Interaction of discrete and rhythmic movements over a wide range of periods
Experimental Brain Research. 2002-11-01; 147(2): 162-174
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1. Exp Brain Res. 2002 Nov;147(2):162-74. Epub 2002 Sep 20.
Interaction of discrete and rhythmic movements over a wide range of periods.
Sternad D(1), de Rugy A, Pataky T, Dean WJ.
(1)Department of Kinesiology, The Pennsylvania State University, 266 Recreation
Building, University Park, PA 16802, USA.
This study investigates a complex task in which rhythmic and discrete components
have to be combined in single-joint elbow rotations. While previous studies of
similar tasks already reported that the initiation of the discrete movement is
constrained to a particular phase window of the ongoing rhythmic movement,
interpretations have remained contradictory due to differences in paradigms,
oscillation frequencies, and data analysis techniques. The present study aims to
clarify these findings and further elucidate the bidirectional nature of the
interaction between discrete and rhythmic components. Participants performed
single-degree-of-freedom elbow oscillatory movements at five prescribed periods
(400, 500, 600, 800, 1,000 ms). They rapidly switched the midpoint of oscillation
to a second target after an auditory signal that occurred at a random phase of
the oscillation, without stopping the oscillation. Results confirmed that the
phase of the discrete movement initiation is highly constrained with respect to
the oscillation period. Further, the duration, peak velocity, and the overshoot
of the discrete movement varied systematically with the period of the rhythmic
movement. Effects of the discrete-onto-rhythmic component were seen in a phase
resetting of the oscillation and a systematic acceleration after the discrete
movement, which also varied as a function of the oscillation period. These
results are interpreted in terms of an inhibitory bidirectional coupling between
discrete and rhythmic movement. The interaction between discrete and rhythmic
movement elements is discussed in comparison to sequential and gating processes
PMID: 12410331 [Indexed for MEDLINE]