An initial way to assess integration is by functional connectivity, defined as the amount of dependency between pairs of regions.39,40 Using functional magnetic resonance imaging (fMRI), electroencephalography (EEG), or magnetoencephalography (MEG) data, studies generally show that anteroposterior connectivity is deficient:41-43 Moreover, these findings have been associated with symptoms. In one fMRI study44 and two EEG studies,45,46 it was outlined that the less the frontal cortex was functionally dependent on the temporal cortex, the more the subject was prone to verbal hallucinations (trait studies). Recently we had the opportunity to assess a patient who signaled his hallucinations during an fMRI session. Though these two areas were normally functionally connected during his resting state, their connectivity vanished during the hallucinations (state study).
