Some effects of cortical and callosal damage on conscious and unconscious processing of visual information and other sensory inputs.

Although new methods of investigation from the molecular level to cognition are promoting major advances in the study of the functions of the human brain, the analysis of behavioral and psychological deficits following brain damage is still a major tool for the understanding of cerebral organization. The present paper reviews some aspects of work on functional losses and residual abilities following cortical damage that have allowed to distinguish conscious and unconscious levels of visual input processing. Attention is given to the possible contribution of residual conscious vision of color to unconscious form analysis in visual agnosia. The paper also reviews findings on temporary and permanent deficits that occur after selective lesions of a prominent input-output system of the cerebral cortex, the corpus callosum, with the aim of assessing the possibility of establishing a functional callosal topography.