Writing to the Mind’s Eye of the Blind
Open accessAbstract
The implantation of electrodes on the visual cortex of blind individuals could lead to the restoration of a rudimentary form of sight. In this issue of Cell, Beauchamp et al. use electrical stimulation of the visual cortex to create visual perception of shapes.
AI snapshot
Written from the paper’s full text.
TL;DR
This Cell Preview comments on Beauchamp et al. (2020), who implanted electrode arrays on the visual cortex of sighted and blind subjects and showed that dynamic, sequential stimulation can write recognizable letter shapes into perception. It reviews the history of cortical prosthetics and the remaining challenges for restoring useful vision.
Key findings
- Beauchamp et al. implanted silastic sheets with multiple embedded electrodes on the visual cortex of sighted individuals (implanted as part of epilepsy treatment) and two blind individuals; one blind subject received a prototype of the Orion device with 60 electrodes, built by Second Sight.
- Simultaneous stimulation of multiple electrodes produced unpredictable percepts: phosphenes typically merged into larger phosphenes, making shape recognition impossible. The current required for a single phosphene with surface stimulation is on the order of a few milliamperes.
- Current steering worked: concurrent stimulation of two electrodes at 70% of the base current each elicited a "virtual" phosphene between the two individual phosphene locations, and varying current proportions controlled its position along the line between them — addressing more visual-field locations than the number of implanted electrodes.
- Rapid successive stimulation tracing letter shapes was readily recognized and reproduced by both seeing and blind subjects, which the author calls the first clear demonstration of shape perception with electrical stimulation of the visual cortex in the blind.
Methods
- This is a Preview/commentary article, not a primary study; it summarizes and contextualizes Beauchamp et al. (2020) and reviews prior work (Brindley, Dobelle, the Argus II retinal prosthesis).
- No new data are collected or analyzed; the described procedures (surface electrode implantation, single- and multi-electrode stimulation, current steering, sequential stimulation) are those of the Beauchamp et al. study being discussed.
Limitations
- Stated by the paper: dynamic stimulation limited to one cortical location at a time limits the bandwidth of shape generation, because viewing time increases with the number of phosphenes needed; it may be difficult to convey information about objects that move or change shape, since drawing a single shape takes time; it is unknown whether multiple items can be presented dynamically (e.g., one per hemifield or quadrant).
- Evident from the text: the article is a commentary rather than primary evidence, so its claims rest on the cited Beauchamp et al. study; the author also declares a competing interest as co-founder of Phosphoenix, a startup developing a visual cortex prosthesis.
Model-written summary. Check it against the paper before relying on it.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
0 of 14 cited sources checked · 0 supported · 0 flagged
- Premiseown data§ Writing to the Mind's Eye of the Blind · p. 2
The subjects easily recognized and reproduced the shape written to their visual cortex.
“the surprising result was that the subjects readily recognized and reproduced the shape that had been written to their visual cortex.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Beauchamp et al., 2020 source
Not checked in the free run.
- Premisecitation§ Writing to the Mind's Eye of the Blind · p. 2
Rapid successive stimulation produces a series of phosphenes that traces the outline of letters.
“phosphenes that traces out the shape of letters (Figure 1).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Beauchamp et al., 2020 source
Not checked in the free run.
- Interpretationreasoning§ Writing to the Mind's Eye of the Blind · p. 2
The study provides the first clear demonstration of shape perception through electrical stimulation of the visual cortex in blind people.
“the study thereby presents the first clear demonstration of shape perception with electrical stimulation of the visual cortex in the blind.”
Quote in the paperSubstantial claim - Premisecitation§ Writing to the Mind's Eye of the Blind · p. 1
Where a phosphene appears depends on which point of the cortical sheet is stimulated.
“phosphene location depended on the stimulation point on the cortical sheet (Brindley and Lewin, 1968).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Brindley and Lewin, 1968 source
Not checked in the free run.
- Premisecitation§ Writing to the Mind's Eye of the Blind · p. 1
Stimulating the visual cortex of blind people electrically produces perceptions of light spots called phosphenes.
