ISSN:0012-1630    

DOI:10.1002/dev.420020102

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe mean membrane potentials of cellular elements were measured during the passage of a glass microelectrode through cortical tissue in fetuses and newborn guinea pigs. The average value of membrane potential increases in fetuses after the 47th day of gestation from 7.6 mV to 28.1 mV in newborn guinea pigs. The developmental changes in histograms of individual values correspond to the increase in mean value. The membrane potentials are sensitive to brain hypoxia following cord clamping only after the 62nd day of gestation. In term fetuses, cord clamping is followed by regular lung ventilation and by the slow gradual increase of mean value in membrane potentials. The development of the mean membrane potential of cortical elements correlates well with the development of the cortical steady potential.

ISSN:0012-1630    

DOI:10.1002/dev.420020103

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

年代:1969

数据来源: WILEY

摘要:

AbstractPregnant rats were placed on reduced food intake or remained on adequate diet during gestation and lactation. Offspring were cross‐fostered to provide for independent experiences of prenatal and/or postnatal mother malnutrition. All offspring were placed on anad libdiet at time of weaning. When evaluated in adulthood, offspring whose mother was food‐deprived during the lactation period showed body weight deficits and increased errors on the Hebb‐Williams maze as compared to controls. There were no observed effects of the prenatal depriv

ISSN:0012-1630    

DOI:10.1002/dev.420020104

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

年代:1969

数据来源: WILEY

摘要:

AbstractAudio‐sensitivity can be induced in strains of mice considered audio‐resistant by exposure to a brief auditory stimulation (60 sec at 95 db) at a critical age. Mice that had been audio‐conditioned were subjected to a battery of seizure‐evoking procedures and the responses interpreted in terms of neurophysiological mechanism. The effect of maturation on the development of sound induced, chemoshock and electroshock convulsion threshold and pattern was also studied. The pattern of maximal seizures induced by electroshock, pentylenetetrazol, and sound are remarkedly similar at a given age. The threshold for low frequency electroshock and for minimal pentylenetetrazol decreased with increased age and weight. There was no significant difference in maximal electroshock seizure threshold with aging, but duration of the seizure pattern markedly changed with increased age. Audio‐conditioning produced profound changes in the ontogeny of low frequency and chemoshock threshold, but maximal seizure threshold and pattern were unaffected. The audio‐sensitized CF# 1 mice differ in several ways from littermate. The oscillator mechanism of the audio‐sensitive mice is more easily discharged by electric and chemical stimulation, and there is an alteration in the neuro‐ontogenic pattern, and a decrea

ISSN:0012-1630    

DOI:10.1002/dev.420020105

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

年代:1969

数据来源: WILEY

摘要:

AbstractA 2 × 2 × 2 factorial experiment was conducted to investigate the combined effects of maternal infantile handling, maternal pregnancy (offspring pre‐natal) stress, and offspring infantile handling on adult open‐field behavior and weight of albino rats. The primary results are as follows: (1) both offspring infantile handling and maternal pregnancy stress tend to increase adult exploratory behavior; (2) adult weight was lower for subjects whose mother had undergone stress during pregnancy than for offspring of non‐stress females; (3) several 2‐way interactions were found to significantly influence open‐field exploration; (4) when offspring infantile handling was combined with maternal pregnancy stress, emotional reactivity (i.e., defecation) was found to increase significantly over that following either type of stimul

ISSN:0012-1630    

DOI:10.1002/dev.420020106

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

年代:1969

数据来源: WILEY

摘要:

AbstractPrior research has found that mice reared and nursed by a lactating rat mother, or reared in the presence of a nonlactating adult female rat, give a significantly smaller adrenocortical response to a novel stimulus than do control mice. The purpose of this paper was to determine whether this phenomenon could be mediated through stimuli that do not require physical contact between the adult rat and the young mouse. Experimental mice were born and reared in a cage that separated them from an adult nonlactating female rat by means of a double mesh wall. Thus, they could see, hear, and smell the rat, but no physical contact was possible. Control mice were reared similarly in the presence of an adult nonlactating female mouse. At the time of weaning the corticosterone response of both groups to a novel stimulus was virtually identical. The data support the hypothesis that direct physical contact between the mouse and rat is necessary to cause physiological and behavioral changes in the mouse.

ISSN:0012-1630    

DOI:10.1002/dev.420020107

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

年代:1969

数据来源: WILEY

摘要:

AbstractHippocampal and neocortical EEG activity was recorded from 48 unanesthetized, intra‐uterine, guinea‐pig fetuses of 35 to 65 days gestational age. The earliest hippocampal electrical activity appeared at around 35 days (i.e., at approximately the same time as such activity appears in the lower brain stem, and earlier than it appears in the neocortex). This indicates that functional maturation of the brain begins almost simultaneously in large parts of the so‐called old brain, not only in its bulbar parts, and spreads to more superficial structures with age. The first activity had a random frequency distribution, whereas more regular periodicity developed later. From 44 days hippocampal bursts and spindles were recorded, especially during hypoxia or fetal distress. The bursts seemed to bear a relation to the reanimation process after hy

ISSN:0012-1630    

DOI:10.1002/dev.420020108

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

年代:1969

数据来源: WILEY

摘要:

AbstractGlutamic acid, glutamine, GABA, aspartic acid, and alanine have been determined throughout the ontogenetic development of the rabbit visual system, i.e., occipital cortex, superior colliculi, lateral geniculate bodies, and retina. At 11 days of age, when the rabbits' eyes were opening, many of the amino acids had decreased significantly in the individual parts, and then later increased to more mature levels. The amino acid level appeared to be fully developed by 30 days of life with glutamic acid having the highest concentration in the cortical area and GABA in the subcortical ones.

ISSN:0012-1630    

DOI:10.1002/dev.420020109

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

年代:1969

数据来源: WILEY

摘要:

AbstractInfant monkeys, 15 to 120 days of age, were tested in a Hebb‐Williams maze. Age was a significant variable affecting error scores, and the relationship between age and performance on this test might best be described as U‐shaped. The operation of changing motor and motivational systems appears to be a crucial factor in determining performance of infant monkeys in this task, rather than learning abilit

ISSN:0012-1630    

DOI:10.1002/dev.420020110

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

年代:1969

数据来源: WILEY

摘要:

AbstractNegative afteraffects (NAE) to prism displacement should not exist without prior positive adaptation (PA) during initial prism exposure. In 4 experiments, chicks wearing hoods containing 8.5° wedge prisms from the day of hatching showed: (a) significant NAE (pecking overcompensation in the direction opposite to their initial displacement error when matched O‐degree clear plates were substituted for the prisms), but not significant PA (reduction in the lateral error of pecking while wearing the prisms) at the sixth day; (b) NAE exceeding the theoretically predicted PA on the sixteenth day; (c) significant short and long duration NAE, and significant short and long duration reversal overcompensation effects (ROE) (left‐right pecking asymmetry following reversal of the prism base directions) on the seventh and eighth days, without prior PA on the seventh day; (d) neither significant NAE nor significant PA on the fourth day. Both significant NAE and significant PA had been reported previously on the eighth day. Geometrical analyses suggest that variables latent in unrestricted application of adult sensory rearrangement techniques to rapidly growing chicks of low sensory‐motor plasticity produce an ontogenetic‐development‐related reciproci

ISSN:0012-1630    

DOI:10.1002/dev.420020111

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

年代:1969

数据来源: WILEY