In 1876 Ferrier1 stated: "There is no reason to suppose that one part of the brain is excitable and another not. The question is, how the stimulation manifests itself." As one is prone to look for active responses, one may fail to observe other manifestations elicited by electrical stimulation of nerve tissue.
In 1845, biologic inhibition was first experimentally demonstrated by the Weber brothers,2 who showed that vagal stimulation slowed the heart. For their studies a background of cardiac activity was necessary. Similarly, a background of activity is necessary for any studies of inhibition, whether central or peripheral. Setschenow3 (1863) employed the "withdrawal" response of the frog's hindlimb as the background of activity for his attempts to localize inhibition within the central nervous system. Bubnoff and Heidenhain4 (1881) showed that inhibition of a muscular contraction may be brought about through tactile stimulation of an ipsilateral member.
GAROL HW, BUCY PC. SUPPRESSION OF MOTOR RESPONSE IN MAN. Arch NeurPsych. 1944;51(6):528-532. doi:10.1001/archneurpsyc.1944.02290300030003