Mechanical load modulates premovement cortical activity during voluntary upper limb movement

Abstract

Examining how scalp electroencephalography (EEG) activity changes under increasing motor demands may provide insights into how the brain prepares for movement. In this exploratory study, premovement EEG activity was examined in ten healthy male participants (n = 10) performing a unilateral bicep curl task. Cue-locked EEG signals preceding kinematically defined movement onset were analyzed using complementary event-related potential analysis (ERP), time–frequency analysis (TF), and cross-frequency coupling analyses to examine load-dependent EEG responses. As mechanical load increased, premovement EEG activity exhibited temporal, frequency-specific, and spatially distributed changes. Mixed-effects analyses indicated that the relationship between graded mechanical load and premovement EEG activity was better described by a non-linear than a linear model. These differences were pronounced at higher load levels and exhibited non-linear and frequency-specific patterns across the frontal, central, and contralateral sensorimotor scalp regions. These findings provide preliminary insights into how increasing mechanical demand is associated with frequency-specific, spatially distributed, and non-linear changes in premovement EEG activity before movement onset.