Visual perception in a blind subject with a chronic microelectronic retinal prosthesis

AbstractIn 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.Retinal 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.These 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.SignificanceRetinal 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.

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Simulation of visual perception and learning with a retinal prosthesis

10.1101/206409 ◽

2017 ◽

Cited By ~ 3

Author(s):

James R. Golden ◽

Cordelia Erickson-Davis ◽

Nicolas P. Cottaris ◽

Nikhil Parthasarathy ◽

Fred Rieke ◽

...

Keyword(s):

Visual Perception ◽

Visual Information ◽

Potential Effect ◽

Retinal Prosthesis ◽

Clinical Findings ◽

Cell Type ◽

Cell Type Specificity ◽

Computational Framework ◽

Optimal Linear ◽

Artificial Activation

AbstractThe nature of artificial vision with a retinal prosthesis, and the degree to which the brain can adapt to the unnatural input from such a device, are poorly understood. Therefore, the development of current and future devices may be aided by theory and simulations that help to infer and understand what prosthesis patients see. A biologically-informed, extensible computational framework is presented here to predict visual perception and the potential effect of learning with a subretinal prosthesis. The framework relies on optimal linear reconstruction of the stimulus from retinal responses to infer the visual information available to the patient. A simulation of the physiological optics of the eye and light responses of the major retinal neurons was used to calculate the optimal linear transformation for reconstructing natural images from retinal activity. The result was then used to reconstruct the visual stimulus during the artificial activation expected from a subretinal prosthesis in a degenerated retina, as a proxy for inferred visual perception. Several simple observations reveal the potential utility of such a simulation framework. The inferred perception obtained with prosthesis activation was substantially degraded compared to the inferred perception obtained with normal retinal responses, as expected given the limited resolution and lack of cell type specificity of the prosthesis. Consistent with clinical findings and the importance of cell type specificity, reconstruction using only ON cells, and not OFF cells, was substantially more accurate. Finally, when reconstruction was re-optimized for prosthesis stimulation, simulating the greatest potential for learning by the patient, the accuracy of inferred perception was much closer to that of healthy vision. The reconstruction approach thus provides a more complete method for exploring the potential for treating blindness with retinal prostheses than has been available previously. It may also be useful for interpreting patient data in clinical trials, and for improving prosthesis design.

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