TY - JOUR
T1 - Anticipatory synergy adjustments in preparation to self-triggered perturbations in elderly individuals
AU - Olafsdottir, Halla B.
AU - Kim, Sun Wook
AU - Zatsiorsky, Vladimir M.
AU - Latash, Mark L.
PY - 2008/5
Y1 - 2008/5
N2 - We tested the ability of healthy elderly persons to use anticipatory synergy adjustments (ASAs) prior to a self-triggered perturbation of one of the fingers during a multifinger force production task. An index of a force-stabilizing synergy was computed reflecting covariation of commands to fingers. The subjects produced constant force by pressing with the four fingers of the dominant hand on force sensors against constant upwardly directed forces. The middle finger could be unloaded either by the subject pressing the trigger or unexpectedly by the experimenter. In the former condition, the synergy index showed a drop (interpreted as ASA) prior to the time of unloading. This drop started later and was smaller in magnitude as compared with ASAs reported in an earlier study of younger subjects. At the new steady state, a new sharing pattern of the force was reached. We conclude that aging is associated with a preserved ability to explore the flexibility of the mechanically redundant multifinger system but a decreased ability to use feedforward adjustments to self-triggered perturbations. These changes may contribute to the documented drop in manual dexterity with age.
AB - We tested the ability of healthy elderly persons to use anticipatory synergy adjustments (ASAs) prior to a self-triggered perturbation of one of the fingers during a multifinger force production task. An index of a force-stabilizing synergy was computed reflecting covariation of commands to fingers. The subjects produced constant force by pressing with the four fingers of the dominant hand on force sensors against constant upwardly directed forces. The middle finger could be unloaded either by the subject pressing the trigger or unexpectedly by the experimenter. In the former condition, the synergy index showed a drop (interpreted as ASA) prior to the time of unloading. This drop started later and was smaller in magnitude as compared with ASAs reported in an earlier study of younger subjects. At the new steady state, a new sharing pattern of the force was reached. We conclude that aging is associated with a preserved ability to explore the flexibility of the mechanically redundant multifinger system but a decreased ability to use feedforward adjustments to self-triggered perturbations. These changes may contribute to the documented drop in manual dexterity with age.
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U2 - 10.1123/jab.24.2.175
DO - 10.1123/jab.24.2.175
M3 - Article
C2 - 18579910
AN - SCOPUS:52149116559
SN - 1065-8483
VL - 24
SP - 175
EP - 179
JO - Journal of applied biomechanics
JF - Journal of applied biomechanics
IS - 2
ER -