Auto- and allo-grooming in pine voles (Microtus pinetorum) and meadow voles (Microtus pennsylvanicus).

Grooming was observed in mixed-sex pairs of voles after one vole had been unilaterally soiled with a carboxymethylcellulose (CMC) gel. In Experiment 1, soiled pine voles spent more time grooming than did clean voles, and groomed the soiled side of their bodies more than the clean side. Soiled voles of both species head-groomed more than did clean voles. Addition of tastants to CMC gel did not alter grooming durations in either species, and there were no sex differences. In Experiment 2, both vole species (taken together) auto-groomed more than they allo-groomed, although clean voles groomed their soiled partners more than themselves. These studies suggest that soiled fur is a powerful stimulus for auto- and allo-grooming.

Influence of gonadal hormones and sexual behavior on ultrasonic vocalization in rats: I. Treatment of females.

Ultrasonic vocalizations were measured when male rats were placed with ovariectomized females that had experienced various hormonal and behavioral treatments. In Experiment 1, 18 males were tested with females in each of the following conditions: nonestrous (OVX), estrogen treated (E), estrogen and progesterone treated (EP), and estrogen and progesterone treated and given two intromissions from a stud male prior to testing (EPI). Control conditions included clean cage (CL) and cage soiled by an estrous female (SOI). The treatments differed in effect on rate and maintenance of vocalization: EP greater than E greater than EPI = OVX greater than SOI greater than CL. In tests in which males produced a high rate of vocalization, some males with short intromission latencies shifted from the normal 50-kHz pulse to a 22-kHz pulse. In Experiment 2, the effect of the female's vocalization and movement on the rate of and latency to vocalization was measured. Twenty-one males were presented with each of the following stimulus conditions: estrous female with red light (EP), estrous female without red light (EP dark), estrous anesthetized female (EP anes), and nonestrous anesthetized female (OVX anes). Effects on vocalization of various treatments were as follows: EP = EP dark greater than EP anes greater than OVX anes. These data suggest that the 50-kHz vocalizations constitute a graded response influenced by the female's hormonal and sexual condition.

The ultrasonic postejaculatory vocalization and the postejaculatory refractory period of the male rat.

After ejaculation, the male rat emits an ultrasonic (22-kHz.) vocalization. This sound is produced repeatedly until about three fourths of the postejaculatory interval has elapsed. In this study, the occurrence of the vocalization was described, and physiological and behavioral evidence was presented that the postejaculatory vocalization reflects an inhibitory state that underlies the postejaculatory refractory period. The vocalization period was characterized by a predominance of slow-wave, spindling, sleep-like electroencephalographic activity. Electrical shock was able to stimulate mating responses only after the cessation of the vocalization period. It was concluded that an absolute refractory period of the postejaculatory interval lasts until the end of the vocalization period and that the time from the termination of the vocalization until the resumption of mating is a relative refractory period.

Sexual behavior: ultrasonic postejaculatory song of the male rat.

During the refractory period that follows ejaculation, the male rat regularly emits 22-kilohertz vocalizations. These cease after about three-fourths of the total period has elapsed, and this corresponds to an "absolute refractory period" during which the male cannot spontaneously initiate copulation. Similar 22-kilohertz vocalizations occur in other social contexts, and in general they appear to be desist-contact signals.