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.