Default mode network connectivity patterns associated with visual processing at different stages of Parkinson's...

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Neurology

Background:

• The default mode network (DMN) typically decreases activity during cognitive tasks, while task-engaged networks increase.
• Visual processing deficits are common in Parkinson's disease dementia (PDD).

Purpose of the Study:

• To investigate DMN effective connectivity in PDD compared to Parkinson's disease (PD) and healthy controls (HC) during a visual cognitive task using functional MRI.
• To understand how DMN connectivity changes when switching from rest to a visual task in these groups.

Main Methods:

• Functional MRI (fMRI) was employed with 14 PDD, 18 PD, and 18 HC participants.
• Psychophysiological interaction (PPI) analysis was conducted using the precuneus (PCu) as the seed region.
• Statistical thresholding was applied at p(FWE) < 0.05.

Main Results:

• Healthy controls exhibited altered PCu connectivity (positive to negative) with visual processing areas during the task.
• Both PD and PDD groups showed impaired DMN connectivity with brain regions involved in bottom-up visual processing.
• PD patients displayed disrupted ventral attentional network integration, while mild PDD patients showed increased dorsal attentional network engagement.

Conclusions:

• Impaired dynamic interplay between large-scale brain networks is evident in Parkinson's disease (PD).
• These disruptions extend beyond the motor system, affecting cognitive and attentional networks.