摘要:

AbstractKittens, dutch‐belted rabbits, and albino rabbits were tested daily after eye opening for development of a reliable avoidance response on the visual cliff under varying conditions of texture density of elements comprising the checkerboard patterns of deep and shallow surfaces. Depth avoidance was demonstrated at an earlier age when coarse (34° to 18° retinal angle) rather than fine (2° or less of retinal angle) elements comprising shallow and deep surfaces were available to the subject. Visually guided placing to surfaces (in cats) developed after onset of visual cliff depth avoidance when coarse texture elements, but not when fine texture elements were used. Differences in onset of depth‐avoidance responding under different conditions of texture density across species as well as non‐coincidence of onset of visual placing with depth avoidance in cats indicated that changes in texture‐processing abilities with age and as a function of species characteristics interact with developing visual‐motor responding. The results were interpreted relative to organismic development of texture‐processing systems affecting degree of degradation of primary visual input during development. The importance of texture‐derived afferent information on development of visual‐motor behav

ISSN:0012-1630    

DOI:10.1002/dev.420030202

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe ontogenesis of sleep was studied in prematures from 32 to 41 weeks of gestational age The characteristics of the EEG, the patterns and rate of respiration, the cardiac rate, body motility comprised of localized and diffuse movements, localized and diffuse jerks, clonic movements and electromyo‐graphic activity of the chin, as well as periods of total quietness were observed and correlated with the progressive organization of behavior in these infants. The data obtained at each gestational age, i.e., at 32–34 weeks, 35–37 weeks, and 38–41 weeks, were compared to those obtained in full‐term newborns. The relationships between the different events and the features of the EEG and of the respiratory patterns were ascertained and compared to similar data obtained in the full‐term newborn. This comparison shows that the premature at 40 weeks of gestational age has not attained a level of organization as high as that of the full‐term newborn. An hypothesis suggesting a possible mechanism of this discrepancy

ISSN:0012-1630    

DOI:10.1002/dev.420030203

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe effects of prenatal reserpine administration upon uptake of tritiated norepinephrine (H3‐NE) by newly hatched chick brain suggests an interference of catecholamine (CA) uptake and/or binding. The relationship between fluorescence from CA and the radioactivity from H3‐NE approached unity in the control group where no such relation was seen in the reserpine treated group. Moreover, 30 days after hatching, CA levels in whole brain of chicks hatched from drug‐injected eggs were significantly higher than vehicle‐injected controls. However, reserpine did cause a slight but significant elevation of total protein in 14‐day‐old embryo brain. These data support the hypothesis that ontogenetic alteration of systems exhibiting end‐product inhibition can be of a long‐lasting, perhaps permanent nature. The direction of change in CA 30 days after hatching, opposite to the change induced pharmacologically during development, is additional support for the concept of „thermostat”︁ type regulation of enzyme activity being determined by product concentration at critical perio

ISSN:0012-1630    

DOI:10.1002/dev.420030204

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe temporal pattern of plasma corticosterone concentrations following electric shock was studied in 10‐week old mice from two inbred strains (C57BL/10J and DBA/2) and their reciprocal crosses, half of which had been subjected to infantile stimulation. The roles of genotype, maternal factors, and handling were assessed as determinants of corticosteroid response to stress. Highly significant and opposing genetic and maternal effects interacted to limit extreme plasma corticosterone concentrations following stress. Infantile stimulation also acted to produce intermediate steroid response

ISSN:0012-1630    

DOI:10.1002/dev.420030205

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

年代:1970

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420030206

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

年代:1970

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420030201

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

年代:1970

数据来源: WILEY