Empathy for pain in fibromyalgia patients: An EEG study

Background: Recent research in cognitive neurosciences highlights how the neural circuitries are activated during pain responses in empathic context. Aims: The present study was designed to test if healthy subjects and Fibromyalgia (FM) patients, both evaluated by Laser Evoked Potentials (LEPs) and Event-Related Spectral Perturbation (ERSP), might reveal the empathic response to the partner's nociceptive stimulation. Methods: The emphatic nociceptive paradigm was recorded through 64 channels EEG and laser stimulation of the right hand in a shared visual open setting (Open Condition) or in a blind setting (Blind condition) where the subjects didn't receive visual information about partner nociceptive condition. Twenty one healthy subjects and 19 FM patients were evaluated in pairs. All subjects were tested by the Empathy for Pain Scale (EPS). Results: The averaged LEPs were similar between patients and controls in the different conditions. In attendance of the partner's stimulation, FM patients desynchronized the same fronto-central regions as before own stimulation, while healthy subjects shared the other's pain by activating scalp areas compatible with visual attention. These EEG features were more represented in subjects with higher EPS scores. Conclusions: While empathic features of healthy subjects seemed influenced by the specific visual attentional task, patients expressed an EEG pattern compatible with somatosensory circuits activation in the expectation of own and other's pain. The visual empathic involvement in other's noxious stimulation could evoke a different EEG response depending upon the experience of chronic pain.