Functional and structural adaptations following immersive audiovisual training in post-stroke hemianopia: A study of behaviour, DTI, and FC

Homonymous hemianopia (HH) is a common post-stroke visual deficit that affects spatial awareness and visual search. While behavioural improvements have been reported following audiovisual (AV) training, the underlying neural mechanisms remain poorly understood, particularly in relation to structural and functional plasticity within spared tissue. This study investigates whether immersive AV training delivered in virtual reality (VR) induced behavioural, microstructural, and functional connectivity (FC) changes in stroke survivors with HH. Fifteen participants with sub-acute/chronic HH completed 6 weeks of AV training (30 minutes/day, 5 days/week). Behavioural performance was assessed pre- and post-training. Diffusion tensor imaging (DTI) and task-based FC analyses were used to examine training-induced changes in non-lesioned regions, with lesion masking applied during group-level analyses. Training led to significant improvements in reaction time (RT). DTI revealed increased fractional anisotropy (FA; an index of diffusion directionality) and reduced axial diffusivity (AD; diffusivity along the principal fibre axis) in the occipital pole, thalamus, and middle temporal gyrus (MTG). FC analysis indicated enhanced connectivity between the medial visual cortex and occipital and auditory cortices. Structural and functional changes overlapped regionally, suggesting convergent plasticity. Immersive AV training can promote coordinated behavioural and neural changes in stroke survivors with HH. The overlap between plasticity in structurally intact regions and behavioural improvement raises the possibility of compensatory reorganisation, although further work is needed to confirm this mechanism. These findings support the use of multisensory interventions for engaging residual networks in chronic visual field loss.