Carrying on the analysis of the transcommissural linkages previously ascertained (by means of mass recording techniques) between the thalamic nuclei ventrales laterales (VL), chloralose-anaesthetized (80 mg/kg i.p.) cats with acute lesions of somatomotor cortex were used to study the transcommissural reactivity of single VL units, isolated with extracellular tungsten microelectrodes and characterized by their responses to dentate nucleus stimulation and, when present, also by their responses to the stimulation of n. entopeduncularis and of peripheral receptive fields. Out of a sample of 144 VL units, 38 (26 p. 100 approximately) were seen to be transynaptically excited by transcommissural impulses originated by contralateral VL stiulation, 20 (about 14 p. 100) were inhibited, and 5 more exhibited complex responses, characterized by early activation followed by prolonged inhibition. The units excited by contralateral VL were distributed throughout the whole nucleus with no topographical segregation, whereas the inhibited group was mainly found in the rostro-median portions. The dentate responses elicited in this group were different (as to latency and discharge patterns) from those of the VL-excited units. No differences were observed, on the other hand, between the dentate responses of the latter and those of the units insensitive to contralateral VL stimulation.
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Con il contributo del Ministero per i Beni e le Attività Culturali