Neural correlates of empathy for pain: an EEG-fNIRS coregistration study

Background: Besides personal features and belonging to a group, even the physical attractiveness of the person might modify the course of an empathic response in different conditions, such as empathy for pain. This research checked the impact of the physical attractiveness of the face in a situation associated with the sensation of pain. Methods: 22 participants (Mage=24.9; SD=3.6) observed faces (Attractive; Unattractive) that express painful conditions (Pain, P; No pain, NP) and were asked to rate the attractiveness and pain feeling of the face while hemodynamic and electrophysiological brain activity was recorded by means of functional Near-Infrared Spectroscopy (fNIRS) and electroencephalogram (EEG) technology. To better deepening the empathy for pain effect, participants attention was drawn on the pain and on the attractiveness of the faces by a specific question. Results: Event-Related Potential (ERP) analysis revealed a significant interaction for N2 component (p= .015) between P and NP condition only for attractive condition, regardless of the question. For P3 component there is a significant difference (p= .008) between P and NP condition only when the participants’ attention is turned on pain. fNIRS single channel analysis showed significant reduction of oxygenated hemoglobin in the left Inferior Frontal Gyrus for pain stimuli (p= .026) and a significant difference for the question about pain (p= .019), between P and NP condition only for unattractive condition. Conclusions: Findings suggested that to process the question about pain or about attractiveness higher cognitive processes are needed, so the question condition might not have an influence on emotional empathy (reflected by early ERP components like N2), but it should have an impact on the cognitive aspect of empathy (reflected by P3). However, as shown by both EEG and fNIRS results physical attractiveness affects frontal areas involved in the appraisal of faces in painful conditions.