Exercising the Brain in Pain -using Fmri to Investigate Intrinsic Connectivity, Cognition and Pain Regulation in Fibromyalgia and How This Is Affected by Physical Exercise
Year: 2015
Type: dissertation
Abstract: The aims of the studies of this thesis were to use functional magnetic resonance imaging (fMRI) to \ninvestigate cerebral activation patterns in fibromyalgia (FM) patients and healthy controls (HC) at \nrest, when performing the stroop colour word test (SCWT) and during pressure pain provocation. \nDistraction induced analgesia (DIA), performance on the SCWT and pressure pain sensitivity was \ninvestigated on the behavioural and psychophysical level. Lastly studies III and IV investigated the \neffects of a 15-week resistance exercise training intervention on SCWT and pain processing. \n \n \n \nThe main finding in study I was that FM was associated with decreased connectivity between pain \nrelated and sensorimotor brain areas, more specifically between insula and primary sensorimotor \nareas (S1/M1). Furthermore increased pain sensitivity in both groups correlated to increased \nconnectivity between the insula and thalamus with the default mode network (DMN). \n \n \n \nStudy II utilised the SCWT were participants are given colour words written in either congruent or \nincongruent colours. To induce DIA, participants were given two versions of the test, one with \ncongruent words and one with incongruent words, this in order to investigate the impact of \ncognitive load on pain perception. In the scanner, the stimuli were mixed and presented in an eventrelated fMRI paradigm. The study revealed that DIA functioned the same in FM as it did in HC, and \nanalgesia was not dependant on cognitive load. Performance on the SCWT showed that both groups \nwere slower on the more cognitively demanding task, but interference disrupted performance more \nin the FM group than in the HC. The fMRI results yielded less activation of the caudate nucleus and \nhippocampus during SCWT in FM patients. These regions are implicated in learning and reward, \nsuggesting that impaired learning mechanisms can contribute to the cognitive dysfunction often \nreported by FM patients. \n \n \n \nIn study III, the SCWT assessments were repeated following the physical exercise intervention. \nPerformance on the SCWT was improved in both groups, in the HC speed of processing had \nimproved significantly, but a specific improvement of cognitive ability was only found in the FM \npatients. The latter was accompanied by an increased activation of the amygdala following the \nintervention in the FM group. Regarding DIA, no effects of exercise were found. \n \n \n \nLastly, in study IV fMRI was used to assess pressure pain processing in FM patients and HC before \nand following the exercise intervention. FM patients were more pain sensitive than HC at both \ntimes, but following the intervention pressure pain sensitivity was significantly reduced in the FM \ngroup. We found no evidence that the exercise intervention had an effect on cerebral processing of \nevoked pain in either group. Our data suggest that the reduced pain sensitivity following exercise in \nFM patients was caused by peripheral mechanisms. \n \n \n \nTaken together the results of the four studies all demonstrated aberrations in cerebral activation in \nFM patients compared to controls, as well as poorer cognitive performance and increased pain \nsensitivity. However, interestingly, normal function of DIA was found in FM patients. Studies three \nand four showed that physical exercise was beneficial to FM patients, both regarding cognitive \nability and by reducing pain sensitivity.
Source: Figshare
Author: Sofia Martinsen
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W1450847218