%0 Journal Article
%T Looking into Task-Specific Activation Using a Prosthesis Substituting Vision with Audition
%A Paula Plaza
%A Isabel Cuevas
%A C¨¦cile Grandin
%A Anne G. De Volder
%A Laurent Renier
%J ISRN Rehabilitation
%D 2012
%R 10.5402/2012/490950
%X A visual-to-auditory sensory substitution device initially developed for the blind is known to allow visual-like perception through sequential exploratory strategies. Here we used functional magnetic resonance imaging (fMRI) to test whether processing the location versus the orientation of simple (elementary) ¡°visual¡± stimuli encoded into sounds using the device modulates the brain activity within the dorsal visual stream in the absence of sequential exploration of these stimuli. Location and orientation detection with the device induced a similar recruitment of frontoparietal brain areas in blindfolded sighted subjects as the corresponding tasks using the same stimuli in the same subjects in vision. We observed a similar preference of the right superior parietal lobule for spatial localization over orientation processing in both sensory modalities. This provides evidence that the parietal cortex activation during the use of the prosthesis is task related and further indicates the multisensory recruitment of the dorsal visual pathway in spatial processing. 1. Introduction When deprived of its natural input, the ¡°visual¡± cortex of early-blind subjects is widely activated during a variety of perceptual and cognitive tasks and its cross-modal recruitment may account for the improved perceptual abilities of these subjects in the auditory and tactile modalities. Sensory substitution prostheses translating vision into touch or vision into audition were developed initially for the blind since these devices could take advantage of the cross-modal plasticity changes induced by blindness. It should be noted, however, that cross-modal interactions are increasingly being recognized as playing a vital role in normal perception too. The visual cortex is functionally divided into a ventral/identification and a dorsal/localization stream [1¨C4]. Interestingly, using a sensory substitution device (SSD) often activates brain areas within both the dorsal and the ventral visual pathways, not only in the blind but also in normally sighted subjects [5¨C11]. Despite the increasing number of studies on sensory substitution, little is known about the specific versus nonspecific nature of these brain activations as regards to the task performed with the SSD. One may hypothesize that the brain activations elicited during the use of an SSD are partly driven by mechanisms specific to sensory substitution (i.e., the conversion of sounds or tactile sensations into ¡°visual¡± representations) but also depend on the nature of the task performed with the SSD (e.g., stimulus identification
%U http://www.hindawi.com/journals/isrn.rehabilitation/2012/490950/