The occipital cortex in the blind: Lessons about plasticity and vision

ABSTRACT—Studying the brains of blind individuals pro-vides a unique opportunity to investigate how the brain changes and adapts in response to afferent (input) and efferent (output) demands. We discuss evidence suggesting that regions of the brain normally associated with the processing of visual information undergo remarkable dy-namic change in response to blindness. These neuroplastic changes implicate not only processing carried out by the remaining senses but also higher cognitive functions such as language and memory. A strong emphasis is placed on evidence obtained from advanced neuroimaging tech-niques that allow researchers to identify areas of human brain activity, as well as from lesion approaches (both reversible and irreversible) to address the functional relevance and role of these activated areas. A possible mechanism and conceptual framework for these physio-logical and behavioral changes is proposed. KEYWORDS—plasticity; visual cortex; blindness; Braille reading; verbal memory Conventional wisdom in neuroscience dictates that the brain possesses only limited capacity to reorganize itself following damage (e.g. from sensory loss or brain injury). However, more recent evidence demonstrates that the brain is capable of re-markable dynamic change and adaptation throughout the life-span. Studying individuals who are peripherally blind (e.g., from eye disease or injury) or using experimental visual deprivation (e.g., prolonged blindfolding) allow researchers to investigate adaptive brain changes and behavioral consequences in re-sponse to changes in sensory input. Lessons learned from how the brain adapts to blindness are likely to apply to other situa-tions (e.g., damage to the inner ear) and will provide novel in-sights for the development of rehabilitative and educational strategies and the advance of sensory substitution and restora