[Hysteretic properties of movements in the elbow joint of unanesthetized cats with various methods of activation of muscle-antagonists].

Abstract

Movements of the elbow joint were studied in unanesthetized cats. These movements were evoked by microstimulation of the motor cortex or by vibration of the forepaw and then compared with reaction from direct stimulation of muscles in the anesthetized animals. Interaction of the hysteretic effects in the antagonistic muscles of the joint was studied during stimulation of two points of the motor cortex which produced opposite-directed movements. Coactivation of the antagonists was shown to increase both the joint stiffness and the uncertainty of the equilibrium value of the joint angle. The uncertainty myotatic reflexes during intracortical microstimulation were more significantly depressed in the muscle receiving more intensive activation from the given point in the motor cortex. On the contrary, myotatic reflexes during vibration were well expressed in the both antagonistic muscles. At the same time the uncertainty effects during forepaw vibration were displayed similarly as it was in the cortically evoked movements.