Integration of cortical and peripheral information in the lateral vestibular nucleus in the cat

Neuronal discharges in the lateral vestibular nucleus (LVN) of the cat were studied during stimulation of a forelimb muscle and of a site in the contralateral motor cortex (area 4) capable of activating the same muscle. About one third of the LVN units were reactive to both stimulations or at least responded to one (cortex or muscle) but modified the response pattern when the other was stimulated also. The patterns evoked by a muscle were mostly enhanced on simultaneous stimulation of the cortical zone controlling the same muscle and vice versa. Only in the dorsal division the excitatory responses to muscle stimulation were depressed by simultaneous cortical stimulation. Some functional implications are proposed.