Functional brain networks involved in fluid intelligence in bipolar disorder.

fMRI data were collected during the Raven's Standard Progressive Matrices (RSPM) to investigate the networks involved in fluid intelligence (Gf) in people with bipolar disorder (BD), compared to community controls. Brain networks were extracted using a multidimensional analysis method that provides network anatomical and temporal information about task-induced BOLD signal changes. Four networks were elicited. Two networks matched the multiple demand network (MDN), one of which consisted of the MDN desynchronized with all other networks and peaked earliest in the trial (∼ 6 s). The other network (MDN/DN-B) involved MDN activation synchronized with default mode network (DMN) deactivation, with a later, more protracted peak (∼ 9-12 s). Another network comprised activations in motor response (RESP) regions and peaked later in the trial (∼ 11-14 s). A fourth network (RE-EV/DN-A) peaked the latest (∼ 14 s) and comprised activations in regions involved in the re-evaluation (RE-EV) of responses and DMN deactivation. The BD and control groups did not differ in RSPM task performance or network activity. These null results might indicate heterogeneity in Gf in BD, with a subgroup of BD patients without Gf deficits.