Figure 3: Simultaneous MEA and EEG seizure recordings share common features in the EEG frequency range.

(a,b) Patient C7 initiation, as recorded from one MEA channel (a) and the nearest active EEG channel (b, electrode 22, Supplementary Fig. 1). Spectrograms computed using the Morlet wavelet transform (1–50 Hz) together with the filtered time series signal are shown. This seizure followed the most common neocortical onset pattern, reflected in both the MEA and EEG channels, with an initial epileptiform discharge followed by rhythmic beta activity that gradually slows to the theta range and gains in amplitude. The seizures recorded from patients C2, C3 and C4 followed this same general pattern. (c,d) Simultaneous MEA and adjacent EEG recordings from patient C5. This seizure, following an electrographic pattern that is less common but still well known in neocortical EEG recordings, was characterized by an initial monomorphic delta rhythm that gradually increased in frequency to the theta range, then slowed to a 3–4-Hz spike and wave rhythm before offset.