Abstract
Functional neuroimaging techniques have provided great insight in the field of pain. Utilising these techniques, we have characterised pain-induced responses in the brain and improved our understanding of key pain-related phenomena. Despite the utility of these methods, there remains a need to assess the test retest reliability of pain modulated blood-oxygen-level-dependant (BOLD) MR signal across repeated sessions. This is especially the case for more novel yet increasingly implemented stimulation modalities, such as noxious pressure, and it is acutely important for multi-session studies considering treatment efficacy. In the present investigation, BOLD signal responses were estimated for noxious-pressure stimulation in a group of healthy participants, across two separate sessions. Test retest reliability of functional magnetic resonance imaging (fMRI) data and self-reported visual analogue scale measures were determined by the intra-class correlation coefficient. High levels of reliability were observed in several key brain regions known to underpin the pain experience, including in the thalamus, insula, somatosensory cortices, and inferior frontal regions, alongside “excellent” reliability of self-reported pain measures. These data demonstrate that BOLD-fMRI derived signals are a valuable tool for quantifying noxious responses pertaining to pressure stimulation. We further recommend the implementation of pressure as a stimulation modality in experimental applications.
Highlights
Since the advent of functional magnetic resonance imaging, our understanding of the neural basis of nociceptive input has substantially increased (Apkarian et al, 2005; Tracey and Mantyh, 2007)
We examined the reliability of acute noxious pressure, a commonly implemented, but previously unassessed stimulation modality
The reliability of the behavioural data was “excellent”, replicating previous findings of high reliability across behavioural measures (e.g. Bijur et al, 2001). These data inform our understanding on the nature of paininduced BOLD signal establishing that pressure stimulation produces robust and reliable evoked-activation
Summary
Since the advent of functional magnetic resonance imaging (fMRI), our understanding of the neural basis of nociceptive input has substantially increased (Apkarian et al, 2005; Tracey and Mantyh, 2007). The relationship between noxious input and pain perception has been extensively studied Becerra et al, 2001; Becerra et al, 2004; Borsook et al, 2008; Brooks et al, 2005; Craig et al, 2000; Tracey et al, 2002) Other modalities, such as noxious pressure, have not been as extensively applied (Apkarian et al, 2005) but are becoming more frequent, in clinical applications The robustness of the applied methodology, and its ability to effectively characterise pain responses in the human brain, requires further investi-
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