摘要:

AbstractIn this study, we examined electromyographic activity for an ensemble of hindlimb muscles during spontaneous activity in chick embryos to advance understanding of early motor coordination and its relationship to later emerging behaviors. Four‐channel recordings were obtained from 6 musclesin ovoat embryonic Days 9 and 10. Analyses indicated that when muscles are repetitively active, patterns during embryonic motility are distinct from those for other behaviors. For example, unlike the muscle patterns for locomotion, extensor muscles and flexor muscles are synchronously activated at 50% of the extensor cycle period. Furthermore, flexor and extensor bursts are similar in duration and show little correlation with extensor cycle period. Finally, our data sugest that the ensemble of muscles active can vary from cycle to cycle. This study provides the basis for future studies that will examine neural and biomechanical interactions underlying the development of coordinated movemen

ISSN:0012-1630    

DOI:10.1002/dev.420230802

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

年代:1990

数据来源: WILEY

摘要:

AbstractLactating guinea pigs required to leave a nest box to obtai food were observed to be separated from their pups almost 10% of the time on Days 13–15 postpartum. The duration of separation was greater in the dark than in the light, and was not different for mother/litters exposed to low (LFD) versus high (HFD) foraging demand. Subsequently, LFD and HFD pups as well as pups reared under standard laboratory conditions (SLC) all exhibited vocalization and plasma cortisol responses to involuntary maternal separation. However, several effects of rearing were also observed. HFD pups vocalized less during separation and had higher resting cortisol levels than did SLC pups: LFD and HFD males spent less time in contact with the mother in a test cage than did SLC males. These effects are discussed in terms of the importance of the physical environment in shaping infant‐mother interactions and the infant's perception of cont

ISSN:0012-1630    

DOI:10.1002/dev.420230803

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

年代:1990

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420230804

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe purposes of this study were: (1) to determine the pattern of variability and relationships in joint kinematics characterizing the development of walking and (2) to determine whether controlling for postural stability in new walkers results in less variability. The variability and relationships among hip, knee, and ankle motions were measured during 10 gait cycles of new walkers, supported new walkers, two‐year‐olds and seven‐year‐olds. Fourier series were generated for each joint motion and standard deviations were compared across groups. An age‐related decline in variability was evident in select portions of the cycle. Stance and swing phase duration correlated with cycle duration for all ages. Postural support did not lessen variability in joint rotations for new walkers. Cross‐correlations for hip‐knee, knee‐ankle, and hip‐knee rotations were strong across all groups. These results suggest that a coordinative structure for walking produces strong intralimb coupling early in development, despite variability in select portions

ISSN:0012-1630    

DOI:10.1002/dev.420230805

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

年代:1990

数据来源: WILEY

摘要:

AbstractAutonomic control of blood pressure (BP) and heart rate (HR) was tested in offspring of rat dams that were unmanipulated (controls) or exposed repeatedly to either (1) Postnatal restraint, (2) Postnatal s.c. injections of alkaline saline, or (3)Prenatals.c. alkaline saline. Under urethane anesthesia, BP was higher than control in 20‐day‐old offspring of restrained dams and lower at 80 days. The magnitude of the BP response to autonomic ganglionic blockade (chlorisondamine) changed in parallel; the control HR accelerator response was reversed at 20 days and enhanced at 80 days. Postnatal maternal injections increased BP in 20‐day‐old offspring and lowered it at 80 days. The BP response to blockade was unchanged; HR acceleration was attenuated at 20 days and increased at 80 days. No influence ofPrenatalmaterial injections was seen in adult offspring. Conclusion: Post–not prenatal maternal stress disrupts BP and HR control in rat offspring; disruption is greater after restraint than injection. There is sympathetic hyperactivity in preweanlings and hypoactivity

ISSN:0012-1630    

DOI:10.1002/dev.420230806

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

年代:1990

数据来源: WILEY

摘要:

AbstractAn assessment was made of the effects of long‐term tactile restriction by bilateral removal of the mystacial vibrissae from an early age on the subsequent somatosensory capacities of rats (i.e., the intramodal consequences) as well as its effects on visual and spatial capacities (i.e., the intermodal consequences). Rearing environment (enriched vs. normal) and method of vibrissae removal (cauterization of follicles vs. plucking) were examined to determine specific factors that might influence the effect of vibrissae removal. Early, long‐term tactile restriction had significant intramodal and intermodal consequences. Dewhiskered rats showed attenuated orientation to tactile stimuli presented to their mystacial pads and enriched‐reared rats whose vibrissae follicles had been cauterized showed increased orientation to visual stimuli. Manipulation of early somatosensory signals had no impact on the development of certain spatial and precise manipulatory skills. These data provide limited evidence for theories of modality interdependence and yield basic information concerning the role of the mystacial vibrissae in the behavior of th

ISSN:0012-1630    

DOI:10.1002/dev.420230807

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

年代:1990

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420230801

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

年代:1990

数据来源: WILEY