Functional Cerebral Reorganization for Auditory Spatial Processing and Auditory Substitution of Vision in Early Blind Subjects

• Published in: Cerebral cortex (New York, N.Y. 1991) Vol. 17; no. 2; pp. 457 - 465
• Main Authors: Collignon, Olivier, Lassonde, Maryse, Lepore, Franco, Bastien, Danielle, Veraart, Claude
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01.02.2007; Oxford Publishing Limited (England)
• Subjects: Adult; Auditory Cortex - physiopathology; Auditory Perception; blindness; Blindness - physiopathology; Blindness - rehabilitation; Female; Humans; Male; Middle Aged; Neuronal Plasticity; occipital cortex; plasticity; sensory substitution; Sound Localization; Space Perception; transcranial magnetic stimulation; Visual Cortex - physiopathology; plasticity; occipital cortex; transcranial magnetic stimulation; blindness; sensory substitution
• ISSN: 1047-3211; 1460-2199
• DOI: 10.1093/cercor/bhj162

Early blind (EB) individuals can recognize bidimensional shapes using a prosthesis substituting vision with audition (PSVA) and activate right dorsal extrastriate visual cortex during the execution of this task. The present study used repetitive transcranial magnetic stimulation (rTMS) to further examine the functional role of this structure in the successful use of the PSVA. Moreover, we investigated which auditory parameter used in the prosthesis (pitch, intensity, or spatial location) might contribute to this occipital activation. Results revealed that rTMS applied to right dorsal extrastriate cortex in EB subjects interferes with both the PSVA use and the auditory spatial location task but not with pitch and intensity discriminations. By contrast, rTMS targeting the same cortical areas in sighted subjects did not affect performance on any auditory tasks. Early visual deprivation thus leads to functional cerebral cross-modal reorganization in the processing of auditory information and auditory-to-visual sensory substitution. The findings also point to the specific involvement of the dorsal visual stream for auditory spatial processing in blind subjects. Moreover, this suggests that sensory substitution prostheses can be developed using these additional neural resources to perform tasks that partially compensate for the loss of vision.