Effects of aging on rapid grip force responses during bimanual manipulation of an active object
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RESEARCH ARTICLE
Effects of aging on rapid grip force responses during bimanual manipulation of an active object Hidetaka Hibino1 · Stacey L. Gorniak1 Received: 13 February 2020 / Accepted: 1 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Rapid grip force responses to unexpected pulling loads on the fingertips are deteriorated in older adults due to, in part, agerelated declines in somatosensory function. Such reports are limited to one-hand conditions despite the higher frequency of using two hands together in daily living activities of older adults. Unexpected perturbations during bimanual movements elicit goal-oriented and cortically-meditated bilateral rapid motor responses. Since aging is associated with declined somatosensory and cognitive functions, we hypothesized that bilateral rapid motor responses differ between young and older adults, such that older adults exert stronger grip forces following perturbation and the unperturbed hand is more involved in stabilizing the object in older adults. We tested our hypothesis by comparing the rapid grip force responses of both hands in young and older adults. A total of 13 right-handed young individuals (24.2 ± 4.0 years old, 5 men) and 13 right-handed older individuals (68.7 ± 7.1 years old, 5 men) were recruited. Tactile detection threshold, fingertip friction, and the rapid grip force responses of both hands triggered by unpredicted pulling loads during grip-lift movements were assessed. Older adults had higher tactile detection thresholds and lower fingertip friction compared to young adults. Regardless of age, rapid motor responses were found in both the perturbed (right) hand and the indirectly perturbed (left) hand at 73 ms and 135 ms after the perturbation, respectively, while magnitudes of the responses depended on perturbation magnitudes. Higher values in maximum grip force and maximum grip force rate were found in older adults as compared to young adults. In older adults, the indirectly perturbed (left) hand was more involved in stabilizing the object as compared to young healthy adults. The current study suggests that age-related changes in the peripheral and central nervous systems contribute to the greater involvement of the indirectly perturbed hand in older adults. Keywords Older adults · Somatosensory system · Cognitive function · Stabilization · Hand · Grasp
Introduction A number of physiological changes occur across the body as one ages. Generally, both sensory and motor function decline in parallel with aging. Specifically, declined somatosensory function, such as deteriorated tactile acuity (Stevens and Patterson 1995), is reported in older adults (Shaffer and Harrison 2007). As afferent feedback plays a critical role in successful object manipulation (Johansson and Flanagan Communicated by Winston D. Byblow. * Stacey L. Gorniak [email protected] 1
Department of Health and Human Performance, University of Houston, 3855 Holman St., Garrison 104, Houston, TX 77204‑6015, USA
2009), it is not surprising that
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