ISSN:0012-1630    

DOI:10.1002/dev.420050202

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

年代:1972

数据来源: WILEY

摘要:

AbstractTwo strains of rats (Zivic‐Millers and F‐344s) were reared in either an enriched or isolated environment for 60 days (experiment I) or 27 days (experiment II). At maturity, independent groups of subjects were tested on both appetitively and aversively motivated learning tasks. The results indicated that the effects of early rearing conditions on later behavior were both task and strain specific. Passive avoidance and appetitively motivated tasks were more sensitive to the early experience variable whereas active avoidance tasks were more sensitive to the genetic varia

ISSN:0012-1630    

DOI:10.1002/dev.420050203

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe morphological development of the cerebellum was examined with quantitative histological techniques in rats which were nursed from birth by mothers that had free access to food during lactation or were fed during that period 40 or 20% of the average ad lib diet. Little or no retardation was observed in the development of the cerebellum except in its germinal matrix (the external granular layer) at 11 days. At 17–21 days there was a substantial reduction in the migratory cells (precursors of granule neurons) and stationary cells (precursors of basket and stellate neurons) of the molecular layer, and in the differentiating granule cells of the internal granular layer. Associated with these reductions in cerebellar microneurons there was a significant decrease in the area occupied by the molecular and internal granular layers, the magnitude of which was a function of the severity of undernutrition. Between 30–60 days a total areal recovery was observed in the molecular and internal granular layers in the mildly undernourished rats and substantial compensation in the severely undernourished rats. This areal recovery was not due to a replacement of the lost cells but to an apparent compensatory increase of the “neur

ISSN:0012-1630    

DOI:10.1002/dev.420050204

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

年代:1972

数据来源: WILEY

摘要:

AbstractRetrieval in lactating females, sensitized virgin females, and sensitized adult male rats was compared in a T‐maze extension of the home cage. The percent of lactating females that retrieved was significantly greater than in either the sensitized virgin of sensitized male groups. No difference was found between the two sensitized groups. The data are discussed in terms of the hormonal involvement in maternal behavio

ISSN:0012-1630    

DOI:10.1002/dev.420050205

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

年代:1972

数据来源: WILEY

摘要:

AbstractAn investigation was carried out of the effect of undernourishing rats during much of gestation and throughout the whole suckling period on their behavior in a passive avoidance situation. All young were fed ad libitum from 21 days of age. Passive avoidance tests were done at 30 and 31 days in a two‐compartment box. On the first test normal rats tended to cross between compartments more promptly than previously underfed rats. Cross‐over latency was always greater on the second test than on the first. There were no significant differences in test 2 latency or in the ratio, test 2 latency/test 1 latency, between sexes, between normal and previously undernourished rats, between groups with 2‐min and 24‐hr interest intervals, or between master and yoked control rats. The last finding indicates that the apparent passive avoidance response may have been either nonspecific ‘freezing’ behavior following unpleasant stimulation, or inhibition specifically of movement, due to its association

ISSN:0012-1630    

DOI:10.1002/dev.420050206

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

年代:1972

数据来源: WILEY

摘要:

AbstractSeveral behavioral and neurochemical consequences of neonatal and/or postneonatal exposure to maneb (ethylenebisdithiocarbamate manganese), a popularly used fungicide, were investigated in male rats at dietary levels of 0, .5, 1.0, or 10 ppm. Three different periods of exposure were employed: (1) during the 28‐day neonatal period; (2) during the 5 months postweaning; and (3) during both the neonatal and postweaning periods of life. Behaviorally, neonatal exposure to maneb depressed exploratory activity of the 30‐day old wealings. As adults, neonatally treated rats demonstrated enhanced learning ability in an operant conditioning procedure. However, no facilitation of learning was found in animals whose exposure to maneb was restricted to only their postweaning period of life. Although unrelated to the behavioral changes, neuroendocrine effects were also found. Regional brain cholinesterase (ChE) activity was reduced in rats exposed to maneb during either the neonatal period alone or during the 5 month postweaning period alone, but continuous exposure to maneb during both the neonatal and postweaning periods did not appreciably affect brain ChE activity. Adult plasma corticosterone levels were elevated by exposure to maneb only postweaning. No such change was found in the neonatally exposed r

