The mating movements of male decorticate rats: evidence for subcortically generated movements by the male but regulation of approaches by the female.
The study shows that although many features of copulation in decorticate male rats are normal, copulatory success is importantly dependent upon the control of approaches exerted by the normal female rat. Copulation by neonatally decorticated adult rats and normal adult rats was studied in cohabitation and videotaped tests. Seven of 10 decorticate rats and 6 of 6 normal rats sired pups in the cohabitation test. When initially paired with ovariectomized and primed female rats, in the videotaped tests, all normal rats, but only one decorticated rat, copulated. All decorticate rats made movements indicative of sexual interest including: treading on the female's back, passing over the female, and sniffing the female's genitals. After activating stimulation, 5 of 6 remaining decorticated males copulated. After one successful mount the remaining copulatory patterns proceeded relatively normally. Numbers of mounts, intromissions, ejaculations, postejaculatory songs, and the intromission and ejaculatory patterns were like those of control rats, although the decorticate rats had fewer mount bouts and showed abnormalities in the execution of movements. Precopulatory movements were notated, using the Eshkol-Wachmann system, and compared with copulatory movements. Non-copulatory and copulatory approaches were similar, except that clasping appeared to be the key movement involved in the transition of an approach movement into a copulatory movement. The analysis also showed that the females' movements of hopping, turning, and kicking were important for regulating the males' approaches, and were instrumental in the success achieved by the decorticated males. The study shows that although the cortex, insofar as it facilitates the appearance of certain movements and contributes to their efficiency, is involved in male sexual activity, in its absence well organized sexual activity is possible, although this is dependent, in part, upon the behaviour of the female.
D000818:Animals; D002540:Cerebral Cortex / Q000473:pathology / Q000502:physiology*; D002541:Cerebral Decortication; D003307:Copulation / Q000502:physiology*; D004542:Ejaculation; D005260:Female; D008297:Male; D009043:Motor Activity / Q000502:physiology; D010152:Pair Bond; D051381:Rats; D011930:Reaction Time; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000502:physiology*; D014743:Videotape Recording; D014828:Vocalization, Animal / Q000502:physiology