Reading with a Simulated 60-Channel Implant

Fornos, Angelica Pérez; Sommerhalder, J.; Pelizzone, M.

doi:10.3389/fnins.2011.00057

Cited by 18 publications

(20 citation statements)

References 28 publications

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“…Various strategies have been explored to optimize SPV rendering. This was especially the case for reading capabilities (12), object grasping (13), or localization tasks (14).…”

mentioning

confidence: 99%

Simplification of Visual Rendering in Simulated Prosthetic Vision Facilitates Navigation

2017

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Visual neuroprostheses are still limited and simulated prosthetic vision (SPV) is used to evaluate potential and forthcoming functionality of these implants. SPV has been used to evaluate the minimum requirement on visual neuroprosthetic characteristics to restore various functions such as reading, objects and face recognition, object grasping, etc. Some of these studies focused on obstacle avoidance but only a few investigated orientation or navigation abilities with prosthetic vision. The resolution of current arrays of electrodes is not sufficient to allow navigation tasks without additional processing of the visual input. In this study, we simulated a low resolution array (15 × 18 electrodes, similar to a forthcoming generation of arrays) and evaluated the navigation abilities restored when visual information was processed with various computer vision algorithms to enhance the visual rendering. Three main visual rendering strategies were compared to a control rendering in a wayfinding task within an unknown environment. The control rendering corresponded to a resizing of the original image onto the electrode array size, according to the average brightness of the pixels. In the first rendering strategy, vision distance was limited to 3, 6, or 9 m, respectively. In the second strategy, the rendering was not based on the brightness of the image pixels, but on the distance between the user and the elements in the field of view. In the last rendering strategy, only the edges of the environments were displayed, similar to a wireframe rendering. All the tested renderings, except the 3 m limitation of the viewing distance, improved navigation performance and decreased cognitive load. Interestingly, the distance‐based and wireframe renderings also improved the cognitive mapping of the unknown environment. These results show that low resolution implants are usable for wayfinding if specific computer vision algorithms are used to select and display appropriate information regarding the environment.

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“…Various strategies have been explored to optimize SPV rendering. This was especially the case for reading capabilities (12), object grasping (13), or localization tasks (14).…”

mentioning

confidence: 99%

Simplification of Visual Rendering in Simulated Prosthetic Vision Facilitates Navigation

2017

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“…Other neural prostheses (e.g. retinal implant) likewise suffer from non-specific neural stimulation and poor spatial resolution 42 .…”

Section: Discussionmentioning

confidence: 99%

Intracellular calcium and cyclic nucleotide levels modulate neurite guidance by microtopographical substrate features

Tuft

et al. 2016

J. Biomed. Mater. Res.

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Objective Micro- and nano-scale surface features have emerged as potential tools to direct neurite growth into close proximity with next generation neural prosthesis electrodes. However, the signaling events underlying the ability of growth cones to respond to topographical features remain largely unknown. Accordingly, this study probes the influence of [Ca2+]i and cyclic nucleotide levels on the ability of neurites from spiral ganglion neurons (SGNs) to precisely track topographical micropatterns. Approach Photopolymerization and photomasking were used to generate micropatterned methacrylate polymer substrates. Dissociated SGN cultures were plated on the micropatterned surfaces. Calcium influx and release from internal stores were manipulated by elevating extracellular K+, maintenance in calcium-free media, or bath application of various calcium channel blockers. Cyclic nucleotide activity was increased by application of cpt-cAMP or 8-Br-cGMP. Main results Elevation of [Ca2+]i by treatment of cultures with elevated potassium reduced neurite alignment to physical microfeatures. Maintenance of cultures in Ca2+-free medium or treatment with the non-selective voltage-gated calcium channel blocker cadmium or L-type Ca2+ channel blocker nifedipine did not signficantly alter SGN neurite alignment. By contrast, ryanodine or xestospongin C, which block release of internal calcium stores via ryanodine-sensitive channels or inositol-1,4,5-trisphosphate receptors respectively, each significantly decreased neurite alignment. Cpt-cAMP significantly reduced neurite alignment while 8-Br-cGMP significantly enhanced neurite alignment. Conclusion Manipulation of [Ca2+]i or cAMP levels significantly disrupts neurite guidance while elevation of cGMP levels increases neurite alignment. The results suggest intracellular signaling pathways similar to those recruited by chemotactic cues are involved in neurite guidance by topographical features.

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“…Early simulations envisaged images made up of regular arrays of small dots representing individual phosphenes, but as the scarcity of visual information reported by prosthesis wearers became evident, these simulations became more sophisticated. In the last year, simulations have been used to explore the ability of sighted individuals to interact with gaze-locked imagery (as a retinal implant wearer with a head-mounted camera would perceive the scene)[55], recognize characters[56], read[57], or recognize objects despite a distorted phosphene map[58]. They have also continued to study the effects of phosphene size, position, and mapping[59-61], a topic which may even be of greater relevance to optic nerve and cortical implants than to retinal prostheses.…”

Section: Voptimizing Information Transfermentioning

confidence: 99%

Retinal implants

Dagnelie

2012

Current Opinion in Neurology

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Purpose of review To summarize the current status of retinal prostheses, recent accomplishments, and major remaining research, engineering, and rehabilitation challenges. Recent findings Retinal research, materials and biocompatibility studies, and clinical trials in patients blind from RP are representative of an emerging field with considerable promise and sobering challenges. A summary of progress in dozens of labs, companies, and clinics around the world is presented through a synopsis of relevant papers, not only to summarize the progress, but also to convey the remarkable increase in interest, effort, and outside funding this field has enjoyed. Summary At the present time, clinical applications of retinal implant technology are dominated by one or two groups/companies, but the field is wide open for others to take the lead through novel approaches in technology, tissue interfacing, information transfer paradigms, and rehabilitation. Where the field will go in the next few years is almost anybody’s guess, but that it will move forward is a certainty.

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Reading with a Simulated 60-Channel Implant

Cited by 18 publications

References 28 publications

Simplification of Visual Rendering in Simulated Prosthetic Vision Facilitates Navigation

Simplification of Visual Rendering in Simulated Prosthetic Vision Facilitates Navigation

Intracellular calcium and cyclic nucleotide levels modulate neurite guidance by microtopographical substrate features

Retinal implants

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