Wave form of motor unit action potential recorded by surface electrode during voluntary muscle contraction

Associative plasticity in human motor cortex during voluntary muscle contraction.

TMS pulses over the hand area of motor cortex activate different subpopulations of synaptic connections if the direction of the induced current in the brain is reversed from posterior-anterior (PA) direction to anterior-posterior (AP). We tested whether this also made a difference to the after-effects of paired associative stimulation (PAS: ulnar nerve stimulation followed 25 ms later by a tran...

Motor Unit Action Potential Clustering—Theoretical Consideration for Muscle Activation during a Motor Task

During dynamic or sustained isometric contractions, bursts of muscle activity appear in the electromyography (EMG) signal. Theoretically, these bursts of activity likely occur because motor units are constrained to fire temporally close to one another and thus the impulses are "clustered" with short delays to elicit bursts of muscle activity. The purpose of this study was to investigate whether...

Motor Unit Action Potential Quantitation

Action Potentials from Single Motor Units in Voluntary Contraction

In 1929 Adrian and Bronk demonstrated a more refined method than had hitherto been used for obtaining action potentials from muscle, not only in the laboratory animal, but also in voluntary contraction in man. These .workers devised very small concentric electrodes which detect activity of the single motor units in a much restricted area. Such electrodes have since been used extensively in this...

The Variation of Action Potential and Impedance in Human Skeletal Muscle Voluntary Contraction

Liao, T.-J. and Nishikawa, H. The Variation of Action Potential and Impedance in Human Skeletal Muscle during Voluntary Contraction. Tohoku J. Exp. Med., 1994, 173 (3), 303-309 We used an insulated acupuncture needle to deliver a 20 kHz alternative current to detect the changes on the electromyogram (EMG) and deep muscle impedance. We found that impedance increased (with a duration of 224.1±75....