Identifying the neural correlates of voluntary stopping in people with Parkinson’s disease using a Virtual Reality gait paradigm

Freezing of Gait (FOG) is a disabling feature of Parkinson’s disease (PD). However, the neural mechanisms underlying voluntary stopping impairments remain unclear. This study used a validated Virtual Reality (VR) gait paradigm to investigate the neural correlates of cued voluntary stopping in 15 PD participants with FOG, 10 PD participants without FOG, and 12 healthy controls. PD participants were assessed on and off dopaminergic medication. Blood-oxygen-level-dependent (BOLD) signals during voluntary stopping were compared with walking and rest periods. In the OFF state, PD participants showed impaired voluntary stopping relative to healthy controls, relying predominantly on the Supplementary Motor Area (SMA). Dopaminergic medication restored stopping performance to levels comparable to healthy controls and was associated with broader recruitment of occipital, cerebellar, and inferior frontal regions. Freezers exhibited greater stopping deficits and relied on the SMA in both medication states. They also demonstrated reduced functional connectivity across occipital, temporal, and cerebellar regions in the ON state and recruited fewer cortical regions compared to non-freezers, particularly in the OFF state. The findings suggest that PD participants with FOG fail to engage a disseminated voluntary stopping network. Future work should explore interactions between the stopping network and brainstem gait and balance systems.