Human Pain Seminar Series
This series was borne out of the COVID-19 Global Pandemic, which posed significant challenges to the pain community. Its purpose was to reinforce the message that the we—those who do human pain research—are part of a community.
I put together the #WeAreAllInThisTogether COVID-19 Journal Club. It's an opportunity to connect, to remain intellectually stimulated, to learn, and to keep up with the literature.
It has evolved into a Seminar Series that highlights the work of our community, and allows members of the community at any stage of their career engage with the speakers.
We are supported by the University of Toronto Centre for the Study of Pain.
We meet over Zoom every so often - about every 3 weeks. The specifics, papers, and link to the Zoom will be posted here.
We look forward to seeing you all.
Title: The human insula processes both modality independent and pain-selective learning signals
Dr. Björn Horing, (Büchel Lab), Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Germany
Abstract:Prediction errors (PEs) are generated when there are differences between an expected and an actual event or sensory input. The insula is a key brain region involved in pain processing, and studies have shown that the insula encodes the magnitude of an unexpected outcome (unsigned PEs). In addition to signaling this general magnitude information, PEs can give specific information on the direction of this deviation—i.e., whether an event is better or worse than expected. It is unclear whether the unsigned PE responses in the insula are selective for pain or reflective of a more general processing of aversive events irrespective of modality. It is also unknown whether the insula can process signed PEs at all. Understanding these specific mechanisms has implications for understanding how pain is processed in the brain in both health and in chronic pain conditions. In this study, 47 participants learned associations between 2 conditioned stimuli (CS) with 4 unconditioned stimuli (US; painful heat or loud sound, of one low and one high intensity each) while undergoing functional magnetic resonance imaging (fMRI) and skin conductance response (SCR) measurements. We demonstrate that activation in the anterior insula correlated with unsigned intensity PEs, irrespective of modality, indicating an unspecific aversive surprise signal. Conversely, signed intensity PE signals were modality specific, with signed PEs following pain but not sound located in the dorsal posterior insula, an area implicated in pain intensity processing. Previous studies have identified abnormal insula function and abnormal learning as potential causes of pain chronification. Our findings link these results and suggest that a misrepresentation of learning relevant PEs in the insular cortex may serve as an underlying factor in chronic pain.
Zoom Link: TBD
Title: Dissociation between individual differences in self-reported pain intensity and underlying fMRI brain activation
Presented by: Dr. Robert C. Coghill, Senior Scientist & Director of Research Department of Anesthesiology, Cincinnati Children’s Hospital Cincinnati, Ohio, USA
Abstract: Pain is an individual experience. Previous studies have highlighted changes in brain activation and morphology associated with within- and interindividual pain perception. In this study we sought to characterize brain mechanisms associated with between-individual differences in pain in a sample of healthy adolescent and adult participants (N = 101). Here we show that pain ratings varied widely across individuals and that individuals reported changes in pain evoked by small differences in stimulus intensity in a manner congruent with their pain sensitivity, further supporting the utility of subjective reporting as a measure of the true individual experience. Furthermore, brain activation related to interindividual differences in pain was not detected, despite clear sensitivity of the Blood Oxygenation Level-Dependent (BOLD) signal to small differences in noxious stimulus intensities within individuals. These findings suggest fMRI may not be a useful objective measure to infer reported pain intensity.
Zoom Link: TBD