Phosphene perceptions and safety of chronic visual cortex stimulation in a blind subject

2020 ◽  
Vol 132 (6) ◽  
pp. 2000-2007 ◽  
Author(s):  
Soroush Niketeghad ◽  
Abirami Muralidharan ◽  
Uday Patel ◽  
Jessy D. Dorn ◽  
Laura Bonelli ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Adverse Events ◽  
Clinical Intervention ◽  
Occipital Cortex ◽  
Neuronal Population ◽  
Serious Adverse Events ◽  
Stimulation Parameters ◽  
The Right ◽  
Visual Cortical ◽  
Stimulation Of

Stimulation of primary visual cortices has the potential to restore some degree of vision to blind individuals. Developing safe and reliable visual cortical prostheses requires assessment of the long-term stability, feasibility, and safety of generating stimulation-evoked perceptions.A NeuroPace responsive neurostimulation system was implanted in a blind individual with an 8-year history of bare light perception, and stimulation-evoked phosphenes were evaluated over 19 months (41 test sessions). Electrical stimulation was delivered via two four-contact subdural electrode strips implanted over the right medial occipital cortex. Current and charge thresholds for eliciting visual perception (phosphenes) were measured, as were the shape, size, location, and intensity of the phosphenes. Adverse events were also assessed.Stimulation of all contacts resulted in phosphene perception. Phosphenes appeared completely or partially in the left hemifield. Stimulation of the electrodes below the calcarine sulcus elicited phosphenes in the superior hemifield and vice versa. Changing the stimulation parameters of frequency, pulse width, and burst duration affected current thresholds for eliciting phosphenes, and increasing the amplitude or frequency of stimulation resulted in brighter perceptions. While stimulation thresholds decreased between an average of 5% and 12% after 19 months, spatial mapping of phosphenes remained consistent over time. Although no serious adverse events were observed, the subject experienced mild headaches and dizziness in three instances, symptoms that did not persist for more than a few hours and for which no clinical intervention was required.Using an off-the-shelf neurostimulator, the authors were able to reliably generate phosphenes in different areas of the visual field over 19 months with no serious adverse events, providing preliminary proof of feasibility and safety to proceed with visual epicortical prosthetic clinical trials. Moreover, they systematically explored the relationship between stimulation parameters and phosphene thresholds and discovered the direct relation of perception thresholds based on primary visual cortex (V1) neuronal population excitation thresholds.

150 Effect of Stimulation Parameters on Visual Percepts Elicited by Stimulation of a Visual Cortical Prosthesis for the Blind

Neurosurgery ◽  
2017 ◽  
Vol 64 (CN_suppl_1) ◽  
pp. 236-236
Author(s):  
Soroush Niketeghad ◽  
Abirami Muralidharan ◽  
Uday Patel ◽  
Jessy Dorn ◽  
Robert Greenberg ◽  
...  
Keyword(s):  
Occipital Lobe ◽  
Stimulation Parameters ◽  
Multiple Contacts ◽  
Stimulus Parameters ◽  
History Of ◽  
The Subject ◽  
The Right ◽  
Visual Cortical ◽  
Stimulation Of

Abstract INTRODUCTION Stimulation of human visual cortex is known to elicit visual percepts (phosphenes) which makes it a suitable candidate for generating artificial vision for blind. Although there have been a few attempts to build visual cortical prostheses, a greater understanding of the physiology of stimulation is required to generate useful perceptions. This study aims to characterize the phosphenes elicited by a neurostimulation device and explore the effects of stimulation parameters (amplitude, frequency, pulse-width and burst duration) on the quality of these percepts. METHODS A 30-year-old volunteer with an 8-year history of bare light perception secondary to Voght-Koaynagi-Harada Syndrome participated in this study. Two parallel cortical strip leads (each with four contacts) were implanted over the right medial occipital lobe. Phosphene characteristics were assessed postoperatively using subject's drawings of on a touch screen as well as subjective description of the percepts intensity and color. The stimulus parameters for eliciting a well-defined phosphene were obtained by varying the stimulus parameters for each contact at the beginning of each session during the eight months' period of the study. RESULTS >Stimulation of each of the eight contacts elicited phosphenes with a consistent shape and location in the visual field. The stimulus parameters for generating a well-defined phosphene were stable for six contacts and had to be adjusted for two over the period of the study. Increasing the amplitude and frequency resulted in more intense perceptions and the subject indicated seeing colored phosphenes for certain amplitudes. Simultaneous stimulation of multiple contacts was perceived as a summation of percepts elicited by stimulating the contacts individually. Sequential stimulation of two contacts generated two phosphenes and the subject was able to identify them in order. CONCLUSION Visual cortical prostheses are feasible candidates for creating artificial sight due to reproducibility of the perceptions and consistency of the stimulation parameters required to generate basic visual perceptions.

