The impact of ischemic stroke on connectivity gradients

Şeyma Bayrak, Ahmed A. Khalil, Kersten Villringer, Jochen B. Fiebach, Arno Villringer, Daniel S. Margulies, Smadar Ovadia-Caro

Research output: Contribution to journalArticlepeer-review

Abstract

The functional organization of the brain can be represented as a low-dimensional space that reflects its macroscale hierarchy. The dimensions of this space, described as connectivity gradients, capture the similarity of areas' connections along a continuous space. Studying how pathological perturbations with known effects on functional connectivity affect these connectivity gradients provides support for their biological relevance. Previous work has shown that localized lesions cause widespread functional connectivity alterations in structurally intact areas, affecting a network of interconnected regions. By using acute stroke as a model of the effects of focal lesions on the connectome, we apply the connectivity gradient framework to depict how functional reorganization occurs throughout the brain, unrestricted by traditional definitions of functional network boundaries. We define a three-dimensional connectivity space template based on functional connectivity data from healthy controls. By projecting lesion locations into this space, we demonstrate that ischemic strokes result in dimension-specific alterations in functional connectivity over the first week after symptom onset. Specifically, changes in functional connectivity were captured along connectivity Gradients 1 and 3. The degree of functional connectivity change was associated with the distance from the lesion along these connectivity gradients (a measure of functional similarity) regardless of the anatomical distance from the lesion. Together, these results provide support for the biological validity of connectivity gradients and suggest a novel framework to characterize connectivity alterations after stroke.

Original languageEnglish
Article number101947
JournalNeuroImage: Clinical
Volume24
DOIs
StatePublished - 2019
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by the German Federal Ministry of Education and Research via the grant center for Stroke Research Berlin ( 01EO0801 and 01EO01301 ), the European Union Seventh Framework Program [FP7/2007–2013] under grant agreement no. 278276 (WAKE-UP) for J.B.F, and the Einstein Foundation Berlin (Grant No. EDP-2016-318 ) for S.O.C.

Funding Information:
This work was supported by the German Federal Ministry of Education and Research via the grant center for Stroke Research Berlin (01EO0801 and 01EO01301), the European Union Seventh Framework Program [FP7/2007?2013] under grant agreement no. 278276 (WAKE-UP) for J.B.F, and the Einstein Foundation Berlin (Grant No. EDP-2016-318) for S.O.C. The authors would like to thank the patients for participating in the study, and to Dr. Julia Huntenburg, Dr. Luke Tudge and Sabine Oligschl?ger for their advice in various stages of this project.

Publisher Copyright:
© 2019 The Authors

Keywords

  • Connectivity gradients
  • Connectome
  • Diaschisis
  • Diffusion embedding
  • Intrinsic functional connectivity
  • Resting-state fMRI

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Neurology
  • Clinical Neurology
  • Cognitive Neuroscience

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