Behavioral biology最新文献

It has been demonstrated in a number of species that species-typical mate preference is affected by early social experience. This study extends the understanding of variables within the sensitive period that influences the development of mate preference in Coturnix coturnix japonica. Hatchlings were individually given 5-day exposure to a normal hen at five different age levels during the first 25 days posthatch. For purpose of control all experimental subjects were exposed to an albino hen for the 20-day period in which they were not exposed to the normal hen. Starting on day 45 all subjects were given a series of 10 mate-choice tests between an albino and normal hen. The data indicate that, first, at any of the age levels examined more than 5 days of social experience is required for the development of reliable mate preference for the normal. Second, the duration of treatment during the sensitive period is an important influence on mate preference. Finally, the sensitive period is nonhomogenous. The first 5 days are the most valuable.

Experiment 1 assessed the preference-aversion function of hamsters for water and 0.08, 0.15, 0.35, and 0.71 M NaCl solutions in the two-bottle test. Unlike rats, the hamsters did not show a strong preference for isotonic (0.15 M) saline, nor did they exhibit any preference for the other solutions. Experiment 2 examined the effects of hydrochlorothiazide on the hamsters' intake of 0.71 M NaCl solution. The results indicated that this diuretic agent did not cause the hamsters to increase their saline intake relative to the baseline level. Experiment 3 also indicated that a high (5 mg) dose of desoxycorticosterone acetate failed to produce sodium appetite in the hamsters. These results contrast with those found with rats.

Previous studies have shown that adrenalectomized rats have a lowered behavioral taste threshold for and consume more sodium chloride solution than do intact rats. We attempted to determine whether altered sodium and/or potassium saliva concentrations might accompany adrenalectomy and mediate these behavioral changes. Twenty-two rats, eleven intact and eleven adrenalectomized, were anesthetized with ether and injected with pilocarpine (7.5 mg/kg body wt): whole saliva was collected for 10 mins. The intact animals produced 0.577 ± 0.189 ml of saliva while the operated animals produced significantly less, 0.329 ± 0.204 ml. The salivary sodium concentration was 43.6 ± 13.0 meq/liter in operated rats and significantly lower, 32.5 ± 4.3 meq/liter in intact animals. There were no significant differences in potassium concentration, but the sodium/potassium ratio was significantly greater in adrenalectomized than control animals. Adrenalectomized rats secreted 14.3 meq of sodium in the 10-min period compared to 18.7 meq by the controls, suggesting that the amount of sodium per unit time in the adrenalectomized animal's oral cavity was markedly decreased. It thus seems that although the sodium concentration is higher in the adrenalectomized animal, much of this difference is accounted for by a decreased flow rate even with equivalent pharmacologic stimulation.

Two experiments were conducted to study the dynamics of copulatory and aggressive behavior in situations where two sexually active male prairie voles were tested with a single receptive female. In Experiment I, 20 males were each tested once in a one-male condition and once in a two-male condition. Although the basic copulatory pattern was identical in both situations, a facilitation, manifested as decreased numbers of mounts, intromissions, and thrusts prior to the first ejaculation, occurred in the two-male condition. In Experiment II, 24 males each received two additional two-male tests conducted in their home cages. Although there were stable dominance relationships and differences in ejaculation frequency, there were no consistent differences between dominant and subordinate males with respect to copulation.

Severe irradiation-produced granule cell losses in the internal granular layer of the main olfactory bulb had no significant effects on homing to home-cage wood shavings in infant rats on postnatal Days 9 and 13. Granule cells of the main olfactory bulb do not seem to be required for the mediation of this behavior.

It has been hypothesized that during the perinatal period androgen alters sexual development only after it is aromatized to estrogen intracellularly. The dose of estrogen needed to cause sexual differentiation, however, is larger than might be expected on the basis of the rate of estrogen production. This could be because estrogens are normally sequestered by plasma fetoneonatal estrogen-binding protein. To test this possibility neonatal female rats were administered a low dose of estrogen alone or in combination with the glucocorticoid prednisolone, a steroid that reduces blood levels of the estrogen-binding protein. The estrogen significantly inhibited adult lordotic behavior only when combined with the prednisolone, a treatment which had no effect by itself. The findings support the “aromatization hypothesis” and the suggestion that the fetoneonatal estrogen-binding protein protects the developing rat from differentiating effects of estrogen.

By 12 hours of life, rat pups attach faster to females similar in lactational age to their own mothers than to females whose lactational ages differ. This attachment pattern correlates with morphological and possible olfactory differences in the nipples of the test mothers, demonstrating the existence of a synchrony between the mother rat and her young during the early postnatal hours. By 10 days of age the pup's deprivational status and its day-night cycle influence its attachment pattern to the different test mothers.

Male and female Mongolian gerbils (Meriones unguiculatus) of both agouti and black coat color variations were tested for ventral marking in an open field. Males marked more than females and black gerbils marked more than the agouti animals. Black females marked at levels equal to those of agouti males, and thus they may be useful in future investigations of neural and hormonal factors affecting ventral marking in females. Such research was difficult in the past because of the extremely low levels of marking normally exhibited by agouti females.

The maze learning ability of male rats castrated at birth, males and females treated with cyproterone acetate or sesame oil, and females treated with testosterone within the first 10 days postpartum was compared to that of nonmanipulated males and females (Experiment 1). Neonatal castration and injections of cyproterone acetate and testosterone were found to significantly reverse normal sex differences in maze learning. In Experiment 2, differences in gonadal hormone secretions and activities during adulthood on maze learning ability were assessed. It was found that gonadectomy did not significantly influence the performance of males and females. In Experiment 3, females were found to exhibit a greater tendency to explore and make irrelevant section entries on a maze that was problem free. It is suggested that differences in maze learning are more greatly influenced by brain sex than by subsequent gonadal hormone secretions during adulthood and are also due to the tendency of females to make more exploration-linked errors.