Interocular torsional disparity and visual cortical development in the cat

1990 ◽  
Vol 64 (4) ◽  
pp. 1352-1360 ◽  
Author(s):  
M. R. Isley ◽  
D. C. Rogers-Ramachandran ◽  
P. G. Shinkman
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Ocular Dominance ◽  
Visual Fields ◽  
Receptive Fields ◽  
Right Visual Field ◽  
Orientation Columns ◽  
Areas 17 And 18 ◽  
The Right ◽  
Visual Cortical

1. The present experiments were designed to assess the effects of relatively large optically induced interocular torsional disparities on the developing kitten visual cortex. Kittens were reared with restricted visual experience. Three groups viewed a normal visual environment through goggles fitted with small prisms that introduced torsional disparities between the left and right eyes' visual fields, equal but opposite in the two eyes. Kittens in the +32 degrees goggle rearing condition experienced a 16 degrees counterclockwise rotation of the left visual field and a 16 degrees clockwise rotation of the right visual field; in the -32 degrees goggle condition the rotations were clockwise in the left eye and counterclockwise in the right. In the control (0 degree) goggle condition, the prisms did not rotate the visual fields. Three additional groups viewed high-contrast square-wave gratings through Polaroid filters arranged to provide a constant 32 degrees of interocular orientation disparity. 2. Recordings were made from neurons in visual cortex around the border of areas 17 and 18 in all kittens. Development of cortical ocular dominance columns was severely disrupted in all the experimental (rotated) rearing conditions. Most cells were classified in the extreme ocular dominance categories 1, 2, 6, and 7. Development of the system of orientation columns was also affected: among the relatively few cells with oriented receptive fields in both eyes, the distributions of interocular disparities in preferred stimulus orientation were centered near 0 degree but showed significantly larger variances than in the control condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Interhemispheric EEG asymmetries during unilateral bright-light exposure and subsequent sleep in humans

2008 ◽  
Vol 294 (3) ◽  
pp. R1053-R1060 ◽  
Author(s):  
Christian Cajochen ◽  
Rosalba Di Biase ◽  
Makoto Imai
Keyword(s):  
Visual Cortex ◽  
Time Course ◽  
Visual Stimulation ◽  
Light Exposure ◽  
Bright Light ◽  
Occipital Cortex ◽  
Alpha Activity ◽  
Hemispheric Dominance ◽  
Eeg Activity ◽  
The Right

We tested whether evening exposure to unilateral photic stimulation has repercussions on interhemispheric EEG asymmetries during wakefulness and later sleep. Because light exerts an alerting response in humans, which correlates with a decrease in waking EEG theta/alpha-activity and a reduction in sleep EEG delta activity, we hypothesized that EEG activity in these frequency bands show interhemispheric asymmetries after unilateral bright light (1,500 lux) exposure. A 2-h hemi-field light exposure acutely suppressed occipital EEG alpha activity in the ipsilateral hemisphere activated by light. Subjects felt more alert during bright light than dim light, an effect that was significantly more pronounced during activation of the right than the left visual cortex. During subsequent sleep, occipital EEG activity in the delta and theta range was significantly reduced after activation of the right visual cortex but not after stimulation of the left visual cortex. Furthermore, hemivisual field light exposure was able to shift the left predominance in occipital spindle EEG activity toward the stimulated hemisphere. Time course analysis revealed that this spindle shift remained significant during the first two sleep cycles. Our results reflect rather a hemispheric asymmetry in the alerting action of light than a use-dependent recovery function of sleep in response to the visual stimulation during prior waking. However, the observed shift in the spindle hemispheric dominance in the occipital cortex may still represent subtle local use-dependent recovery functions during sleep in a frequency range different from the delta range.

Excitatory amino acid receptor-mediated transmission in geniculocortical and intracortical pathways within visual cortex

1991 ◽  
Vol 66 (1) ◽  
pp. 293-306 ◽  
Author(s):  
L. J. Larson-Prior ◽  
P. S. Ulinski ◽  
N. T. Slater
Keyword(s):  
Visual Cortex ◽  
Amino Acid ◽  
Cortical Neurons ◽  
Excitatory Amino Acid ◽  
Nmda Antagonist ◽  
Receptor Subtypes ◽  
Excitatory Amino Acid Receptor ◽  
Visual Cortical ◽  
Stimulation Of

