Abstract
Background: In most individuals, auditory and visual perception have strong interactions and influence over each other. 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 unknown whether this reorganization is permanent, or whether auditory-visual interactions can be re-established in cases of partial visual recovery. Retinal prostheses restore visual perception to the late blind and provide an opportunity to determine if those auditory-visual connections and interactions are still viable after years of plasticity and neglect. Methods: Participants were seated about 20 inches away from an iMac 27-inch computer. The computer was placed on a black felt covered table and wall. Visual stimuli presented were vertical white rectangles (2.75 inches by 13 inches) on a black background (0.5 second duration). The auditory beeps were 0.07 seconds long and delivered via headphones (auditory location conveyed via intensity differences). Results: We tested Argus II retinal prosthesis patients (N=7) for the auditory-visual illusion, the ventriloquist effect, where the perceived location of an auditory stimulus is modified by the presence of a visual stimulus. These patients showed a significant modification of the auditory perception by the restored prosthetic visual perception (N=7; t(6)=4.59, p=0.004) that was not significantly different from sighted participants (N=10; t(15)=1.62, p=0.13). Furthermore, the strength of this auditory-visual interaction in prosthesis patients was significantly partially-correlated to patient’s age and their duration of prosthesis use (Age of Argus II user: rho=−0.95, p=0.004, Duration of Argus II use: rho=0.86, p=0.03). Discussion: This result indicates that auditory-visual interactions can be restored after decades of blindness, and that auditory-visual processing pathways and regions can be re-engaged. Furthermore, it indicates the resilience of multimodal interactions to plasticity during blindness.
Acknowledgement: We are grateful for support from the National Institutes of Health, the Philanthropic Educational Organization Scholar Award Program, and Arnold O. Beckman Postdoctoral Scholars Fellowship Program.