“The subjects perceived dots of light upon stimulation, known as phosphenes, and Brindley studied the properties of these percepts.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Brindley and Lewin, 1968 source
Not checked in the free run.
- Interpretationreasoning§ Writing to the Mind's Eye of the Blind · p. 1
More positions in the visual field can be addressed than there are implanted electrodes.
“Hence, it is possible to address more locations in the visual field than the number of implanted electrodes.”
Quote in the paperSubstantial claim - Interpretationreasoning§ Writing to the Mind's Eye of the Blind · p. 1
Implanting electrodes on the visual cortex of blind people could restore a basic form of sight.
“The implantation of electrodes on the visual cortex of blind individuals could lead to the restoration of a rudimentary form of sight.”
Quote in the paperSubstantial claim - Interpretationreasoning§ Writing to the Mind's Eye of the Blind · p. 2
Dynamic stimulation confined to a single cortical location at a time restricts the bandwidth of shape generation, since viewing time grows with the number of phosphenes required to perceive a shape.
“dynamic stimulation that is limited to only one cortical location at a time limits the bandwidth of the shape generation process, because viewing time increases with the number of phosphenes necessary for shape perception.”
Quote in the paperSubstantial claim - Premisecitation§ Writing to the Mind's Eye of the Blind · p. 1
Stimulating single electrodes electrically produced phosphenes whose positions matched the retinotopic map of the visual cortex.
“As expected, electrical stimulation of individual electrodes elicited phosphenes with locations that corresponded to the retinotopic map in the visual cortex.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Beauchamp et al., 2020 source
Not checked in the free run.
- Premisecitation§ Writing to the Mind's Eye of the Blind · p. 1
Stimulating two electrodes together, each at 70% of the base current, produces a virtual phosphene located between the two individual phosphene positions.
“The surprising result was that concurrent stimulation of both A and B, both at 70% of the base current, elicits a ''virtual'' phosphene at a point between LA and LB.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Beauchamp et al., 2020 source
Not checked in the free run.
- Premisecitation§ Writing to the Mind's Eye of the Blind · p. 1
Changing the current proportions allowed the position of the virtual phosphene to be steered along a line between the two phosphene positions.
“With different current proportions, they could control the location of the virtual phosphene on a line through LA and LB.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Beauchamp et al., 2020 source
Not checked in the free run.
- Classified as probably not a substantial claim. 3
- May combine two claims. 9
Probably not a substantial claim: may not pass S3 (load-bearing).
Premisecitation§ Writing to the Mind's Eye of the Blind · p. 1Dobelle placed electrodes on the visual cortex surface in a greater number of blind people between 1970 and 2000.
“One of these scientists was William Dobelle, who implanted electrodes on the surface of the visual cortex in a larger number of blind individuals between 1970 and 2000 (Dobelle, 2000).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Dobelle, 2000 source
Not checked in the free run.
May combine two claims.
Interpretationown data§ Writing to the Mind's Eye of the Blind · p. 1A single phosphene from surface stimulation needs a current of a few milliamperes, and the combined current from stimulating several electrodes may activate neurons in poorly controlled patterns.
“The current required for a single phosphene with surface stimulation is in the order of a few milliamperes, and the total current produced by the stimulation of multiple electrodes may combine to activate neurons in poorly controlled constellations.”
Quote in the paperSubstantial claimMay combine two claims.
Premisecitation§ Writing to the Mind's Eye of the Blind · p. 1Stimulating several electrodes at once made the extent to which the phosphenes merged into recognizable shapes unpredictable, and they usually fused into larger phosphenes so that shapes could not be recognized.
“However, when multiple electrodes were stimulated at the same time, the degree to which the phosphenes combined into recognizable shapes was unpredictable. Typically, they merged into larger phosphenes, making shape recognition impossible.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Beauchamp et al., 2020 source
Not checked in the free run.
May combine two claims.
