[Electrophysiologic analysis of the organization of somatosensory inputs into the thalamus of the cat].

Potentials in the frog thalamus evoked by electrical stimulation of peripheral nerves were studied by the current source-density method. Sinks, considered to be the sites of potentials generations, were found in three regions: in cell-free zone of the ventral thalamus neighbouring the ventrolateral nucleus; in the ventromedial and ventrolateral nuclei; in the caudal part of the dorsal thalamus. The evoked activity of single neurons was registered in the regions of the second and third sinks. After transection of the spinal cord dorsal columns the first sink was absent and the latent periods of two other sinks were prolonged. It is proposed that nuclei of ventral and caudal parts of the dorsal thalamus receive somatic information through the systems connected not only with ventrolateral, but also with dorsal columns of the spinal cord. The direct projections of the primordial nuclei of dorsal columns can participate in the afferentation of the ventral thalamus.