Career Development Award

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Patten C, Zajac FE, Burgar CG, McGill KC. Motor-unit firing patterns in hemiplegia. VA RR&D Career Development Award, 1998-2001.

Abstract: This project will involve recording needle and fine-wire EMG signals from the leg muscles of patients with post-stroke hemiplegia and normal control subjects during isometric and non-isometric contractions on an instrumented pedal ergometer. The non-isometric contractions will include both concentric contractions (in which the leg pushes or pulls the pedal against resistance) and eccentric contractions (in which the leg resists the pedal which is driven by a servomotor). The EMG signals will be decomposed to identify the individual motor-unit action potential trains. The specific objectives will be to identify abnormalities of motor-unit recruitment and firing-rate modulation in the stroke patients, to document the facilitory or inhibitory effects of contractions of the contralateral leg, and to test the hypothesis that eccentric contractions involve a different neural activation strategy than isometric and concentric contractions. This work is important because it will help identify mechanisms associated with functional weakness in post-stroke hemiplegia, and because it will provide a sensitive method for assessing the effects of facilitation methods and therapeutic treatments.