Task Demands Attenuate Age- and Hand-Dependent Ipsilateral Beta Power Modulation During a Functional Grasp Movement

Human motor control is governed by contralateral brain regions; however, ipsilateral cortical neurons also play a crucial role in motor function. Although previous studies have explored ipsilateral activity during isometric and maximum voluntary contraction (MVC) tasks, the role of ipsilateral neural activation during tasks such as grasping and lifting, across age groups and hands remains unclear. This study compared ipsilateral EEG band power between young and older adults during a grasp-and-lift task performed under two conditions: fixed (thumb platform secured) and free (thumb platform movable), using both dominant and non-dominant hands. Twenty right-handed young adults (20–30 years, mean 26.96 ± 2.68) and fourteen right-handed older adults (58–72 years, mean 62.57 ± 3.58) completed 25 randomized trials per hand and condition, grasping a handle for five seconds, then lifting and holding it for five seconds. Results showed older adults had significantly increased ipsilateral EEG band power compared to younger adults, only in the fixed condition, indicating age-related compensatory recruitment of ipsilateral motor regions likely due to contralateral decline and reduced interhemispheric inhibition. Both groups exhibited greater ipsilateral activation during non-dominant (left) hand movements, reflecting hemispheric dominance and corticospinal asymmetries. No age- or hand-related differences were observed in the free condition, suggesting compensatory mechanisms in older adults may be limited under increased task demands.