Gary L. Soderberg

Postural adjustments preceding rapid arm movements in parkinsonian subjects

The electromyographic (EMG) responses in postural (thigh and trunk) and agonist (shoulder) muscles were examined in standing parkinsonian subjects and healthy controls prior to visual reaction time and self-paced rapid arm flexion movements. Recruitment of postural muscles typically preceded arm displacement in normals, but was less frequent, of shorter duration, and characterized by multiple EMG bursts which extended to the agonist in parkinsonians. Moreover, parallel delays in EMG recruitment times relative to the visual signal for both postural and agonist muscles were observed in akinetic patients. These abnormalities suggest that the basal ganglia may serve a preparatory motor function, by linking synergistic muscles through a common selection process.

Muscular function in chronic low-back dysfunction.

The purpose of this study was to use electromyography to determine the level and pattern of muscle activity of the rectus abdominus and T10, L1, and L3 erector spinae muscle in healthy subjects and patients with chronic low-back dysfunction during various postures and activities. Statistically significant differences in erector spinae activities were found between groups for the Valsalva maneuver and for portions of the sit-up exercise. Comparisons between the 4.5-kg and 16-kg lifts completed with bent and straight knees showed few differences during actual lifts, but the patients with chronic dysfunction maintained an increased level of activity when lifts had been completed.

Laser etched bifilar fine wire electrode for skeletal muscle motor unit recording

To selectively record a limited number of skeletal muscle motor unit action potentials, a bifilar fine wire electrode was developed. Two 8 micrometers wires were braided together, a hook formed, and ends insulated. A round beam, pulsed laser, etched a 5 micrometers piece of insulation from each wire near the hooked end. Bipolar recordings from a select number of skeletal muscle motor units were obtained from these two uninsulated 5 micrometers areas. Reactive and capacitative components for each set of electrodes were measured. These electrodes were selective in recording from 3 to 5 single motor unit action potentials at low isometric tension levels.

An adaptable, multiple plate dynamometer and electromyograph for the study of quadruped postural responses ☆

An EMG-force measurement system which can be placed inside a sound dampened testing chamber to study subtle postural responses in the standing quadruped is described. The dynamometer is adjustable to accommodate different foot placement strategies and to afford a more natural standing posture. A non-telemeterized method of recording EMG from an unrestrained animal is also discussed.

Technique for EMG fine wire connections

A fine wire electrode connector has been developed to incorporate the benefits of on-site pre-amplification, while concurrently providing the ease of repeatable quick connections for fine wires. Results show artifact-free electromyograms in studies of single motor unit action potentials or during functional activities.