Planning-related hubs and brain network organization during motor decision-making

Motor planning emerges from the integration of sensory information, effector selection, and inhibitory control within large-scale cortical networks. Although behavioral asymmetries between dominant and non-dominant hands have been widely reported, the network-level mechanisms remain poorly understood. Here, we examined whether differences in motor planning efficiency reflect distinct patterns of cortical network organization. Seventeen healthy right-handed individuals performed a visually guided hand-selection task while EEG, EMG, and kinematic signals were recorded. Motor planning time was defined as the interval between stimulus onset and the onset of agonist muscle activity. Functional coupling during planning was estimated in the beta band and characterized using graph-theoretical measures of network integration, segregation, and regional hubness. Planning time was significantly longer for dominant-hand movements, yet correlated across hands, indicating partially shared planning processes. Only dominant-hand planning showed systematic relationships between behavior and network organization. Longer planning times were associated with increased global efficiency and clustering, suggesting enhanced integration and local specialization as planning demands increased. Regional analyses revealed a left-lateralized set of temporal, sensorimotor, and parietal functional hubs selectively engaged during dominant-hand planning. In particular, planning time increases with functional coupling between a left parietal and contralateral frontal regions pointed to dynamic interhemispheric coordination. No comparable network-behavior relationships were observed during non-dominant hand planning. These findings demonstrate that motor planning efficiency is constrained by the dynamic reconfiguration of large-scale cortical networks rather than by isolated regional activations. Dominant-hand planning recruits an asymmetric parieto-frontal network whose increasing integration scales with planning demands, consistent with bounded evidence-accumulation frameworks.