Altered directional functional connectivity underlies post-stroke cognitive recovery.

Area of Science:

• Neuroscience
• Cognitive Neurology
• Systems Neuroscience

Background:

• Cortical and subcortical ischaemic strokes can lead to cognitive deficits, including attention and processing speed impairments.
• These deficits may stem from generalized disruption of cognitive networks, irrespective of lesion location.
• Longitudinal studies on functional connectivity changes post-stroke are limited.

Purpose of the Study:

• To investigate longitudinal changes in directional functional connectivity after minor stroke.
• To correlate these connectivity changes with cognitive recovery.
• To understand the neural basis of early post-stroke cognitive dysfunction at the network level.

Main Methods:

• Evaluated six patients with minor stroke and cognitive impairment, alongside four controls.
• Collected resting-state magnetoencephalography (MEG) data at multiple time points (6-8 weeks, 6 months, 12 months post-infarct).
• Utilized Network Localized Granger Causality to analyze directional connectivity and correlated findings with clinical performance.

Main Results:

• Stroke patients showed increased inter-hemispheric connectivity between frontoparietal and non-frontoparietal cortices, correlating with improved cognitive scores and reaction times.
• Initial functional links post-stroke shifted from contralateral to ipsilesional brain regions, with a subsequent increase in ipsilesional to contralesional directed connections.
• Patients with continued cognitive recovery demonstrated reduced reliance on inter-hemispheric connections by the final visit.

Conclusions:

• Early post-stroke cognitive dysfunction is rooted in network-level disruptions.
• The evolution of inter-hemispheric connectivity is a key neural mechanism underlying cognitive recovery after stroke.
• Functional connectivity patterns stabilize in healthy individuals but dynamically change in stroke survivors during recovery.