Contributions
Abstract: EP1450
Type: ePoster
Abstract Category: Pathology and pathogenesis of MS - Imaging
Background: The brain is not a static network of functionally connected areas, but displays high levels of flexible connectivity (flexibility), resulting in complex human behavior such as cognition. To date, cognitive decline in MS has often been investigated using static functional network measures, such as resting-state (RS) functional connectivity (FC) analysis. Investigating flexibility of RS networks (e.g. frontoparietal network (PFN) and default mode network (DMN)) or between brain areas (hippocampus-posterior cingulate cortex (PCC)) that are highly relevant for specific cognitive function may provide better understanding of cognitive decline in MS. Currently, stability and robustness of the new measure of flexibility are not sufficiently clear, although essential to know before this novel method can be applied to study cognitive decline in MS.
Aim: To investigate whether RS flexibility is reproducible over a period of 1.5 years in healthy subjects (HS), and to study its relationship with cognition.
Methods: Twenty-two HS (mean age 44.5±9.0 years) underwent neuropsychological testing (extended version of the BRB-N, including tests for verbal, visuospatial, short-term memory, working memory, information processing speed and verbal fluency) and structural and RS functional magnetic resonance imaging on two occasions (mean follow-up time 1.5±0.6 years). Using two different atlases, we obtained time series from brain regions and networks. Pearson correlations between atlas regions were calculated for each RS volume. The standard deviation of each connection was calculated over 43 sliding windows (length 60s, shift 11s) and normalized for its average FC (i.e. coefficient of variation), resulting in individual flexibility matrices of brain regions and networks. Finally, flexibility measures were correlated to cognition.
Results: Whole-brain flexibility was consistent across time points (t=0.43, p=0.68), but did not correlate with overall cognitive functioning. More specifically, flexibility between FPN and DMN did not correlate with working memory or information processing speed. However, flexibility between the hippocampus and PCC correlated with visuospatial memory (Spearman"s ρ=0.55, p=0.01).
Conclusion: RS flexibility is reproducible over time in HS. Higher levels of hippocampus/PCC flexibility were related to better visuospatial memory. Currently, we are applying this novel method to MS, to better understand cognitive decline from a dynamic network perspective.
Disclosure:
Q. van Geest serves as a consultant for Novartis.
H.E. Hulst research support from the Dutch MS Research Foundation, grant number 08-648 and serves as a consultant for Genzyme, Merck-Serono, Teva Pharmaceuticals and Novartis.
J.J.G. Geurts serves on the editorial boards of MS Journal, BMC Neurology, MS International and Neurology and the Scientific Advisory Board of the Dutch MS Research Foundation and of MS Academia, MerckSerono and has served as a consultant for Merck-Serono, Biogen Idec, Novartis, Genzyme and Teva Pharmaceuticals.
L. Douw receives research support from the Dutch Organization for Scientific Research (Rubicon; grant number 825.11.002, Veni; grant number 016.146.086), and a Branco Weiss Fellowship from Society in Science.
Abstract: EP1450
Type: ePoster
Abstract Category: Pathology and pathogenesis of MS - Imaging
Background: The brain is not a static network of functionally connected areas, but displays high levels of flexible connectivity (flexibility), resulting in complex human behavior such as cognition. To date, cognitive decline in MS has often been investigated using static functional network measures, such as resting-state (RS) functional connectivity (FC) analysis. Investigating flexibility of RS networks (e.g. frontoparietal network (PFN) and default mode network (DMN)) or between brain areas (hippocampus-posterior cingulate cortex (PCC)) that are highly relevant for specific cognitive function may provide better understanding of cognitive decline in MS. Currently, stability and robustness of the new measure of flexibility are not sufficiently clear, although essential to know before this novel method can be applied to study cognitive decline in MS.
Aim: To investigate whether RS flexibility is reproducible over a period of 1.5 years in healthy subjects (HS), and to study its relationship with cognition.
Methods: Twenty-two HS (mean age 44.5±9.0 years) underwent neuropsychological testing (extended version of the BRB-N, including tests for verbal, visuospatial, short-term memory, working memory, information processing speed and verbal fluency) and structural and RS functional magnetic resonance imaging on two occasions (mean follow-up time 1.5±0.6 years). Using two different atlases, we obtained time series from brain regions and networks. Pearson correlations between atlas regions were calculated for each RS volume. The standard deviation of each connection was calculated over 43 sliding windows (length 60s, shift 11s) and normalized for its average FC (i.e. coefficient of variation), resulting in individual flexibility matrices of brain regions and networks. Finally, flexibility measures were correlated to cognition.
Results: Whole-brain flexibility was consistent across time points (t=0.43, p=0.68), but did not correlate with overall cognitive functioning. More specifically, flexibility between FPN and DMN did not correlate with working memory or information processing speed. However, flexibility between the hippocampus and PCC correlated with visuospatial memory (Spearman"s ρ=0.55, p=0.01).
Conclusion: RS flexibility is reproducible over time in HS. Higher levels of hippocampus/PCC flexibility were related to better visuospatial memory. Currently, we are applying this novel method to MS, to better understand cognitive decline from a dynamic network perspective.
Disclosure:
Q. van Geest serves as a consultant for Novartis.
H.E. Hulst research support from the Dutch MS Research Foundation, grant number 08-648 and serves as a consultant for Genzyme, Merck-Serono, Teva Pharmaceuticals and Novartis.
J.J.G. Geurts serves on the editorial boards of MS Journal, BMC Neurology, MS International and Neurology and the Scientific Advisory Board of the Dutch MS Research Foundation and of MS Academia, MerckSerono and has served as a consultant for Merck-Serono, Biogen Idec, Novartis, Genzyme and Teva Pharmaceuticals.
L. Douw receives research support from the Dutch Organization for Scientific Research (Rubicon; grant number 825.11.002, Veni; grant number 016.146.086), and a Branco Weiss Fellowship from Society in Science.