MODULATORY CAPACITY · Modulatory capacity: Understanding individual differences in the relationship between sensory input and pain perception

Pain serves a critical function, warning the organism of danger and potential injury. While it is often related to the level of sensory input, this relationship is not linear. The relationship between sensory input and pain can be modulated by the central nervous system based on various sensory, cognitive and affective factors. Individual differences in the capacity to modulate pain centrally have been associated with chronic pain symptoms as well as the onset of chronic pain following surgery (Arendt-Nielsen & Yarnitsky, 2009). What is suggested is that the ability to modulate the relationship between sensory input and pain perception (hereafter referred to as “modulatory capacity”) may be a stable, trait-like and clinically relevant individual difference variable that underlies the ability to dynamically and adaptively adjust pain based on the immediate context.The goal of the research proposed here is to find reliable markers of modulatory capacity at the level of the brain using in vivo neuroimaging techniques. In collaboration with Dr. Tom Johnstone (the scientist supervising the project) I have developed a parametric technique for analyzing how the brain instantiates the perceptual transition from innocuous to painful levels of sensory input (Johnstone et al, 2012). We were able to predict the non-linear transition from innocuous to painful perception with high accuracy based on activation in regions such as the periaqueductal gray that have previously been implicated in central modulation of pain.The research proposed here, to be performed at the University of Reading, aims to find clinically applicable biomarkers for modulatory capacity. Towards this goal I aim to examine the intra-individual stability of the relationship between sensory input, brain activation and pain perception and whether behavioral markers of central modulation can predict how these relationships change under various physical and psychological challenges.