摘要:

AbstractThe occipital cortical depth was determined in laboratory mice at both 14 and 20 days of age and after various periods of postweaning exposure to enrichment or isolation. The depth was found to be maximal at 20 days of age. It declined thereafter, irrespective of environment, but the isolate cortical depth decreased faster than the enriched. The postweaning depth of the occipital cortex appears to be determined by an inevitable age‐related decrease whose rate of decline may be attenuated by sensory stimulation. The postweaning cortical depth may reflect the extent of cortical neuronal development and associated metabolic activit

ISSN:0012-1630    

DOI:10.1002/dev.420150302

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

年代:1982

数据来源: WILEY

摘要:

AbstractInfants of gerbil mothers whose ventral scent gland had been excised were compared on a number of developmental indices with pups of mothers who had had an equivalent section of lateral skin removed. The removal of the mother's ventral scent gland retarded the offsprings' pattern of ultrasounding during the 1st 21 days of development. In addition, infants from such mothers showed a retarded righting reflex. Inhibitions in the developmental behavior of gerbil pups might have resulted from less effective heat transfer during mother‐pup contact. Indeed, excision of the gland resulted in lower ventral temperatures. The duality of function of the gland as an odor source for communication and as a heat source for offspring development suggests integrated communicative and thermoregulatory processe

ISSN:0012-1630    

DOI:10.1002/dev.420150303

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

年代:1982

数据来源: WILEY

摘要:

AbstractRapid Eye Movement (REM) Storms, intense REM bursts during Active Sleep (or REM Sleep), were investigated as an expression of the neural mechanisms involved in overall control of the sleep and waking states. Twenty normal full‐term infants were observed in their homes for a 7‐hr period when they were 2, 3, 4, and 5 weeks old. Sleep and waking states, and co‐occurring behaviors of the mother, were recorded at 10‐sec intervals throughout the observation day. During each 10‐sec epoch of Active Sleep a rating was made of the infant's rapid eye movements, as follows: No REM, Light REMs, Moderate REMs, or intense REMs (REM Storms).REM Storm rates were related to a measure of stability in the distribution of the sleep and wake states over weeks, derived separately for time the infant was alone and for time the infant was with its mother. REM Storm rates were negatively correlated with state stability in each of these contexts. The results demonstrated a commonality between the incidence of REM Storms and overall sleep‐wake state

ISSN:0012-1630    

DOI:10.1002/dev.420150304

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

年代:1982

数据来源: WILEY

摘要:

AbstractSmall mammals subjected to early stress show decreased aggression and emotionality, accelerated rates of maturation, and increased sexual activity, affiliation, and size. The purpose of this experiment was to test the phyletic generality of this phenomenon using fish (Poecilia reticulata) and, also, to control for the sensitivity of the measures, to determine if controls for both water quality and rearing‐testing conditions might produce different effects than have previously been reported for fish, and to see in what respects the effects of isolation and crowding are similar to those generally found in mammals. Early‐stressed guppies showed reduced aggression, but did not differ from controls on any other measure. Isolated and crowded guppies differed from each other and from the controls on 4 of the 6 measures. Isolated fish matured more rapidly and attained greater adult length than did the controls; the reverse was true for crowded fish. Crowded fish showed higher levels of emotionality than controls, whereas isolates showed lower levels than controls. No differences were noted in affiliation, although crowded fish spent more time in the vicinity of empty stimulus boxes. Crowded fish did not differ from controls in levels of sexual activity or display, but isolated fish showed low levels of sexual activity and high levels of display. These findings suggest that at least part of the early stress phenomenon shown in small mammals may be demonstrated in f

ISSN:0012-1630    

DOI:10.1002/dev.420150305

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe number of ultrasonic calls produced per minute by infant mice in response to room temperature increases during the 1st week after birth and decreases during the 2nd. These vocalizations show a distinct bout organization that changes with age. The initial increase in call production is due to an increase in the number of bouts whereas the subsequent decline is primarily due to bouts of fewer calls. The rate of calling within bouts, however, increases steadily with age. These findings are discussed in terms of maturational and motivational changes.

