Behavioral biology最新文献

The majority of pairs of Popillia japonica follow the same sequence of sexual behaviors: The male approaches the female, mounts her, intromits, withdraws his genitalia, and remains mounted on her. “Mounted courtship,” that is, courtship exhibited while a male is mounted on the female, also occurs in this beetle. The mean duration of copulation was 132.5 sec for 33 pairs. The leg positions of P. japonica males mounted on females were generally consistent among individuals but varied considerably from those of other scarabs. Males remained mounted on females for up to 2 hr after copulation. Popillia japonica is polygamous in the laboratory and exhibits homosexual behavior. Males comprised 60% of field-collected adults. Sexual and related behaviors, sex ratios, and mating systems are variable in the Scarabaeidae.

Albino rats were allowed to hoard a variety of inedible objects. All objects were hoarded during the initial trials, but marked preferences developed subsequently for objects which could be taken apart by gnawing. In addition, by presenting half of the group with either of two nonpartible objects for the entire experiment and presenting both objects on the last four trials, it was found that an object was hoarded more often when it was presented for the first time than when it was familiar. Therefore partibility and novelty seem to be factors which induce hoarding of inedible objects.

The hypothesis that pain produces aggression was examined by comparison of behaviors in an established rat colony (for dominant colony males and strange intruders) to those seen in “reflexive fighting” and in a tube-test involving tailshock. During reflexive fighting dominant colony rats switched abruptly from the attack pattern displayed in the colony, to show activities (boxing, freezing) typical of colony intruders in either task. Moreover, forelimb movements similar to the “strikes” seen in reflexive fighting could be obtained during footshock to rats held alone on the grid. Finally, bites to an anesthetized conspecific were potentiated by footshock or tailshock, but only when the snout could be bitten: Such snout-bites are typical of colony intruders and not of attacking colony rats. These data indicate that pain produces a pattern of behaviors different in every detail from the activities typical of a dominant colony rat attacking colony intruders: There is, however, excellent agreement between pain-elicited behaviors and the defensive activities of colony intruders, suggesting that pain produces not aggression but defense.

Rats implanted with cannulas in the intraventricular foramen were tested after repeated daily injections of ACTH 1–24 or saline. Animals were either observed in their home cages or transported to an experimental room and observed in a “novel” Plexiglas chamber. Animals treated with the ACTH peptide evidenced an excessive, natural-type grooming which did not differ in the two experimental situations. No sign of adaptation of the ACTH-induced grooming was found over 10 consecutive days of testing. Saline-treated animals evidenced more grooming in the novel experimental chambers than when observed in their home cages. Some suggestion of adaptation of the grooming response was found in the saline-treated animals tested in the novel chambers. The results suggest that ACTH 1–24 induces a specific grooming response that is not dependent on being tested in a novel environment.

Cue stimuli defining the receptive female rat may be arbitrarily dichotomized as olfactory and nonolfactory, the latter primarily relating to assorted precopulatory movements. Experiment 1 compared the ability of sexually experienced anosmic and intact males to discriminate an estrous female within a group of nonestrous females. Although anosmic males were handicapped during the initial minutes of exposure, both groups readily identified the receptive female. Experiment 2 compared anosmic and intact groups of males exposed to an haloperidol-treated, immobile, estrous female within a group of nonestrous females. Although intact males were fully capable of identifying and copulating with the motionless estrous female, anosmic males were obviously disadvantaged as revealed by their high incidence of copulatory attempts with nonreceptive females. The results emphasize a functional duality of olfactory and nonolfactory behaviors of the female as redundant arousal and directional systems for guiding male copulatory behaviors.

Rats were exposed to short light—dark cycles to study the redistribution of paradoxical sleep (PS). PS predominated during the short dark periods in the albino strain, and to a lesser extent in the pigmented strain. Hypophysectomy did not affect the predominance of PS during the dark periods. We conclude that neither the albino condition nor the presence of the pituitary gland is a prerequisite for the redistribution of PS to short dark periods.

The effects of subdiaphragmatic vagotomy and atropine administration on thresholds for stimulation-induced feeding and self-stimulation were investigated in male rats. The animals first received permanent bipolar-stimulating electrode implants in the lateral hypothalamus. Once stable thresholds for stimulation-elicited feeding and self-stimulation were obtained, bilateral subdiaphragmatic vagotomies were performed (Experiment 1) or intraperitoneal injections of atropine sulfate were administered (Experiment 2). The first experiment indicated that vagotomy produces a marked disruption of stimulation-elicited feeding but does not interfere with either self-stimulation elicited from the same electrode or stimulation-induced gnawing obtained from comparable lateral hypothalamic sites. Additional observations suggest that a quantitative histological analysis of the vagal trunks can predict the degree of disruption of stimulus-elicited feeding and may provide a discriminating test for completeness of vagotomy. In the second experiment, production of an acute blockade of efferent vagal activity by an injection of atropine sulfate (8 mg/kg) 1 hr before testing had little effect on either feeding or self-stimulation. These results suggest that the vagus may play a significant role in the mediation of stimulation-induced feeding and that the effects of vagotomy on feeding cannot be reproduced by acute cholinergic blockade. The effects of surgical vagotomy on stimulation-induced feeding may reflect interruption of afferent mechanisms, elimination of atropine-refractory efferent systems, or disruption of feeding behavior caused by the sequelae of chronic vagal dysfunction.

Female rats (Experiment 1A) were tested for aggression against an adult male intruder in a home-cage test situation at several-day intervals from Day 18 of gestation through Day 21 of lactation. The peak frequencies of attacks and bites and the lowest latency to the first attack occurred on Day 9 of lactation, with concomitant increases in subordinate behaviors by the intruders occurring at that time. Virgin females (Experiment 1B) isolated for comparable periods of time in the test cage showed no differences in fighting levels as a function of length of residence in the home cage. Removal of the litter 4 hr prior to aggression testing on either Day 9 or 10 of lactation (Experiment 2) resulted in significant decreases in fighting levels by lactating females and in significant decreases in subordinate behaviors by intruders. These studies demonstrate that high levels of intraspecific aggression are exhibited during lactation in the rat and that the aggression is dependent upon stimuli from the litter for its expression.

Spontaneous motor activity and catecholamine responsiveness of brain adenylate cyclases were measured in albino rats after 4 days of reserpine injections (0.25 mg/kg/day, subcutaneous). Motor activity was significantly decreased in reserpine-treated rats in the 24-hr period following the final reserpine injection. Responses of cerebral cortex adenylate cyclase to norepinephrine (1–100 μM) and dopamine (10–100 μM) were increased during this same period. Catecholamine responses of striatal adenylate cyclase were not significantly increased by reserpine treatment. These results support prior suggestions that the cerebral cortex adenylate cyclase system may have an inhibitory function with respect to spontaneous motor behavior in the rat.

Human event-related potentials were evaluated during the trial-and-error learning of a sorting criterion for complex visual stimuli. Prior to the discovery of the correct criterion a sustained positivity was observed in frontal-mastoid recordings during the visual stimuli. A parieto-occipital negativity preceded auditory feedback. Two late positive waves following feedback—P₃ (355 msec) and P₄ (647 msec)—were both of greater amplitude in the trials before the subject finally confirmed the correct criterion. Their scalp distributions were, however, distinctly different, the P₄ wave being of relatively greater amplitude in the parieto-occipital regions. A general negative baseline shift occurred with a change in criterion.