Premisecitation§ Writing to the Mind's Eye of the Blind · p. 1The Argus II assists blind people in locating objects, but it is of limited use for recognizing shapes.
“The Argus II helps blind individuals to localize objects, but its utility for the recognition of shapes is limited (Stronks and Dagnelie, 2014).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Stronks and Dagnelie, 2014
Not checked in the free run.
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
Premisecitation§ Writing to the Mind's Eye of the Blind · p. 2Optogenetics can stimulate neural tissue with high bandwidth, reaching single-cell resolution.
“Researchers are also developing other methods to stimulate neuronal tissue with a high bandwidth, such as optogenetics with up to singlecell resolution (Marshel et al., 2019).”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Marshel et al., 2019 source
Not checked in the free run.
May combine two claims.
Interpretationreasoning§ Writing to the Mind's Eye of the Blind · p. 1People whose retina or early visual pathways are damaged can still receive a cortical implant, which is an advantage of cortical over retinal devices.
“One advantage of cortical compared with retinal devices is that patients with damage to the retina or early visual pathways are still candidates for cortical implantation.”
Quote in the paperNot a substantial claimMay combine two claims.
Premisecitation§ Writing to the Mind's Eye of the Blind · p. 2Both sighted and blind subjects recognized the letters.
“Both seeing and blind subjects recognized letters”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Beauchamp et al., 2020 source
Not checked in the free run.
May combine two claims.
Premisecitation§ Writing to the Mind's Eye of the Blind · p. 1Dobelle's devices worked for only a short time, and the patients seemed to gain little overall benefit in daily life.
“However, the useful lifespan of his devices was short, and patients appeared to receive little overall benefit in their daily lives, leading to diminished enthusiasm for cortical prosthetics.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Dobelle, 2000 source
Not checked in the free run.
May combine two claims.
Premisecitation§ Writing to the Mind's Eye of the Blind · p. 2Penetrating electrodes need far less current and create smaller phosphenes than surface electrodes.
“Penetrating electrodes require orders of magnitude less current and produce smaller phosphenes (Schmidt et al., 1996).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Schmidt et al., 1996 source
Not checked in the free run.
Classified as probably not a substantial claim. May combine two claims.
Interpretationreasoning§ Writing to the Mind's Eye of the Blind · p. 2It may be possible to stimulate several nearby penetrating electrodes at once, which would improve the resolution of artificial vision.
“It might therefore be possible to simultaneously stimulate multiple nearby electrodes, enhancing the resolution of artificial vision.”
Quote in the paperSubstantial claim
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
Electrical stimulation of individual electrodes elicited phosphenes with locations that corresponded to the retinotopic map in the visual cortex.
“As expected, electrical stimulation of individual electrodes elicited phosphenes with locations that corresponded to the retinotopic map in the visual cortex (7, 8).”
From Visual percepts evoked with an intracortical 96-channel microelectrode array inserted in human occipital cortex (2021) · cites this paper as [8]
When multiple surface electrodes were stimulated at the same time, the perceptions typically merged into larger phosphenes, making shape recognition practically impossible.
“However, when multiple electrodes were stimulated at the same time, the perceptions typically merged into larger phosphenes, making shape recognition practically impossible.”
From Visual percepts evoked with an intracortical 96-channel microelectrode array inserted in human occipital cortex (2021) · cites this paper as [8]
Cites
The sensations produced by electrical stimulation of the visual cortex
Brindley, G. S., & Lewin, W. S. (1968) · The Journal of Physiology · doi:10.1113/jphysiol.1968.sp008519 · Cited by 1,170 · cited 1× · see citing works
“The visual cortex contains a two-dimensional map of visual space, and phosphene location depended on the stimulation point on the cortical sheet (Brindley and Lewin, 1968).”
Schmidt, E. M., Bak, M. J., Hambrecht, F. T., Kufta, C. V., O'Rourke, D. K., & Vallabhanath, P. (1996) · Brain · doi:10.1093/brain/119.2.507 · Cited by 672 · cited 1× · see citing works
“Penetrating electrodes require orders of magnitude less current and produce smaller phosphenes (Schmidt et al., 1996).”
