Functional hemispheric asymmetry can be lost with aging. In this electroencephalographic study, we assessed hemispheric asymmetries in regulating motor responses by analyzing oscillatory brain activity during a go/nogo task in younger and older right-handed participants. Three conditions were embedded in the task: go, high-conflict and low-conflict nogo. The hand used to respond to go stimuli was varied block-wise. Independently of the go/nogo conditions and responding hand, young participants showed asymmetric desynchronizations in the mu (10 Hz) and beta (18-22 Hz) frequency bands that was stronger in the scalp sensorimotor region contralateral to the hand used for the go responses, while older adults showed a more symmetric pattern of desynchronization. These findings indicate that a loss of hemispheric asymmetry is a hallmark of the aging motor system, consistent with a decline of inter-hemispheric motor inhibition in normal aging.
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