TY - JOUR
T1 - Lateralization of motor adaptation reveals independence in control of trajectory and steady-state position
AU - Duff, Susan V.
AU - Sainburg, Robert L.
N1 - Funding Information:
Acknowledgments This research was supported by the National Institutes of Health, National Institute of Child Health and Human development grant #R01HD39311. We thank Dr. Toby MordkoV for scholarly discussions regarding this manuscript and advice regarding statistical analysis.
PY - 2007/6
Y1 - 2007/6
N2 - We recently provided evidence that the dominant and nondominant arms are specialized for controlling different aspects of reaching movements. In this study, we test whether these specializations lead to qualitatively different adaptive mechanisms, when exposed to novel inertial dynamics. Two groups of six right-handed adults performed a reaching task toward a single target with either the dominant or nondominant arm. After 39 trials of task familiarization without a load, subjects performed 180 trials with a 1.5 kg mass, positioned 25 cm lateral to the forearm. To assess the time course of adaptation, we quantified changes in movement direction and linearity, and to assess the quality of adaptation, we randomly interspersed aftereffect trials and generalization trials. The former were assessed by removing the mass and the latter by changing the location of the movement in the workspace. Whereas, final position accuracy improved to the same extent for both arms, initial movement direction improved only for the dominant arm. In contrast, nondominant arm adaptation occurred mainly by making more effective corrections for persistent errors in initial direction. Consistent with these findings, aftereffect trials, an indicator of feedforward control processes, showed progressive increases in error for only the dominant arm. In addition, substantial generalization only occurred for the dominant arm. These results support our hypothesis that interlimb differences in control mechanisms produce different patterns of adaptation to novel inertial dynamics.
AB - We recently provided evidence that the dominant and nondominant arms are specialized for controlling different aspects of reaching movements. In this study, we test whether these specializations lead to qualitatively different adaptive mechanisms, when exposed to novel inertial dynamics. Two groups of six right-handed adults performed a reaching task toward a single target with either the dominant or nondominant arm. After 39 trials of task familiarization without a load, subjects performed 180 trials with a 1.5 kg mass, positioned 25 cm lateral to the forearm. To assess the time course of adaptation, we quantified changes in movement direction and linearity, and to assess the quality of adaptation, we randomly interspersed aftereffect trials and generalization trials. The former were assessed by removing the mass and the latter by changing the location of the movement in the workspace. Whereas, final position accuracy improved to the same extent for both arms, initial movement direction improved only for the dominant arm. In contrast, nondominant arm adaptation occurred mainly by making more effective corrections for persistent errors in initial direction. Consistent with these findings, aftereffect trials, an indicator of feedforward control processes, showed progressive increases in error for only the dominant arm. In addition, substantial generalization only occurred for the dominant arm. These results support our hypothesis that interlimb differences in control mechanisms produce different patterns of adaptation to novel inertial dynamics.
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U2 - 10.1007/s00221-006-0811-1
DO - 10.1007/s00221-006-0811-1
M3 - Article
C2 - 17171336
AN - SCOPUS:34248998899
SN - 0014-4819
VL - 179
SP - 551
EP - 561
JO - Experimental Brain Research
JF - Experimental Brain Research
IS - 4
ER -