摘要:

AbstractThe appetitive behavior of 3‐ to 6‐day‐old rat pups was studied by testing their ability to direct their ingestive behavior to a restricted food source. We found that, from 3 days of age, pups were able to feed efficiently from such a source. More specifically, pups that were deprived of nutrition but not of maternal care as well as pups that were dehydrated ingested significantly more than nondeprived animals, and did so whether liquid diet was spread over the entire floor surface beneath them or restricted to a fraction of the floor surface. However, pups that had been nutritionally and maternally deprived were not able to direct their feeding. The general locomotor activation of pups in this latter group appeared to interfere with their ability to direct their behavior to the restricted source. These results indicate that from early ages, developing rats possess the appetitive competence to guide their behavior and suggest that previous findings of poorly directed behavior were a confound of the behavioral activation shown by pups tested in a state of maternal depriv

ISSN:0012-1630    

DOI:10.1002/dev.420240702

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

年代:1991

数据来源: WILEY

摘要:

AbstractIntraoral lemon infusion elicits facial wiping behavior in fetal rats on Days 20 and 21 of gestation. On Day 19, fetuses tested in a warm saline bath respond to infusion but do not express the wiping response. In contrast, fetuses tested within the amniotic sac exhibit wiping. Fetal movements after infusion were analyzed on Days 19 and 20 in both the bath and amnion environments. Facial wiping is assembled from simpler components in both real time (during the 15 s after infusion) and developmental time (over Days 19–20 of gestation). In real time, the wiping response occurs following a brief period of fetal activity comprising head and forelimb movements. After the wiping bout is initiated, strokes by left and right forelimbs increase in duration and become synchronized. In developmental time, components of the wiping response (forelimb strokes) are consistently expressed on Day 19, but other components (head stabilization) are lacking when fetuses are tested in bath. The amniotic sac appears to provide scaffolding that reduces head movement and promotes paw‐face contact, thus facilitating facial wip

ISSN:0012-1630    

DOI:10.1002/dev.420240703

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

年代:1991

数据来源: WILEY

摘要:

AbstractThis manuscript reports on the effects of stressors repeated at a 24‐hr interval on three samples of human newborns. In Study 1, newborns meeting criteria for obstetric and perinatal optimality experienced either 2 mock Discharge Exams, viewed as a type of handling stressor, or 2 Heelstick Blood Draws, viewed as a type of nocioceptive stressor. As in a previous study, newborns meeting optimality criteria showed habituation of the adrenocortical response to the repeated Discharge Exam. The adrenocortical response to the repeated Heelstick tended to increase or sensitize. In Studies 2 and 3, samples of newborns with more nonoptimal obstetric complication scale scores were examined. These newborns failed to show habituation of the adrenocortical response to the Discharge Exam, but responded like ‘Optimal’ newborns to the repeated Heelstick. The applicability to these data of the Groves and Thompson (1970) Dual‐Process Model of Habituation is discussed. The results also provided evidence of stability in behavioral distress independent of stability in adrenocortical activity. The implications of these data for studies using cortisol as an index of the physiological basis of early temperament are con

ISSN:0012-1630    

DOI:10.1002/dev.420240704

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

年代:1991

数据来源: WILEY

摘要:

AbstractGenetic and maternal influences on hypertension were studied by comparing the SHR and SS/Jr inbred rat strains and their reciprocal F1 hybrids under identical conditions. When raised on a low salt (LS) diet (0.3% NaCl), SHR rats had higher systolic blood pressure (SBP) than SS/Jr rats by 9 weeks of age. Direct recordings from freely moving rats at 18–24 weeks confirmed this difference. Placement on a high salt (HS) diet (8% NaCl) at 5 weeks of age significantly increased SBP within 3 weeks in all groups, although the degree of increment was significantly smaller in SHR females. Inbred strains had higher SBP than their F1 hybrids when measured indirectly and directly from arterial cannulae. After exposure to HS diet, F1 females reared by SHR dams exhibited larger increments in SBP, greater weight loss, and greater debilitation and associated mortality than F1 females reared by SS/Jr dams. Differences between inbred strains and F1s maintained on LS diet were consistent with dominance for low BP, and differential genetic control of hypertension in each inbred strain. F1 differences demonstrated that maternal factors affected body weight in weanlings, pressor response to HS diet, and associated debilitatio

ISSN:0012-1630    

DOI:10.1002/dev.420240705

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

年代:1991

数据来源: WILEY

摘要:

AbstractChanges in exploratory activity and spontaneous alternation were examined across postnatal Days 8–31 in Lister hooded rat pups whose eyelids were surgically opened at 6–8 postnatal days. Compared with controls, whose eyes open naturally at 14–16 days, the treated animals showed accelerated behavioral development. Open‐field activity increased more rapidly in the week following surgery, but only when all pups in the litter had their eyelids opened, and not when only half of the litter was treated. Rearing on the hind paws emerged earlier in treated animals, but grooming was unaffected. Pups having unilateral early eyelid opening made pivotal circling movements contraversive to the opened eye in an open‐field arena in the early neonatal period. When tested in a T‐maze, treated pups showed earlier spontaneous alternation than controls. Possible physiological systems underlying such changes are discussed. Our results show that unusually early visual stimulation has behavioral consequences, producing a brief speeding of some attentional and investigatory behaviors, though such changes may also depend upon environmen

ISSN:0012-1630    

DOI:10.1002/dev.420240706

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

年代:1991

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420240701

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

年代:1991

数据来源: WILEY