Altered Effective Connectivity during a Processing Speed Task in Individuals with Multiple Sclerosis

Dobryakova, Ekaterina; Costa, Silvana L.; Wylie, Glenn R.; DeLuca, John; Genova, Helen M.

doi:10.1017/s1355617715001034

Cited by 14 publications

(15 citation statements)

References 34 publications

(44 reference statements)

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“…Although WM damage or deep GM atrophy were not identified as the most important predictors for IPS in our sample, we did observe that NCGMV could explain up to 26% of variance in IPS outside the scanner. With respect to sFC, we did not observe differences between pwMS and controls, whereas previous studies did show differences in DMN effective and stationary FC at rest and during an IPS task, both related to IPS ( Dobryakova et al, 2016 ; Wojtowicz et al, 2014 ). These contradictory findings might be explained by methodological differences, such as sample size and operationalization of FC.…”

Section: Discussioncontrasting

confidence: 99%

“…The other study investigated the directionality of FC (i.e. effective FC) during IPS, which provides differential information than sFC, and is therefore difficult to compare ( Dobryakova et al, 2016 ). Furthermore, we normalized FC measures for whole-brain average FC, as this average FC can vary greatly between subjects and potentially drive differences between groups, which is not always performed in other studies.…”

Section: Discussionmentioning

confidence: 99%

“…These include white and grey matter damage (e.g. lesions, atrophy and reduced tissue integrity) ( Randolph et al, 2005 ; Mazerolle et al, 2013 ; Batista et al, 2012 ), but also changes in activation and functional connectivity (FC) during an IPS task or during resting-state (RS) ( Genova et al, 2009 ; Dobryakova et al, 2016 ; Wojtowicz et al, 2014 ). Although these measures do explain IPS to a certain extent, there is still room to improve the relationship between brain measures and IPS.…”

Section: Introductionmentioning

confidence: 99%

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Information processing speed in multiple sclerosis: Relevance of default mode network dynamics

Geest

Douw

Klooster

et al. 2018

NeuroImage: Clinical

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ObjectiveTo explore the added value of dynamic functional connectivity (dFC) of the default mode network (DMN) during resting-state (RS), during an information processing speed (IPS) task, and the within-subject difference between these conditions, on top of conventional brain measures in explaining IPS in people with multiple sclerosis (pwMS).MethodsIn 29 pwMS and 18 healthy controls, IPS was assessed with the Letter Digit Substitution Test and Stroop Card I and combined into an IPS-composite score. White matter (WM), grey matter (GM) and lesion volume were measured using 3 T MRI. WM integrity was assessed with diffusion tensor imaging. During RS and task-state fMRI (i.e. symbol digit modalities task, IPS), stationary functional connectivity (sFC; average connectivity over the entire time series) and dFC (variation in connectivity using a sliding window approach) of the DMN was calculated, as well as the difference between both conditions (i.e. task-state minus RS; ΔsFC-DMN and ΔdFC-DMN). Regression analysis was performed to determine the most important predictors for IPS.ResultsCompared to controls, pwMS performed worse on IPS-composite (p = 0.022), had lower GM volume (p < 0.05) and WM integrity (p < 0.001), but no alterations in sFC and dFC at the group level. In pwMS, 52% of variance in IPS-composite could be predicted by cortical volume (β = 0.49, p = 0.01) and ΔdFC-DMN (β = 0.52, p < 0.01). After adding dFC of the DMN to the model, the explained variance in IPS increased with 26% (p < 0.01).ConclusionOn top of conventional brain measures, dFC from RS to task-state explains additional variance in IPS. This highlights the potential importance of the DMN to adapt upon cognitive demands to maintain intact IPS in pwMS.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Information processing speed in multiple sclerosis: Relevance of default mode network dynamics

Geest

Douw

Klooster

et al. 2018

NeuroImage: Clinical

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“…Nevertheless, studies in MS samples have reported a decline in gait performance in response to adding a cognitive load vs. walking alone (Sosnoff et al, 2011; Doi et al, 2013; Learmonth et al, 2014; Downer et al, 2016). Indeed, such declines might be a product of cognitive problems associated with MS (Diamond et al, 1997; DeLuca et al, 2004a,b; Beckmann et al, 2005; Lengenfelder et al, 2006; Dobryakova et al, 2016), given that successful dual-tasking requires divided attention and the ability to process information simultaneously from multiple internal or external sources. Yet, there is equivocal evidence regarding the association between the dual-task cost of walking (DTCW; i.e., the reduction in walking performance under single- vs. dual-task conditions) and cognition in MS (Motl et al, 2014; Sosnoff et al, 2014; Kirkland et al, 2015; Sandroff et al, 2015a).…”

Section: Introductionmentioning

confidence: 99%

The Role of Premotor Areas in Dual Tasking in Healthy Controls and Persons With Multiple Sclerosis: An fNIRS Imaging Study

Saleh

Sandroff

Vitiello

et al. 2018

Front. Behav. Neurosci.

