Abstracts

Rationale: We investigated the connectivity of the human frontal and insular network using corticocortical evoked potential (CCEP). Methods: This retrospective analysis included 18 patients with medically intractable focal epilepsy who underwent stereoelectroencephalography and CCEP. Alternating 1 Hz electrical stimuli were delivered to parts of the frontal lobe and anterior insula [prefrontal cortex (PFC), ventrolateral and dorsolateral premotor area (vPM, dPM), pre-supplementary motor area (preSMA), supplementary motor area (SMA), frontal operculum, anterior insula]. A total of 40-60 stimuli were averaged in each trial to obtain CCEP responses. CCEP distributions were evaluated by calculating the root mean square of CCEP responses. Results: Prefrontal cortex stimulation elicited prominent CCEP responses in medial prefrontal cortex and premotor areas over the ipsilateral hemisphere. The stimulation of vPM and dPM induced CCEP responses in the ipsilateral fronto-parietal areas, whereas the stimulation of preSMA and SMA induced CCEP responses in the bilateral fronto-parietal areas. The stimulation of frontal operculum induced CCEP responses in the ipsilateral insula and temporal operculum. CCEPs were observed in the ipsilateral medial and lateral frontal and fronto-temporal operculum in the insular stimulation. Conclusions: Various regions within the frontal lobe are linked to specific ipsilateral and contralateral regions, which may reflect distinct functional roles.