Insights into the control of arm movement during body motion as revealed by EMG analyses
Brain Research. 2010-01-01; 1309: 40-52
DOI: 10.1016/j.brainres.2009.10.063
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Blouin J(1), Guillaud E, Bresciani JP, Guerraz M, Simoneau M.
Author information:
(1)Neurobiology and Cognition, CNRS and Aix-Marseille University, 3 Place Victor
Hugo, Marseille Cedex 3, France.
Recent studies have revealed that vestibulomotor transformations contribute to
maintain the hand stationary in space during trunk rotation. Here we tested
whether these vestibulomotor transformations have the same latencies and whether
they are subject to similar cognitive control than the visuomotor transformations
during manual tracking of a visual target. We recorded hand displacement and
shoulder-muscle activity in two tasks: a stabilization task in which subjects
stabilized their hand during passive 30 degrees body rotations, and a tracking
task in which subjects tracked with their finger a visual target as it moved 30
degrees around them. The EMG response times recorded in the stabilization task
(approximately 165 ms) were twice as short as those observed for the tracking
task (approximately 350 ms). Tested with the same paradigm, a deafferented
subject showed EMG response times that closely matched those recorded in healthy
subjects, thus, suggesting a vestibular origin of the arm movements. Providing
advance information about the direction of the required arm movement reduced the
response times in the tracking task (by approximately 115 ms) but had no
significant effect in the stabilization task. Generally, when providing false
information about movement direction in the tracking task, an EMG burst first
appeared in the muscle moving the arm in the direction opposite to the actual
target motion (i.e., in accord with the precueing). This behavior was rarely
observed in the stabilization task. These results show that the sensorimotor
transformations that move the arm relative to the trunk have shorter latencies
when they originate from vestibular inputs than from visual information and that
vestibulomotor transformations are more resistant to cognitive processes than
visuomotor transformations.