Pain Enhances Functional Connectivity of a Brain Network Evoked by Performance of a Cognitive Task

1 Institute of Medical Science and 2 Department of Surgery, University of Toronto; and 3 Toronto Western Research Institute, Division of Brain, Imaging and Behaviour-Systems Neuroscience, University Health Network, Toronto, Canada Submitted 16 November 2006; accepted in final form 13 February 2007 Experimental and clinical evidence indicates that pain can affect cognitive processes, but the cortical networks involved in pain-cognition interactions are unclear. In this study, we determined the effect of pain on the activity of cortical areas involved in cognition acting as a whole (i.e., a network). Subjects underwent functional magnetic resonance imaging (fMRI) while engaged in an attention-demanding cognitive task (multisource interference task) of varying difficulty and simultaneously receiving painful stimuli at varying intensities. The control (baseline) condition was simple finger tapping that had minimal cognitive demands and without pain. Functional connectivity analysis revealed a cortical network consisting of two anti-correlated parts: a task-negative part (precuneus/posterior cingulate cortex, medial frontal and inferior parietal/temporal) the activity of which correlated negatively with the cognitive task and positively with the control baseline, and a task-positive part (inferior frontal, superior parietal, premotor, and anterior insula cortices) the activity of which correlated positively with the cognitive task and negatively with the baseline. Independent components analysis revealed these opposing networks were operating at a low frequency (0.03–0.08 Hz). The functional connectivity of the task-positive network was increased by cognitive demand and by pain. We suggest this attention-specific network balances the needs of general self-referential and environmental awareness versus focused attention to salient information. We postulate that pain affects cognitive ability by its reliance on this common attention-specific network. These data provide evidence that pain can modulate a network presumed to be involved in focused attention, suggesting a mechanism for the interference of pain on cognitive ability by the consumption of attentional resources. Address for reprint requests and other correspondence: K. D. Davis, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Room MP14-306, 399 Bathurst St., Toronto, Ontario M5T 2S8, Canada (E-mail: kdavis{at}uhnres.utoronto.ca )