Assessing Cortical Excitability and Functional Network in Post-Stroke Unilateral Neglect: A Transcranial Magnetic Stimulation- Electroencephalography Investigation.

Objective: Unilateral neglect (UN) is a common post-stroke condition, yet its underlying pathological mechanisms are not fully elucidated. This study aims to explore cortical function and brain network connectivity in patients with UN by employing transcranial magnetic stimulation-electroencephalography (TMS-EEG).

Methods: The study involved three groups: 10 healthy controls, 10 patients with UN, and 10 stroke patients without UN. TMS was applied to the P4 site, and the resulting EEG responses were recorded and analysed.

Results: UN patients demonstrated significant alterations in the N100 (p <0.05) and cortical excitability amplitude (CEA) between 25-275 ms (p <0.05). Time-frequency analysis further revealed a marked increase in theta-band activity in the parietal region of UN patients. Source localisation analysis indicated that, in later stages, neural signal propagation was predominantly confined to the parietal region. Time-varying EEG network analysis revealed that, during the early stages, patients with UN exhibited enhanced interhemispheric frontal connectivity, coupled with a reduction in connectivity between the affected parietal lobe and the contralateral frontal lobe. In the later stages, a notable decrease in parieto-occipital connectivity was observed, alongside increased connectivity within the frontal and parietal regions of both hemispheres, suggesting a widespread functional reorganisation of brain networks.

Conclusion: UN patients exhibit diminished cortical excitability in the affected parietal cortex, coupled with altered brain network connectivity and increases in connectivity within specific regions. These findings suggest that the brain engages in functional compensation and network reorganisation to mitigate the neurological deficits induced by stroke.