Final Report Summary - PERCEPTUAL AWARENESS (Perceptual Awareness in the Reorganizing Brain)
The general strategy we followed is to carry out neuropsychological testing in conjunction with several non-invasive brain imaging techniques such as Electroencephalography (Event Related Potentials), Structural and Functional Magnetic Resonance Imaging, Functional Near Infrared Spectroscopy. A first achievement is to have established that the intact cerebral hemisphere plays an important role in compensating for the visual impairment caused by damage to the other hemisphere. This encourages to devise rehabilitation techniques aimed at reinforcing the activity of the nervous fibers enabling communcation between the two hemispheres. Secondly, another finding is that visual stimuli, especially when moving, evoke strong neural activity when presented to the blind hemifield not only in the intact but also in some cortical areas in the occipital and parietal lobe of the damaged hemisphere. Unfortunately, this activity may not be sufficient to enable the patient to reach full conscious vision but it might do so with appropriate visual training. At any rate, this is an important finding showing that the cortical machinery for vision is still mostly intact despite blindness. A third achievement concerns the role of visual spatial attention that we found in some patients and in some visual tasks could still be at work by facilitating appropriate behavioural and neural responses despite lack of consciousness. Finally, we found that the residual unconscious vision present in some patients has a perceptual organization broadly similar to that of healthy individuals being sensitive to the configuration and numerosity of the visual stimuli presented to the bind field: In other words, blindsight is unlike a misted windshield. This makes us rather optimistic about a positive outcome of new neurally based rehabilitation techniques suggested by our experimental findings.