Abstracts

Rationale: Stereotactic electroencephalography (SEEG) is used in patients with medically refractory focal epilepsy (MRE) to localize the seizure onset zone when noninvasive studies (i.e. scalp EEG, multi-modal imaging) fail to do so. With SEEG electrodes in place, brain mapping with high-frequency stimulation is performed to define eloquent cortex and to further localize the seizure onset zone by stimulating the patient's typical aura and triggering seizures. The cingulate lies in the medial cerebral hemisphere, lying above the corpus callosum and extending beyond it both anteriorly and posteriorly. The cingulate gyrus is involved in the integration of emotional experiences with movement and autonomic function. Prior work has shown that stimulation of the cingulate can lead to a lessened experience of pain, to laughter (both mirthless and with mirth) and to autonomic sensations which are interdigitated with emotional responses such as hot flushes and tachycardia. Further understanding of the role of the cingulate in emotional experience has the potential to reveal new targets for the treatment of refractory mood disorders. Methods: Two patients with MRE underwent SEEG with electrodes in the cingulate. The first patient had bilateral SEEG electrodes and the second patient had only right sided electrodes. Brain mapping using the Natus stimulator was done in adjacent electrode pairs at 50 Hz with a current from 1 mA to 4 mA for 1.5-3 seconds. At each location, the patient was asked to extend their arms, count, and report any sensations they experience. Results: During brain mapping, both patients experienced a feeling of euphoria with stimulation to the cingulate gyrus without exhibiting laughter. The descriptions of the sensation were similar in both patients but the locations were different with one being in the anterior and the second being in the middle part of the cingulate. Conclusions: To our knowledge, this is the first report of induced euphoria without laughter following stimulation of the cingulate. It suggests that similar functions may have person specific locations within the cingulate. Further exploration of the cingulate and its relationship to euphoria may have utility in our understanding and treatment of mood disorders. Funding: No funding