1. A preparation of turtle (Chrysemys picta and Pseudemys scripta) brain in which the integrity of the intracortical and geniculocortical pathways in visual cortex are maintained in vitro has been used to differentiate the excitatory amino acid (EAA) receptor subtypes involved in geniculocortical and intracortical synapses. 2. Stimulation of the geniculocortical fibers at subcortical loci produces monosynaptic excitatory postsynaptic potentials (EPSPs) in visual cortical neurons. These EPSPs are blocked by the broad-spectrum EAA receptor antagonist kynurenate (1-2 mM) and the non-N-methyl-D-aspartate (NMDA) antagonist 6, 7-dinitroquinoxaline-2,3-dione (DNQX, 10 microM), but not by the NMDA antagonist D,L-2-amino-5-phosphonovalerate (D,L-AP-5, 100 microM). These results indicate that the geniculocortical EPSP is mediated by EAAs that access principally, if not exclusively, EAA receptors of the non-NMDA subtypes. 3. Stimulation of intracortical fibers evokes compound EPSPs that could be resolved into three components differing in latency to peak. The component with the shortest latency was not affected by any of the EAA-receptor antagonists tested. The second component, of intermediate latency, was blocked by kyurenate and DNQX but not by D,L-AP-5. The component of longest latency was blocked by kynurenate and D,L-AP-5, but not by DNQX. These results indicate that the compound intracortical EPSP is comprised of three pharmacologically distinct components that are mediated by an unknown receptor, by quisqualate/kainate, and by NMDA receptors, respectively. 4. Repetitive stimulation of intracortical pathways at 0.33 Hz produces a dramatic potentiation of the late, D,L-AP-5-sensitive component of the intracortical EPSP. 5. These experiments lead to a hypothesis about the subtypes of EAA receptors that are accessed by the geniculocortical and intracortical pathways within visual cortex.

scholarly journals Magnetic Stimulation of the Right Visual Cortex Impairs Form-specific Priming

2007 ◽  
Vol 19 (6) ◽  
pp. 1013-1020 ◽  
Author(s):  
Gorana Pobric ◽  
Stefan R. Schweinberger ◽  
Michal Lavidor
Keyword(s):  
Magnetic Stimulation ◽  
Semantic Processing ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Brain Activity ◽  
Occipital Lobe ◽  
Occipital Cortex ◽  
Object Form ◽  
The Right ◽  
Specific Priming ◽  
Stimulation Of

Recent evidence suggests that priming of objects across different images (abstract priming) and priming of specific images of an object (form-specific priming) are mediated by dissociable neural processing subsystems that operate in parallel and are predominantly linked to left and right hemispheric processing, respectively [Marsolek, C. J. Dissociable neural subsystems underlie abstract and specific object recognition. Psychological Science, 10, 111–118, 1999]. Previous brain imaging studies have provided important information about the neuroanatomical regions that are involved in form-specific and abstract priming; however, these techniques did not fully establish the functional significance of priming-related changes in cortical brain activity. Here, we used repetitive transcranial magnetic stimulation (rTMS) in order to establish the functional role of the right occipital cortex in form-specific priming [Kroll, N. E. A., Yonelinas, A. P., Kishiyama, M. M., Baynes, K., Knight, R. T., & Gazzaniga, M. S. The neural substrates of visual implicit memory: Do the two hemispheres play different roles? Journal of Cognitive Neuroscience, 15, 833–842, 2003]. Compared to no TMS and sham TMS, rTMS of the right occipital cortex disrupted immediate form-specific priming in a semantic categorization task. Left occipital rTMS, on the other hand, had no converse effect on abstractive priming. Abstract priming may involve deeper semantic processing and may be unresponsive to magnetic stimulation of a single cortical locus. Our TMS results show that form-specific priming relies on a visual word-form system localized in the right occipital lobe, in line with the predictions from divided visual field behavioral studies [Marsolek, 1999].

scholarly journals tDCS Modulation of Visually Induced Analgesia

2012 ◽  
Vol 24 (12) ◽  
pp. 2419-2427 ◽  
Author(s):  
Flavia Mancini ◽  
Nadia Bolognini ◽  
Patrick Haggard ◽  
Giuseppe Vallar
Keyword(s):  
Visual Cortex ◽  
Pain Perception ◽  
Occipital Cortex ◽  
Body Representation ◽  
The Body ◽  
Left Hand ◽  
Analgesic Effects ◽  
Extrastriate Visual Cortex ◽  
Multisensory Interactions ◽  
The Right

Multisensory interactions can produce analgesic effects. In particular, viewing one's own body reduces pain levels, perhaps because of changes in connectivity between visual areas specialized for body representation, and sensory areas underlying pain perception. We tested the causal role of the extrastriate visual cortex in triggering visually induced analgesia by modulating the excitability of this region with transcranial direct current stimulation (tDCS). Anodal, cathodal, or sham tDCS (2 mA, 10 min) was administered to 24 healthy participants over the right occipital or over the centro-parietal areas thought to be involved in the sensory processing of pain. Participants were required to rate the intensity of painful electrical stimuli while viewing either their left hand or an object occluding the left hand, both before and immediately after tDCS. We found that the analgesic effect of viewing the body was enhanced selectively by anodal stimulation of the occipital cortex. The effect was specific for the polarity and the site of stimulation. The present results indicate that visually induced analgesia may depend on neural signals from the extrastriate visual cortex.

