Functional Magnetic Resonance Imaging analysis of the Central Nervous System response to pain

Background: Different methods of pain relief are used worldwide, with a variable efficacy intrinsic to the individual behavioural response to pain, which is mediated by the Central Nervous System (CNS). This efficacy is also difficult to measure and compare. Subjective pain ratings alone are often used with this purpose, but they prove to be rather unsatisfying in the evaluation of the central pain circuitry. As functional magnetic resonance imaging (fMRI) can be used to objectively appraise the central pain circuitries, we will use it to evaluate healthy volunteers under noxious stimuli and without it. In this context, we aim to develop a device that is compatible with magnetic resonance imaging (MRI) and can elicit pain, in order to compare the fMRI findings with the results of the analogue pain scale. Objectives: We intend to: (1) Develop a device that is both compatible with the functional magnetic resonance imaging and adequate to the designed paradigm; (2) Determine if we can obtain images compatible with the pain areas described in the literature (3) Assess if we can relate the analogue pain scale ratings to the functional magnetic resonance imaging results; Methods: Three healthy volunteers participated in the study (2 males, 1 female, mean age =23.77; standard deviation=0,557). Prior to the scan, subjects were given instructions on how to rate their pain using a numerical analogue scale (NAS), consisting of a pain scale ranging from 0 to 10, asked during the procedure. A magnetic resonance imaging for structural and functional purposes was performed in all subjects. Results: The single and group level analysis revealed blood-oxygen-level-dependent contrast (BOLD) activations consistent with the brain pain-matrix. The group-level analysis revealed the highest activations in the insular cortex, anterior cingulate cortex, dorsolateral prefrontal cortex, frontal cortex, primary and secondary somatosensory cortex.