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Persons with multiple sclerosis (pwMS) experience declines in physical and cognitive abilities and are challenged by dual-tasks. Dual-tasking causes a drop in performance, or what is known as dual-task cost (DTC). This study examined DTC of walking speed (WS) and cognitive performance (CP) in pwMS and healthy controls (HCs) and the effect of dual-tasking on cortical activation of bilateral premotor cortices (PMC) and bilateral supplementary motor area (SMA). Fourteen pwMS and 14 HCs performed three experimental tasks: (1) single cognitive task while standing (SingCog); (2) single walking task (SingWalk); and (3) dual-task (DualT) that included concurrent performance of the SingCog and SingWalk. Six trials were collected for each condition and included measures of cortical activation, WS and CP. WS of pwMS was significantly lower than HC, but neuropsychological (NP) measures were not significantly different. pwMS and HC groups had similar DTC of WS, while DTC of CP was only significant in the MS group; processing speed and visual memory predicted 55% of this DTC. DualT vs. SingWalk recruited more right-PMC activation only in HCs and was associated with better processing speed. DualT vs. SingCog recruited more right-PMC activation and bilateral-SMA activation in both HC and pwMS. Lower baseline WS and worse processing speed measures in pwMS predicted higher recruitment of right-SMA (rSMA) activation suggesting maladaptive recruitment. Lack of significant difference in NP measures between groups does not rule out the influence of cognitive factors on dual-tasking performance and cortical activations in pwMS, which might have a negative impact on quality of life.

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“…Both tests have been recommended as the standardized tools for cognitive assessment in MS (19) and have been adapted to task-driven fMRI research. Studies have investigated effective functional connectivity among the test-specific regions and shown that information flow between two hemispheres is required for both SDMT and PASAT performance (20,21).…”

Section: Introductionmentioning

confidence: 99%

Both Stationary and Dynamic Functional Interhemispheric Connectivity Are Strongly Associated With Performance on Cognitive Tests in Multiple Sclerosis

et al. 2020

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Although functional connectivity has been extensively studied in MS, robust estimates of both stationary (static connectivity at the time) and dynamic (connectivity variation across time) functional connectivity has not been commonly evaluated and neither has its association to cognition. In this study, we focused on interhemispheric connections as previous research has shown links between anatomical homologous connections and cognition. We examined functional interhemispheric connectivity (IC) in MS during resting-state functional MRI using both stationary and dynamic strategies and related connectivity measures to processing speed performance. Twenty-five patients with relapsing-remitting MS and 41 controls were recruited. Stationary functional IC was assessed between homologous Regions of Interest (ROIs) using correlation. For dynamic IC, a sliding window approach was used to quantify changes between homologous ROIs across time. We related IC measures to cognitive performance with correlation and regression. Compared to control subjects, MS demonstrated increased IC across homologous regions, which accurately predicted performance on the symbol digit modalities test (SDMT) (R 2 = 0.96) and paced auditory serial addition test (PASAT) (R 2 = 0.59). Dynamic measures were not different between the 2 groups, but dynamic IC was related to PASAT scores. The associations between stationary/dynamic connectivity and cognitive tests demonstrated that different aspects of functional IC were associated with cognitive processes. Processing speed measured in SDMT was associated with static interhemispheric connections and better PASAT performance, which requires working memory, sustain attention, and processing speed, was more related to rigid IC, underlining the neurophysiological mechanism of cognition in MS.

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Altered Effective Connectivity during a Processing Speed Task in Individuals with Multiple Sclerosis

Abstract: Effective connectivity results reveal that MS individuals with processing speed impairment not only have connections that differ from healthy participants and MS individuals without processing speed impairment, but also have increased strengths of connections.

Cited by 14 publications

References 34 publications

Information processing speed in multiple sclerosis: Relevance of default mode network dynamics

Information processing speed in multiple sclerosis: Relevance of default mode network dynamics

The Role of Premotor Areas in Dual Tasking in Healthy Controls and Persons With Multiple Sclerosis: An fNIRS Imaging Study

Both Stationary and Dynamic Functional Interhemispheric Connectivity Are Strongly Associated With Performance on Cognitive Tests in Multiple Sclerosis

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