Electrophysiological effects of a multisensory training for hemianopia on spatial attention

Multisensory (i.e., audio-visual) stimulation of the hemianopic visual field improves visual detection and visual search performance. Here we present evidence that this improvement co-occurs with a shift of spatial attention away from the intact field, suggesting a reduction in hyperactivation in the intact hemisphere. Seven hemianopia patients underwent a two-week course of multisensory treatment (Bolognini et al, 2005); stimulation effects were indexed by collecting behavioural and electrophysiological data, before and after the treatment. Stimulation drove behavioural oculomotor improvements, but also reduced amplitudes of P3 event related potentials elicited by stimuli in the intact visual field, during a simple visual detection paradigm. Results suggest the mechanism underlying the recovery of visual function after multisensory stimulation at least in part involves a rebalancing of activation between the lesioned and intact hemispheres.