Coordination of a step with a reach

Linda Daghestani, John H. Anderson, Martha Flanders

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Although natural reaching behavior can easily include forward body movement, most laboratory studies of reaching have constrained the body to be stationary. Recently, however, it has been shown that normal subjects exhibit a different pattern of errors when attempting to pinpoint remembered target locations, depending on whether or not the reach includes a step. In the study of Flanders et al. [1], these errors appeared to be due to the strategy of eye/head/hand coordination which normally comes into play when the body is moving toward the target. Since the spatial positioning of the head was found to partially explain the errors in hand placement, the present study examined the movements of patients with bilateral vestibular deficits in order to further analyze the whole-body coordination. Somewhat surprisingly, the patients exhibited the same pattern of head movement and the same errors in hand placement as did the control subjects. Nevertheless, the patients' movements clearly exhibited evidence for an abnormal decomposition of elbow extension and trunk rotation. Furthermore the patients' (spatial) hand paths were significantly more curved than those of control subjects and, only in the patients, paths to remembered targets were significantly more curved than paths to visible targets. Thus for movements to remembered targets, the patients tended to move the hand to the same incorrect spatial positions as control subjects but spatiotemporal aspects of the arm and body movement differed. The results are consistent with the idea that vestibular patients are overly dependent upon visual cues, and support the hypothesis that this stepping and reaching behavior is largely dependent upon a visual reference signal.

Original languageEnglish (US)
Pages (from-to)59-73
Number of pages15
JournalJournal of Vestibular Research: Equilibrium and Orientation
Volume10
Issue number2
StatePublished - 2000

Keywords

  • Decomposition of movement
  • Hand path curvature
  • Reaching
  • Vestibular

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