Diencephalic and hippocampal mechanisms of motor activity in the rat: Effects of posterior hypothalamic stimulation on behavior and hippocampal slow wave activity

Abstract

Summary Slow wave activity was recorded from the hippocampus in chronically prepared rats. During spontaneous or learned behavior, rhythmical slow activity (RSA) accompanied walking, rearing, climbing, manipulation of objects with the forelimbs, isolated movements of the head or one limb and changes in posture (voluntary movement) but did not accompany alert immobility, licking, chewing, face-washing, or scratching (more automatic behavior). During stimulation of the hypothalamus similar behavior-EEG relations were observed. Walking, running, jumping, and isolated head movements were always accompanied by RSA, but this waveform was absent during alert immobility, chewing, face washing, piloerection or chattering of the teeth. Stimulation of the dorsomedial posterior hypothalamus was especially effective in the elicitation of RSA in the hippocampus and also consistently produced head movement, running, or jumping when administered in conscious animals. Sites in the dorsomedial-posterior hypothalamus would also support self-stimulation behavior. Increases in the voltage of posterior hypothalamic stimulation produced increases in the frequency of the RSA during the first few seconds of stimulation, and a corresponding increase in running speed or in the force with which jumping was initiated. Relations between behavior and hippocampal activity were the same during tests of learning (active and passive avoidance) and during spontaneous behavior ( e.g. , exploration). It is suggested that an ascending hypothalamo-hippocampal mechanism plays a role in the control of voluntary movement.