Ictal EEG and its tensor decompositions in patient 2. (a) A segment of the seizure. The whole 10 s window was used to model the frequency evolution of the seizure. (b) CPD of the seizure of patient 2. Only the first component is shown. This component corresponds to the seizure source, with clear left temporal localisation and a rhythmic oscillatory temporal pattern with increasing frequency. However, these peculiar frequency characteristics can not be directly seen on the frequency signature, which shows a single peak at 6 Hz. (c) CWT-BTD of the seizure. BTD captures the seizure source in the first block term; the second block term is now shown. Note the close resemblance between S1 of BTD and S1 of CPD. Moreover, T1a captures the late fast, while T1b captures the early slow oscillatory pattern of the seizure. The frequency characteristics can be directly seen from the frequency signatures, namely, the 8-Hz peak in F1a and the 4-Hz peak in F1b. (d) Hankel-BTD of the seizure. The first BTD term captures the seizure source. The reconstructed time course (R1) clearly reflects the peculiar characteristics of the seizure pattern, starting with a slow oscillation and evolving into a fast oscillation. For comparison, (e) and (f) show the reconstructed time course of the seizure sources obtained by CPD and CWT-BTD, respectively.