Journal of comparative and physiological psychology最新文献

Behavioral effects of subtotal amygdaloid lesions were investigated in an attempt to dissociate some of the abnormalities seen after total amygdalectomy. Twelve monkeys received bilateral stereotaxic lesions centered in the basolateral amygdala, lateral amygdala, dorsal amygdala, or the temporal white matter lying adjacent to the lateral amygdala. These monkeys were compared with others with control operations. The control monkeys then received total amygdaloid lesions (AMX). The AMX monkeys exhibited the typical amygdaloid syndrome of hypoemotionality, meat eating, coprophagia, and excessive exploration. In contrast, the monkeys with subtotal amygdaloid lesions would not eat meat or feces, though they were more willing than control monkeys to investigate inanimate objects. Although minor changes in affect were observed, the extreme emotional changes seen after total amygdalectomy were found only in the monkey with the largest subtotal lesion. Only those animals that were hypoemotional showed a deficit in learning successive reversals of an object discrimination. This close association suggests that both the hypoemotionality and the successive reversal deficit arise from the same underlying dysfunction.

Six different attraction tasks (one stimulus presented at a time) and five preference tasks were compared. In five of the six attraction tasks, one stimulus (vaginal secretion) was sniffed by males longer than any other stimulus, but the degree of difference between the stimulus and the others, and the relative attractiveness or aversiveness of the other stimuli, varied greatly across methods. One method was not useful for demonstrating differences in attraction to positive neutral odors but was useful for demonstrating aversions. In the preference tasks females demonstrated a significant preference for the odors of intact males over those of castrated males in four of the five methods, and again the strength of the preferences differed across methods. It is suggested that preference tasks are more sensitive and less subject to variability due to details of the method employed than are attraction tasks. Procedures in which the test animal's own home cage was used as the testing environment tended to emphasize effects due to novelty rather than the inherent attractiveness of the odorants. It is suggested that the use of novel objects as sources for test odors and the use of airstreams for delivery of odors reduce the salience of the test odorants.

An examination was made of the heart rate (HR) and blood pressure (BP) responses of 7-9-wk-old spontaneously hypertensive rats (SHR) and genetical control Wistar/Kyoto (WKY) rats during aversive classical conditioning. Subsequent to the development of conditioned responding (CRs), assessments were made of the effects of selective autonomic blockade by methyl atropine (10 mg/kg), phentolamine (2 mg/kg), and propranolol (2 mg/kg). The CR complex in the two strains consisted of pressor BP CRs in conjunction with vagally mediated decelerative HR CRs in the SHR strain and sympathetically mediated accelerative HR CRs in the WKY strain. The decelerative SHR HR CR did not appear to be secondary to baroreceptor reflex activity, although such activity did appear to be involved in the pressor BP and decelerative HR orienting response (OR) and unconditioned response (UR) complex of the SHRs on the initial application of the CS and the US, respectively. Augmented pressor BP ORs, CRs, and URs in the SHRs relative to the WKYs and differential drug effects on BP and HR baselines of the two strains suggested the presence of enhanced sympathetic activity in the SHRs that was not reflected in the SHR decelerative HR CR. Phentolamine unmasked evidence of reflex beta 2-vasodilation deficiency in the SHRs that could have contributed to the enhancement of their BP OR and CR.

A total of 385 suckling rats were used to investigate the effects of 24-hr biorhythmicity on performance. Nest seeking (homing) in 7-day-old pups and its facilitation by d-amphetamine varied across time of day. Analysis of initial choice revealed that the pups' ability to detect and position themselves in the direction of the nest did not vary across time of day. Homing behavior was not an artifact of random activity level but was related to the pups' motor performance which varied with a daily rhythm. Circadian rhythmic influences on the acquisition and retention of an amphetamine-induced odor aversion were shown by manipulating time of day of conditioning and subsequent retention testing. The time of day effect on conditioning was attributed, in part, to daily rhythmic changes in the effectiveness of the unconditional stimulus. Retention was optimal in pups tested at the time of day corresponding to that of their original training. Time of day may serve as a contextual stimulus that is important for retention in immature as well as adult animals. An appreciation of these 24-hr rhythms is warranted for an accurate assessment of the behavioral competence of developing animals.

