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English: pone-0008081-g002: Intra-cranial corticography recording.Picture of a grid, placed directly on the cortex for intra-cranial recording. Mentions: Intra-operative neocortical registrations were performed using 4×5 subdural electrode grids (interelectrode distance 1 cm; see figure 2) and recorded with a Brainlab ® digital EEG system (OSG, Rumst, Belgium). Sample frequency was 500 Hz. The grid was placed directly on the lateral temporal cortex, covering T1-T3. The grid position was documented during the procedure on schematic representations of the brain. For every patient, five artefact-free epochs of 4096 samples (8,19 s) were selected off-line by careful visual inspection (ED, CJS). All selected epochs were recorded while patients were in an interictal state (as determined by the ECoG recording) and before resection of the lesion had taken place.