BackgroundCortical layer-specific critical dynamics triggering perception
Marshel, J. H., Kim, Y. S., Machado, T. A., Quirin, S., Benson, B., Kadmon, J., Raja, C., Chibukhchyan, A., Ramakrishnan, C., Inoue, M., et al. (2019) · Science · doi:10.1126/science.aaw5202 · Cited by 652 · see citing works
Artificial Vision for the Blind by Connecting a Television Camera to the Visual Cortex
Dobelle, W. H. (2000) · ASAIO Journal · doi:10.1097/00002480-200001000-00002 · Cited by 584 · see citing works
Pitch perception by cochlear implant subjects
Townshend, B., Cotter, N. E., Compernolle, D. V., & White, R. L. (1987) · The Journal of the Acoustical Society of America · doi:10.1121/1.395554 · Cited by 306 · see citing works
Dynamic Stimulation of Visual Cortex Produces Form Vision in Sighted and Blind Humans
Beauchamp, M. S., Oswalt, D., Sun, P., Foster, B. L., Magnotti, J. F., Niketeghad, S., Pouratian, N., Bosking, W. H., & Yoshor, D. (2020) · Cell · doi:10.1016/j.cell.2020.04.033 · Cited by 257 · cited 4× · see citing works
“In this issue of Cell, Beauchamp et al. (2020) used electrical stimulation of the visual cortex to produce visual percepts.”
BackgroundInfluentialThe functional performance of the Argus II retinal prosthesis
Stronks, H. C., & Dagnelie, G. (2014) · Expert Review of Medical Devices · doi:10.1586/17434440.2014.862494 · Cited by 189 · see citing works
Clinical applications of penetrating neural interfaces and Utah Electrode Array technologies
Normann, R. A., & Fernandez, E. (2016) · Journal of Neural Engineering · doi:10.1088/1741-2560/13/6/061003 · Cited by 135 · see citing works
Mind Reading and Writing: The Future of Neurotechnology
Roelfsema, P. R., Denys, D., & Klink, P. C. (2018) · Trends in Cognitive Sciences · doi:10.1016/j.tics.2018.04.001 · Cited by 107 · see citing works
Self-citationBosking, W. H., Beauchamp, M. S., & Yoshor, D. (2017) · Annual Review of Vision Science · doi:10.1146/annurev-vision-111815-114525 · Cited by 93 · cited 1× · see citing works
“Scientists have long dreamed of restoring vision in blind individuals by stimulating the visual cortex, bypassing malfunctioning eyes to directly deliver information to higher visual centers (Bosking et al., 2017).”
Flagged first, then by citations
Cited by
Sorted by citations
Fernández, E., Alfaro, A., Soto-Sánchez, C., Gonzalez-Lopez, P., Lozano, A. M., Peña, S., Grima, M. D., Rodil, A., Gómez, B., Chen, X., et al. (2021) · Journal of Clinical Investigation · doi:10.1172/jci151331 · Cited by 250 · see citing works
Self-citationLiu, X., Chen, P., Ding, X., Liu, A., Li, P., Sun, C., & Guan, H. (2022) · Annals of Translational Medicine · doi:10.21037/atm-22-2858 · Cited by 28 · see citing works
Nanotechnology for vision restoration
Lanzani, G., Chiaravalli, G., Colombo, E., Manfredi, G., Marco, S. D., Vurro, V., & Benfenati, F. (2024) · Nature Reviews Bioengineering · doi:10.1038/s44222-024-00210-4 · Cited by 18 · see citing works
Halfmann, C., Rüland, T., Müller, F. U., Jehasse, K., & Kampa, B. M. (2023) · Frontiers in Cellular Neuroscience · doi:10.3389/fncel.2023.1258773 · Cited by 7 · see citing works
Somatosensory Feedback in BCIs: Why Aiming for Naturalness Raises Ethical Concerns
van Balen, B. (2025) · AJOB Neuroscience · doi:10.1080/21507740.2025.2478427 · Cited by 6 · see citing works
Optimal placement of high-channel visual prostheses in human retinotopic visual cortex
