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Sara Garcia, Karin Petrini, Lyndon da Cruz, Gary Rubin, Marko Nardini; Cue combination with a new sensory signal: multisensory processing in blind patients with a retinal prosthesis. Journal of Vision 2014;14(10):1132. doi: 10.1167/14.10.1132.
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Prolonged visual deprivation can result in enhanced perception by non-visual modalities, reflecting neural pathway re-organisation (e.g. Collignon, Lassonde, Lepore et al., 2007). However, it is not yet clear whether further re-organisation is possible when visual information is partially restored. Here we ask whether patients implanted with retinal prostheses, which partially restore vision, can combine this new visual signal with non-visual information for faster or more accurate perception. Five participants (4 retinitis pigmentosa, 1 choroideremia; aged 49-76yrs) implanted with Second Sight's Argus II retinal prostheses in 2008-09, took part. They completed three tasks: a visual-haptic size judgment task, in which they compared two balls using vision, touch, or both; a visual-auditory detection task, in which they made speeded responses to flash, beep, or flash-beep stimuli; and a navigation task, in which they used visual and/or self-motion information to reproduce a path or complete a triangle. When discriminating ball sizes, no participants gained from added visual information, as haptic estimates alone were highly reliable. Two participants, however, showed multisensory speed gains exceeding those expected by probability summation on the audio-visual task. Of four tested so far on navigation, all showed less accurate performance with visual information on the path reproduction task, indicating that they used vision but that it was detrimental. These results suggest that after the retinal implant some sensory re-organisation is possible, specifically for temporal judgments and simple audiovisual tasks. However, these patients' prosthetic vision is not reliable for more complex spatial judgments. This likely reflects difficulties in interpreting spatial information due to differences between prosthetic and native vision. However, training may enable patients to learn the statistical relationship between the new visual and non-visual signals.
Meeting abstract presented at VSS 2014
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