[Responses of neurons of the posterior ventral and ventrolateral thalamic nuclei to stimulation of the reticular nucleus of the thalamus]

Abstract

Responses of 72 ventral posterior (VP) and 116 ventral lateral (VL) thalamic neurons to electrical stimulation of the thalamic reticular nucleus were studied in cats immobilized with d-tubocurarine. All investigated neurons were identified according to their responses to stimulation of the first somatosensory (SI), first motor (MI) cortical zones, medial lemniscus (LM) and nucleus interpositus (n. INP) of cerebellum. It was shown that to reticular nucleus stimulation responded predominantly those VP and VL neurons (73.7% and 86.2%, respectively) which responded to stimulation of MI and n. NIP. 19.8% of VL neurons responded to R stimulation with antidromic spike (latency 0.5-2.0 ms) and 46.6% with orthodromic excitation. The latency of 23% of orthodromic excitatory responses was 0.9-3.5 ms and of 77% of them 4.0-21.0 ms. 19.8% of VL neurons responded to R stimulation with inhibition. Among registered IPSP only one could be considered as monosynaptic (the latency 1.0 ms). A suggestion is made that most of R neurons are excitatory and that inhibition developing in VL neurons in response to R stimulation is mainly connected with the excitation of inhibitory interneurons located outside R.