Community Research and Development Information Service - CORDIS


Perceptual Awareness Report Summary

Project ID: 339939
Funded under: FP7-IDEAS-ERC
Country: Italy

Periodic Report Summary 2 - PERCEPTUAL AWARENESS (Perceptual Awareness in the Reorganizing Brain)

Our project has two aims: i) To study the neural bases of visual perceptual awareness in patients with hemianopia, that is, with loss of vision in one part of the visual field as a result of cortical damage as it happens rather frequently after a stroke, ii) to develop novel rehabilitation procedures for restoring normal vision or improving residual vision in these patients. Our general strategy is to compare the neural cerebral response to visual stimuli presented to the blind portion of the visual field with that of a corresponding portion of the intact field of the same patients as well with that of normally sighted voluntary participants. In particular we focus our attention on a restricted but very interesting group of patients who despite being unable to perceive visual stimuli in their blind field perform above chance in various visual tasks. In other words, when asked to guess about the stimuli presented they report seeing nothing but give the correct response. This phenomenon termed “Blindsight” by Weiskrantz and colleagues in the UK many decades ago is currently widely studied because it enables to assess the neural bases of the shift from unconscious to conscious vision. In the work carried out up until now we have provided new information on the presence of higher-level perceptual processes in the unconscious vision of patients with blindsight such as detection of stimulus numerosity and presence of a structured perceptual organization (known to psychologists as Gestalt principles). Moreover, we have been able to establish that many patients with blindsight rely on information from the intact hemisphere for their above-chance performance. This is a very relevant finding for devising rehabilitation strategies. In other studies we are testing patients with blindsight by means of EEG and functional MRI procedures to establish which cerebral areas are selectively activated during unconscious and conscious vision, respectively. So far, we found that many hemianopic patients with or without blindsight give an electrophysiological response when visual stimuli are presented to the blind field and this is of great help for trying to establish which neural structures might subserve recovery of visual perception. ii) The other aim, which is pursued mainly in the second part of the project, is to provide the basis for a novel rehabilitation method to be applied to hemianopic patients by using visual imagery. The rationale of this procedure derives from the notion that in normally sighted individuals mentally imaging a visual stimulus activates similar cortical areas as when perceiving real stimuli. We believe that this method, by means of training with an appropriate feedback, might help re-activating areas rendered inactive by the cerebral damage and contribute to restore vision either partially or completely.

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