ISSN:0012-1630    

DOI:10.1002/dev.420050207

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

年代:1972

数据来源: WILEY

摘要:

AbstractRats fed a 5% L‐phenylalanine diet from 28 days of age were tested 33 to 44 days later (61–72 days old) for spontaneous alternation, habituation to auditory stimulation, and passive avoidance. In spontaneous alternation and passive avoidance tests there was no significant difference from control rats. Habituation was faster than in the controls, interpreted as an inability to sustain arousal and attention. This may be a basic behavioral deficit in L‐phenylalanine fed rats, accounting for deficits reported in more complex learning tests. Phenistix tests for phenylpyruvic acid in the urine were positive only during the first 4 weeks the 5% diet was fed. The behavioral deficit was present even after this period. To reestablish positive Phenistix tests the excess L‐phenylalanine in the diet had to be raised to 10%. This diet severely affected the nutrition of the

ISSN:0012-1630    

DOI:10.1002/dev.420050208

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

年代:1972

数据来源: WILEY

摘要:

AbstractIntraperitoneal injections of p‐chlorophenylalanine (pCPA) were given to 71 rats in the first 7 weeks of life, decreasing brain 5‐hydroxytryptamine concentrations to 20% of control values. The brain weight was significantly decreased, evident after 2 weeks of treatment, and also 52 days after the last injection. The retarded brain growth was not due to a general growth inhibition only: body weight was decreased initially, but from Day 24 the experimental animals gained weight more rapidly than the controls, resulting in a significantly higher body weight from Day 67.The decrease in brain growth was accompanied by behavioral changes, evident later in life. The first test was given 4 weeks after the last pCPA‐injection. The changes observed were moderate, but consistent in all the tests. There were no learning deficits or clear motivational changes. In all the tests there was evidence of a reduced arousal level in the pCPA‐treated rats: latencies were long, exploration was low, habituation to new environment was fast, and the reactivity

ISSN:0012-1630    

DOI:10.1002/dev.420050209

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

年代:1972

数据来源: WILEY

摘要:

AbstractHypoactivity was observed in the open field performance of 28 rats fed a diet containing 3% excess L‐phenylalanine and .12% p‐chlorophenylalanine between 21–51 days of age (PKU group) compared to both pair‐fed and ad lib control groups. Open field testing was conducted 4–11 days following termination of the phenylalanine, p‐chlorophenylalanine diet. While on the diet serum phenylalanine levels of the PKU group ranged between 16.6–38.0 mg%. Twenty‐four to 48 hours following termination of the PKU diet serum phenylalanine levels had returned to normal (i.e., 2–10 days prior to open field testing). The reduced open field activity of the PKU group is not attributable to differences in food consumption or weight at the time of testing. Hypoactivity is consistent with previous investigations administering chronic doses of phenylalanine, but employing different induction techniques, treatment durations, and

ISSN:0012-1630    

DOI:10.1002/dev.420050210

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

年代:1972

数据来源: WILEY

摘要:

AbstractHeat‐light reinforcement procedures are described which were developed for key‐peck conditioning of 1‐day‐old chicks. 24 Vantress x Arbor Acre and 24 White Leghorn chicks were randomly assigned to two preference conditions in a successive discrimination problem: bright yellow as S+and dim blue as S−, or the reverse. During 7 sessions of 48 discrete conditioning trials each, the chicks learned quickly to peck the key when the S+was presented and to inhibit pecks when the S−was presented. This differential responding to S+and S−was evident when the chicks were 1 day old (sessions 1 and 2) and became more evident with further training when the chicks were 2 days old (sessions 3–7). There were no significant preference or breed differences. Contrary to previous results, this experiment demonstrated that neural mechanisms involved in inhibition of responses are well developed in

ISSN:0012-1630    

DOI:10.1002/dev.420050211

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

年代:1972

数据来源: WILEY