This thesis examines Beach's hypothesis that the sexual behaviour of male rats is under multisensory control and is resistant to the loss of tactile information from the vibrissae. The loss of perioral sensation was found to profoundly disrupt sexual behaviour in sexually inexperienced males tested with females showing five ascending levels of precopulatory behaviour. Males did not copulate with females displaying presenting, presenting and hopping, hopping and darting levels of proceptive behaviour. However, males paired with darting females displaying the highest level level of proceptive behaviour did copulate in the presence of perioral anapsis caused by intramystacial injection of lidocaine. Injection of lidocaine intraperitoneally and intramasseterically showed that this effect was not due to systemic toxicity. Prior sexual experience was found to attenuate the effect of perioral anapsis and males given three prior copulatory trials copulated with presenting females in the presence of perioral perioral anapsis. Males given one prior copulatory trial also copulated with presenting females in the presence of perioral anapsis. These results complement recent research which has called for a revision of the multisensory hyopothesis and indicate that trigeminally mediated tactile information from the vibrissae plays an important role in the initiation of sexual behaviour in the naive male rat.

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