[The cerebral substrate of visual consciousness: a neurological approach]

Since the last thirty Years, scientific study of the cerebral substrate of consciousness has been marked by significant achievements, resulting in part from a rich interaction between the exploration of cognition in both brain-damaged patients and healthy subjects. Several neuropsychological syndromes contain spectacular dissociations which permit to identify principles related to the neurophysiology of consciousness. The generality of those principles can then be evaluated in the healthy subject using the combination of experimental psychology paradigms, and functional brain-imaging tools. In this paper, we review some of the recent results relevant to visual phenomenal consciousness, which is the most scientifically investigated aspect of consciousness. We isolate several of those general principles through the exploration of neuropsychological syndromes such as "blindsight", visual agnosias and neglect, and expose how their generality has been demonstrated in the healthy subject using conditions such as visual illusions or subliminal perception. Finally, we describe the bases of a scientific model of consciousness, based on the concept of a "global workspace", which takes into account the data reviewed.