Figure 3

Ictal EEG and its tensor decompositions in patient 1. (a) Seizure onset. The first 2 s window was used to model and localise the seizure onset. (b) CPD of the seizure of patient 1. The spatial signature of both components show a distribution typical for eye movement-related artefacts; thus, CPD failed to extract an epileptic source where the spatial signature matches the seizure onset zone. (c) CWT-BTD of the seizure. The second CWT-BTD component captures both eye movement-related CPD components in one block term. Note the similarity between the spatial signatures S1 of CPD and S2 of BTD, and the correspondence of F1 and T1 with F2b and T2b, as well as of F2 and T2 with F2a and T2a. The seizure activity is successfully modelled in the first block term. The spatial signature corresponds well with the seizure onset zone as assessed by the epileptologist during the presurgical evaluation. Moreover, the frequency signature F1b indicates the dominant frequency of the seizure pattern (5 Hz), and the temporal signature T1b reflects the semi-rhythmic time course of the ictal pattern. (d) H-BTD of the seizure. The first H-BTD component capturing the seizure source is shown. The spatial signature corresponding to this source closely resembles the spatial map of the ictal source obtained with CWT-BTD. As the mode-2 and mode-3 signature do not carry physiological information, these are omitted here. Instead, R1 shows the reconstructed time course of the seizure source.