Journal of comparative and physiological psychology最新文献

The physiological properties of the in vitro hippocampal slice of the golden hamster are described. Hamster hippocampal tissue displays features similar to those seen in other species in terms of postsynaptic response characteristics to stimulation of monosynaptic afferents in the three primary subfields of the hippocampus. This pattern of physiological similarity supports the contention of the uniformity of hippocampal function across species, an important consideration with regard to the role of the hippocampus in brain and behavioral function. These results will permit the utilization of the hamster hippocampal slice in neurophysiological and neuroendocrine studies.

New Zealand albino rabbits received sham lesions or complete, medial, lateral, or posterior septal lesions and were subjected to differential conditioning in which tones of different frequencies served as conditioned stimuli and paraorbital electric shock was the unconditioned stimulus. Electromyographic (EMG), heart rate (HR), and blood pressure (BP) conditioned responses (CRs) as well as hippocampal rhythmic slow wave activity (RSA) were recorded. Lateral or complete septal lesions enhanced the bradycardiac HR CR but had no effect on the BP depressor response. Both unconditioned and conditioned EMG responses occurred infrequently and were unaffected by any lesion. Unconditioned HR responses and somatomotor threshold determinations to unsignaled electric shock were also unaffected by the lesions. Complete septal lesions increased locomotor activity relative to sham or other septal lesions. Little hippocampal RSA was detected in animals with medial lesions, but the HR CR was unimpaired in these animals. These data implicate the septo-hippocampal circuit in classical conditioning of cardiovascular changes and further suggest that diencephalic forebrain structures may modulate forebrain processing of sensory stimulation, perhaps in terms of assessing its biological significance.

Three experiments with New Zealand albino rabbits examined the role of anterior and posterior cingulate cortex in Pavlovian conditioning. Tones served as conditioned stimuli, and paraorbital electric shock served as the unconditioned stimulus. Anterior cingulate lesions attenuated conditioned heart rate (HR) decelerations, relative to posterior cingulate or sham lesions, but enhanced the magnitude of the bradycardiac component of the orienting reflex. Posterior cingulate lesions enhanced the bradycardiac component of the conditioned response, particularly late in training, relative to anterior or sham lesions. Somatomotor eye-blink conditioning, shock thresholds, and HR unconditioned responses were unaffected by cingulate lesions. Electrical stimulation of cingulate cortex revealed effective sites for eliciting heart rate and blood pressure (BP) changes only in anterior cingulate cortex. Relatively large (70-100 beats per minute) HR decelerations accompanied by small (1-5-mm Hg) BP depressor responses were elicited by stimulation of this area; the HR decreases were abolished by atropine methyl nitrate but were unaffected by either propranolol hydrochloride or phentolamine hydrochloride. These results are discussed in terms of cingulate involvement in the mediation of the cardiovascular component of a response pattern related to stimulus processing.

The performance of rats trained in a radial arm maze was tested before and after chemical lesions of the thalamic mediodorsal nucleus or the ventral tegmental area. Their behavior was compared with that of a sham-operated control group. Lesions were produced with ibotenic acid, a compound that selectively destroys neurons while apparently leaving fibers of passage intact. Results revealed no intergroup difference in the number of errors performed when all six trials were given in one session without interruption. The group with mediodorsal lesions made, however, significantly more errors than either of the other two groups when a delay of 1 hr was interposed between the first four and the last two trials. Furthermore, these rats differed from rats of the other groups in the number of sessions necessary to reach criterion, in the time needed to finish a session, and in the directness with which a goal was approached. Rats with lesions of the ventral tegmental area did not differ from rats of the sham-operated control group in any of the measures taken. It is suggested that the deficits of rats with mediodorsal lesions resemble qualitatively those found in human patients with lesions of the mediodorsal nucleus.

The contribution of nonassociative neophobia and sensitization to the potentiation of odor by taste in rats was tested in three experiments. In Experiment 1, neophobia for almond odor (O), saccharin taste (T), and odor-taste compound (OT) cues was tested before and after noncontingent lithium chloride poisoning and compared with conditioned aversions produced by OT-LiCl temporal pairing. The OT compound potentiated unconditioned neophobia, but there was no evidence of poison-enhanced neophobia, disinhibition of neophobia, or sensitization by noncontingent LiCl; temporal pairing produced aversions for the compound and its elements. In Experiment 2, generalization to a novel odor was tested after O-LiCl or compound OT-LiCl pairing. The potentiated odor aversion did not generalize to the novel odor; it was specific to the odor paired with taste and LiCl. In Experiment 3, potentiation of the odor component by a discriminant or nondiscriminant taste component was tested. Potentiation was evident only when a novel discriminant taste was in compound with odor prior to LiCl poisoning. These studies support an associative "indexing" hypothesis of the potentiation effect in rats.

