as a result of time-offset resetting of the phases of the subpopulations  31  to  34  of the pathologically synchronous neuron population  30 . By way of example, stimulation signals that bring about a reset in the phase of neurons can be emitted with time delay to the respectively stimulated nerve tissue by means of the various stimulation contact surfaces  51  to  54 . Furthermore, the stimulation signals can be applied e.g. with phase offset or with different polarity, and so these also lead to a time-offset reset in the phases of the various subpopulations  31  to  34 . 
     By way of example, the device  100  can be operated in a so-called “open loop” mode, in which the generator unit  13  produces predetermined first stimuli  21  and emits these to the nerve tissue by means of the stimulation contact surfaces  51  to  54 . Moreover, the device  100  can also be developed to form the device  300  shown in  FIG. 3 , the latter device constituting a so-called “closed loop” system. The device  300  additionally contains the measuring unit  15 , which provides one or more measurement signals  26  recorded in the patient and transmits said signals to the control unit  10 . 
     The measurement signals  26  can be used to carry out demand-driven stimulation. To this end, the control unit  10  detects the presence and/or extent of one or more pathological features using the measurement signals  26  recorded by the measuring unit  15 . By way of example, as already explained above, the amplitude or the magnitude of the neuronal activity can be measured, can be compared to one or more prescribed thresholds and a particular mode of operation can be selected, depending on the result of the comparison. The generator unit  13  can be embodied such that stimulation or the first mode of operation is started as soon as the prescribed threshold is exceeded. Furthermore, the measurement signals  26  recorded by the measuring unit  15  can be used to set e.g. the strength of the first stimuli  21 . By way of example, one or more thresholds can be prescribed, and a certain strength of the first stimuli  21  is set when the amplitude or the magnitude of the measurement signals  26  exceeds a certain threshold. 
     Moreover, provision can be made for the measurement signals  26 , recorded by the measuring unit  15 , to be utilized directly or, if need be, after one or more processing steps as first stimuli  21  and for said signals to be transmitted to the stimulation electrode  14  by the generator unit  13 . By way of example, the measurement signals  26  can be amplified and can be processed with a time delay and with linear and/or nonlinear calculation steps and combinations, optionally after mathematical calculations (e.g. after mixing the measurement signals), and can be transmitted to the stimulation electrode  14 . Here, the calculation mode is selected such that the pathological neuronal activity is counteracted and the stimulation signal likewise disappears, or is at least significantly reduced in strength, with decreasing pathological neuronal activity. 
     A stimulation method suitable for the above-described purposes, which can, for example, be carried out with one of the devices  100  and  300 , is schematically illustrated in  FIG. 6 . There, the first stimuli  21  applied by the stimulation contact surfaces  51  to  54  are plotted, one above the other, against time t. The period of time shown in  FIG. 6  constitutes an interval from a time interval Δt 1 . The illustrated stimulation can be continued to the end of the time interval Δt 1 . 
     In the method illustrated in  FIG. 6 , each of the stimulation contact surfaces  51  to  54  periodically administers the first stimulus  21  to the respective region of the tissue on which the stimulation contact surface  51  to  54  has been placed. The frequency f 21 , at which the first stimuli  21  are repeated for each stimulation contact surface  51  to  54 , can lie in the region of between 1 and 30 Hz and more particularly in the region of between 1 and 20 Hz or in the region of between 5 and 20 Hz or in the region of between 10 and 30 Hz, but it can also assume smaller or larger values. 
     According to the embodiment shown in  FIG. 6 , the first stimuli  21  are administered by the individual stimulation contact surfaces  51  to  54 , with there being a time delay between the administrations by the individual stimulation contact surfaces  51  to  54 . By way of example, the start of successive first stimuli  21 , applied by different stimulation contact surfaces  51  to  54 , can be shifted by a time ΔT j,j+1 . 
     In the case of N stimulation contact surfaces, the time delay ΔT j,j+1  between two successive first stimuli  21  can for example lie in the region of an N-th of the period 1/f 21 . In the exemplary embodiment (N=4) shown in  FIG. 6 , the delay ΔT j,j+1  then is 1/(4×f 21 ). 
     By way of example, the frequency f 21  can lie in the region of the mean frequency of the pathological rhythmic activity of the target network. In the case of neurological and psychiatric diseases, the mean frequency typically lies in the region of between 1 and 30 Hz, but it can also lie outside of this region. It should be noted here that the frequency at which the affected neurons fire synchronously in neurological and psychiatric diseases usually is not constant but can by all means have variations and, moreover, has individual deviations in each patient. 
     By way of example, current-controlled or voltage-controlled pulses can be used as first stimuli  21 . Furthermore, a first stimulus  21  can be a pulse train consisting of a plurality of individual pulses  210 , as illustrated in  FIG. 7 . The pulse trains  21  can each consist of 1 to 100, more particularly 2 to 10, electric-charge-balanced individual pulses  210 . The pulse trains  21  are applied e.g. as sequence with up to 20 or more pulse trains. Within one sequence, the pulse trains  21  are repeated with the frequency f 21  in the region of 1 to 30 Hz. 
       FIG. 8  shows a pulse train  21 , which consists of three individual pulses  210 , in an exemplary fashion. The individual pulses  210  are repeated with a frequency f 210  in the region of 50 to 500 Hz, more particularly in the region of 100 to 150 Hz. The individual pulses  210  can be current-controlled or voltage-controlled pulses, which are composed of an initial pulse component  211  and a subsequent pulse component  212  flowing in the opposite direction, wherein the polarity of the two pulse components  211  and  212  can also be interchanged compared to the polarity shown in  FIG. 8 . The duration  213  of the pulse component  211  lies in the region of between 1 μs and 450 μs. The amplitude  214  of the pulse component  211  is in the region of between 0 mA and 25 mA in the case of current-controlled pulses and in the region of between 0 and 20 V in the case of voltage-controlled pulses. 
     The amplitude of the pulse component  212  is smaller than the amplitude  214  of the pulse component  211 . Instead, the pulse component  212  has a longer duration than the pulse component  211 . Ideally, the pulse components  211  and  212  are dimensioned such that the charge transmitted thereby has the same magnitude in both pulse components  211  and  212 , i.e. the areas shaded in  FIG. 8  have the same size. As a result, an individual pulse  210  introduces precisely the same amount of charge into the tissue as is removed from the tissue. 
