摘要:

AbstractThe present study was designed to provide further information on the enduring cognitive effects of experimental phenylketonuria (PKU) in rats, produced by the administration of alphamethylphenylalanine and phenylalanine on postnatal days 3–21. These rats evidenced: (1) impaired learning set formation, (2) stimulus preservation, particularly after an error, and (3) difficulty in utilizing the less salient features of their environment in mastering discrimination problems. In contrast, long‐term memory function and the ability to form simple associations did not differ from controls. This pattern of intact and impaired cognitive functions bears remarkable similarity to that of mentally retarded humans and neonatally hyperphenylalaninemic rhesus monkeys, thus affirming the use of rats to study mental retardation. In addition, possible reasons for the mildness of the impairments commonly observed in animal models of severe mental retardation syndromes are discussed. We suggest that transfer of learning paradigms that assess the animal's ability to use information acquired in other problems are more likely to uncover significant cognitive impairments in such models than are procedures that test only the animals' ability to solve a single prob

ISSN:0012-1630    

DOI:10.1002/dev.420230302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractDuring postweaning development, rats exhibit several well documented trends in their play fighting: (1) It peaks between 30–40 days and then declines with the approach of sexual maturity; (2) males initiate more play fights than females; and (3) the overall complexity of play fights, as expressed by such measures as duration of bouts, also decreases with increasing age. Such trends could arise from changes in attack or defense, or some combination of both. In this article it is shown that (a) the decline in play fighting with the onset of sexual maturity in rats results from a decline in attack, not in defense; (b) the differences in play fighting by male and female rats are due to sex‐specific rates of both attack and defense; (c) the developmental decrease in the complexity of play fighting arises from a decrease in the frequency of counterattacks (i.e., after an animal defends itself, it is less likely to launch an attack). In this way, age and sex differences in play fighting can be traced to differences in its subcompone

ISSN:0012-1630    

DOI:10.1002/dev.420230303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe ontogeny of antiphonal calling was studied in free‐living European starlings. Nestlings participate in three types of vocal exchanges: (1) Broodmates exchange calls while the parents are away; (2) parents and nestlings exchange calls during feeding; (3) nestlings exchange calls with parents approaching from a distance. Analysis of the temporal patterning of vocal interactions revealed call alternation and avoidance of acoustic overlap in exchanges of the first and third types. The antiphonal exchanges between parents and young develop shortly before fledging and appear to help family groups maintain contact after the young have left the nest. Early antiphonal exchanges between broodmates are as smooth as later ones between parents and chicks, suggesting that chicks quickly attain proficiency at antiphonal interactions and do not rely on an adult partner to maintain the pattern. There are parallels with the development of vocal turn‐taking in human infa

ISSN:0012-1630    

DOI:10.1002/dev.420230304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe immediate behavioral and immunological consequence of a single 2‐week maternal separation experience were studied in socially housed 7‐month old bonnet and pigtail macaques. Maternal separation was associated with species dependent behavioral changes. Both species showed significant increases in ingestive behaviors associated with separation. Separated and matched controls showed an increase in disturbance behaviors (vocalization, startles, shaking, temper‐tantrums) that subsided after 24–36 hours in control subjects, but continued, albeit with species‐dependent patterns, in the separated monkeys. Allomaternal care of the separated bonnet infants but not the pigtail infants was associated with a progressive reduction of these disturbance behaviors during the separation period. Following a period of agitation, pigtail infants showed a depressive phase characterized by slouched, withdrawn postures and reduced motor activity. As a group, the separated infants of both species were not different from controls with respect to lymphocyte activation by mitogens, a measure of immunocompetence. However, when individual behavioral responses which reflected disturbance, such that the change in lymphocyte activation following in vitro stimulation with the mitogens phytohemagglutinin and Concanavalin A (makers of the immunocompetence of T lymphocytes) was related to levels of vocalization and time spent in slouched postures. The activation of B lymphocytes by pokeweed mitogen was not influenced by the separation experience nor was it associated with specific behavioral responses to separation. The importance of assessing the affective consequences of stressors is

ISSN:0012-1630    

DOI:10.1002/dev.420230305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe role of age‐dependent responses in infantile amnesia was examined. Ten‐ and 15‐day old rats were trained in an approach‐mother, avoid‐shock paradigm and tested for retention immediately and after a 1‐day delay. Ten‐day‐old rats were also tested after 6 days. Half of all the pups received a shock reactivation treatment before the delayed retention tests and half did not. In comparison to immediate retention, performance declined after 1 day but was reinstated by reactivation. A similar reactivation effect was found on 10‐day‐old pups tested after 6 days except that a different age‐specific response was substituted for the original behavior. These effects were not found in untrained controls. These data show that learning may be expressed differently when acquisition and retention are measured at different developmental stages, a pattern that may be mistaken

ISSN:0012-1630    

DOI:10.1002/dev.420230306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThis study examined some aspects of the developmental phase of social bonding in newborn lambs. In Experiment 1, 3‐day‐old Merino lambs (singles and twins) were tested in a 2‐choice situation for mother discrimination at a distance. In Experiment 2, the ability of twins to discriminate their siblings at a distance was studied 3 and 7 days after birth. When released at 9m from two postparturient ewes after a latency of 30 s, which allowed the lambs to hear and to see both animals, most lambs chose to run and to stay with their own mothers before the end of the 2‐min test (Experiment 1). There was no difference between singles and twins, nor between males and females in their distant discriminative ability. However, twins were initially undecided, slower to reach their mothers, and spent significantly less time with them. When the same testing procedure was used for sibling discrimination, most 3‐day‐old twins went to a lamb, but the proportion of lambs reaching the sibling first did not differ significantly from random, and the time spent near either lamb was similar (Experiment 2). During these tests, female lambs performed better than males. When tested 7 days after birth, all twins reached a lamb and a high proportion of them chose to go to the sibling first. They also spent most of the time near it. These results demonstrate that mother discrimination from a distance is well established in 3‐day‐old lambs and sibling discrimination takes longer to develop but has occurred b

ISSN:0012-1630    

DOI:10.1002/dev.420230307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420230301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY