Corticomotoneuronal Postspike Effects in Shoulder, Elbow, Wrist, Digit, and Intrinsic Hand Muscles During a Reach and Prehension Task

Brian J. McKiernan , Joanne K. Marcario , Jennifer Hill Karrer , and Paul D. Cheney Department of Molecular and Integrative Physiology, and Smith Mental Retardation and Human Development Research Center, University of Kansas Medical Center, Kansas City, Kansas 66160 McKiernan, Brian J., Joanne K. Ma...

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Bibliographic Details
Published in:	Journal of neurophysiology 1998-10, Vol.80 (4), p.1961-1980
Main Authors:	McKiernan, Brian J, Marcario, Joanne K, Karrer, Jennifer Hill, Cheney, Paul D
Format:	Article
Language:	eng
Subjects:	Action Potentials - physiology Animals Arm - physiology Carpus, Animal - physiology Elbow - physiology Electromyography Fingers - physiology Hand - physiology Joints - physiology Macaca mulatta Male Motor Cortex - physiology Motor Neurons - physiology Muscle, Skeletal - physiology Psychomotor Performance - physiology Shoulder - physiology Space life sciences Time Factors
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Summary:	Brian J. McKiernan , Joanne K. Marcario , Jennifer Hill Karrer , and Paul D. Cheney Department of Molecular and Integrative Physiology, and Smith Mental Retardation and Human Development Research Center, University of Kansas Medical Center, Kansas City, Kansas 66160 McKiernan, Brian J., Joanne K. Marcario, Jennifer Hill Karrer, and Paul D. Cheney. Corticomotoneuronal postspike effects in shoulder, elbow, wrist, digit, and intrinsic hand muscles during a reach and prehension task. J. Neurophysiol. 80: 1961-1980, 1998. We used spike-triggered averaging of rectified electromyographic activity to determine whether corticomotoneuronal (CM) cells produce postspike effects in muscles of both proximal and distal forelimb joints in monkeys performing a reach and prehension task. Two monkeys were trained to perform a self-paced task in which they reached forward from a starting position to retrieve a food reward from a small cylindrical well. We compiled spike-triggered averages from 22 to 24 separate forelimb muscles at both proximal (shoulder, elbow) and distal (wrist, digits, intrinsic hand) joints. Of 174 cells examined, 112 produced postspike effects in at least one of the target muscles. Of those cells, 45.5% produced postspike effects in both proximal and distal forelimb muscles. A nearly equal number (44.7%) produced postspike effects in distal muscles only, whereas a clear minority (9.8%) produced postspike effects in only proximal muscles. The majority of CM cells (71.4%) produced effects in two or more muscles, with an average muscle field of 3.1 ± 2.1 (mean ± SD) for facilitation plus suppression. Of 345 postspike effects identified, 70.7% were facilitation effects and 29.3% were suppression effects. The large majority of effects (72.2%) were in distal muscles. When averaged by joint, the latency and peak magnitude of postspike facilitation showed a stepwise increase from proximal to distal joints. The results of this study show that the majority of CM cells engaged in coordinated forelimb reaching movements facilitate and/or suppress muscles at multiple joints, including muscles at both proximal and distal joints. The results also show that CM cells make more frequent and more potent terminations in motoneuron pools of distal compared with proximal muscles.
ISSN:	0022-3077 1522-1598