Brain activity during complex imagined gait tasks in Parkinson disease

•Neural correlates of simple and complex gait imagery were assessed in people with Parkinson disease (PD).•PD exhibited more activity in the supplementary motor area during imagined turning than imagined forward or backward gait.•Across gait imagery tasks, globus pallidus activity was lower in PD compared to controls and was positively correlated to overground walking speed.

ObjectiveMotor imagery during functional magnetic resonance imaging (fMRI) allows assessment of brain activity during tasks, like walking, that cannot be completed in an MRI scanner. We used gait imagery to assess the neural pathophysiology of locomotion in Parkinson disease (PD).MethodsBrain activity was measured in five locomotor regions (supplementary motor area (SMA), globus pallidus (GP), putamen, mesencephalic locomotor region, cerebellar locomotor region) during simple (forward) and complex (backward, turning) gait imagery. Brain activity was correlated to overground walking velocity.ResultsAcross tasks, PD exhibited reduced activity in the globus pallidus compared to controls. People with PD, but not controls, exhibited more activity in the SMA during imagined turning compared to forward or backward walking. In PD, walking speed was correlated to brain activity in several regions.ConclusionsAltered SMA activity in PD during imagined turning may represent compensatory neural adaptations during complex gait. The lowered activity and positive correlation to locomotor function in GP suggests reduced activity in this region may relate to locomotor dysfunction.SignificanceThis study elucidates changes in neural activity during gait in PD, underscoring the importance of testing simple and complex tasks. Results support a positive relationship between activity in locomotor regions and walking ability.