Precision functional mapping in individuals with bipolar and unipolar depression

Precision functional mapping is the practice of delineating functional brain areas or networks and studying brain-behavior relationships within individuals, as opposed to at the group-level, typically using a large amount of fMRI data per-subject acquired longitudinally. In this talk, I will describe how we applied precision functional mapping in adults with unipolar and bipolar depression who were densely-sampled (serial clinical assessments, fMRI) up to 1.5 years. This work revealed that the salience network is expanded nearly 2-fold in cortex relative to healthy controls due primarily to borders of the network shifting outwards and encroaching upon neighboring functional systems. This expansion was trait-like – stable over time, regardless of fluctuations in mood state. In contrast, functional connectivity strength in particular fronto-striatal circuits tracked fluctuations in symptom severity and mood state switches (transitioning from a euthymic state to depressed or hypomanic episode) within these individuals. Together, these findings reveal new patterns of functional network topology and connectivity that are neural traits and states, respectively, characteristic of mood disorders, and highlight the utility of deeper characterizations of functional neuroanatomy and behavior within individuals as an alternative to studying population-level central tendencies.