Figure 1.

Subject 1. (A) EEG in bipolar AP montage and five virtual sensor channels showing average of 146 interictal spike epochs in bandwidth 3–70 Hz, digitized at 300 Hz. Topographic maps for MEG and EEG signals are top of head views centered at vertex Cz with anterior (nose) at top of map. For this averaged spike, epochs were aligned based on spike peak detected at VS location V3 in right frontal lobe in the 20–70 Hz bandwidth. (B) Inset is enlarged view virtual sensor (VS) channels showing timing of peaks. V5 peak occurs earliest followed by V4 (40 ms), V3 and V2 (50 ms), and V1 (63 ms). Note that although largest amplitude peaks at V1–V4 are delayed after V5 peak, each has a small peak at about the time of V5 peak. Onset of spike peak at V5 location precedes apparent onset at the other four VS locations. Although the averaged epochs shown were aligned based on the spike at V3, the earlier onset of a spike at V5 was detected. (C) Subjects MRI scan showing VS locations of V1–V5. Green dot is location of V5, earliest of the VS peaks. (D) Subject’s MRI scan showing one possible pattern of spread based on timing of peaks and shortest distances between VS locations. The arrows are only to show relative timing, since propagation and pathways cannot be discerned solely with spike peaks separated in time. (E) 3D reconstruction of subject’s MRI and subdural electrode locations. (F) Intraoperative photograph of left brain surface. Green dots represent electrodes showing spikes at onset of seizures. Ictal onset was in left frontal lobe at LIPF2–4 (red frontopolar electrodes and purple anterior frontal lobe electrodes) with rapid spread to left anterior temporal lobe (blue electrodes). Yellow overlay represents resection plan.