摘要:

AbstractThirty kittens were given a 30‐min exposure to a moderately cool environment and drop in body temperature was measured. One group was tested every day from age 2 days to 21 days of age. A 2nd group was tested on Days 6–21 and a 3rd group tested only at 19 days of age. The 1st group (tested on Days 2–21) became homeothermic at an earlier age than did the other groups. The data are interpreted to indicate that early exposure to cool temperatures facilitates acquisition of temperature regulation in the cat, and that observed deficits in passive avoidance learning in young cats are not due to increased motor activity produced by a fall in body temper

ISSN:0012-1630    

DOI:10.1002/dev.420130102

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe ontogeny and substrates of amphetamine‐induced changes in flurothyl‐induced myoclonic and clonic seizure thresholds were investigated in 2 selectively bred lines of mice. The long‐sleep mice exhibited dose‐dependent increases in myoclonic and clonic susceptibility following amphetamine, irrespective of age. The noradrenergic agonist clonidine and the dopaminergic agonist apomorphine produced increases in susceptibility comparable to those seen with amphetamine. The short‐sleep mice, however, exhibited a dichotomous myoclonic response to amphetamine that was age‐dependent. Between 15 and 35 days of age amphetamine decreased seizure susceptibility whereas increases in susceptibility were noted at later ages. With the exception of 80 days, amphetamine did not affect clonic thresholds. In respect to myoclonus, clonidine persisted in producing effects similar to those seen in the long‐sleep mice whereas apomorphine exhibited the same ontogenetic alteration in effect seen with amphetamine. These results confirm that the short‐sleep mice might be a naturally occurring animal model of preadolescent hyperkinesis. Furthermore, the neuropharmacological tests demonstrate that the paradoxical response to amphetamine in the young short‐sleep mice is mediated via a dopaminergic mechanism that must undergo dramatic chang

ISSN:0012-1630    

DOI:10.1002/dev.420130103

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe ontogeny of primary socialization in a litter of 5 German shepherd puppies was investigated using both arena tests and rearing environment (kennel) conditions. Tests for exploratory behavior, conducted at 5 1/2, 8 1/2, and 11 1/2 weeks of age, showed reversals in amount of exploration over the 6‐week period. Dominance was also investigated at 5 1/2, 8 1/2, and 11 1/2 weeks, using both a bone‐in‐pen test and a rearing environment setting. By comparison of the subjects' dominance scores at each age for both settings, evidence was found for the separation of the development of dominance behavior into 2 kinds: competitive and social dominance. The scores for exploratory behavior (stimulus reactivity) and competitive dominance were clearly related: those pups at 5 1/2, 8 1/2, and 11 1/2 weeks that were most exploratory also ranked highest for competitive domi

ISSN:0012-1630    

DOI:10.1002/dev.420130104

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

年代:1980

数据来源: WILEY

摘要:

AbstractWeanling rats, 20 days old, received 0, 1, 2, 4, or 8 pre‐exposures to 12% sucrose prior to a single pairing of sucrose with an intraperitoneal injection of lithium chloride (LiCl; 3.0 mEq of a .15Msolution) or distilled water (20 mg/kg). Testing for sucrose taste aversion with a 2‐bottle‐choice procedure on 9 test trials reliably showed that increasing numbers of pre‐exposures to sucrose directly attenuated taste aversion effects in the LiCl‐injected groups but did not appreciably affect intake performance in the distilled water‐injected groups. Comparisons between the injection conditions yielded reliable evidence for sucrose taste aversion at each pre‐exposure level. These results show that flavor stimulus pre‐exposures reliably attenuate subsequent taste aversion in weanling rats as had previously been reported

ISSN:0012-1630    

DOI:10.1002/dev.420130105

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe results of this study indicate that birth weight in normal term infants is related to changes in heart rate in response to auditory stimulation. Only infants above the median in birth weight responded to stimulus onset and offset. They exhibited a change in response to onset from a heart rate acceleration (defensive response) on the 1st trial to heart rate deceleration (orienting response) on later trials. The response to stimulus offset was a deceleration. Those infants below the median in birth weight showed no significant responses to onset or offset.

