摘要:

AbstractIn colonies of the fire ant,Solenopsis invicta, eclosion is facilitated by adult workers which strip away and consume the pupal cuticle. This stage‐specific social interaction involves chemical stimuli which are present at the onset of eclosion, concurrent with the initiation of gross movements and separation of the pupal cuticle. Fire ant workers retrieved inanimate objects treated with an extract of eclosing pupae and placed them in the colony brood chamber with the appropriate age group where they were tended by several workers. The facilitation of eclosion by adult colony members appears to be an obligatory process in the development of this species; pupae denied the aid of adult workers during eclosion are unable to remove the pupal cuticle and rapidly succum

ISSN:0012-1630    

DOI:10.1002/dev.420180502

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

年代:1985

数据来源: WILEY

摘要:

AbstractPreweanling rat pups do not display an aversion to a flavor conditioned stimulus (CS) paired with illness if the CS is presented during the act of suckling. In contrast, 20‐day‐old pups do form such a conditioned taste aversion while suckling (Martin&Alberts, 1979). The dissolution of the nursing‐related “blockade” of toxiphobia correlates with the onset of solid food intake. Moreover, prevention of weaning prolongs the blockade; ingestive experience with solid food is necessary for the expression of nursing‐related taste aversions in 26‐day‐old “food naive” pups (Gubernick amp;Alberts, 1984). The present experiments tested the possibility that premature weaning to solid food might accelerate the onset of nursing‐related toxiphobia. Pups were weaned at 13 days of age and ingested only food and water. These prematurely weaned pups received taste aversion conditioning while suckling on Day 16, but showed no aversion to the CS flavor during a later food test. Thus, conditions that lead to early weaning (ingestion of solid food) do not accelerate the onset of taste avers

ISSN:0012-1630    

DOI:10.1002/dev.420180503

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

年代:1985

数据来源: WILEY

摘要:

AbstractRats exposed perinatally to dietary commercial soy lecithin preparation (SLP) showed alterations in sensorimotor development and brain cell maturation. Latencies for righting responses (measured on postnatal Days 1–4) and negative queotaxis (measured on postnatal Days 5–8) were shorter in the SLP treated animals. This pattern was accompanied by specific alterations in cerebellar development; biochemical markers for cellular maturation indicated a compression of the ontogenetic time course, as assessed by ornithine decarboxylase (ODC) activity, and levels of nucleic acids and proteins. In contrast, cellular development in the cerebral cortex indicated a generalized slowing of the time course of maturation and a deficit in the number of cells which persisted into adulthood. Behavioral abnormalities also did not disappear in adulthood, as morphine analgesia was markedly reduced in the SLP group. These results indicate that exposure of the fetus and neonate to dietary SLP during development leads to regionally specific alterations in brain cell maturation associated with disruption or behavioral patte

ISSN:0012-1630    

DOI:10.1002/dev.420180504

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

年代:1985

数据来源: WILEY

摘要:

AbstractA Pavlovian fear conditioning procedure was used to examine the ontogeny of the hooded rats' learned responses to visual stimulation. The data suggests adissociationin the emergence of the processes required to detect visual events and those necessary for learning an association between visual stimulation and shock. Pups did not condition to a visual conditioned stimulus (CS) paired with a shock unconditioned stimulus (US) until they were 17 days old, even though 15‐day‐olds were clearly able to detect the visual CS. Although 15‐day‐olds failed to condition to the visual CS, they conditioned successfully when an auditory CS was paired with shock. Thus, the 15‐day‐olds' failure to condition to the visual CS was not due to a performance deficit or to a general ineffectiveness of shock as an US. These data suggest that the components of the visual system that mediate detection and those required for associative learning mature s

ISSN:0012-1630    

DOI:10.1002/dev.420180505

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe spontaneous movements of human fetuses were studied longitudinally between 21 and 41 weeks of gestation. At each age, spectral analysis of the fluctuations in fetal movement revealed strong cyclic patterns. The frequency of the dominant motor rhythms ranged from .13 to 1.91 cycles per minute. The strength of oscillations between .18 and 1.02 cycles per minute increased slightly with gestation, but the frequency of the dominant motility cycle, the width of the corresponding spectral peak, and the incidence of weaker (usually faster) rhythms did not change. Neuromuscular activity is known to serve important developmental functions in the embryo and fetus. The ubiquity and relative consistency of cyclic motility in the last half of human gestation, and the existence of similar periodicity in other species, suggest that the cyclic activation of developing motor circuits may possess particular adaptive value.

ISSN:0012-1630    

DOI:10.1002/dev.420180506

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

年代:1985

数据来源: WILEY

摘要:

AbstractFour experiments assessed the acquisition of aversions by preweanling rats to odors experienced during isolation from their home‐nest environment. Conditioned aversion occurred for animals given a second novel odor paired with the home‐nest environment, depending upon the duration of the odor‐isolation pairing. With a brief duration of pairing (two pairings of 3 min each) novel odors became more preffered when paired with isolation or, to a lesser extent, when paired with home. With longer durations of pairing (two pairings of 4 hr each) the odor paired with isolation became absolutely aversive, although the odor paired with home did not become absolutely preferred. With intermediate durations neither aversion nor preference for the odors was substantial. Animals conditioned at ages 9, 16 or 23 days postnatal acquired aversions to odors paired with isolation, but 30‐day‐old rat

ISSN:0012-1630    

DOI:10.1002/dev.420180507

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

年代:1985

数据来源: WILEY

摘要:

AbstractTwo experiments were conducted on human neonates examining their behavior and adrenocortical activity in response to physical restraint. In both experiments, newborns (9 per condition in Experiment I; 10 per condition in Experiment II) were tested in one of three conditions: Restraint, which involved strapping newborns to a circumstraint board for 20 min; Strapping Control, which involved strapping newborns to the board and then immediately taking them off the board and returning them to their cribs; and Control, which did not involve any restraining manipulation. In Experiment I, blood samples for plasma cortisol determination were obtained via heel‐stick immediately prior to the assigned manipulations and 30 min later. In Experiment II, only the postmanipulation blood sample was taken. Two behavioral states, Active Awake and Crying, were examined as indices of behavioral distress. In Experiment I, the effects of the blood sampling procedure on behavioral distress and plasma cortisol were significant; however, no significant effects of restraint were observed. In Experiment II, restraint was associated with small but significant increases in behavioral distress and in plasma cortisol level

ISSN:0012-1630    

DOI:10.1002/dev.420180508

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

年代:1985

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420180509

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

年代:1985

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420180501

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

年代:1985

数据来源: WILEY