[Selectivity of the neuronal responses of the human brain to different angular orientations of visual stimuli].

In parkinsonic patients with long-term intracerebral electrodes implanted into different nuclei of the thalamus and striopallidar complex the neuronal impulse activity was recorded during visual testing for orientation sensitivity. Visual testing revealed significant responses in multiple unit activity of studied neuronal populations to the angular orientations of the presented stimuli differing from background stimulus orientation. This responses were spatially specific and were not the result of modulation of the activity of these units by the common afferent signal. Neuronal populations differently responding to stimuli which differ only in the angular orientation were observed. These findings might be interpreted as an orientation sensitivity. Such orientation sensitivity of various units differs both in optimal orientation angle and sharpness of responses, some unit groups responding to the definite orientation of the stimuli only. It is suggested that the neuronal populations with significant responses to the visual stimuli used are the elements of thalamostriopallidar system which plays an important role in the maintenance of motor functions. The convergence of motor and visual information within this system probably enables their comparison and interaction, related to the visual perception constancy.