Disentangling perceptual judgment and online feedback deficits in Parkinson's freezing of gait.

Although the underlying mechanisms of freezing of gait in Parkinson's disease (PD) are not fully understood, impaired sensory-perceptual processing has been proposed as an important contributor to freezing episodes. The aims of this cross-sectional study were to disentangle how sensory-perceptual deficits involved in planning (prior to movement) and sensory-perceptual feedback processing (during movement execution) contribute to freezing of gait in narrow spaces. Thirteen PD participants with freezing (PD FOG), 14 PD participants without freezing (PD non-FOG), and 15 healthy individuals made a perceptual estimate of the width of the distal opening of a corridor in two conditions: parallel and narrowing walls.