New light from the dark: what blindness can teach us about brain function.

PURPOSE OF REVIEW In this review, we discuss findings from some recent brain imaging studies that shed new light on our understanding of the role of visual experience on the development of the brain morphological and functional architecture in humans. To what extent is vision truly necessary to 'see' the world around us? RECENT FINDINGS Congenitally blind and sighted individuals present analogous cognitive and social performances. Findings from structural and functional brain studies in both sighted and congenitally blind individuals have shown the existence of supramodal brain regions able to process external information regardless of the sensory modality through which such an information has been acquired. This more abstract nature of functional cortical organization may enable congenitally blind individuals to acquire knowledge, form mental representations of and interact effectively with an external world that they have never seen. SUMMARY Altogether, findings from both behavioural and imaging studies indicate that the brain functional organization is to a large extent independent from visual experience and able to process information in a supramodal fashion. The study of the blind brain is a very powerful approach to understanding not only the cross-modal plastic, adaptative modifications that occur in the 'visual' regions but primarily the functional architecture of the human brain itself.