Percepts evoked by multi-electrode stimulation of human visual cortex

Bosking, William H.; Oswalt, Denise; Foster, Brett L.; Park, Sun; Beauchamp, Michael S.; Yoshor, Daniel

doi:10.1016/j.brs.2022.08.007

Cited by 15 publications

(14 citation statements)

References 41 publications

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“…These percepts can be enhanced by a 'dynamic current steering' stimulation paradigm 6 , enhancing the salience of the percept and reducing the number of stimulation sites needed 52,74 . In a study by Fernández et al 4 , a blind subject implanted with a Utah array was able to discriminate evoked sizes and shapes as well as spatially small percepts, marking a significant advance in spatial resolution (see also Yoshor and Bosking 75 ). Roelfsema's group implanted an astounding 1024-channel-count electrode interface (16 Utah arrays, 0.3-0.6MΩ, <100uA) into monkey V1 and V4, achieving percepts of shapes, letters, and motion direction 5 .…”

Section: Previous Studies With Electrical Stimulationmentioning

confidence: 99%

A novel interface for cortical columnar neuromodulation with multi-point infrared neural stimulation

Tian,

Zhang,

Schriver

et al. 2024

Preprint

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Cutting edge advances in electrical visual cortical prosthetics (VCPs) have evoked perception of shapes, motion, and letters in human and nonhuman primates. However, there is no existing method that employs a targeted columnar approach with a non-penetrating array of stimulation points. Neither has there been a direct demonstration that higher order cortical response can be elicited from externally stimulated lower order cortical sites. Here, we take an approach that employs images maps of cortical columns combined with delivery of optical stimulation through a fiber optic array to stimulate selected sets of columns. Specifically, using infrared neural stimulation (INS) delivered through a linear optic fiber array in anesthetized cat visual cortex, we predicted that the orientation of the array would selectively activate different higher order orientation domains in contralateral cat area 18. We found that INS modulation of response to ongoing visual oriented gratings produced enhanced responses in orientation-matched domains and reduced response in non-matched domains, consistent with a known higher order integration mediated by callosal inputs. This establishes proof-of-principle that an external device can access existing cortical circuitry via a column-targeted approach, and provides groundwork for a targeted column-based approach to cortical prosthetics using dense optical fiber bundle arrays.

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Section: Previous Studies With Electrical Stimulationmentioning

confidence: 99%

A novel interface for cortical columnar neuromodulation with multi-point infrared neural stimulation

Tian,

Zhang,

Schriver

et al. 2024

Preprint

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“…Současná stimulace dvojicí elektrod vzdálených od sebe více než 4 mm měla tendenci vyvolat vnímání dvou odlišných fosfenů. Stimulace více elektrodami ale nevedla k vnímání rozpoznatelných forem [25].…”

Section: Současnostunclassified

Visual Neuroprosthesis – Stimulation of Visual Cortical Centers in The Brain. Design of Non-Invasive Transcranial Stimulation of Functional Neurons

Lešták

2024

CSO

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Purpose: The purpose of the article is to present the history and current status of visual cortical neuroprostheses, and to present a new method of stimulating intact visual cortex cells. Methods: This paper contains an overview of the history and current status of visual cortex stimu-lation in severe visual impairment, but also highlights its shortcomings. These include mainly the stimulation of currently damaged cortical cells over a small area and, from a morphological point of view, possible damage to the stimulated neurons by the elec-trodes and their encapsulation by gliotic tissue. Results: The paper also presents a proposal for a new technology of image processing and its transformation into a form of non-invasive transcranial stimulation of undamaged parts of the brain, which is protected by a national and international patent. Conclusion: The paper presents a comprehensive review of the current options for compensating for lost vision at the level of the cerebral cortex and a proposal for a new non-invasive method of stimulating the functional neurons of the visual cortex.

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“…Previous studies showed that stimulation of the visual cortex via multiple electrodes generates phosphenes that form discriminable percepts [59], such as lines and letters [19,33,35,60]. Here, we examined the number of electrodes that successfully evoked phosphenes over time, to determine the efficacy and longevity of the prosthesis and evaluate the potential of using this technology for a future clinical device.…”

Section: Phosphene Inductionmentioning

confidence: 99%

Chronic stability of a neuroprosthesis comprising multiple adjacent Utah arrays in monkeys

et al. 2023

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Objective. Electrical stimulation of visual cortex via a neuroprosthesis induces the perception of dots of light (‘phosphenes’), potentially allowing recognition of simple shapes even after decades of blindness. However, restoration of functional vision requires large numbers of electrodes, and chronic, clinical implantation of intracortical electrodes in the visual cortex has only been achieved using devices of up to 96 channels. We evaluated the efficacy and stability of a 1024-channel neuroprosthesis system in non-human primates (NHPs) over more than 3 years to assess its suitability for long-term vision restoration. Approach. We implanted 16 microelectrode arrays (Utah arrays) consisting of 8 × 8 electrodes with iridium oxide tips in the primary visual cortex (V1) and visual area 4 (V4) of two sighted macaques. We monitored the animals’ health and measured electrode impedances and neuronal signal quality by calculating signal-to-noise ratios of visually driven neuronal activity, peak-to-peak voltages of the waveforms of action potentials, and the number of channels with high-amplitude signals. We delivered cortical microstimulation and determined the minimum current that could be perceived, monitoring the number of channels that successfully yielded phosphenes. We also examined the influence of the implant on a visual task after 2–3 years of implantation and determined the integrity of the brain tissue with a histological analysis 3–3.5 years post-implantation. Main results. The monkeys remained healthy throughout the implantation period and the device retained its mechanical integrity and electrical conductivity. However, we observed decreasing signal quality with time, declining numbers of phosphene-evoking electrodes, decreases in electrode impedances, and impaired performance on a visual task at visual field locations corresponding to implanted cortical regions. Current thresholds increased with time in one of the two animals. The histological analysis revealed encapsulation of arrays and cortical degeneration. Scanning electron microscopy on one array revealed degradation of IrOx coating and higher impedances for electrodes with broken tips. Significance. Long-term implantation of a high-channel-count device in NHP visual cortex was accompanied by deformation of cortical tissue and decreased stimulation efficacy and signal quality over time. We conclude that improvements in device biocompatibility and/or refinement of implantation techniques are needed before future clinical use is feasible.

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Percepts evoked by multi-electrode stimulation of human visual cortex

Cited by 15 publications

References 41 publications

A novel interface for cortical columnar neuromodulation with multi-point infrared neural stimulation

A novel interface for cortical columnar neuromodulation with multi-point infrared neural stimulation

Visual Neuroprosthesis – Stimulation of Visual Cortical Centers in The Brain. Design of Non-Invasive Transcranial Stimulation of Functional Neurons

Chronic stability of a neuroprosthesis comprising multiple adjacent Utah arrays in monkeys

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