Nature and electrophysiologic properties of thalamic ventrolateral nucleus neurons reactive to the paleocerebellar stimulation: An extracellular and intracellular study

Acute experiments were carried out in cats under chloralose and artificially ventilated to learn the consistency and the nature (thalamocortical relay or interneuronal) of the thalamic ventrolateral nucleus neuronal population reactive to stimulation of the cerebellar fastigial nucleus. From a unitary analysis of both extra-and intracellular recording, we may conclude that (i) excitatory and inhibitory effects are exerted by cerebellar fastigial nucleus stimulation on neurons of the thalamic ventrolateral nucleus; (ii) these effects were found in about 50% of the thalamic ventrolateral neuronal population tested using an extracellular recording technique, and in about 75% of the neurons tested using an intracellular recording technique; and (iii) from the results obtained by stimulation of the somatomotor cortical areas, a large proportion of the ventrolateral nucleus units reactive to fastigial nucleus stimulation, consists of thalamocortical relay cells.