Hooded rats which begin to kill mice while deprived of food display an orderly development of attack topography. Attack complexity is maximal at onset of killing when four component attacks comprising chasing, carrying, pawing, and biting mice predominate. Attack simplifies to two component pawing-biting attacks with repeated killing experience which result in rapid kills. Food satiation and a gradual decline in killing behavior reinstates attacks of intermediate complexity, comprised of chasing, pawing and biting. Redepriving the rats of food immediately results in simple and rapidly lethal pawing-biting attacks. With further killing experience some rats show the chasing-pawing-biting attacks once again. The data suggest that prey self-defense and the sensitivity of attacking rats to prey defense account for variation in some aspects of attack complexity. Factors intrinsic to the rat and dependent upon response to food deprivation and experience of killing account for other aspects of attack topography. Rats which do not begin to kill mice while food deprived show simple and fragmented attack topography unlike that of mouse-killing rats. The study was written for publication while the first author was supported by a grant to Drs. Goddard and Adamec from NIMH, grant number MH25995-02, and by Dr. Kenneth Livingston and the Scott Laboratory. The critical reading of the manuscript by Alex Stiglick is also gratefully acknowledge.
Reproductive cycles of females in a breeding group of 10 to 18 patas monkeys (Erythrocebus patas) were followed over 5 years using vaginal smear and lavage techniques. Two hundred hours of behavioral observations were made during the same period. The social organization centered on an inner circle of six females with a complex web of interrelationships; other females, and males, had a peripheral position linked to the central circle at one or two points only. Mating activity was periodic: either several or no females were receptive at one time. Most mating activity and most conceptions occurred between September and November but there was no strict association of mating periods with a particular season. Menstrual cycles in mating periods differed from those in nonmating periods in having heavier menstrual bleeding, more vaginal epithelial activity throughout the cycle, and midcycle leukocyte peaks were common. There was very little differentiation of stages of the menstrual cycle in terms of vaginal histology, but there was a clear midcycle peak in heterosexual interaction, especially during mating periods. Friendly and avoiding interactions between females did not change during their cycles or when they were pregnant, but did increase dramatically in early lactation. The return to receptivity postpartum was greatly influenced by the social environment. It seemed that sexual activity had a social facilitatory effect but was in turn inhibited by the presence of small infants. This interactive mechanism favors increased reproductive synchrony within the group.
Juvenile (17–34 days of age), young adult (2–3 months) and adult rats (6–8 months) were tested for behavioral effects of focal, low-level X irradiation of the hippocampal region during the first two weeks after birth. The elimination of essentially all postnatally acquired granule cells of the dentate gyrus and the “syndrome” of hippocampal related behavioral changes were confirmed. In rats first tested in adulthood (6–8 months), only two components of the behavioral syndrome persisted. Adult X-irradiated rats continued to perform randomly in a spontaneous alternation task and had an extremely low rate of open-field defecation. It was hypothesized that with advancing age, X irradiation produced hyperactivity was reduced and behavioral differences which were dependent on heightened motor responsivity were diminished.
The first experiment demonstrated that removals of frontal cortex disrupted manipulation (latch opening) but not locomotion; damage of medial parietal cortex (sensorimotor cortex) produced the reverse effects. In the second study, serial lesions of medial parietal cortex resulted in more rapid recovery of locomotion than damage imposed in a single operation. Cinematographic analysis of locomotor movements indicated differences in the hindlimb patterns between animals with medial parietal lesions that had recovered and sham-operated controls. In contrast to these findings, a third experiment produced no evidence of serial lesion effects following one- and two-stage frontal damage.
Behavioral and cardiovascular measures were obtained from spontaneously hypertensive (SHR) and matched normotensive (WKY) male rats before, during, and after exposure to electric footshock. During shock, SHRs jumped more frequently and were more active than WKYs. Transfer from the home cage to the shock chamber resulted in a greater increase in heart rate and mean arterial pressure in SHRs than in WKYs. During footshock, however, in SHRs, the mean arterial pressure decreased although the heart rate increased. Both mean arterial pressure and heart rate increased during shock in WKYs.
