Symptomatic Emotional Responses and Changes in Networks Elicited by Direct Electrical Stimulation

Emotion is a major area of research in psychology and neuroscience. However, the role of direct electrical stimulation (DES) in emotional localization has not yet been fully explored. This study aimed to analyze the use of DES in examining the local connectivity of brain regions eliciting emotional responses, thereby providing evidence for a new perspective of local changes in brain networks during emotional responses.

We reviewed the clinical data of 500 patients with refractory epilepsy who underwent stereoencephalogram (SEEG) implantation to locate the epileptogenic area and functional mapping of the brain. The three-dimensional reconstruction was employed for the qualitative and positioning analysis on the emotional responses elicited using DES. We used Granger causality (GC), directed transfer function (DTF), and partial directed coherence (PDC) to analyze the changes in functional connectivity before and after stimulation in selected patients.

Emotional responses were evoked without aura using DES in 85 contacts in 31 patients, including 35 (41.2%) contacts with fear, 37 (43.5%) contacts with happiness, 6 (7.1%) contacts with anxiety, and 7 (8.2%) contacts with depression. Three contacts of interest in two patients experiencing transient emotional symptoms underwent GC, DTF, and PDC analyses; the analysis revealed significant differences in brain networks before and after stimulation in selected patients.

DES can evoke emotions across various brain regions, such as the bilateral amygdala, hippocampus, temporal lobe, frontal lobe, insula, cingulate cortex, paracentral gyrus, fusiform, orbitofrontal cortex, left thalamus, and putamen. These elicited emotional experiences may largely result from the alterations in local brain networks.