Electrophysiological and ultrasonic correlates of reproductive behavior in the male rat

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Monitored the ultrasonic vocalizations of 13 male Long-Evans rats and determined the correlation of these vocalizations with electrophysiological activity measured by chronically implanted hippocampal and cortical electrodes during mating with a female rat. Hippocampal theta rhythms were significantly correlated with high activity, mounting, intromissions, and preejaculatory excitatory behavior and were also significantly associated with 50-kHz short ultrasonic vocalizations. Postmount or postintromission behaviors (grooming, exploration) were closely correlated with an absence of ultrasonic vocalizations and the onset of irregular low-amplitude hippocampal EEG recordings. Long 22-kHz vocalizations occurred during the postejaculatory refractory period. Shorter 22-kHz vocalizations occurred during mating and were associated with unsuccessful intromissions or mounting attempts. Postejaculatory long 22-kHz vocalizations were significantly associated with irregular high-amplitude hippocampal EEG tracings, while preejaculatory short 22-kHz vocalizations were also accompanied by sleeplike irregular high-amplitude hippocampal EEG tracings with cortical spindling. Findings suggest that ultrasonic vocalizations are indicators of the sexual arousal of mating rats. (14 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)

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