Figure 4. Travelling waves propagating across the microelectrode array correspond to those propagating across the ECoG grid.

(a) Examples of ictal discharges recorded across ECoG electrodes in two patients colour coded by when the maximally decreasing slope occurs, with cyan indicating earlier electrodes and magenta later electrodes. Colour-coded circles above the discharges indicate a spatial representation of delays over the ECoG grid, with the same colour code as the voltage traces. (b) Reconstructions of ECoG grid and MEA locations for the same patients in a. Average delays across ECoG electrodes are colour coded as in a. Black arrows indicate MEA locations. (c) Distributions of MEA pre-recruitment travelling waves (black) and travelling waves ECoG (orange). (d) Three channels of LFP recorded from ECoG electrodes during one seizure (patient 3) and a representative increase in variance explained by the first-principal component, across all ECoG electrodes on the grid shown in b (lower), during the pre-termination epoch. The black dotted line shows linear regression used to determine the slope of the variance explained during the pre-termination epoch for the example seizure.