By Eye² Staff
A "sonar vision" system that enables people who are blind from birth to perceive the shape of a face, a house or even words and letters, is being developed by a team at the Hebrew University of Jerusalem, according to
CEA, a French government-funded technological research organization. Using this device, the researchers have shown that, in people that are blind from birth, the areas of the cerebral cortex normally devoted to reading become activated in response to stimulation. The results of this study, conducted in conjunction with researchers at the ICM Brain and Bone Marrow Institute Research Center (Inserm/UPMC/AP-HP) and NeuroSpin (CEA-Inserm), were published in
Neuron on November 8.
According to Neuron, the researchers used an visual-to-auditory sensory-substitution algorithm to teach congenitally fully blind adults to read and recognize complex images using "soundscapes"—sounds topographically representing images. fMRI was used to examine key questions regarding the visual word form area (VWFA): its selectivity for letters over other visual categories without visual experience, its feature tolerance for reading in a novel sensory modality, and its plasticity for scripts learned in adulthood. The blind activated the VWFA specifically and selectively during the processing of letter soundscapes relative to both textures and visually complex object categories and relative to mental imagery and semantic-content controls.
VWFA recruitment for reading soundscapes emerged after two hours of training in a blind adult on a novel script. This demonstrated that the VWFA shows category selectivity regardless of input sensory modality, visual experience, and long-term familiarity or expertise with the script. The VWFA may perform a flexible task-specific rather than sensory-specific computation, possibly linking letter shapes to phonology, the researchers said.
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