(259) Brain Activation during Pain Evaluation/Reporting is Independent of Individual Differences in Pain Sensitivity and Psychological Modulators of Pain

Pain evoked by a carefully controlled experimental stimulus differs widely across individuals. The underlying mechanisms of these differences remain unclear. Such differences may arise from true experiential differences but may also result from differences in the evaluation and reporting of pain. The aim of this study is to characterize brain activation during the evaluation/reporting process and to assess its relationship with individual differences in pain sensitivity and other psychological factors that may influence the reports of pain. For this purpose, data of 102 participants (60 males, 42 females, age: 29 ±7.1 years old) enrolled in an ongoing study, were included in the analyses reported here. Participants rated the perceived pain intensity and unpleasantness of 48°C stimuli while whole-brain images were acquired. A General Linear Model analysis (GLM) was performed to investigate changes in brain activation associated with the rating activity. Additional regression analyses were performed to characterize the effect of pain sensitivity, defined as pain intensity and unpleasantness, and possible psychological modulators, such as catastrophizing and mindfulness traits, on changes in brain activation associated with the rating activity. Results of the GLM highlighted increased activation bilaterally in areas, encompassing the sensorimotor cortex, the anterior cingulate cortex, the thalamus, the insula, the putamen, and the parietal lobule, and contralaterally in the frontal pole. In addition, decreased activation was observed bilaterally in the PCC/precuneus and other areas. There was no significant effect of pain sensitivity or psychological modulators on brain activation associated with the rating activity. These results suggest that brain areas previously associated with the perceptive-cognitive dimension of pain are also involved in its evaluative/reporting process. Furthermore, this process is not influenced by pain sensitivity nor by pain modulators, such as catastrophizing or mindfulness traits. Future analyses will focus on highlighting the effect of other nociceptive mechanisms on individual differences.