TY - JOUR
T1 - Pointing movements may be produced in different frames of reference depending on the task demand
AU - Ghafouri, Mohammad
AU - Archambault, Philippe S.
AU - Adamovich, Sergei V.
AU - Feldman, Anatol G.
N1 - Funding Information:
We want to thank Drs Mindy Levin, Howard Poizner, Elliot Saltzman and the reviewers for constructive comments on the manuscript. Supported by the CIHR, FCAR-center (Canada), and NIH NS36449 (USA).
PY - 2002/3/1
Y1 - 2002/3/1
N2 - Movements are likely guided by the nervous system in task-specific spatial frames of reference (FRs). We tested this hypothesis by analyzing fast arm pointing movements involving the trunk made to targets located within the reach of the arm. In the first experiment, subjects pointed to a motionless target and, in the second experiment, to a target moving synchronously with the trunk. Vision of the arm and targets was prevented before movement onset. Each experiment started after three to five training trials. In randomly selected trials of both experiments, an electromagnet device unexpectedly prevented the trunk motion. When the trunk was arrested, the hand trajectory and velocity profile remained invariant in an FR associated with the experimental room in the first or in an FR moving with the trunk in the second experiment. Substantial changes in the arm interjoint coordination in response to the trunk arrest were observed in the first but not in the second experiment. The results demonstrate the ability of the nervous system to rapidly adapt behavior at the joint level to transform motor performance from a spatial FR associated with the environment to one associated with the body. A theoretical framework is suggested in which FRs are considered as pre-existing neurophysiological structures permitting switching between different FRs and guiding multiple joints and muscles without redundancy problems.
AB - Movements are likely guided by the nervous system in task-specific spatial frames of reference (FRs). We tested this hypothesis by analyzing fast arm pointing movements involving the trunk made to targets located within the reach of the arm. In the first experiment, subjects pointed to a motionless target and, in the second experiment, to a target moving synchronously with the trunk. Vision of the arm and targets was prevented before movement onset. Each experiment started after three to five training trials. In randomly selected trials of both experiments, an electromagnet device unexpectedly prevented the trunk motion. When the trunk was arrested, the hand trajectory and velocity profile remained invariant in an FR associated with the experimental room in the first or in an FR moving with the trunk in the second experiment. Substantial changes in the arm interjoint coordination in response to the trunk arrest were observed in the first but not in the second experiment. The results demonstrate the ability of the nervous system to rapidly adapt behavior at the joint level to transform motor performance from a spatial FR associated with the environment to one associated with the body. A theoretical framework is suggested in which FRs are considered as pre-existing neurophysiological structures permitting switching between different FRs and guiding multiple joints and muscles without redundancy problems.
KW - Arm-trunk coordination
KW - Compensatory synergy
KW - Interjoint coordination
KW - Kinematic invariant
KW - Motor control
KW - Movement correction
KW - Trajectory formation
KW - Trunk arrest
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U2 - 10.1016/S0006-8993(01)03332-7
DO - 10.1016/S0006-8993(01)03332-7
M3 - Article
C2 - 11852038
AN - SCOPUS:0036498484
SN - 0006-8993
VL - 929
SP - 117
EP - 128
JO - Brain Research
JF - Brain Research
IS - 1
ER -