Default brain functionality in blind people.
We studied whether default functionality of the human brain, as revealed by task-independent decreases in activity occurring during goal-directed behaviors, is functionally reorganized by blindness. Three groups of otherwise normal adults were studied: early blind, adventitiously blind, and normally sighted. They were imaged by using functional MRI during performance of a word association task (verb generation to nouns) administered by using auditory stimuli in all groups and Braille reading in blind participants. In sighted people, this task normally produces robust task-independent decreases relative to a baseline of quiet wakefulness with eyes closed. Our functional MRI results indicate that task-independent decreases are qualitatively similar across all participant groups in medial and dorsal prefrontal, lateral parietal, anterior precuneus, and posterior cingulate cortices. Similarities in task-independent decreases are consistent with the hypothesis that functional reorganization resulting from the absence of a particular sensory modality does not qualitatively affect default functionality as revealed by task-independent decreases. More generally, these results support the notion that the brain largely operates intrinsically, with sensory information modulating rather than determining system operations.
Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA. harold@touch.wustl.edu
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H
Burton
A Z
AZ
Snyder
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ME
Raichle
D001766:Blindness / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging