Functional relationship between claustrum and pyramidal tract neurons, in the cat.

Electrophysiological relationships between the claustrum and the motor cortex were studied in cats preliminarily anesthetized with ketamine and then with chloralose. Single shock electrical activation of the claustrum induced a decrease of the spontaneous unitary activity of the pyramidal tract neurons (PTNs) both in area 4 and in area 6. Eighty percent of the total number of PTNs was inhibited whereas the remaining 20% was unaffected. The inhibitory effect lasted about 200 msec and appeared about 19 msec after claustrum activation. The results show a functional linkage between the claustrum and the efferent cells of the motor cortex. This relationship suggests the hypothesis that the claustrum, a multisensory structure, may be involved in motor activity integration.