ISSN:0012-1630    

DOI:10.1002/dev.420130106

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe effects of early handling on the exhibition of positive and negative contrast effects were investigated. Over two 4‐day testing sessions, animals were given alternating 1‐min access periods to 2 bottles containing either 32 or 4% sucrose solutions. Measures of lick rate and latency to switch bottles revealed that both handled and nonhandled animals exhibited contrast effects of equal magnitudes. The results did not support an emotional interpretation of contrast effects but were interpreted as support for the perceptual theory of this phenome

ISSN:0012-1630    

DOI:10.1002/dev.420130107

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

年代:1980

数据来源: WILEY

摘要:

AbstractEarly patterns of social interaction, including fighting while nursing, social grooming, and social play, were analyzed in a litter of mountain lion kittens to determine if interactive patterns formed during nursing persist into subsequent social stages (i.e., social grooming and social play). The data suggest that the nursing order established by mountain lion kittens has an important role in early social development by initially directing interactive patterns among littermates.

ISSN:0012-1630    

DOI:10.1002/dev.420130108

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

年代:1980

数据来源: WILEY

摘要:

AbstractIn 2 studies Gunn rats carrying 2 recessive alleles for jaundice (jj) were compared with their heterozygous littermates (Jj) under varied litter size (4 vs 12 pups) and handling conditions. Handling did not produce long‐term effects. Litter size interacted with Genotype to increase the differential response ofjjrats by 21, 23, and 50 days of age. A decrease in survival rates and weight gain was found inJjand especiallyjjrats from large litters. Forjjrats only, being reared in a large litter increased the severity of ataxia. Jaundiced rats from large litters showed less rearing and tended to enter fewer squares than those from small litters whereasJjlittermates showed an equivalent amount of rearing and number of squares entered in large as compared to small litter sizes. Differences betweenJjandjjrats in frequency of pivoting were greater in those from large litters than in those from small litter

ISSN:0012-1630    

DOI:10.1002/dev.420130109

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe central hypothesis was that, in young as compared with adult rats, Pavlovian excitation is weaker and extinguishes more slowly, whereas internal inhibition is weaker but extinguishes more rapidly. In Experiment I, the suitability of free operant (Sidman) avoidance as a baseline for measuring Pavlovian effects was assessed in 5 age groups between 19 and 98 days of age trained in a shuttle box. Although clear age‐related increases were evident in avoidance capacity, efficient “high criterion” avoiders were found in all age groups, indicating that the response was suitable. In Experiment II, groups of 26‐, 38‐, and 95‐day‐old rats first received Pavlovian aversive excitatory and differential inhibitory conditioning, or the conditional stimuli and shock randomly, or no treatment. Three days later they received free avoidance training. Prior Pavlovian conditioning facilitated subsequent avoidance learning in young subjects, but depressed it in adults. Among “high criterion” avoiders, such effects were absent. Following the avoidance training phase, 3 age groups of matched “high criterion” avoiders received conditioned stimuli superimposed on the baseline (a conditioning test). These results confirmed t

ISSN:0012-1630    

DOI:10.1002/dev.420130110

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe present study examined the responsiveness of 19‐ to 20‐day‐old C57BL/6J (C) and A/J (A) mouse pups to maternal cues. The C pups were found to spend more time near their C or A foster mother than they did near a virgin female. The A pups showed no such preference. Attempts to increase the motivation of A pups to approach the mother did not produce any preference for maternal cues. However, when the bedding on which odorous substances had been permitted to accumulate for an extended period of time was used as choice stimuli, pups of both lines showed a preference for the bedding of the mother as opposed to that of a virgin female. These results support findings with other rodents of a change in the female's odor during lactation which increases her attractiveness to her pups; and they demonstrate a genetic difference between pups of 2 inbred strains in their approach to maternal

ISSN:0012-1630    

DOI:10.1002/dev.420130111

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

年代:1980

数据来源: WILEY