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Halla B. Olafsdottir, Sun Wook Kim, Vladimir M. Zatsiorsky and Mark L. Latash

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 feed-forward adjustments to self-triggered perturbations. These changes may contribute to the documented drop in manual dexterity with age.

Open access

Jung-Woo Oh, JungJun Lim, Sang-Hwa Lee, Yu-sun Jin, Bumjo Oh, Chung Gun Lee, Deok Hwan Lee, Eun-Young Lee, Han Joo Lee, Hyon Park, Hyun Joo Kang, Justin Y. Jeon, Mi-Seong Yu, Sang-Hoon Suh, SeJung Park, So Jung Lee, Soo Jung Park, Wook Song, Yewon Yu, Yoonkyung Song, Youngwon Kim and Yeon Soo Kim