Studies were made of the sexual behavior of 22 gonadectomized adult rhesus macaques (Macaca mulatta) given no hormonal treatment, treated with estradiol benzoate (EB, 20 microgram/day), and treated with testosterone propionate (TP, 10 mg/day). Experimentally produced female pseudohermaphrodites (hermaphrodites, n = 6), long-term castrated males (n = 9), and ovariectomized females (n = 7) were given 36 pair tests of 10-min duration with ovariectomized, estrogen-primed female partners. Twelve tests were given under each treatment condition. Yawning was the only behavior that showed a significant effect across treatments for hermaphrodites and females; the yawning rate was greater with TP treatment. The number of tests during which hermaphrodites showed erections increased significantly under TP treatment. One hermaphrodite mounted, but none achieved intromission or ejaculated. Males displayed several significant treatment effects, including increased mounting, intromitting, and ejaculating frequencies under TP treatment. The EB had little effect on any of the behaviors in any group. Rates of aggression and grimacing were greater among hermaphrodites than among males and females. Males displayed significantly greater rates of sexual behavior than hermaphrodites or females. As infants and juveniles, these hermaphrodites had displayed social and sexual behavior characteristic of males, but as mature adults, their behavior and responsiveness to testosterone at a dose capable of activating a high level of sexual behavior in castrated males gave little evidence of masculinization.

Plasma corticosterone levels were used to assess the response to stress induced by intraperitoneal injections of hypertonic saline in rats with lateral hypothalamic (LH) or sham lesions. Rats with LH lesions displayed a corticosterone response equal to that of normal animals under basal conditions, after control injections of isotonic saline, and 20 min after injection of hypertonic saline (1.5 M, 1.0 ml/100 g of body weight). The corticosterone response of animals with LH lesions, however, was significantly less than that of normal animals 90 min after injection of hypertonic saline when no water was available. With access to water, normal animals displayed substantial drinking (14.5 ml/90 min), which resulted in a reduction in plasma corticosterone concentrations to a level observed after a control injection of isotonic saline, but the little water ingested by animals with LH lesions (2.5 ml) had no effect on the pituitary-adrenal system. It is concluded that the failure of animals with LH lesions to drink following a hydrational challenge is not the result of an exaggerated response to stress.

A series of experiments evaluated the extent to which copulatory stimulation could ameliorate the anestrus and sterility exhibited by neonatally androgenized female rats. The age at which animals began to exhibit persistent vaginal estrus and the degree of sexual receptivity exhibited under several testing paradigms were found to be inversely related to the dose of testosterone propionate (TP) injected neonatally. With increasing numbers of mounts received, both the number of androgenized animals exhibiting sexual receptivity and the quality of the estrous behavior exhibited tended to increase. The extent to which copulatory stimulation modified receptivity varied with the dose of TP injected neonatally and the condition of testing. Animals injected with high doses of TP (500 microgram) usually showed little or no receptive behavior even in the most extensive behavioral tests. However, under some testing conditions animals receiving 50 micrograms of TP neonatally, while showing little or no receptivity during initial mounts, showed increased receptivity as behavioral tests were extended. Following matings that included one to five ejaculations, only control animals were observed to become pregnant. However, when androgenized females cohabited with males for an extended period, animals that had neonatally received .5 microgram of TP, but not higher doses, did become pregnant. It is concluded that the capacity of systems mediating reproductive physiology and behavior to be facilitated by stimuli associated with males and that mating is a characteristic of the female rat which can be manipulated by injection of hormones during the neonatal period.

Two experiments explored the possibility that lesions of avian hyperstriatum, which disrupt reversal learning, might have that effect through a potentiation of the influence of proactive interference. Neither experiment found any evidence to suggest excessive interference in hyperstriatal pigeons, from preceding training on a position (or color) discrimination, on retention of a color (or position) discrimination, and this was true both after a short (30 min) and after a long (6 or 7 day) retention interval. There was, however, evidence of a disturbance, not easily interpreted, in retention following the lesions. There was also convincing evidence, from both experiments, for the disruption by hyperstriatal lesions not only of reversal learning but also of tasks not involving reversals, a disruption that suggests a general tendency to perseverate in hyperstriatal birds.

A series of experiments was performed to further understand the behavioral and physiological determinants of postfast anorexia in golden hamsters. Postfast anorexia and/or the failure to adapt to a feeding schedule was not restricted to a particular photoperiod condition or strain of hamster. The anorexia was also observed with a liquid diet, but hamsters were able to show large increases in water intake on a water deprivation schedule. When the animals were group housed, they pouched food during scheduled feeds and ate it later: Meal size was not increased. Measures of gastric fill and plasma metabolites indicated that filling and emptying of the forestomach may occur with a periodicity similar to that of spontaneous meals, and the data were consistent with strong peripheral satiation/satiety mechanisms in this species.