Document Type
Article
Language
eng
Format of Original
13 p.
Publication Date
12-1-2007
Publisher
American Physiological Society
Source Publication
Journal of Neurophysiology
Source ISSN
0022-3077
Original Item ID
doi: 10.1152/jn.00652.2007
Abstract
We previously reported that the kinematics of reaching movements reflect the superimposition of two separate control mechanisms specifying the hand's spatial trajectory and its final equilibrium position. We now asked whether the brain maintains separate representations of the spatial goals for planning hand trajectory and final position. One group of subjects learned a 30° visuomotor rotation about the hand's starting point while performing a movement reversal task (“slicing”) in which they reversed direction at one target and terminated movement at another. This task required accuracy in acquiring a target mid-movement. A second group adapted while moving to—and stabilizing at—a single target (“reaching”). This task required accuracy in specifying an intended final position. We examined how learning in the two tasks generalized both to movements made from untrained initial positions and to movements directed toward untrained targets. Shifting initial hand position had differential effects on the location of reversals and final positions: Trajectory directions remained unchanged and reversal locations were displaced in slicing whereas final positions of both reaches and slices were relatively unchanged. Generalization across directions in slicing was consistent with a hand-centered representation of desired reversal point as demonstrated previously for this task whereas the distributions of final positions were consistent with an eye-centered representation as found previously in studies of pointing in three-dimensional space. Our findings indicate that the intended trajectory and final position are represented in different coordinate frames, reconciling previous conflicting claims of hand-centered (vectorial) and eye-centered representations in reach planning.
Recommended Citation
Ghez, Claude; Scheidt, Robert A.; and Heijink, Hank, "Different Learned Coordinate Frames for Planning Trajectories and Final Positions in Reaching" (2007). Biomedical Engineering Faculty Research and Publications. 178.
https://epublications.marquette.edu/bioengin_fac/178
ADA Accessible Version
Comments
Accepted version. Journal of Neurophysiology, Vol. 98, No. 6 (December 1, 2007): 3614-3626. DOI. © 2007 American Physiological Society. Used with permission.