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This Article Full Text Full Text (PDF) All Versions of this Article: 99/4/1653    most recent 00980.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Gosselin-Kessiby, N. Articles by Kalaska, J. F. PubMed PubMed Citation Articles by Gosselin-Kessiby, N. Articles by Kalaska, J. F.

Evidence for Automatic On-Line Adjustments of Hand Orientation During Natural Reaching Movements to Stationary Targets

¹Département de Physiologie, ²Département de Kinésiologie, ³Research Group in Neurological Sciences, Canadian Institutes of Health Research; ⁴Groupe de Recherche sur le Système Nerveux Central, Fonds de la Recherche en Santé du Québec; and ⁵Centre de Recherche Institut Universitaire de Gériatrie de Montréal, Université de Montréal, Montreal, Quebec, Canada

Submitted 30 August 2007; accepted in final form 1 February 2008

Control of the spatial orientation of the hand is an important component of reaching and grasping movements. We studied the contribution of vision and proprioception to the perception and control of hand orientation in orientation-matching and letter-posting tasks. In the orientation-matching task, subjects aligned a "match" handle to a "target" handle that was fixed in different orientations. In letter-posting task 1, subjects simultaneously reached and rotated the right hand to insert a match handle into a target slot fixed in the same orientations. Similar sensory conditions produced different error patterns in the two tasks. Furthermore, without vision of the hand, final hand-orientation errors were smaller overall in letter-posting task 1 than in the orientation-matching task. In letter-posting task 2, subjects first aligned their hand to the angle of the target and then reached to it with the instruction not to change their initial hand orientation. Nevertheless, hand orientation changed during reaching in a way that reduced the initial orientation errors. This did not occur when there was no explicitly defined target toward which the subjects reached (letter-posting task 3). The reduction in hand-orientation errors during reach, even when told not to change it, suggests the engagement of an automatic error correction mechanism for hand orientation during reaching movements toward stationary targets. The correction mechanism was engaged when the task involved transitive actions directed at the target object. The on-line adjustments can occur without vision of the hand and even when target orientation is defined only by proprioceptive inputs.