Magdalena Wojtowicz1, Erin L Mazerolle2, Virender Bhan3, John D Fisk4. 1. Department of Psychology and Neuroscience, Dalhousie University, Canada. 2. McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Canada. 3. Department of Medicine, Dalhousie University, Canada. 4. Department of Psychology and Neuroscience, Dalhousie University, Canada Department of Medicine, Dalhousie University, Canada Psychology, QEII Health Sciences Centre, Canada Department of Psychiatry, Dalhousie University, Canada john.fisk@cdha.nshealth.ca.
Abstract
BACKGROUND: Patients with multiple sclerosis (MS) demonstrate slower and more variable performance on attention and information processing speed tasks. Greater variability in cognitive task performance has been shown to be an important predictor of neurologic status and provides a unique measure of cognitive performance in MS patients. OBJECTIVES: This study investigated alterations in resting-state functional connectivity associated with within-person performance variability in MS patients. METHODS: Relapsing-remitting MS patients and matched healthy controls completed structural MRI and resting-state fMRI (rsfMRI) scans, as well as tests of information processing speed. Performance variability was calculated from reaction time tests of processing speed. rsfMRI connectivity was investigated within regions associated with the default mode network (DMN). Relations between performance variability and functional connectivity in the DMN within MS patients were evaluated. RESULTS: MS patients demonstrated greater reaction time performance variability compared to healthy controls (p<0.05). For MS patients, more stable performance on a complex processing speed task was associated with greater resting-state connectivity between the ventral medial prefrontal cortex and the frontal pole. CONCLUSIONS: Among MS patients, greater functional connectivity between medial prefrontal and frontal pole regions appears to facilitate performance stability on complex speed-dependent information processing tasks.
BACKGROUND:Patients with multiple sclerosis (MS) demonstrate slower and more variable performance on attention and information processing speed tasks. Greater variability in cognitive task performance has been shown to be an important predictor of neurologic status and provides a unique measure of cognitive performance in MSpatients. OBJECTIVES: This study investigated alterations in resting-state functional connectivity associated with within-person performance variability in MSpatients. METHODS: Relapsing-remitting MSpatients and matched healthy controls completed structural MRI and resting-state fMRI (rsfMRI) scans, as well as tests of information processing speed. Performance variability was calculated from reaction time tests of processing speed. rsfMRI connectivity was investigated within regions associated with the default mode network (DMN). Relations between performance variability and functional connectivity in the DMN within MSpatients were evaluated. RESULTS:MSpatients demonstrated greater reaction time performance variability compared to healthy controls (p<0.05). For MSpatients, more stable performance on a complex processing speed task was associated with greater resting-state connectivity between the ventral medial prefrontal cortex and the frontal pole. CONCLUSIONS: Among MSpatients, greater functional connectivity between medial prefrontal and frontal pole regions appears to facilitate performance stability on complex speed-dependent information processing tasks.
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