HIPPOCAMPAL ELECTRICAL ACITVITY AND VOLUNTARY MOVEMENT IN RAT

Stainless steel macro-electrodes were chronically implanted in 24 adult male hooded rats. EEG recordings were taken from the hippocampal formation, diencephalon and neocortex and were correlated with observations of spontaneous or conditioned behavior. Trains of rhythmical 6-12 c/sec waves in the hippocampus and medial thalamus precede and accompany gross voluntary types of movement such as walking, rearing, jumping, etc. Behavioral immobility (in the alert state) and automatic movement patterns such as blinking, scratching, washing the face, licking or biting the fur, chewing food or lapping water are associated with irregular hippocampal activity. Small movements, such as shifts of posture or isolated movements of the head or limbs occurring during immobility, or during grooming or feeding behavior, are associated with rhythmical activity of reduced amplitude and lowered mean frequency. A shock avoidance response is preceded by an increase in wave frequency. Peak frequency is reached just before the occurrence of the motor response. It is suggested that rhythmical slow activity in the hippocampus and diencephalon are the electrical sign of activity in a forebrain mechanism which organizes or initiates higher (voluntary) motor acts. No support is found for previous suggestions that such waves are specifically related to generalized arousal, orienting responses, learning, attention or approach behavior. © 1969.