Disrupted resting-state EEG alpha-band interactions as a novel marker for the severity of visual field deficits after brain lesion

Objective: Homonymous visual field deficits (HFVDs) are frequent following brain lesions. Current restoration treatments aim at activating areas of residual vision through numerous stimuli, but show limited effect. Recent findings suggest that spontaneous neural alpha-band coupling is more efficient for enabling visual perception in healthy humans than task-induced activations. Here, we evaluated whether it is also associated with the severity of HFVD. Methods: Ten patients with HFVDs after brain damage in the subacute to chronic stage and ten matched healthy controls underwent visual stimulation with alternating checkerboards and electroencephalography recordings of stimulation-induced power changes and of spontaneous neural interactions during rest. Results: Visual areas of the affected hemisphere showed reduced event-related power decrease in alpha and beta frequency bands, but also reduced spontaneous alpha-band interactions during rest, as compared to contralesional areas and healthy controls. A multivariate stepwise regression retained the degree of disruption of spontaneous interactions, but not the reduced task-induced power changes as predictor for the severity of the visual deficit. Conclusions: Spontaneous alpha-band interactions of visual areas appear as a better marker for the severity of HFVDs than task-induced activations. Significance: Treatment attempts of HFVDs should try to enhance spontaneous alpha-band coupling of structurally intact ipsilesional areas. (C) 2021 International Federation of Clinical Neurophysiology. Published by Elsevier B.V.