Objective: The aim of this observational study was to assess brain functional MRI (fMRI) activity during a “FoG observation task” in PD-FoG patients relative to healthy controls.

Background: Freezing of gait (FoG) is a complex phenomenon in Parkinson’s disease. Recent fMRI findings suggest a problematic interplay between motor, cognitive and emotional circuits in the mechanisms underlying FoG. However, to date, specific task-based fMRI studies assessing the emotional circuit in PD-FoG patients are very few. Studying fMRI patterns of brain activity during the observation of another person experiencing FoG can be helpful to explore the role of the emotional circuit in FoG.

Method: Twenty-four PD-FoG patients and 18 age- and sex-matched healthy controls performed clinical and neuropsychological evaluations, and fMRI experiments including: i) “FoG-observation-task” consisting of watching a patient experiencing FoG during a walking task (usually evoking FoG); ii) “gait-observation-task” consisting of watching a healthy subject performing similar walking tasks without experiencing FoG.

Results: During both tasks, PD-FoG patients showed reduced activity of the fronto-parietal mirror neuron system (MNS) relative to controls. In the “FoG-observation-task” relative to the “gait-observation-task”, PD-FoG patients revealed an increased recruitment of the anterior medial prefrontal cortex and a reduced recruitment of the dorsomedial prefrontal cortex and hippocampus relative to controls. Healthy controls in the “FoG-observation-task” relative to the “gait-observation-task” showed increased recruitment of cognitive empathy areas and decreased activity of the fronto-parietal MNS.

Conclusion: Our results suggest that when PD-FoG patients observe a subject experiencing FoG, there is an increased activity of brain areas involved in self-reflection emotional processes and a reduced activity of areas related to motor programming, executive functions and cognitive empathy. These findings support previous evidence on the critical role of the emotional circuit in the mechanisms underlying FoG.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/brain-activity-of-the-emotional-circuit-in-parkinsons-disease-patients-with-freezing-of-gait/