Reciprocal thalamo-hippocampal EEG augmenting and muscle responses in rabbits.

Waxing and waning electrographic responses (augmenting) and primary evoked responses could be induced in restricted regions of hippocampus, thalamus, and skeletal muscle by bipolar, low-frequency (7-10 Hz), low-amplitude (35 mV-4V) stimulation of selected sites within the hippocampus or thalamus of rabbits. Induction of the immobility reflex (IR) (animal hypnosis) lowered the threshold and increased the amplitude of both kinds of responses. An additive enhancement of both kinds of responses was often produced by concurrent treatment with a tranquilizer and the immobility reflex. These results suggest the thalamus and the hippocampus have interacting modulating mechanisms which affect motor activity.