The somato-cognitive action network in parkinsonian gait dysfunction and closed-loop neuromodulation

Parkinsonian gait dysfunction and freezing of gait (FoG) emerge from interactions among motor, cognitive-control and neuromodulatory systems. The somato-cognitive action network (SCAN) adds an anatomically defined cortical component to these distributed accounts. This narrative review examines its contribution across disease associations, targeted perturbation, state-contingent treatment, and incremental clinical value. SCAN-subcortical hyperconnectivity in Parkinson’s disease and its treatment sensitivity link inter-effector cortex to established disease circuits. A randomized comparison of individualized SCAN and effector-region intermittent theta-burst stimulation supports target-dependent improvement in total motor scores; FoG-specific efficacy remains unresolved because the axial outcome combined gait and non-gait items. In parallel, gait-phase and activity-dependent deep-brain stimulation demonstrate that neural signals can guide behaviorally timed treatment, with early benefits in selected gait outcomes. Across these accounts, neurochemical and distributed-network measures characterize vulnerability, while episode-linked decoupling identifies candidate state markers. SCAN contributes a more specific cortical hypothesis: transition-related activity in individually mapped SCAN may distinguish impending freezing beyond neighboring cortex and established gait signals. Cortical target selection and adaptive timing have separate empirical support; their combination is a proposed therapeutic strategy. Matched input and stimulation comparisons can determine whether SCAN adds predictive information or clinical benefit to existing controllers.