Figure 2 : Ictal discharges form travelling waves across the microelectrode array.

From: The ictal wavefront is the spatiotemporal source of discharges during spontaneous human seizures

Figure 2

(a) Example, low-frequency LFP recorded from each microelectrode during three ictal (EEG) discharges, one from each seizure epoch as indicated by the coloured asterisks in the seizure traces, colour coded by when the maximally negative slope of the travelling wave occurs on each microelectrode. Seizures from two patients (patient 3 and 5) are shown. (b) The footprint of the microelectrode array corresponding to the three ictal discharges in a, with electrode positions colour coded the same way as the LFP in a. Vectors indicating travelling wave direction are superimposed on the microelectrode array footprint in white. (c) Histograms of delays between the first and last discharges on array microelectrodes during each epoch (pre-recruitment in light blue, post-recruitment in purple and pre-termination in pink). (d) Measures of discharge speed across all patients, during the three epochs shown in a. Post hoc Tukey’s range test determined that pre-recruitment bursts (N=273) were significantly slower than both post-recruitment (N=315) and pre-termination (N=282) bursts (P=9.5 × 10−10 and P=9.5 × 10−10). Post-recruitment and pre-termination bursts did not exhibit significantly different speeds (P=0.82). Error bars indicate s.e.