Auditory-Visual Interactions in the Blind with Artificial Vision: Are Multisensory Perceptions Restored After Decades of Blindness?

Abstract

In the sighted, auditory and visual perception typically interact strongly and influence each other significantly. Blindness acquired in adulthood alters these multisensory pathways. During blindness, it has been shown that the senses functionally reorganize, enabling visual cortex to be recruited for auditory processing. It is yet unknown whether this reorganization is permanent, or whether auditory-visual interactions can be re-established in cases of partial visual recovery.\n\nRetinal prostheses restore visual perception to the late blind and provide an opportunity to determine if these auditory-visual connections and interactions are still viable after years of plasticity and neglect. We tested Argus II retinal prosthesis patients (N = 7) for an auditory-visual illusion, the ventriloquist effect, in which the perceived location of an auditory stimulus is modified by the presence of a visual stimulus. Prosthetically-restored visual perception significantly modified patients auditory perceptions, comparable to results with sighted control participants (N = 10). Furthermore, the auditory-visual interaction strength in retinal prosthesis patients exhibited a significant partial anti-correlation with patient age, as well as a significant partial correlation with duration of prosthesis use.\n\nThese results indicate that auditory-visual interactions can be restored after decades of blindness, and that auditory-visual processing pathways and regions can be re-engaged. Furthermore, they indicate the resilience of multimodal interactions to plasticity during blindness, and that this plasticity can either be partially reversed or at least does not prevent auditory-visual interactions. Finally, this study provides hope for the restoration of sensory perception, complete with multisensory integration, even after years of visual deprivation.\n\nSignificanceRetinal prostheses restore visual perception to the blind by means of an implanted retinal stimulator wirelessly connected to a camera mounted on glasses. Individuals with prosthetic vision can locate and identify simple objects, and identify the direction of visual motion. A key question is whether this prosthetic vision will interact with the other senses, such as audition, in the same way that natural vision does. We found that artificial vision, like natural vision, can alter auditory localization. This suggests that the brain processes prosthetic vision similarly to natural vision despite altered visual processing in the retina. In addition, it implies that reorganization of the senses during blindness may be reversible, allowing for the rehabilitation of crossmodal interactions after visual restoration.