With the objective to investigate the role of the insula in recognizing emotion, we performed direct electrical stimulation over the anterior insular cortex during awake surgery while simultaneously delivering an emotional sensitivity task. We registered 18 consecutive patients with brain tumors associated with the insular lobe, who were undergoing tumor resection. An emotional sensitivity task was employed to measure the patients' ability to recognize emotions from facial expressions before, during, and after awake surgery. Furthermore, we performed voxel-based lesion symptom mapping (VLSM) to identify the association between relevant brain lesions and emotion recognition. When we performed direct electrical stimulation over the anterior insular cortex during awake surgery, the results showed that the ability to recognize anger was significantly enhanced with the presence of anterior insular stimulation (p < 0.05). Comparing the performance in the emotional sensitivity task before and after surgery, the performance in the anger condition became worse (p < 0.01), but became better in the sadness condition after surgery (p < 0.01). In the case of anger recognition, lower scores in the correct response index were associated with lesions involving the left insula in the VLSM study. Direct electrical stimulation over the anterior insular cortex enhanced anger recognition in patients with insular tumors. In contrast, accuracy of anger recognition was significantly reduced, and sadness was improved, when the performance of emotional sensitivity was compared pre- and post-surgery. Our findings suggest that the insular cortex is involved in changes in emotion recognition, including anger and sadness recognition by modulating arousal level that is closely connected with interoception.
Keywords: Anger recognition; Anterior insular cortex; Awake surgery; Brain tumor; Emotion recognition.