Visual percepts evoked with an intracortical 96-channel microelectrode array inserted in human occipital cortex

Fernández, Eduardo; Alfaro, Arantxa; Soto-Sánchez, Cristina; González-López, Pablo; Lozano, Antonio; Peña, Sebastian; Murcia, María Dolores Grima; Rodil, Alfonso; Gómez, Bernardeta; Chen, Xing; Roelfsema, Pieter; Rolston, John D.; Davis, Tyler; Normann, Richard A.

doi:10.1172/jci151331

Cited by 111 publications

(181 citation statements)

References 58 publications

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“…Different neural targets along the visual pathway can be stimulated to elicit flashes of light known as phosphenes, which can be used as rudimentary visual feedback for people with blindness. To date, visual neuroprostheses have been implanted for at least several months in the retina (Humayun et al 2012; Stingl et al 2013; Fujikado et al 2016; Petoe et al 2021; Barnes et al 2016; Palanker et al 2022; Xu et al 2021), optic nerve (Veraart et al 2003), and visual cortex of human subjects (Beauchamp et al 2020; Fernández et al 2021). The Argus® II (Second Sight Medical Products, Sylmar, CA, USA) is a device that was implanted commercially in the United States from 2014 through 2020.…”

Section: Introductionmentioning

confidence: 99%

Sequential epiretinal stimulation improves discrimination in simple shape discrimination tasks only

Christie

Sadeghi

Kartha

et al. 2022

Preprint

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ObjectiveElectrical stimulation of the retina can elicit flashes of light called phosphenes, which can be used to restore rudimentary vision for people with blindness. Functional sight requires stimulation of multiple electrodes to create patterned vision, but phosphenes tend to merge together in an uninterpretable way. Sequentially stimulating electrodes in human visual cortex has recently demonstrated that shapes could be “drawn” with better perceptual resolution relative to simultaneous stimulation. The goal of this study was to evaluate if sequential stimulation would also form clearer shapes when the retina is the neural target.ApproachTwo human participants with retinitis pigmentosa who had Argus® II retinal prostheses participated in this study. We evaluated different temporal parameters for sequential stimulation in phosphene shape mapping and forced-choice discrimination tasks. For the discrimination tasks, performance was compared between stimulating electrodes simultaneously versus sequentially.Main resultsPhosphenes elicited by different electrodes were reported as vastly different shapes. Sequential electrode stimulation outperformed simultaneous stimulation in simple discrimination tasks, in which shapes were created by stimulating 3-4 electrodes, but not in more complex discrimination tasks involving 5+ electrodes. For sequential stimulation, the optimal pulse train duration was 200 ms when stimulating at 20 Hz and the optimal gap interval was tied between 0 and 50 ms. Efficacy of sequential stimulation also depended strongly on selecting electrodes that elicited phosphenes with similar shapes and sizes.SignificanceAn epiretinal prosthesis can produce coherent simple shapes with a sequential stimulation paradigm, which can be used as rudimentary visual feedback. However, success in creating more complex shapes, such as letters of the alphabet, is still limited. Sequential stimulation may be most beneficial for epiretinal prostheses in simple tasks, such as basic navigation, rather than complex tasks such as object identification.

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Section: Introductionmentioning

confidence: 99%

Sequential epiretinal stimulation improves discrimination in simple shape discrimination tasks only

Christie

Sadeghi

Kartha

et al. 2022

Preprint

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“…Perturbation of neural activity in the visual system alters visual perception (Brindley & Lewin, 1968;Dobelle et al, 1974;Fernández et al, 2021;Foerster, O., 1929;Jonas et al, 2014;Murphey et al, 2009;Parvizi et al, 2012;Rangarajan et al, 2014;Schalk et al, 2017).…”

Section: Main Textmentioning

confidence: 99%

Optical stimulation of inferior temporal cortex induces object-specific visual distortions.

Azadi¹,

Bohn²,

Lopez³

et al. 2022

Preprint

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To be able to effectively restore vision by direct cortical stimulation, we need to understand the perceptual events induced by stimulation of high-level visual cortices. We trained macaque monkeys to detect and report optogenetic impulses delivered to their inferior temporal cortices. In a series of experiments, we observed that detection of cortical stimulation highly depends on the choice of images presented to the eyes and that detection of cortical stimulation is most difficult when the animal fixates on a blank screen. We show that local stimulation of object selective parts of the visual cortex induce perceptual events that are easy to detect as object-dependent distortions of the concurrent contents of vision. These findings invite expanding the scope of visual prosthetics beyond the primary visual cortex.

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“…Similarly, stimulation of face-and color-sensitive subregions of the fusiform gyrus is reported to induce the perception of 'facephenes' (hallucinatory faces) and 'rainbows' respectively, independent of the object being viewed (Jonas et al, 2014;Schalk et al, 2017). Historically, stimulation induced hallucinatory events have provided the main promise and shaped the conceptual framework for the development of visual prosthetics (Fernández et al, 2021). If stimulation of a given cortical location elicits a specific hallucinatory element (eg.…”

Section: Main Textmentioning

confidence: 99%

Perceptual effects of optogenetic stimulation of inferior temporal cortex: hallucination or distortion?

Azadi¹,

Bohn²,

Lopez³

et al. 2022

Preprint

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Local artificial stimulation in high level visual areas of the brain induces complex perceptual events. Anecdotal descriptions of these events fall into two broad categories: ‘hallucinations’, which add a consistent and specific pictorial element to the contents of perception, and ‘distortions’, which transform the ongoing visual perception. Distortions are not pictorially consistent as they vary based on the visual input. Systematic description of such characteristics of stimulation-induced perceptual events is a necessary step for understanding how neural activity gives rise to perception, and is also critical for development of visual prosthetic devices. Here, we implanted arrays of LEDs over inferior temporal cortices of macaque monkeys and trained them to detect and report short optogenetic impulses delivered to their cortices. In a series of experiments, we observed that the ability to detect cortical stimulation highly depends on the choice of images presented to the eyes and that detection of cortical stimulation is most difficult when the animal fixates on a blank screen. Local stimulation of object selective parts of the visual cortex is shown here to induce perceptual events that are easy to detect and contain a strong distortive component. The causal contribution of inferior temporal neurons to perception does not seem to be strongly predetermined, as it depends on the state of vision. These findings also open the door to expanding the scope of visual prosthetics beyond the primary visual cortex.

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Visual percepts evoked with an intracortical 96-channel microelectrode array inserted in human occipital cortex

Cited by 111 publications

References 58 publications

Sequential epiretinal stimulation improves discrimination in simple shape discrimination tasks only

Sequential epiretinal stimulation improves discrimination in simple shape discrimination tasks only

Optical stimulation of inferior temporal cortex induces object-specific visual distortions.

Perceptual effects of optogenetic stimulation of inferior temporal cortex: hallucination or distortion?

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