Direct Electrical Stimulation of the Opercula

SUMMARY: Direct electrical stimulation (DES) has long been used in patients undergoing epilepsy surgery for two key purposes: functional brain mapping and seizure triggering. In this review, the findings from DES applications to the opercula are synthesized, with the aim of mapping opercular functions and investigating seizure induction. Clinical responses to opercular DES are frequent and diverse, showing a partial segregation with spatial overlap, and exhibiting topographical differences: Emotion is evoked in the most anterior part of frontal operculum, expressive aphasia is the mid-posterior part, followed by oropharyngeal, dysarthria, and gustatory in the central opercula, somatosensory and vestibular in the posterior opercula, and auditory (or rarely visual) in the temporal opercula. No studies have specifically looked at DES-induced seizures from the opercula. Only a small number of studies about insulo-opercular epilepsy have mentioned that DES of the opercula induced seizures. Overall, opercular DES studies converge on the view that the opercula comprise a complex multimodal cortex integrating especially sensorial perception. Each subdivision had a different dominant response to DES, whose organization helps understand the different subgroups of opercular epilepsy.