     The rectangular shape of the individual pulses  210  illustrated in  FIG. 8  constitutes an ideal shape. There are deviations from the ideal rectangular shape, which depend on the quality of the electronics producing the individual pulses  210 . 
     Instead of pulse-shaped stimulation signals, the generator unit  13  can for example also produce differently embodied stimulation signals, e.g. stimulus patterns that are continuous in time. The above-described signal shapes and the parameters thereof should merely be understood as being exemplary. Provision can by all means be made for there to be deviations from the aforementioned signal shapes and the parameters thereof. 
     There can be various deviations from the strictly periodic stimulation pattern shown in  FIG. 6 . By way of example, the time delay ΔT j,j+1  between two successive first stimuli  21  need not necessarily always be of the same magnitude. Provision can by all means be made for the time separations between the individual first stimuli  21  to be selected such that they differ. Furthermore, the delay times can also be varied during the treatment of a patient. The delay times can also be adjusted in respect of the physiological signal run times. 
     Furthermore, pauses can be provided during the application of the first stimuli  21 , during which pauses there is no stimulation. Such a pause is shown in an exemplary fashion in  FIG. 9 . The pauses can be selected to have any duration and more particularly be an integer multiple of the period T 21  (=1/f 21 ). Moreover, there can be a pause after any number of stimulations. By way of example, stimulation can be performed over n successive periods of length T 21 , and there can subsequently be a pause without stimulation over m periods of length T 21 , wherein n and m are small whole numbers, for example in the region of between 1 and 10. This scheme can be either continued periodically or modified stochastically and/or deterministically, e.g. chaotically. 
     A further option for deviating from the strictly periodic stimulation pattern shown in  FIG. 6  consists of stochastic or deterministic or mixed stochastic-deterministic variation of the temporal sequence of the individual first stimuli  21 . 
     Additionally, the order in which the stimulation contact surfaces  51  to  54  apply the first stimuli  21  can be varied during each period T 21  (or else during other time steps), as illustrated in  FIG. 10  in an exemplary fashion. This variation can be stochastic or deterministic or mixed stochastic-deterministic. 
     Furthermore, it is possible for only a certain number of stimulation contact surfaces  51  to  54  to be used for stimulation in each time interval T 21  (or in another time interval) and the stimulation contact surfaces involved in the stimulation can be varied in each time interval. This variation can also be stochastic or deterministic or mixed stochastic-deterministic. 
     All stimulation forms described above can also be performed in a “closed loop” mode by means of the device  300 . With respect to the stimulation form shown in  FIG. 9 , the start time and the length of the pause can for example be selected as controlled by demand. 
     As already described above in conjunction with the device  300 , the “closed loop” mode of the device  300  can be embodied such that the measurement signals  26  recorded by the measuring unit  15  are converted into electrical first stimuli  21  by the generator unit  13 , either directly or, if need be, after one or more processing steps, and are applied by the stimulation electrode  14 . In this case, the device  300  does not necessarily require at least two stimulation contact surfaces. This type of stimulation, in which the measurement signals recorded on the patient are transmitted back into the body of the patient, could, in principle, also be carried out with only a single stimulation contact surface; however, an arbitrary larger number of stimulation contact surfaces can also be provided. 
     The above-described “closed loop” mode can likewise be used for desynchronization of a neuron population with an pathologically synchronous and oscillatory neuronal activity. 
     By way of example, in order to produce the first stimuli  21 , the measurement signals  26  can be amplified and can be used as first stimuli  21  for the electrical stimulation with a time delay and with linear and/or nonlinear calculation steps, optionally after mathematical calculations (e.g. after mixing the measurement signals). Here, the calculation mode can be selected such that the pathological neuronal activity is counteracted and the stimulation signal likewise disappears, or is at least significantly reduced in strength, with decreasing pathological neuronal activity. 
     In the following text, linear and nonlinear processing steps are described, which can be used to process the measurement signals  26  obtained with the aid of the measuring unit  15  before they are transmitted to the stimulation electrode  14 . 
     In the case of nonlinear processing of the measurement signals  26 , it is not the phase of the neuronal activity in the respective stimulated subpopulations that is reset, but the synchronization in the pathologically active neuron population is suppressed by influencing the saturation process of the synchronization. 
     In the case of linear processing of a measurement signal  26  obtained from the measuring unit  15 , the measurement signal  26  can, for example, be filtered and/or amplified and/or be subjected to a time delay before the thus processed signal is transmitted to the stimulation electrode  14  and applied by the stimulation contact surface or surfaces. By way of example, the measurement signal  26  has been recorded by an EEG electrode and reproduces the pathological activity in the target area. Accordingly, the measurement signal  26  is a sinusoidal oscillation with a frequency in the region of between 1 and 30 Hz. By way of example, the measurement signal  26  furthermore has a frequency of 5 Hz. The measurement signal  26  can be filtered by a band-pass filter with a pass-band in the region of 5 Hz and can be amplified by an amplifier such that it has suitable levels for the electrical brain stimulation or spinal-cord stimulation. The amplified sinusoidal oscillation thus obtained is subsequently used to actuate the stimulation electrode  14 . 
     Provided that a plurality of stimulation contact surfaces are used for the stimulation, the measurement signal  26  can be subjected to the time delays ΔT j,j+1 , illustrated in  FIG. 6 , before it is transmitted to the corresponding stimulation contact surfaces as first stimulus  21 . According to the preceding example, sinusoidal oscillations with a frequency of 5 Hz are applied instead of the rectangular stimulation signals  21  shown in  FIG. 6 . 
     With the aid of an example, the following text explains how a measurement signal  26  obtained by the measuring unit  15  can be subjected to nonlinear processing before it is used as a first stimulus  21  for electrical brain stimulation or spinal-cord stimulation. As in the case of linear processing, the measurement signal  26  can in this case also be filtered and/or amplified and/or be subjected to a time delay. 
     The start point is an equation for the stimulation signal S(t) (first stimulus):
 
