摘要:

AbstractThe acquisition and retention of habituation to air‐puff was studied in rats on Days 1‐19 postpartum. Animals of all ages demonstrated habituation but the rate of habituation varied with age: slower on each successive day from Day 1 to Day 8, but thereafter more rapid on each successive day. This peak of elicited responding is discussed in relation to the peak of spontaneous activity at Day 16 and to the pattern of neural development, including changes in acetylcholinesterase, norepinephrine, and serotonin, measured during the preweaning period. All ages showed 30‐min retention of habituation, with 60‐min retention developing after the 1st week. No evidence of 24‐hr retention appeared a

ISSN:0012-1630    

DOI:10.1002/dev.420090202

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe relative efficacy of (1) repeated auditory and somesthetic stimulation for the habituation of cardiac acceleration responses and (2) intramodal and cross‐modal stimulation for the dishabituation of cardiac responses was studied in 45 full‐term 2‐day‐old infants. Although the 2 stimuli were equally effective initially, repeated presentation of the somesthetic stimulus had a greater decremental effect than repeated presentation of the auditory stimulus. The stimuli were equally effective in producing dishabituation when in a different modality from that of the habituating stimulus (cross‐modal) but not when in the same modality (intramodal). Changes in the locus of stimulation without a change in modality were ineffective for producing dishabituation. The findings indicate the human newborn discriminates auditory and somesthetic inputs effectively and equally but does not discriminate contralateral from ipsilateral stimulation in either

ISSN:0012-1630    

DOI:10.1002/dev.420090203

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

年代:1976

数据来源: WILEY

摘要:

AbstractOffspring from pregnant rats injected with 4mg/kg body weight colchicine on Embryonic Days 18, 19, and 20 were found to have isocortical and hippocampal structures greatly reduced in mass when examined at birth. Cells with pyknotic nuclei were found in Layers 5, 4, and 3 of the cerebral isocortex, the habenula, and anterior medial nuclei of the thalamus. Brains taken at Postnatal Days 22 and 132 were reduced in overall size, and had a 20‐30% reduction of cells at the vertex of the neocortex with up to 50% reduction in the thickness of the corpus callosum. A decrease in activity, an increase in fearfulness and/or decreased tendency to explore, reduced error scores on the Hebb‐Williams maze, poor performance on the Maier elevated maze, and a lessened sensitivity to sound‐induced seizures were correlated with these anatomical ch

ISSN:0012-1630    

DOI:10.1002/dev.420090204

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe behavior of rats injected once every 2 days between Postnatal Days 4 and 20 with 62.5 m̈g/g or 125 m̈g/g body weight of taurine was compared with saline‐ or .5 M NaCl‐injected litter‐mate controls. Taurine‐injected rats ran significantly less in the running wheel test anddisplayed lower response/reinforcement ratios following step‐like changes in DRL reinforcement schedules. The quicker adjustments to the changes in DRL schedules did not occur immediately but during sessions following the change. We concluded that taurine administration during early juvenile development could weakly influence adult inhibito

ISSN:0012-1630    

DOI:10.1002/dev.420090205

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe present study was designed to determine whether environmental factors other than light would alter the daily periodicity in the rat's maternal behavior and whether such a change in the dam's behavior pattern would in turn alter the pattern of her sucklings' milk intake. Experiment 1 determined the daily pattern of litter weight gain (which presumably reflects milk intake) displayed by young reared by dams fed and watered either ad lib (Group C), only during the day (Group D), or only at night (Group N). Experiment 2 compared nocturnal and diurnal frequency of maternal behavior in Groups C, D, and N. The pattern of both litter weight gain and maternal behavior was observed to be diurnal in Groups C and N and nocturnal in Group D.

ISSN:0012-1630    

DOI:10.1002/dev.420090206

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe norepinephrine content of the whole brainstem and of its differnt parts and the epinephrine and norepinephrine (NE) content in the blood and adrenals in dogs and rats during ontogenesis were studied.The catecholamine (CA) level in the blood and different parts of the dog brainstem increased to the age of 20‐30 days and then decreased. The NE value of the whole dog brainstem increased to the age of 9‐30 days, and then decreased. The content of NE of the rat brainstem increased to the age of 120 days and then decreased. The amount of CA of the dog and rat adrenals increased progressively from birth to adulthood. The CA brain and adrenal level of dogs during postnatal ontogenesis was lower than in r

ISSN:0012-1630    

DOI:10.1002/dev.420090207

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

年代:1976

数据来源: WILEY

摘要:

AbstractExperimental maternal hyperphenylalaninemia produced in pregnant F344 rats by the combined use of p‐Chloro‐DL‐phenylalanine and L‐phenylalanine reduced fetal birth weight in comparison to saline‐injected controls. Offspring who experienced hyperphenylalaninemiain uterodied within 5 days after birth. Fetal plasma phenylalanine levels were several times higher than maternal plasma phenylalanine levels, indicating that the placenta actively concentrates maternal phenylalanine. Fetal brain phenylalanine levels rose in direct proportion to elevations in fetal plasma phenylanaline, whereas maternal brain phenylalanine levels remained low during maternal plasma phenylalanine elevation; the contrast suggests that the maternal brain is better able than the fetal brain to screen itself against high circulating plasma phenylalani

ISSN:0012-1630    

DOI:10.1002/dev.420090208

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

年代:1976

数据来源: WILEY

摘要:

AbstractC3H/HeJ male mice, an inbred strain showing retinal degeneration (rd), and normal‐eyed DBA/1J male mice were studied in a task requiring discrimination of horizontally and vertically oriented rectangles. The apparatus was a modified Yerkes discrimination apparatus. The mice were given 30 days of discrimination training, 10 trials/day, after which 10 more trials were given on the 31st day with positive and negative cues reversed. Both strains showed a highly significant decrease in errors during acquisition, therdstrain making significantly fewer errors than the DBA/1J animals. Reversal of the cues brought about a sharp increase in percentage of error

ISSN:0012-1630    

DOI:10.1002/dev.420090209

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

年代:1976

数据来源: WILEY

摘要:

AbstractKittens of 25 and 50 days of age were tested on a passive avoidance task in a 2‐compartment black‐white shuttle box. Latency t o enter the dark side of the box was the same for both groups on Day 1, but the latency to enter the dark side on Day 2 was much shorter for the younger kittens. Other kittens were trained in a step‐up active avoidance task also at 25 and 50 days of age. No differences were found in active avoidance performance between the younger and older animals, indicating that active and passive avoidance tasks may possibly reflcct separate devclopmcntal proccsses that mature at different rates in th

ISSN:0012-1630    

DOI:10.1002/dev.420090210

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe effect of gonadectomy, sham‐gonadectomy, pinealectomy, and sham‐pinealectomy on the concentration of NaCl in the total volume of fluid drunk per day ([NaCl]I) in male rats offered a free choice between water and 3% saline was measured. Neonatal gonadectomy increased [NaCl]Iin adult males but had no effect on immature rats. If the rats, however, were neonatally pinealectomized as well as gonadectomized, the increase of [NaCl]Ialso appeared in the immatures. Neonatal sham‐pinealectomy decreased [NaCl]Iin immature and adult rats, both gonadectomized and sham‐gonadectomized. In adult neonatally gonadectomized males the effects of sham‐pinealectomy did not occur in those animals actually pinealectomized. The role of the pineal gland in the regulation of water and salt intake is discussed in relation to the function of hypothalamus, neonatal stress, and sexual m

ISSN:0012-1630    

DOI:10.1002/dev.420090211

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

年代:1976

数据来源: WILEY