Mapping Brain Function After Stroke: From Early Disorganization to Late Compensation.

Area of Science:

• Neuroscience
• Clinical Neurology
• Biomarkers

Background:

• Electroencephalography (EEG) is valuable for assessing brain function post-stroke.
• The relationship between EEG changes, time since stroke, and functional deficits requires further clarification.

Purpose of the Study:

• To investigate how cortical power and functional connectivity change over time after stroke.
• To determine the association between EEG measures, stroke duration, and motor deficit severity.

Main Methods:

• A cross-sectional study involving 100 stroke patients and 45 healthy controls.
• Dense-array (256-lead) resting-state EEG was used to record cortical power and coherence.
• Analyses included subgroups based on time post-stroke and motor status (Fugl-Meyer score), employing permutation tests and partial Spearman's correlations.

Main Results:

• Early post-stroke, EEG showed supranormal low-frequency power and subnormal high-frequency power, with widespread subnormal connectivity.
• Over time, beta and gamma connectivity increased, and overall brain connectivity became supranormal in the late phase.
• Motor status correlated with cortical power in specific patient groups and with connectivity in a manner dependent on deficit severity and lesion location.

Conclusions:

• EEG measures show promise as biomarkers for brain reorganization post-stroke.
• Understanding EEG requires consideration of time post-stroke, deficit severity, and lesion location for personalized rehabilitation strategies.
• Network connectivity is crucial for understanding motor deficits, emphasizing context-specific interpretation of EEG biomarkers.