Differential interictal activity of the precuneus/posterior cingulate cortex revealed by resting state functional MRI at 3T in generalized vs. partial seizure

PURPOSE: To characterize, using functional MRI (fMRI), the pattern of active brain regions in the resting state in patients with epilepsy. MATERIALS AND METHODS: We studied 28 patients with epilepsy, divided into a partial seizure (PS; N = 9) and a generalized seizure group (GS; N = 19), and 34 control subjects. Resting state fMRI was performed using a GE 3T scanner by collecting 200 volumes of echo-planar imaging (EPI) images with subjects relaxed, eyes closed. Data were processed using a modification of the method of Fransson (Hum Brain Mapp 2005;26:15-29), which reveals information on regional low-frequency Blood Oxygenation Level Dependent (BOLD) signal oscillations in the resting state without any a priori hypothesis. The significant active areas in brain were identified with both individual and group analysis. RESULTS: Controls showed active regions in the precuneus/posterior cingulate cortex (PCC) and medial prefrontal cortex (MPFC)/ventral anterior cingulate cortex (vACC), theregions associated with the brain "default mode." Similar active regions were observed in PS, whereas GS showed no significant activation of precuneus/PCC. CONCLUSION: In GS, the lack of activation in precuneus/PCC may partly account for their more severe interictal deficits, compared to PS, in cognitive functions such as concentration and memory.