The effects of p-chloramphetamine (PCA) on tonic immobility (TI) duration, activity, and temperature in chickens were examined in six experiments. In Experiment 1, intraperitoneal doses of 10 or 15 mg/kg PCA produced a significant attenuation of TI duration. The involvement of norepinephrine or dopamine in this effect is questionable since catecholamine synthesis inhibition with alpha-methyl-p-tyrosine in Experiment 2 did not alter the PCA attenuation of TI duration. However, in the third and fourth experiments, serotonin synthesis inhibition with p-chlorophenylalanine produced a blockade of the PCA effect on TI when subjects were tested at 60, but not 10, min after PCA injection. A competing response interpretation of the PCA effect in terms of enhanced motor activity was ruled out in Experiment 5 since, in contrast to the hyperactivity observed in mammals, PCA produced a decrease in both open-field and stabilimeter activity. A PCA-induced decrease in core temperature was observed in Experiment 6, and this effect also contrasts with the hyperthermia reported in rats following PCA injection. These results provide additional evidence that drug treatments that produce a serotonergic behavioral syndrome in rats result in attenuated TI duration in chickens, and they further document the existence of a curious mammalian-avian reversal in drug effects.

Rats with complete removal of the cortex anterior to bregma in adulthood (frontal cortex) were compared behaviorally and neuroanatomically with rats with similar removals at 7 or 25 days of age. Excision of the frontal cortex in adult rats produced transient aphagia, chronic motor abnormalities in feeding, a chronic drop in body weight, increased activity in running wheels, impaired performance at a spatial reversal learning task, and chronic abnormalities in a variety of species-typical behaviors, including swimming, food hoarding, and defensive burying. In contrast, similar lesions in infant rats failed to produce aphagia, a chronic drop in body weight, increased activity, or impaired learning of a spatial reversal task. Infant lesions did not allow sparing of complex species-typical behaviors, however, such as those involved in feeding, swimming, hoarding, or defensive burying. Furthermore, when the brains of neonatally operated rats were compared with those of control rats or rats operated on in adulthood, there were striking differences. The cerebral hemispheres of the neonatal operates were smaller both in surface dimensions and weight, the thalamus was smaller, and the cerebral cortex was thinner. These data imply that there may be substantially less sparing of function following frontal cortex lesions in infancy than previously believed and that neonatal frontal lesions in rats have significant effects on brain development in regions far removed from the actual site of surgical excision.

Terry-cloth texture, home odor, and the presence of siblings modulate the ingestive behavior of infant rats. Unlike warmth, which affects ingestion in pups until at least 15 days of age, the relative importance of these other cues varies with the age of the pup. At 3 days, ingestion is dependent on warmth but is not influenced by the other cues. At 6 days, texture and home odor enhance ingestive behavior (intake, activity, mouthing, and probing), but the presence of siblings has no effect. Home odor or terry-cloth texture did not alter the ingestive behavior of 12-day-olds, but the presence of siblings enhanced milk intake. Thus, during development, the external sensory controls for ingestion become progressively more complex. Warmth serves as a primary permissive cue for ingestion in developing pups, but as pups grow older, other types of cues (such as odor, texture, or social stimuli) also gain significance.

Prostaglandin E2 (PGE2) suppressed drinking induced by angiotensin II (A II) when both were injected into the cerebral ventricles of the rat. This antidipsogenic effect of PGE2 was correlated with its known pyrexic actions. Intracerebroventricular injection of arachidonic acid (AA), the precursor of PGE2, also suppressed A II-induced drinking. This antidipsogenic effect of AA was similarly correlated with pyrexia and was dependent upon the conversion of the precursor to a prostaglandin within the brain. These observations are consistent with the hypothesis that newly synthesized cerebral PGEs, in response to elevated A II levels, contribute to the cessation of drinking by opposing the dipsogenic action of A II. However, blockade of cerebral prostaglandin biosynthesis by central injection of indomethacin did not enhance drinking elicited by A II even at doses that completely eliminated the antidipsogenic and pyrexic actions of AA. Collectively, the results suggest that exogenous PGEs or AA may inhibit A II-induced drinking by elevating body temperature or some other pharmacological action and that endogenously synthesized PGEs of cerebral origin do not play an important role in the normal termination of drinking induced by centrally administered A II.

Rats, one groups with fornicotomies, and another group with control operations, were trained in several versions of a bar-press, spatial alternation task. In free operant conditions the fornicotomized rats showed adequate alternation performance when the bars were relatively separated by placement either at the ends of an alley or at the ends of the arms of a T-maze, but they were impaired when the bars were adjacent. Also, the fornicotomized rats failed to alternate after interpolation of either baffles or a 10-sec delay in the stem, both of which manipulations resulted in intervening turning responses before each choice. A failure to discriminate memories of relevant, discrete events from those of similar, intervening events appears best to account for the results.