title: Phasing of muscle activity during rapid finger oscillations.
abstract: In rapid limb oscillations, bursts of muscle activity occur during certain phases of the movement. The authors examined phase stabilization in rapid oscillations of the index finger in a horizontal plane. Phase stabilization was rapid; therefore, a deviation from the mean phase was, on average, (almost) completely corrected in the subsequent movement cycle. Participants (N = 11) achieved rapid phase stabilization by using phase-dependent modulations of both the frequency of finger oscillation and the duration of interburst intervals. For example, with an early phase of a burst, oscillation frequency was increased immediately and the next burst of muscle activity was delayed. Whereas phase-stabilizing modulations of oscillation frequency are likely to be mechanically mediated, phase-stabilizing modulations of the timing of bursts of muscle activity must be neurally mediated. The present findings therefore strongly suggest that a central pattern generator does not generate rapid finger oscillations in an open-loop mode, but the pattern-generator network integrates, individually or in combination, afferent signals or predictive signals on the current or future states of the oscillating finger.
authors.affiliation: Institut für Arbeitsphysiologie an der Universität Dortmund, Ardeystrasse 67, 44139 Dortmund, Germany. heuer@arb-phys.unidortmund.de
authors.forename: Herbert
authors.initials: H
authors.lastname: Heuer
authors.forename: Raphael
authors.initials: R
authors.lastname: Schulna
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D004576:Electromyography / Q000379:methods; D005260:Female; D005385:Fingers / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D009142:Musculoskeletal Physiological Phenomena; D013997:Time Factors; D055815:Young Adult