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. 2009 Nov 17;1298:78-91.
doi: 10.1016/j.brainres.2009.08.063. Epub 2009 Sep 1.

Dissociation of Initial Trajectory and Final Position Errors During Visuomotor Adaptation Following Unilateral Stroke

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Free PMC article

Dissociation of Initial Trajectory and Final Position Errors During Visuomotor Adaptation Following Unilateral Stroke

Sydney Y Schaefer et al. Brain Res. .
Free PMC article

Erratum in

  • Brain Res. 2010 Mar 19;1321:180-1

Abstract

Previous studies have demonstrated that following stroke, motor impairment can occur ipsilateral to the lesion. Such impairments have provided insight into the contributions of each hemisphere to movement control, showing that left and right hemisphere damage produce different effects on movement: Left hemisphere damage produces deficits in specifying features of movement trajectory, while right hemisphere damage produces deficits in achieving an accurate and stable final position. We now propose that left and right hemisphere damage should also produce different deficits in the adaptation of trajectory and position. To test this idea, we examined adaptation to visuomotor rotations in the ipsilesional arms of hemiparetic stroke patients with left (LHD) and right hemisphere damage (RHD). We found that LHD interfered with adaptation of initial direction, but not with the ability to adapt the final position of the limb. In contrast, RHD interfered with online corrections to the final position during the course of adaptation. These findings support our hypothesis that the control of trajectory and steady-state position may be lateralized to the left and right hemispheres, respectively.

Figures

Figure 1
Figure 1
Lesion locations were traced on 11 axial slices (see inset for slice level) from MRI or CT scans for each LHD (1-5) and RHD (1-5) patient. Slices are displayed left-to-right from inferior to superior (i-xi) for both groups of patients. Arrows in top row indicate location of central sulcus.
Figure 2
Figure 2
Mean movement time, peak tangential velocity, and (absolute) final position error of the last cycle of baseline trials are displayed for each subject (1-7) in the LHC and RHC groups and each patient (1-5) in the LHD and RHD groups.
Figure 3
Figure 3
Mean movement times, peak tangential velocities, final position errors, and handpath curvatures of the last cycle of baseline trials, first and last cycles of rotation trials, and first cycle of post-rotation trials are displayed for the left and right arms of healthy control groups (LHC,RHC; gray) and the ipsilesional arms of left and right hemisphere damage groups (LHD,RHD; black). Bars indicate standard error of mean.
Figure 4
Figure 4
A) Mean final position error (top) and handpath curvature (bottom) of each cycle of the rotation session (cycles 1-26) is displayed for the left and right arms of healthy control groups (LHC,RHC; gray) and the ipsilesional arms of left and right hemisphere damage groups (LHD,RHD; black). The LHC and LHD groups are overlapped on the left; the RHC and RHD groups are overlapped on the right. Bars indicate standard error of mean. Horizontal gray bars denote first 10 cycles. B) Mean final position error (top) and handpath curvature (bottom) of each cycle of the rotation session for the first 10 cycles (gray bar) is displayed for the ipsilesional arms of each left and right hemisphere damage patient (LHD,RHD).
Figure 5
Figure 5
Cursor trajectories. A) The last 8 trials (last cycle) of the baseline session are shown for a representative subject from each group (LHC4, RHC3, LHD3, RHD5). B) The first 8 trials (first cycle) and last 8 trials (last cycle) of the rotation session are shown for these representative subjects.
Figure 6
Figure 6
A) Mean final position error of each cycle of the rotation session is plotted as a function of mean initial direction error of each cycle of the rotation session for representative LHD and RHD patients (LHD1 and RHD5). Each dot represents one cycle; the solid black dots indicate the first and last cycle of the rotation session. Corresponding r2 values are displayed in the bottom right corner of each scatterplot. B) Mean normalized r (Fisher z-score) of mean final position error vs. mean initial direction error is displayed for the left and right arms of healthy control groups (LHC,RHC; gray) and the ipsilesional arms of left and right hemisphere damage groups (LHD,RHD; black). Bars indicate standard error of mean. C) Mean initial direction error (baseline subtracted out) at peak acceleration of the first and last cycle of the rotation session is displayed for the left and right arms of healthy control groups (LHC,RHC; gray) and the ipsilesional arms of left and right hemisphere damage groups (LHD,RHD; black). Bars indicate standard error of mean.
Figure 7
Figure 7
A) Side and top view of experimental apparatus are shown. B) Experimental task required movement of cursor from start circle to 1 of 8 target circles located 12 cm from a constant starting position. All targets were presented in the ipsilateral hemispace. C) A schematic of the relationship between the display cursor and the actual location of the fingertip during the rotation session is shown.

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