[Effect of low frequency stimulation of the head of the caudate nucleus on an instrumental defense reaction in dogs].

The effect of low-frequency stimulation of the caudate nucleus head (CNH) on motor components of instrumental defensive reaction (IDR) (IDR "coordination" program) and on realization of the instrumental task itself--avoidance of electrical current (IDR "sense" program) was compared in chronic experiments on six dogs with a model of IDR. Low-frequency stimulation of CNH of the right and left hemispheres exerted an inhibitory influence on the IDR components which characterize its coordination program. Inhibitory effects increased proportionally to the intensity of stimulation current. The changes were mostly pronounced in the early electromyographic components of the support extremity's muscle activity preceding IDR, which suggests an important role of CNH in rearrangment of the posture, preceding voluntary movement. Achievement of the instrumental task itself (avoidance of the electrical current) was inhibited only with a very high intensity of stimulation (higher than 1 ma).