This study indicates that broad-band functional connectivity recorded intra-operatively over the temporal neocortex is lower in patients with a longer history of TLE. The association between pathology and lower functional connectivity is in line with other studies. Correlations between functional connectivity loss and pathological states such as epilepsy, brain tumors, and schizophrenia have been described previously [15], [21], [31]. Bartolomei and others found a correlation between duration of epilepsy and the number of cortical structures with epileptogenic characteristics by analyzing intracerebral EEG recordings of TLE patients [7]. A correlation has been reported between brain tumors and decreased broad-band functional connectivity [21]. It is hypothesized that pre-ictal hypersynchronized epileptogenic zones may be surrounded by isolating zones of hyposynchronization [15]. Ponten and others found that synchronization increases during a seizure in TLE patients [11]. Based on these studies, it is hypothesized that epileptogenic zones might be identified by their synchronization pattern. Synchronization analysis may therefore be useful as a method to functionally map the temporal cortex of TLE patients, hereby locating specific sites that participate in the initiation and propagation of seizures
