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.
Over the past 25 years, neuroscience has focused on perceptual consciousness, but the dynamic experience of the stream of thought—first described by William James—has received less attention. The Dynamic Framework of Thought (DFT) provides a taxonomy of thought dynamics. This study used four experiments, including laboratory, online, and fMRI-based settings, to test whether people can introspectively access and distinguish two thought dimensions: freely moving and deliberately directed. In all experiments, participants reported their thought dynamics during a probed resting period with eyes open. Using mixed methods, the findings suggest that individuals have some introspective access to these dynamics.