Application of Functional MRI in Parkinson's Disease and Default Mode Network: Review of the Literature.

Parkinson's disease (PD), the second most common neurodegenerative disorder in aging individuals, involves dopamine neuron loss in the midbrain, causing motor and non-motor issues like cognitive and psychological abnormalities. The default mode network (DMN), a brain network active during rest involved in memory, self-referential processing, social cognition, and consciousness, includes regions such as the medial prefrontal cortex, posterior cingulate cortex, inferior parietal lobule, precuneus, and lateral temporal cortex. Normal DMN connectivity is vital for consciousness and self-awareness. PD disrupts DMN connectivity. Functional MRI studies show impaired DMN connectivity in the posterior cingulate cortex, medial prefrontal cortex, and precuneus in PD patients. Greater motor symptoms correlate with larger alterations in DMN connections within the frontal lobe and posterior cingulate cortex. Future research should clarify mechanisms linking DMN abnormality to PD severity.

Study at a glance

Abstract

Parkinson's disease (PD) has become the second most prominent neurogenerative disorder relating to aging individuals. PD involves the loss of neurons containing dopamine in the midbrain and leads to a number of motor issues as well as non-motor complications such as cognitive and psychological abnormalities. The default mode network (DMN) is a complex brain network primarily active during rest and serves multiple roles relating to memory, self-referential processing, social cognition and consciousness and awareness. Multiple brain regions are involved in the DMN such as the medial prefrontal cortex (mPFC), the posterior cingulate cortex (PCC), the inferior parietal lobule, the precuneus and the lateral temporal cortex. Normal DMN connectivity is vital to preserving consciousness and self-awareness. Neurological pathologies such as PD disrupt DMN connectivity, leading to complex issues. Functional MRI (fMRI) is a neuroimaging modality used to observe brain activity through measuring blood flow differences as it relates to brain activity. DMN connectivity experiments using fMRI find that individuals with PD exhibit impaired DMN connectivity in specific regions including the PCC, mPFC and the precuneus. Individuals with greater PD motor symptoms have also been found to suffer larger alterations in DMN connections anatomically within the frontal lobe and PCC. While fMRI has been utilized as a tool to explore the relationship between PD patients and DMN connectivity, future research should look to develop a better understanding of the specific mechanisms of action that drive this link between DMN abnormality and PD severity.