van Hoof, R., Lozano, A., Wang, F., Klink, P. C., Roelfsema, P. R., & Goebel, R. (2025) · Journal of Neural Engineering · doi:10.1088/1741-2552/adaeef · Cited by 6 · see citing works
Self-citationTowards precise synthetic neural codes: high-dimensional stimulation with flexible electrodes
Kim, R., Liu, Y., Zhang, J., Xie, C., & Luan, L. (2025) · npj Flexible Electronics · doi:10.1038/s41528-025-00447-y · Cited by 4 · see citing works
Grani, F., Soto‐Sánchez, C., Doblado, A. R., Grima, M. D., Farfán, F. D., Calvo, M. V., Soo, L., Wacławczyk, D., Ferrandez, J., González, P., et al. (2022) · Lecture notes in computer science · doi:10.1007/978-3-031-06242-1_51 · Cited by 2 · see citing works
Guided by Noise: Correlated Variability Channels Task-Relevant Information in Sensory NeuronsPreprint
Srinath, R., Xu, Y., Ruff, D. A., Ni, A. M., Doiron, B., & Cohen, M. R. (2025) · bioRxiv (Cold Spring Harbor Laboratory) · doi:10.1101/2025.08.13.669902 · Cited by 2 · see citing works
The brain as image processor and generator: towards function-restoring brain-computer-interfaces
van Hoof, R. (2022) · doi:10.26481/dis.20220603rh · Cited by 1 · see citing works
Les prothèses visuelles du futur
Lanese, N. (2020) · Cerveau & Psycho · doi:10.3917/cerpsy.125.0014
Hahn, N., Moure, P., & Liu, S. (2025) · Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) · doi:10.1109/embc58623.2025.11253749
The structure of correlated variability reflects task-relevant information in sensory neurons
Srinath, R., Xu, Y., Ruff, D. A., Ni, A. M., Doiron, B., & Cohen, M. R. (2026) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.2523217123
- Authors
- Roelfsema, P. R.
- Affiliations
- Netherlands Institute for Neuroscience (NL)
- Corresponding author
- Roelfsema, Pieter R.
- ORCID
- Roelfsema, Pieter R.
- Venue
- Cell
- Publisher
- Elsevier BV
- Published
- 2020-05
- Volume
- 181
- Issue
- 4
- Pages
- 758-759
- ISSN
- 0092-8674 (ISSN-L)
- OpenAlex
- W3024092857
- Semantic Scholar
- c6217daef5a19e763cdf06f81dd599fa8eeb802e
- Cited by
- 14
- References
- 10
- Citations by year
- 2026: 1 · 2025: 5 · 2024: 1 · 2023: 1 · 2022: 4 · 2021: 1 · 2020: 1
- FWCI
- 0.80
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- Locations
- Cell (publishedVersion)
- PubMed (publishedVersion)
- Pure Amsterdam UMC (submittedVersion, other-oa)
- Data Archiving and Networked Services (DANS) (submittedVersion)
- Data Archiving and Networked Services (DANS) (submittedVersion, cc-by-nc-nd)
- KNAW Research Portal (The Royal Netherlands Academy of Arts and Sciences) (submittedVersion, cc-by-nc-nd)
- VU Research Portal (submittedVersion)
- Funders
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek
- Topics
- Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neural Engineering
- Life Sciences › Neuroscience › Cognitive Neuroscience › Tactile and Sensory Interactions
- Life Sciences › Neuroscience › Cognitive Neuroscience › Visual perception and processing mechanisms
- Keywords
- visual cortex, electrical stimulation, visual perception, blindness, vision restoration, cortical implants, shape perception, brain-computer interface
- MeSH terms
- Eye, Humans, Visual Cortex, Visual Perception, Writing
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-08.
Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-08.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
