ISSN:0012-1630    

DOI:10.1002/dev.420050302

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

年代:1972

数据来源: WILEY

摘要:

AbstractElectrical brain stimulation in puppies during the first week of life was correlated with crawling from a demonstrably preferred to nonpreferred tactual stimulus. Preferences changed when the structures stimulated were the same as reward areas in adult mammals, thus demonstrating that electrical stimulation in the infant brain has positive reinforcement value.

ISSN:0012-1630    

DOI:10.1002/dev.420050303

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe effects of differential preweaning social isolation of rats during Days 17–22 on the development of muricide, open field behavior, and starvation stress tolerance were examined. Four weaning isolation groups were used in order to separate the effects of maternal and littermate isolation during this period.EMLIwas deprived of maternal and littermate contact;EMI, maternal contact; andELI, littermate contact.NWIrats were isolated on the day following normal laboratory weaning. The results indicated a marked decrease in muricide in response to maternal isolation (EMLIandEMI) and a slight decrease in response to littermate isolation. In the open field the maternally isolated rats were more active than the other groups and exhibited less defecation. There were, however, notable differences betweenEMLIandEMI. EMLIwas more active thanEMIin the open field and exhibited an increase in activity over the 4 testing periods whileEMI,ELI, andNWIdecreased activity.EMLIwas clearly hyperactive during muricide testing whileEMIwas the least active.EMIrats weighed less than those in the other groups on Days 35, 50, and 100 but survived terminal food deprivation the longest. Significant differences in nonstressed adrenal gland weight were observed among groups but did not appear to correlate with any of the other measures. Terminal starvation eliminated these differences. Starvation also induced muricide in nonkillers in each of the groups.NWIrats appeared to be most easily converted and exhibited more consistent muricide than the other groups. These results are discussed in terms of a theory of altered forebrain regulation of emotional reactivity in response to preweaning stress and isolatio

ISSN:0012-1630    

DOI:10.1002/dev.420050304

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

年代:1972

数据来源: WILEY

摘要:

AbstractRats were handled daily throughtout gestation. Their litters and those of nonhandled rats were fostered to nonhandled mothers, half of whom were then housed with a virgin female (aunt). Prenatal handling decreased serotonin levels in 21‐day‐old offspring tested at the trough of the 24‐hr serotonin rhythm. Rearing with aunts resulted in lower brain weights among males, but had no effect on the serotonin levels of weanling rats. Both prenatal handling and rearing with aunts affected scores of female offspring in a reaction‐to‐handling test administered at age 56 days, but an open‐field test yielded only sex differences. Rearing with aunts differentially affected trough serotonin levels at that age, males showing a signficant decrease, whereas female value

ISSN:0012-1630    

DOI:10.1002/dev.420050305

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

年代:1972

数据来源: WILEY

摘要:

AbstractBlocking latency of the EEG (BL) and reaction time (RT) were investigated in 53 normal boys aged 88–207 months. The purpose was to discover whether changes inBLwhich have been reported to occur during growth in children parallel the well known decrease inRTthat accompanies development. EEGs were recorded (1) during an experiment in which the tracings were attenuated by short, high intensity flashes of white light, and, (2) while the subjects performed an auditory reaction task in which they responded to a tone that occurred without warning by closing a switch as quickly as possible.As expected, findings showed an inverse relationship betweenRTand age of substantial magnitude (r= −.822). By contrast, no relationship was apparent betweenBLand age in the group tested. This finding, together with the fact that the correlation betweenBLandRTwas not significantly different from zero, suggested thatBLandRTfollow different developmental courses and may be measures of essentially independent systems in children 7 years and ol

ISSN:0012-1630    

DOI:10.1002/dev.420050306

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

年代:1972

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420050307

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

年代:1972

数据来源: WILEY

摘要:

AbstractNewly hatched Leghorn cockerels (124) wearing hoods containing 8.5° prisms were reared in large or small groups and with high or low ratios of spatially distributed seeds on a sand filler. Only chicks reared in large groups demonstrated negative aftereffects when O° plates were substituted for the prisms on the seventh day. For large groups, high seed density resulted in smaller lateral pecking errors with prism displacement but larger negative aftereffect errors without displacement than did low seed density. For small groups, however, high seed density produced a reversal of negative aftereffect directions. High group density was necessary for negative aftereffect development, probably by its influence on socially mediated pecking rate

ISSN:0012-1630    

DOI:10.1002/dev.420050308

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

年代:1972

数据来源: WILEY

摘要:

AbstractRetinal degenerate C3H mice were tested in the open field under 2 illumination conditions before, during, and after the ages at which the early degenerate process occurs to determine whether the progressive destruction of the retina would result in the loss of brightness discrimination ability. From data collected on mice tested at 10, 14, 18, 22, 26, and 30 days of age, longitudinal and cross‐sectional analyses were performed upon activity and and defecation scores to separate the effects of prior test experience and age at testing. Whereas illumination differences had no effect upon defecation scores, activity differences under the 2 illumination levels formed an inverted U‐shaped function, with the greatest activity difference at 22 days of age. Prior experience was found to have no effect upon total activity scores at a particular age, although it did affect the pattern of activity over test days at the later ages. Naive animals tended to defecate less on their first day than did animals of the same age with prior test experience. The results of this experiment provide further evidence that retinal degeneration does not lead to complete blindness in this mouse strain, although it does lead to a loss of brightness discrimination ability following the degeneration per

ISSN:0012-1630    

DOI:10.1002/dev.420050309

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe development of 24‐hr memory of an escape response in neonatal C3H mice was examined in 2 experiments. In experiment 1, separate groups of mice received 25 trials of escape training for 3 consecutive days (24 hour Inter‐session‐interval) beginning at 5, 7, and 9 days of age. Several different measures demonstrated witin‐session improvement for all ages on all test days. However, between‐session improvement which was not due to maturation did not occur until after 9 days of age. In experiment 2, separate groups of mice received 25 escape training trials at either 8 or 10 days of age, and were retested 24 hrs later. Comparisons of the retest scores with original training scores as well as with littermate controls without prior training experience, showed that 8‐day old mice failed to show retention effects of prior training, whereas 10‐day old mice performed better on the retention test than they had on original training, as well as better than controls without previous training. The results suggest that 24‐hr memory of the escape task develops at 9–10 days of age

ISSN:0012-1630    

DOI:10.1002/dev.420050310

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

年代:1972

数据来源: WILEY

摘要:

AbstractMale rats were exposed prenatally to a .5 Hz, .5–3 to 10–30 gauss rotating magnetic field (RMF), comparable in frequency (but of slightly higher magnitude) to extreme low frequency magnetic fields associated with some geomagnetic and meteorological disturbances. In three replications, RMF‐exposed rats showed significantly greater suppression in response rate (relative to controls) during the 4‐min conditioned stimulus (CS) preceding a .5 mA, .5 sec shock in a conditioned suppression procedure. The RMF‐exposed animals showed the greatest suppression, relative to controls, during the first few shock exposures. Subsequent CS‐shock pairings were followed by similar suppression in both groups. RMF‐exposed rats also showed more initial suppression during the first presentation of the CS without shock. These findings are consistent with previous open field and Sidman avoidance data that suggest that the RMF‐exposed animals are more reactive to novel and aversive stimuli, and underline the importance of understanding the effects of everyday geophysical‐meteorological variables upon development and consequent b

ISSN:0012-1630    

DOI:10.1002/dev.420050311

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

年代:1972

数据来源: WILEY