The prefrontal cortex contains multiple subregions linked to different large-scale brain networks, supporting a wide range of mental phenomena from goal-directed thought and executive functions to mind-wandering and psychedelic experiences. A key dimension distinguishing conscious experiences is the stability or variability of mental states over time, which is central to the dynamic framework of thought (DFT) and the relaxed beliefs under psychedelics (REBUS) model. This review synthesizes these frameworks to explain how prefrontal subregions may differentially contribute to the stability and variability of thought and conscious experience, and suggests future research directions.
Abrupt transitions in thought content occur at surprising times but lead to unsurprising content, while wayward transitions occur at surprising times and also lead to surprising content. The authors distinguish these two types using probabilistic and predictive processing concepts, employing transition and occurrence probability metrics. They discuss how these transitions may contribute to mental function and their possible neural implementation.
The default mode network (DMN) is linked to self-referential thinking, memory, and goal-directed cognition. Its functional connectivity with frontoparietal networks involved in attention and executive control may indicate cognitive health. This review examines DMN connectivity metrics as potential biomarkers across states like attention, mind wandering, and meditation, and in conditions such as Alzheimer's disease, Parkinson's disease, depression, and ADHD. It also addresses the reliability of network estimation and offers recommendations for using functional connectivity measures as biomarkers of cognitive health.
The default mode network (DMN) supports self-referential thinking, memory, and understanding others. Its functional connectivity with frontoparietal and dorsal attention networks is anti-correlated: when attention turns outward, the DMN deactivates. This switching between internal and external modes, mediated by salience networks, may indicate cognitive health. Resting-state fMRI enables large-scale datasets for standardized connectivity benchmarks. This review examines DMN connectivity metrics as potential biomarkers of cognitive state in attention, mind wandering, meditation, and clinical conditions like anxiety, depression, ADHD, and PTSD. It also addresses reliability issues and offers recommendations for using connectivity measures as biomarkers of cognitive health.