As is known, the nucleus ventralis lateralis of the thalamus (VL) should not only be regarded as a simple relay for the cerebello-cortical path, but rather as an integrative centre in which extracerebellar afferents can modulate the action exerted by the cerebellum on the motor cortex. Having this in mind, electrophysiological experiments have been performed in cats, in order to ascertain: (a) whether the VL also receives connections from the contralateral homonymous nucleus, and (b) whether such connections can modulate VL reactivity to dentate and peripheral impulses. It was found that direct electrical stimulation of the VL nucleus of one side does elicit evoked potentials in the other, and that such stimulation actually can modify the other's reactivity. In fact, VL responses to dentate and peripheral impulses were seen to be enhanced and, respectively, inhibited by subliminal conditioning stimuli applied to the contralateral VL nucleus (interactive intervals: up to 90-100 msec for enhancement, up to 190-200 msec for inhibition). The commissural pathways involved were seen to cross the midline through the massa intermedia of the thalamus.
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Con il contributo del Ministero per i Beni e le Attività Culturali