Functional Connectivity Within the Dynamic Pain Connectome Underlying Inter-Subject Differences in Acute and Chronic Pain

Pain is an individual experience. Given an identical noxious stimulus, some individuals perceive a high level of pain, whereas others perceive minimal pain. Even when a similar level of pain is experienced, individuals’ response to its perception varies. Some people focus on the pain at the detriment of other tasks-at-hand, whereas other people focus on the task-at-hand as a distraction from pain. These differences across people likely reflect differences in their brain circuitry, specifically in and between networks which are involved with pain processing and coping. Clinically, the degree of abnormality across these networks may underlie the level of pain experienced by chronic pain patients. Thus, this thesis investigated how functional communication between brain networks involved with pain processing and coping, as assessed by static and dynamic measures of resting-state functional connectivity, are related to inter-individual differences in pain perception and coping in healthy individuals and in patients with chronic pain. We found that healthy individuals who had greater central sensitization, had an imbalance towards stronger functional connectivity within their ascending nociceptive compared to descending pain-modulatory pathway. In response to a similar level of pain delivered during the performance of a cognitive task, we also found in healthy individuals that those who have more flexible communication between their salience and executive control networks are better able to prioritize cognitive task-performance in the face of pain. Lastly, the use of a machine learning approach with chronic pain patients revealed that more dynamic engagement of executive control networks was related to milder pain, whereas greater engagement of limbic networks was related to greater pain. Across these connections, patients who had greater pain were more dissimilar compared to healthy individuals. Thus, this thesis provides insight into the differences in dynamics in brain communication that underlie inter-subject differences in acute and chronic pain.Ph.D