The discharge activity of 637 neurons of the human subthalamic nucleus (STN), which were extracellularly recorded during twelve stereotactic surgeries in patients with Parkinson’s disease, has been analyzed. On the basis of the parameters of interspike intervals (ISIs), we have distinguished three major patterns of spontaneous neuronal activity: bursting neurons, regular tonic and irregular tonic neurons. Parametric analysis has enabled us to determine the values of basic parameters in the activity of these three distinguished types of neurons. It has been shown that the representativeness and the activity parameters of three different patterns change in the dorsoventral direction of the STN from the motor to the associative regions. The results will allow researchers to perform targeted search of pathological neuronal activity patterns associated with the motor symptoms of Parkinsonism.

Event-related functional MRI (fMRI) was used to study the temporospatial dynamics of the activation of both cortical and subcortical brain formations in humans on execution of goal-directed movements triggered by verbal stimuli. Studies using this method showed that execution of voluntary movements was accompanied by signifi cant activation of various parts of the sensorimotor cortex (primary motor and somatosensory cortex, premotor cortex, supplementary motor area) and the insula and its adjacent structures (operculum) on the side contralateral to the arm being studied, as well as activation of various areas of the ipsilateral cerebellum. Of particular note were the marked reactions of the contralateral striopallidal complex and the ventral thalamus. The dynamics in the involvement of various brain areas in subjects in the phasic and tonic components of voluntary movements were determined. Differences were demonstrated in the dominant foci of brain activity in humans on clenching the right and left hands. These results widen our understanding of the mechanisms of the functioning of the human motor system and the roles of subcortical formations in organizing voluntary movements.

The use of event-related fMRI makes it possible to investigate spatio-temporal dynamics of cortical and subcortical human brain structures activity during voluntary movement performance in response to presentation of relevant verbal stimuli. The results of the study showed that voluntary movement was associated with higher contralateral brain activation in a number of areas: primary motor and somatosensory cortex, premotor cortex, supplementary motor area and insula with adjacent regions. Ipsilateral activation of the cerebellum also was observed. It should be emphasized that contralateral strio-pallidal complex and ventral thalamus showed significant response to motor tasks. Similarly, the dynamics of cortex and deep brain structures activation involving in the phasic and tonic components of voluntary movement was uncovered. We showed, in particular, the noticeable difference in brain activation between the right and left hand movement performance. The obtained results enable to enhance understanding of the role of deep brain structures in voluntary movement organization in human and motor control system as a whole.

The time-frequency characteristics and interaction in the cell ensembles of the nonspecific (CM-Pf) and motor (Voi) thalamus were analyzed. Neuronal activity was registered by microelectrode technique during 18 stereotactic neurosurgery operations in spasmodic torticollis patients. The presentation of functionally significant verbal stimuli was accompanied by the emergence of short-term (0.5–1.5 s) local synchronization and stabilization of the oscillatory (3–6 Hz) activity in neighboring neurons of the nonspecific (CM-Pf) thalamus. These focuses of synchronized oscillatory neuronal activity were correlated with the moment of the greatest concentration of selective attention. A similar phenomenon of shortterm synchronization was observed in the motor (Voi) and nonspecific (CM-Pf) thalamus of the human brain during voluntary movements. Synchronization of neuronal activity occurred at the height of the implementation of the motor act, correlating with the maximum muscle tension, as well as in the aftereffect of the voluntary movement. In general, the findings suggest an important role of the local oscillations (3–6 Hz) and synchronization of thalamic neurons in the mechanisms of the relevant information transmission during goal-directed human behavior.

Activity of 144 parafascicular CM-Pf thalamic neurons was studied and recorded by means of microelectrodes during 18 stereotactical neurosurgical operations in spasmodic torticollis patients. High reactivity of two previously classified neurons with single sporadic activity (A-type) and bursts of Ca2(+)-dependent activity (B-type) were found during verbally ordered voluntary movements. There are coordinated reciprocal activation-inhibition A-type and B-type neuronal responses at the stage of verbal command presentation and synergic activation responses on the high of movement and in the aftereffect. Voluntary movement realization was accompanied by short-term local synchronization and stabilization of oscillatory (3-5 Hz) neuronal activity. The neuronal response differences between voluntary movements with and without neck muscle exertion and involuntary pathological movements prove the CM-Pf involvement in the pathology of spasmodic torticollis desease.