 S ( t )= K·  Z     2 ( t )·   Z   *( t −τ).  (1)
 
     In equation (1), K is an amplification factor that can be selected in a suitable fashion and  Z (t) is an average state variable of the measurement signal.  Z (t) is a complex variable and can be represented as follows:
 
   Z   ( t )= X ( t )+ iY ( t ),  (2)
 
wherein X(t) can correspond to e.g. the neurological measurement signal. Since the considered frequencies lie in the region of 10 Hz=1/100 ms=1/T α , the imaginary part Y(t) can be approximated by X(t−τ α ), wherein for example τ α =T α /4 holds true. This results in:
 
 S ( t )= K·[X ( t )+ iX ( t−τ   α )] 2   ·[X ( t−τ−τ   α )].  (3)
 
     Equation (3) can be rewritten as follows:
 
 S ( t )= K·[X ( t ) 2   ·X ( t −τ)+ i 2 X ( t )·( t−τ   α )· X ( t −τ)− X ( t−τ   α )· X ( t −τ)− iX ( t−τ−τ   α )· X ( t ) 2 +2 X ( t )· X ( t−τ   α )· X ( t−τ−τ   α )+ iX ( t−τ−τ   α )· X ( t−τ   α )].  (4)
 
     The real part of equation (4) is used as the stimulation signal:
 
real[ S ( t )]= K·[X ( t ) 2   ·X ( t −τ)− X ( t−τ   α )· X ( t −τ)+2 X ( t )· X ( t−τ   α )· X ( t−τ−τ   α )]  (5)
 
