摘要:

AbstractFour studies are reported examining the development of spontaneous alternation behavior in rats. Spontaneous alternation was found to increase from a rate of around 20% in 15‐16 day old rats to around 90% in 100‐day olds. Increasing the length of confinement in the 1st chosen goal arm did not affect alternation rats. Spontaneous alternation could be disrupted or facilitated in mature animals by the administration of either scopolamine hydrobromide or physostigmine sulphate, drugs which had no effect on the typical alternation pattern of 16‐day olds, but appeared to begin to have an effect at around 24 days. Dose response curves revealed certain age‐dose level interactions which were consistent with the hypothesis that cholinergic inhibitory mechanisms in the brain develop gradually in

ISSN:0012-1630    

DOI:10.1002/dev.420060402

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

年代:1973

数据来源: WILEY

摘要:

AbstractTranscallosal and transhippocampal evoked responses were studied in the guinea pig from 50 days of fetal life to adulthood. Variations in the time of appearance and in response latency of these 2 evoked potentials were observed during maturation. In 50‐day fetuses transcallosal responses could not be elicited; however, transhippocampal responses were present. In newborn animals, latency of transhippocampal responses was the same as that observed in adults, whereas latency of transcallosal responses was 3‐4 times longer than the adult respo

ISSN:0012-1630    

DOI:10.1002/dev.420060403

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

年代:1973

数据来源: WILEY

摘要:

AbstractAnalysis of the behavioral development of 64 socially‐reared guinea pigs revealed that the head‐shaking which frequently in trudes into the mating pattern of adult isolation‐reared males is a common response among young animals. The behavioral context in which young socially‐reared animals typically display head‐shaking includes the pre‐copulatory hip‐sway‐purring display and running (pursuit). The aberrant behavior of adult isolation‐reared males may stem from a post‐isolation “stimulus overload” which causes the mating pattern to get sidetracked into another pattern with which it

ISSN:0012-1630    

DOI:10.1002/dev.420060404

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

年代:1973

数据来源: WILEY

摘要:

AbstractFemale neonates of the A, BALB/c, and C57BL/6 mouse strains were injected with androgen, estrogen, or oil and the effects upon their sex behavior studied. Genotype and treatment combined interactively on a substantial number of variables, indicating that the effects of perinatally administered sex hormones and genotype cannot be considered separately. Effects of the 2 hormones were often in different directions. The lordosis response of one genotype appeared relatively insensitive to neonatal treatment, particularly with androgen.

ISSN:0012-1630    

DOI:10.1002/dev.420060405

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

年代:1973

数据来源: WILEY

摘要:

AbstractCalculations are given illustrating appropriate and inappropriate methods of statistical evaluation of data involving effects on offspring of experimental treatments given to pregnant rats. Failure to recognize the cluster effect in experiments of this nature can give rise to erroneous utilization of statistical procedure.

ISSN:0012-1630    

DOI:10.1002/dev.420060406

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

年代:1973

数据来源: WILEY

摘要:

AbstractChick embryos between the 15th and 20th day of incubation were subjected to hypothermia of 20°C followed by nitrogenous hypoxia until the cerebral EEG showed no fluctuations of potential. The embryos were exposed to air 15 or 30 min later. Body temperature was raised to 30°C and maintained there for 1 hr before being raised to 36°C, during which time 2 types of seizure episodes of rhythmic waves appeared. Type I was characterized by an ontogenetically later appearance (after the 15th day), larger amplitude, spike and slow wave patterns, a frequency of .3‐3.5 Hz with the slowest in the younger embryos, and a duration of 1 to several minutes. Type II was characterized by an earlier ontogenetic appearance, small amplitude, a frequency of 1‐30 Hz, and a duration of a few seconds to several minutes. None of these seizure episodes was observed after body temperature had reached 36°C. About the 17th day of incubation, the physiological components responsible for producing EEG patterns during episodes seem to undergo an abrupt maturational change indicated by the increase in percentage of embryos undergoing Type I episodes, and by changes in frequency of waves and duration of e

ISSN:0012-1630    

DOI:10.1002/dev.420060407

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe effects of infantile Stimulation × Genotype interaction on GABA production in rat cortex were investigated using an 8 × 8 diallel cross. Stimulation reversed the direction of dominance and epistasis typical of unstimulated controls, suggesting that a homeostatic genetic system has evolved in the rat ensuring an intermediate, optimal level of GABA productio

ISSN:0012-1630    

DOI:10.1002/dev.420060408

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

年代:1973

数据来源: WILEY

摘要:

AbstractAn autocorrelation technique was used to determine the periodicity underlying successive recurrences of specific sleep states (Quiet Sleep and Active Sleep). Groups of short (2–3 hr) polygraphic records and individual all‐night recordings were analyzed. Active Sleep and Quiet Sleep periodicities at 32 weeks conceptional age were 12 min. At 36 weeks, 40 weeks (term), and 1, 3, and 8 months, the periodicity of both Active and Quiet Sleep was consistently in the 40–60 min range. At all ages, the cycle time of one state was consistently longer than the other. The appearance of clear periodicities underlying both states and the similarity of the periodicities found in 36 week records to those found in much older infants' records indicate that this biological rhythm is basic to human CNS functioning. The Index of Rhythmicity values in these records and other investigators' data suggest that this rhythm reaches a mature form by 36 weeks postconce

ISSN:0012-1630    

DOI:10.1002/dev.420060409

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

年代:1973

数据来源: WILEY

摘要:

AbstractHousemice from 6 inbred lines and their F1crosses were reared in standard or enriched laboratory cages. A genetic analysis of brain and body weights indicated a significant directional dominance effect toward larger brain in F1crosses among enriched animals only, even when adjustments for body weight were made. The proportion of additive genetic variance was greater in standard caged animals than in enriched animals. Maternal effects played a small but significant role in influencing brain weights apart from those indirectly caused by body weight effects. The use of laboratory reared animals for genetic studies is questioned when environmental influences are known to have a strong effect on the character being studied, and the results are to be used to make inferences concerning the adaptive significance of the character.

ISSN:0012-1630    

DOI:10.1002/dev.420060410

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe approach‐generating properties associated with intermittent white light favoring 4 flashes/sec over adjacent rates of flicker, become evident between 512 and 530 hr after the onset of incubation independent of hatch time. The appearance of these properties can be attributed largely to the decline in approach elicited by nonflashing white light during this period rather than to a change in attractiveness associated with the 4 flash/sec rate itsel

ISSN:0012-1630    

DOI:10.1002/dev.420060411

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

年代:1973

数据来源: WILEY