O157 Mapping the function and connectivity of the cingulate gyrus using stereo-encephalography (SEEG)

Objectives We aim to map the function and connectivity of the cingulate gyrus (CG) using cortical direct electrical stimulation. Methods We selected patients explored by SEEG at the Emergency University Hospital Bucharest and at the Strasbourg University Hospital, that had minimum one electrode sampling the CG (anterior-ACG, middle-MCG or posterior-PCG), outside the epileptogenic zone. We systematically reviewed the functional stimulations (bipolar, 50 Hz, 0.25–3 mA). For 17 patients explored in Bucharest, cortico-cortical evoked potentials (CCEPs) elicited by single pulse electrical stimulations (SPES) were used to obtain the effective connectivity at a group level for each part of the CG. Results We included 429 bipolar stimulations from 108 patients. From 151 stimulations in the ACG, 24.5% elicited a clinical response like: emotions (19%), vestibular (13.5%), thoracic sensation (13.5%), smile (11%). There are 135 stimulations in the MCG of which 53.3% elicited clinical responses like: elementary motor (24.94%), proprioception (22.22%), elementary somatosensitive (13.2%), compulsive motor (2.77%). There were 143 stimulations in the PCG and only 18.88% were positive, for example: executive function (11.11%), vestibular (7.4%). CCEPs analysis revealed that ACG is connected with the prefrontal (frontobasal and frontopolar) regions, anterior insula, mesiotemporal regions. MCG is connected with the primary and supplementary motor areas, insulo-perisylvian region and parietal lobe. PCG is connected with the ACG, MCG, prefrontal, parietal and temporal regions. Discussion High frequency stimulations elicit clinical responses as a result of a network effect that we have mapped with CCEPs. Conclusions There is a regional organization of the cingulate gyrus for each part both in function and connectivity. Significance These findings help us understand the functional organization of the cingulate gyrus with possible implications in epilepsy surgery, depression or other mental disorders.