       FIG. 11  schematically illustrates the device  100  or  300  during its intended operation. To this end, at least one stimulation electrode  14  has been implanted into one or both sides of the brain of a patient. The stimulation electrodes  14  placed into one or more of the aforementioned target areas are each connected to the generator unit  13  by a cable  70 , via a connector  71  and a further-connecting cable  72 . In the present embodiment, the generator unit  13  also comprises the control unit  10 . The aforementioned components of the device  100  are implanted in the body of the patient. The connecting cables  70  and  72 , and the connector  71 , are implanted under the skin. As an alternative to a pectorally implanted generator unit  13 , as illustrated in  FIG. 11 , a smaller generator can also be implanted directly into the drilled hole. This can reduce the infection rate in the generator pouch, and breaks in the connecting cables  70  and  72  can be avoided. Furthermore, a semi-implant with a radio link can be used instead of a full implant. In the case of a “closed loop” stimulation, the device  300  also contains a measuring unit  15 . The second stimulation unit  12  for producing the non-specific second stimuli  22  is attached to the arm of the patient in the present example. The second stimulation unit  12  can communicate with the control unit  10  situated in the body of the patient by means of e.g. a radio link. 
       FIGS. 12A and 12B  illustrate an exemplary embodiment of the second stimulation unit  12  for producing the non-specific second stimuli  22 . In the present case, the second stimulation unit  12  is embodied as a so-called “conditioning watch”, which the patient can wear comfortably.  FIG. 12A  shows the front view;  FIG. 12B  shows the rear view of the conditioning watch  12 . The conditioning watch  12  consists of a central part  80 , straps  81 , a fastener part  82  and associated holes  83 . Alternatively, use can also be made of a hook-and-loop fastener or any other equivalent fastener. The central part  80  contains a loudspeaker  84  for generating non-specific acoustic signals  22 , e.g. a melody or a pleasant buzzer sound, and also a display  85  for generating a pleasant, non-blinding non-specific optical stimulus  22 , e.g. a flower blowing in the wind or an abstract light pattern with bright and warm colors. Furthermore, the conditioning watch  12  can be equipped with one or more vibrators  86 , which generate non-specific tactile and/or vibratory stimuli  22 . In order to produce tactile stimuli  22 , the vibrators can be operated at frequencies of less than 1 Hz. More particularly, the moveable parts of the vibrators  86  can in this case be aligned such that they can implement pressure stimuli in an improved fashion, i.e. the main movement direction of the vibrators  86  should be directed into the skin. Furthermore, the tactile stimuli  22  could also be produced by pressure actuators or elements that move slowly relative to the skin, which elements can for example be integrated into the conditioning watch. Provided that vibratory stimuli  22  should be produced by means of the vibrators  86 , vibration frequencies in the region of between 10 and 160 Hz or above can be implemented. In this case, the moveable parts of the vibrators  86  can have a pronounced movement direction substantially parallel to the skin. The vibrators  86  can also be operated such that they produce tactile and vibratory stimuli  22  at the same time. 
     The conditioning watch  12  can also be embodied such that it only generates a non-specific stimulus  22  for one of the senses, e.g. only an optical stimulus. The conditioning watch  12  is supplied with current by a battery and/or solar cells and/or a mechanical flywheel in the interior of the conditioning watch  12 . 
     In order to monitor the stimulation effect, the conditioning watch  12  can additionally contain an accelerometer, which can measure the pathological oscillatory activity, e.g. from an pathological tremor, or else the mean activity level of the patient. The mean activity level of the patient reflects the slowing down or dropping off of the movement of the patient or the inability of the patient to move (i.e. bradykinesia, hypokinesia, and akinesia). 
     A further exemplary embodiment of the second stimulation unit  12  is illustrated schematically in  FIG. 13 . Here, this is, for example, a cellular-phone-shaped stimulator, which can be carried in e.g. the shirt pocket or trouser pocket of the patient and which generates non-specific acoustic stimuli  22  by means of a loudspeaker  87 . 
     Furthermore, provision can be made for an external programming instrument for the medical practitioner, by means of which instrument the parameters of the control unit  10 , the generator unit  13  and/or the non-specific, physiological stimulation unit  12  can be set. Moreover, the patient can likewise be provided with an external programming instrument, by means of which the patient can switch off the stimulation equipment or can modify parameters of the stimulation units  11  and  12  within narrow limits set by the medical practitioner. Furthermore, the programming instrument intended for the patient can contain the functionality already explained above, by means of which the patient can independently, e.g. by actuating a button, switch into the first mode of operation, i.e. into the learning phase, from the second mode of operation if he/she feels that the therapy is insufficient, i.e. if e.g. the tremor or the hypokinesia are too pronounced. The programming instruments can communicate with the respective components of the stimulation instrument by means of radio links, for example.