[Thalamic somatosensory potentials after peripheral stimulation and cortical somatosensory potentials after electric stimulation of thalamic nuclei VOa and VOp (preliminary report)].

In patients with extrapyramidal syndromes thalamic action potentials were recorded during operations with a five-point brain electrode and in the same cases somatosensory evoked potentials were recorded from the skull. Thalamic potentials were recorded after peripheral stimulation, and evoked potentials from the skull were recorded after electrostimulation of thalamic nuclei VOa and VOp. At the thalamic level a short-latency positive-negative potential had a maximal amplitude in one only lead, which confirmed sharp projection of body surface into various thalamic nuclei. Somatosensory evoked potentials recorded from the skull in response to stimulation of thalamic nuclei were usually biphasic and stimulation of VOa and VOp nuclei gave potentials with similar configuration of phases. This confirms the divergence of the projection fibres from the thalamus to the cortex.