CHARACTERISTICS OF BEHAVIORAL AND ELECTROENCEPHALOGRAPHIC AFTER-REACTIONS TO COPULATION AND VAGINAL STIMULATION IN THE FEMALE RABBIT1

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Abstract
Electro-encephalographic (EEG) changes have been recorded from the brain of the conscious unrestrained female rabbit following coitus and vaginal stimulation. In the estrous estrogen-primed rabbit with electrodes permanently implanted in cortical and deep regions of the brain the following sequence of EEG changes has been observed (1) A phase of sleep spindles lasting from several seconds to half an hour or more, during which the rabbit appears drowsy if not actually sleeping. (2) A phase of "hippocampal hyperactivity" characterized by an 8/sec. high amplitude synchronous EEG record from the hippocampus and its projections. During this period the rabbit is further depressed be-haviorally: its head on the floor, ears retracted, eyes almost closed, pupils contracted, heart and respiratory rates slowed, and its only other motion consisting of twitches of the eyelids and jaw movements. Following this phase, which lasts only a few minutes, the rabbit usually stands and starts eating either food or feces which may be extracted directly from her anus. All of these phases occur too late to be causally related to neurogenous activation of the release of pituitary ovulating hormone. Rather, their timing suggests that they may themselves be induced by the "feed-back" to the nervous system of pituitary hormones released in response to the coital or vaginal stimulus.