Enhanced Neural Reinstatement for Evoked Facial Pain Compared With Evoked Hand Pain.

Memory retrieval is accompanied by a reactivation of cortical and subcortical areas that have been active during encoding. This neural reinstatement is stronger during retrieval of pain-associated material compared with other unpleasant events. In this functional magnetic resonance imaging study, we investigated the differences in neural reinstatement during recognition of visual stimuli that had been paired with face or hand pain during memory encoding. Body site-specific neural reinstatement was tested in 23 healthy young volunteers who performed a visual categorization and a surprise recognition task. Our data shows increased neural reinstatement in task-specific and encoding-related areas, such as the parahippocampus (left: x = -26, y = -30, z = -18, t = 4.11; right: x = 26, y = -38, z = -6, t = 4.36), precuneus (x = 2, y = -56, z = 2, t = 3.77), fusiform gyrus (left: x = -24, y = -26, z = -20, t = 5.41; right: x = 18, y = -58, z = -14, t = 4.52), and amygdala (x = -34, y = -4, z = -20, t = 4.49) for pictures that were previously presented with face compared with hand pain. These results correlated with the individual's recognition confidence, although recognition rates did not differ between the conditions. Functional connectivity was increased between the amygdala and parahippocampus (x = 34, y = -10, z = -28, t = 5.13) for pictures that had previously been paired with face compared with hand pain. Our results were positively correlated with pain-related fear, represented by neural activation in the thalamus (x = -14, y = -35, z = 4, t = 3.54). The reported results can be interpreted as compensatory resource activation and support the notion of a stronger affective component of face compared with hand pain, potentially in line with its greater biological relevance. PERSPECTIVE: This study demonstrates neural reinstatement of face pain-related information, which might be related to the increased biological and affective component of face pain compared with pain on the extremities. Our results might contribute to the understanding of the development and prevalence of head and face pain conditions.