Figure 3.

Connectivity of the insula. (A) Connectivity probability (upper part) and connectivity latency (lower part) maps obtained using CCEPs of the insula in 107 patients of the F-tract database (f-tract.eu) (unpublished data). The insula is part of a dense and widely extended network in which CCEPs propagate quickly, first with a higher probability around the insular DCS site and then to other cortical regions. (B) Epileptogenicity map of an SEEG-recorded spontaneous seizure, which evaluates the propensity of a brain region to generate significant fast activities (60–200 Hz) at seizure onset. This 21-year-old male patient was suffering from seizures characterized by a painful reflex left arm sensation followed by loss of contact, bilateral dystonic posturing of the upper limbs, hypermotor behavior, and postictal aphasia. Note how both insula are involved at seizure onset, though with a right-side predominance, which underlines how lateralization can be an issue in insular epilepsy due to the close and fast inter-insular connections. (C) Time frequency analysis at seizure onset of the same seizure, which confirms the simultaneous and asymmetric involvement of two homologous insular subregions (L and R postero-superior insula). Note how fast frequencies are suppressed (*) concurrently with the increase in high frequencies. L: left; R: right.