The Wandering Mind: An Integrated Review of the Default Mode Network

Abstract

This thesis reviews current literature on the Default Mode Network (DMN), a set of brain regions including the medial prefrontal cortex (MPFC), posterior cingulate/retrosplenial cortex (PCC/Rsp), and left and right inferior parietal lobules (IPLs) that are deactivated during externally focused tasks and activate during internally oriented processes such as self-reflection and mind-wandering. I examine the DMN through an integrated lens, exploring the factors that influence both intra-network connectivity and its interactions with other networks, especially the Central Executive and Salience Networks. The DMN has significant clinical relevance, with altered connectivity patterns observed in disorders such as schizophrenia, depression, autism spectrum disorder, and neurodegenerative diseases such as Alzheimer’s disease and Parkinson's disease. It also plays a significant role in emotion regulation, as both adaptive and maladaptive regulatory strategies have been linked to specific DMN connectivity patterns. Furthermore, various factors including meditation, psychedelic use, aging, religious belief, creativity, and physical activity can modulate DMN connectivity. Meditation and psychedelics tend to reduce intranetwork connectivity and increase integration with other networks, and behaviors like physical activity and spiritual practice can also influence DMN connectivity patterns. Overall, these findings suggest that the DMN plays an important role in how the brain can internally process experience, and changes in its connectivity patterns may offer important insights for clinical intervention and informing the public about what behaviors can positively influence mental states.