ISSN:0012-1630    

DOI:10.1002/dev.420150306

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

年代:1982

数据来源: WILEY

摘要:

AbstractA series of experiments in 2 strains of Wistar rats explored which aspects of maternal separation were responsible for the sleep disturbance of the young. Neither their own mother, after mammary duct ligation, nor constant intragastric infusion of nutrient during the day of separation were found to ameliorate significantly the changes in sleep‐wake state organization. However, a periodic nutrient delivery schedule and a formula closely resembling rat milk each ameliorated, and together entirely prevented, the sleep‐wake disturbance. Decreased ambient temperature during separation tended to exaggerate the disturbance and periodic tactile‐vestibular stimulation tended to reduce it. These findings suggest that the infant rat's normal sleep‐wake pattern is maintained by the thythmicity and composition of the milk delivered to it by its mother, although her warmth and behavioral interaction with it may play subsidiary roles. Separation produces its effects by removing these regulating features of the relat

ISSN:0012-1630    

DOI:10.1002/dev.420150307

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe performance of bilaterally synchronous wing‐flapping by chick hatchlings suggests but does not prove the existence of a bilateral coordinating mechanism. The present research tests for bilateral coordination by using the technique of induced asymmetry. The onset of bilateral wing coordination was defined as the age when induced bilateral asymmetry produced by right wing amputation, immobilization, or weighting influenced the drop‐evoked flapping rate of the left wing. Unilateral right wing immobilization or weighting immediately before testing reduced the flapping rate of the contralateral left wing of 3–5‐day chicks, the youngest examined. Weighted and unweighted wings flapped synchronously. Therefore, a mechanism which acts across the body midline to synchronize wing‐flapping by slowing the rate of the more rapidly flapping wing to match that of its slower contralateral partner was present by 3–5 days. This is several days before the onset of flight. The flapping rate of the left wing of chicks that had their right wing amputated on Day 1 was similar in rate to that of intact chicks when tested at 7 and 13 days. “Wing‐flapping” on the amputated side of some unilateral amputees was made visible by a prosthesis attached to the stump of the amputated wing. Bilaterally coordinated flapping in the unilateral amputees indicated that the sensory and trophic periphery of a given wing and flight‐related adaptive significance are not necessary for the postnatal production of bilaterally synchronized wing‐flapping. However, the slowed flapping produced by unilateral wing weighting or immobilization indicates that wing‐flapping rate is modulated by sensory feedback, e

ISSN:0012-1630    

DOI:10.1002/dev.420150308

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

年代:1982

数据来源: WILEY

摘要:

AbstractThis study describes infant socialization in captive parent‐young units of the caviomorph rodentOctodon degus. Types of parent‐young contact (huddling or squatting) and social interaction (body nosing and accompanying behaviors) are described and their ontogenetic trends examined between postnatal Days 1 and 46. Fathers spent less time than mothers in contact with the young. Mother‐young contact decreased postnatally, whereas the amounts of mother‐young and father‐young social interaction, measured in terms of body‐nosing exchanges, showed a continuous increase postnatally; sibling interactions also showed a continuous increase. Father‐young interactions tended to be dominated by the father. Young reared with the father cohabiting huddled less with their mother, and engaged in less body‐nosing, than young reared in the father's absence. Observations suggested that paternal control of the young may curb juvenile interactions. Young observed without their parents in an unfamiliar enclosure did not groom or “play” as in their home cage with parents present, but engaged in relatively more vocalizing, neck‐nosing

ISSN:0012-1630    

DOI:10.1002/dev.420150309

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

年代:1982

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420150310

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

年代:1982

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420150311

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

年代:1982

数据来源: WILEY