Although there is debate about whether patients with UWS can perceive their own pain, our data indicate that many of them respond to the signals of pain in others. One can speculate that "affective consciousness" can remain even in patients with very severe brain damage who have no capacity for cognition.

A major challenge in the diagnosis of disorders of consciousness is the differential diagnosis between the vegetative state (VS) and the minimally conscious state (MCS). Clinically, VS is defined by complete unawareness, whereas MCS is defined by the presence of inconsistent but clearly discernible behavioural signs of consciousness. In healthy individuals, pain cries have been reported to elicit functional activation within the pain matrix of the brain, which may be interpreted as empathic reaction. In this study, pain cries were presented to six VS patients, six MCS patients, and 17 age-matched healthy controls. Conventional task-related functional magnetic resonance imaging (fMRI) showed no significant differences in functional activation between the VS and MCS groups. In contrast to this negative finding, the application of a novel data-driven technique for the analysis of the brain's global functional connectivity yielded a positive result. The weighted global connectivity (WGC) was significantly greater in the MCS group compared to the VS group (p < 0.05, family-wise error corrected). Using areas of significant WGC differences as 'seed regions' in a secondary connectivity analysis revealed extended functional networks in both MCS and healthy groups, whereas no such long-range functional connections were observed in the VS group. These results demonstrate the potential of functional connectivity MRI (fcMRI) as a clinical tool for differential diagnosis in disorders of consciousness.

The human voice is one of the principal conveyers of social and affective communication. Recent neuroimaging studies have suggested that observing pain in others activates neural representations similar to those from the first-hand experience of pain; however, studies on pain expressions in the auditory channel are lacking. We conducted a functional magnetic resonance imaging study to examine brain responses to emotional exclamations of others' pain. The control condition comprised positive (e.g., laughing) or negative (e.g., snoring) stimuli of the human voice that were not associated with pain and suffering. Compared to these control stimuli, pain-related exclamations elicited increased activation in the superior and middle temporal gyri, left insula, secondary somatosensory cortices, thalamus, and right cerebellum, as well as deactivation in the anterior cingulate cortex. The left anterior insular and thalamic activations correlated significantly with the Empathic Concern subscale of the Interpersonal Reactivity Index. Thus, the brain regions involved in hearing others' pain are similar to those activated in the empathic processing of visual stimuli. Additionally, the findings emphasise the modulating role of interindividual differences in affective empathy.