Electroencephalographic index of spatial attention shift following multisensory stimulation training for hemianopia N Dundon1, M E Maier2, C Bertini1, E Ladavas1 |
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1Centro Studi e Ricerche in Neuroscienze Cognitive, University of Bologna, Italy |
| Hemianopia is a homonymous visual field deficit, resulting from posterior cortical lesion, which can contribute towards inefficient eye-saccades in the hemianopic visual field. Here we present evidence that this inefficient eye movement behaviour may be at least in part a function of post-lesion hyperactivation of the intact hemisphere, with concurrent hypoactivation of the damaged hemisphere; i.e., patients focus their attention on the ipsilesional field and the contralesional field lacks sufficient attentional resources. In the present data, we observed that by stimulating the collicular-extrastriate pathway (known to contribute to spatial orienting behaviours) with a multi-sensory training paradigm, visual oculomotor exploration improved in a sample of seven hemianopia patients; this improvement allowed patients to compensate for the loss of vision with more efficient eye saccades. In addition, amplitudes of P3 event related potentials elicited by a simple visual detection paradigm were significantly reduced after the treatment when the stimuli were presented to the intact field. One interpretation of the behavioural improvement in the hemianopic field, and concurrent ERP amplitude reduction in the intact field, might be a shift in spatial attention away from the hyperactivated intact visual field. |
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