Objective: To investigate (1) the differences in neural activation during complex walking that possesses different cognitive demands and (2) the influence of neurodegenerative disease as Parkinson’s disease on these neural circuits.

Background: Behavioral studies suggest that deficits in cognitive domains and sensory-motor processes associated with aging and neurodegeneration impair the ability to walk in complex environments. However, the neural correlates of locomotion in complex environments are still unclear.

Methods: Twenty healthy older adults (mean age 69.7±1.3 yrs) and 20 subjects with Parkinson’s disease (PD) (mean age 72.9±1.1 yrs; mean disease duration: 6.8±1.3 yrs; UPDRS_III: 29.8±2.4) were asked to imagine themselves walking in different virtual environments while in the MRI scanner. Three imagined walking tasks with different complexity were performed: imagined usual walking, imagined obstacle negotiation, and imagined walking while navigating to specific targets shown on a map. Watching the same virtual scenes without imagining walking served as the control tasks. Whole brain analyses were used to detect neural activation associated with the imagined walking tasks.

Results: Compared to usual walking, both groups had increased activation during obstacle negotiation in the middle occipital gyrus (MOG) (pFWEcorr<0.001), middle frontal gyrus (MFG) (pFWEcorr<0.005), and cerebellum (pFWEcorr<0.001). The healthy older adults had higher activation in the precuneus and MOG (pFWEcorr<0.023) during the navigation task, while no differences in activation were observed in patients with PD. Between group comparisons revealed that patients with PD had a significant higher activation in usual walking and obstacle negotiation (pFWEcorr<0.039). However, during the navigation task, healthy older adults had higher activation than patients with PD (pFWEcorr<0.047).

Conclusions: These findings demonstrate that patients with PD require greater activation during imagined usual walking and obstacle negotiation compared to healthy older adults. This increased activation may reflect a compensatory attempt to overcome inefficient neural activation. In addition, this increased activation may reduce the functional reserve needed during more demanding tasks such as during navigation and in turn, this may contribute to the high prevalence of falls and the dual tasking difficulties that are common among patients with PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/altered-brain-activation-in-complex-walking-conditions-in-patients-with-parkinsons-disease/