Key result
Inter-run synchronization fMRI analysis detects widespread brain activations underestimated by traditional GLM.
Why the study?
Traditional fMRI analysis using the general linear model may under-detect brain areas involved in pain processing that do not present a canonical hemodynamic response function.
Inter-run synchronization analysis of fMRI data reveals additional brain regions involved in pain processing that are missed by traditional GLM analysis due to non-canonical hemodynamic responses.
Traditional GLM analysis may miss non-canonical pain responses; leaves open whether refined models enhance detection in future studies.
Pain is a complex experience that is thought to emerge from the activity of multiple brain areas, some of which are inconsistently detected using traditional fMRI analysis. One hypothesis is that the traditional analysis of pain-related cerebral responses, by relying on the correlation of a predictor and the canonical hemodynamic response function (HRF)- the general linear model (GLM)- may under-detect the activity of those areas involved in stimulus processing that do not present a canonical HRF. In this study, we employed an innovative data-driven processing approach- an inter-run synchronization (IRS) analysis- that has the advantage of not establishing any pre-determined predictor definition. With this method we were able to evidence the involvement of several brain regions that are not usually found when using predictor-based analysis. These areas are synchronized during the administration of mechanical punctate stimuli and are characterized by a BOLD response different from the canonical HRF. This finding opens to new approaches in the study of pain imaging.
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Cauda et al. (2014) studied Healthy volunteers (Pain processing) (n=29). Inter-run synchronization (IRS) fMRI analysis vs. General Linear Model (GLM) fMRI analysis was evaluated on Detection of brain areas activated by mechanical nociceptive stimulation. Inter-run synchronization analysis of fMRI data during mechanical nociceptive stimulation identified widespread brain activations, including in prefrontal, premotor, and basal ganglia regions, that were underestimated by traditional general linear model analysis.