Network analysis detects changes in the contralesional hemisphere following stroke

Area of Science:

• Neuroscience
• Medical Imaging
• Network Science

Background:

• Focal brain damage, like stroke, causes structural changes in remote brain regions.
• These structural changes can disrupt information processing across widespread neural networks.

Purpose of the Study:

• To investigate alterations in brain network connectivity following stroke using diffusion MRI and network analysis.
• To quantify changes in information flow ('communicability') between brain regions in stroke patients compared to controls.

Main Methods:

• Diffusion MRI tractography was used to map white matter pathways in 9 chronic stroke patients and 18 controls.
• Complex network analysis, specifically 'communicability', was applied to assess information travel ease across brain networks.
• Clustering analysis was performed based on communicability scores to differentiate patients and controls.

Main Results:

• Patients and controls were distinguished by communicability patterns in both lesioned and contralesional hemispheres.
• Reduced communicability was observed in stroke patients in regions adjacent to the lesion and in homologous contralesional areas.
• Increased communicability was noted in specific brain regions, suggesting potential adaptive plasticity.

Conclusions:

• Secondary degeneration of interconnected fiber pathways occurs even in remote, structurally intact brain regions post-stroke.
• Network analysis effectively detects subtle, widespread functional network alterations following stroke.
• Findings highlight the utility of network science in understanding stroke-induced brain changes and potential recovery mechanisms.