Visual percepts evoked with an intracortical 96-channel microelectrode array inserted in human occipital cortex
Eduardo Fernández, … , Tyler S. Davis, Richard A. Normann
Eduardo Fernández, … , Tyler S. Davis, Richard A. Normann
Published October 19, 2021
Citation Information: J Clin Invest. 2021;131(23):e151331. https://doi.org/10.1172/JCI151331.
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Clinical Medicine Neuroscience Ophthalmology

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

Abstract

BACKGROUND A long-held goal of vision therapy is to transfer information directly to the visual cortex of blind individuals, thereby restoring a rudimentary form of sight. However, no clinically available cortical visual prosthesis yet exists.METHODS We implanted an intracortical microelectrode array consisting of 96 electrodes in the visual cortex of a 57-year-old person with complete blindness for a 6-month period. We measured thresholds and the characteristics of the visual percepts elicited by intracortical microstimulation.RESULTS Implantation and subsequent explantation of intracortical microelectrodes were carried out without complications. The mean stimulation threshold for single electrodes was 66.8 ± 36.5 μA. We consistently obtained high-quality recordings from visually deprived neurons and the stimulation parameters remained stable over time. Simultaneous stimulation via multiple electrodes was associated with a significant reduction in thresholds (P < 0.001, ANOVA) and evoked discriminable phosphene percepts, allowing the blind participant to identify some letters and recognize object boundaries.CONCLUSIONS Our results demonstrate the safety and efficacy of chronic intracortical microstimulation via a large number of electrodes in human visual cortex, showing its high potential for restoring functional vision in the blind.TRIAL REGISTRATION ClinicalTrials.gov identifier NCT02983370.FUNDING The Spanish Ministerio de Ciencia Innovación y Universidades, the Generalitat Valenciana (Spain), the Europan Union’s Horizon 2020 programme, the Bidons Egara Research Chair of the University Miguel Hernández (Spain), and the John Moran Eye Center of the University of Utah.

Authors

Eduardo Fernández, Arantxa Alfaro, Cristina Soto-Sánchez, Pablo Gonzalez-Lopez, Antonio M. Lozano, Sebastian Peña, Maria Dolores Grima, Alfonso Rodil, Bernardeta Gómez, Xing Chen, Pieter R. Roelfsema, John D. Rolston, Tyler S. Davis, Richard A. Normann

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Figure 1

Utah Electrode Array (UEA) implantation and electrophysiological recordings.

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Utah Electrode Array (UEA) implantation and electrophysiological recordi...
(A) Scanning electron microscopy image of the UEA and numbering system used to identify specific electrodes (electrode side shown). (B) Location of the UEA implantation site on the right occipital cortex. Inset: Image of the UEA to be implanted during surgery. (C) Predicted retinotopic map organization superimposed on the 3D reconstruction of the volunteer’s cerebral cortex with the implantation site indicated (left, location of visual areas; middle, eccentricity; and right, polar angle). (D) Average electrode impedances across the 6-month study period. The mean impedances increased by 20% in the first week, and gradually decreased toward their initial values (blue line). (E) Examples of recorded waveforms on days 3, 77, and 154 with summary statistics of recorded multiunit responses. Color in the heatmap represents the number of days on which more than 50 reliable action potentials were recorded on a given electrode over the 2-minute recording period.