Document Detail

Neuromuscular patterns of stereotypic hindlimb behaviors in the first two postnatal months. I. Stepping in normal kittens.
MedLine Citation:
PMID:  3342330     Owner:  NLM     Status:  MEDLINE    
Neuromuscular patterns associated with the development of hindlimb stepping behaviors were studied from birth to postnatal day 60 in normal kittens. Hindlimb muscles were chronically implanted with EMG electrodes at birth to characterize interlimb coordination and intralimb synergies during development of overground and treadmill stepping. Airstepping was also examined but seldom occurred after the second postnatal week. All kittens performed stepping under each condition, including weight-supported stepping, by postnatal day 3. The number of sequential steps on the treadmill and overground increased with age and cycle periods decreased. At onset, stepping behaviors were characterized by adult-like EMG patterns. Interlimb coordination was typified by alternating extensor bursts of similar duration. Extensors at the knee and ankle were coactive during the stance phase, and extensor burst durations were strongly correlated with the cycle periods over a wide range of stepping frequency. Ankle flexor and extensor muscles were reciprocally active during postural tremor, bouts of airstepping, and weight-supported steps on the treadmill and overground. The duration of the reciprocal flexor bust did not vary with cycle period or age. Observations of stepping behaviors and adult-like EMG patterns during initial postnatal development were contingent on optimal testing conditions. Taken together, the data suggest that pattern-generating circuits for regulating interlimb coordination and intralimb muscle synergies are potentially functional prior to the normal ontogenetic onset of locomotion. Perhaps the prolonged postnatal development of locomotion reflects the time required to establish adaptive mechanisms, such as postural control and agility, rather than spinal pattern-generating circuits for locomotion.
N S Bradley; J L Smith
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Brain research     Volume:  466     ISSN:  0006-8993     ISO Abbreviation:  Brain Res.     Publication Date:  1988 Jan 
Date Detail:
Created Date:  1988-03-28     Completed Date:  1988-03-28     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0045503     Medline TA:  Brain Res     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  37-52     Citation Subset:  IM    
Department of Kinesiology, University of California, Los Angeles 90024.
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MeSH Terms
Animals, Newborn
Cats / growth & development*,  physiology
Functional Laterality / physiology
Hindlimb / growth & development,  innervation*,  physiology
Motor Activity / physiology
Motor Neurons / physiology*
Muscle Contraction
Muscle Development
Muscles / innervation*,  physiology
Stereotyped Behavior / physiology*
Grant Support

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