Intracerebral electrical stimulation of a face-selective area in the right inferior occipital cortex impairs individual face discrimination

NeuroImage ◽  
2014 ◽  
Vol 99 ◽  
pp. 487-497 ◽  
Author(s):  
Jacques Jonas ◽  
Bruno Rossion ◽  
Julien Krieg ◽  
Laurent Koessler ◽  
Sophie Colnat-Coulbois ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Occipital Cortex ◽  
Selective Area ◽  
The Right ◽  
Stimulation Of

scholarly journals Dynamic Electrical Stimulation of Sites in Visual Cortex Produces Form Vision in Sighted and Blind Humans

2018 ◽  
Author(s):  
Michael S. Beauchamp ◽  
William Bosking ◽  
Ping Sun ◽  
Brett Foster ◽  
Soroush Niketeghad ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Visual Cortex ◽  
Visual Display ◽  
Current Steering ◽  
Form Vision ◽  
Visual Cortical ◽  
Stimulation Paradigm ◽  
Blind Humans ◽  
Field Location ◽  
Stimulation Of

AbstractVisual cortical prosthetics (VCPs) offer the promise of restoring sight to blind patients. Electrical stimulation of a single site in visual cortex can reliably produce a percept of a spot of light in a fixed visual field location, known as a phosphene. Researchers developing VCPs have assumed that multiple phosphenes produced by concurrent stimulation of multiple sites in visual cortex can combine to form a coherent form, like pixels in a visual display. However, existing data do not support this assumption. Therefore, we developed a novel stimulation paradigm for VCPs termed dynamic current steering in which the visual form to be conveyed is traced on the surface of visual cortex by electrically stimulating electrodes in a dynamic sequence. When tested in sighted and blind subjects, this method of stimulating visual cortex allowed for the immediate recognition of a variety of letter shapes without training and with high accuracy.One Sentence SummaryStimulating human visual cortex using dynamic patterns of activity allows both blind and sighted patients to perceive visual percepts of useful forms.

Retinotopy with coordinates of lateral occipital cortex in humans

2004 ◽  
Vol 101 (1) ◽  
pp. 114-118 ◽  
Author(s):  
Takanobu Kaido ◽  
Tohru Hoshida ◽  
Toshiaki Taoka ◽  
Toshisuke Sakaki
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Occipital Lobe ◽  
Occipital Cortex ◽  
Cortical Stimulation ◽  
Content Type ◽  
X Ray ◽  
Lateral Occipital Cortex ◽  
Fine Print ◽  
Stimulation Of

Object. The lateral occipital cortex in humans is known as the “extrastriate visual cortex.” It is, however, an unexplored field of research, and the anatomical nomenclature for its surface has still not been standardized. This study was designed to investigate whether the lateral occipital cortex in humans has retinotopic representation. Methods. Four right-handed patients with a diagnosis of intractable epilepsy from space-occupying lesions in the occipital lobe or epilepsy originating in the occipital lobe received permanently implanted subdural electrodes. Electrical cortical stimulation was applied directly applied to the brain through metal electrodes by using a biphasic stimulator. The location of each electrode was measured on a lateral skull x-ray study. Each patient considered a whiteboard with vertical and horizontal median lines. The patient was asked to look at the midpoint on the whiteboard. If a visual hallucination or illusion occurred, the patient recorded its outline, shape, color, location, and motion on white paper one tenth the size of, and with vertical and horizontal median lines similar to those on, the whiteboard. Polar angles and eccentricities of the midpoints of the phosphenes from the coordinate origin were measured on the paper. On stimulation of the lateral occipital lobe, 44 phosphenes occurred. All phosphenes were circular or dotted, with a diameter of approximately 1 cm, except one that was like a curtain in the peripheral end of the upper and lower visual fields on stimulation of the parietooccipital region. All phosphenes appeared in the visual field contralateral to the cerebral hemisphere stimulated. On stimulation of the lateral occipital lobe, 22 phosphenes moved centrifugally or toward a horizontal line. From three-dimensional scatterplots and contour maps of the polar angles and eccentricities in relation to the x-ray coordinates of the electrodes, one can infer that the lateral occipital cortex in humans has retinotopic representation. Conclusions. The authors found that phosphenes induced by electrical cortical stimulation of the lateral occipital cortex represent retinotopy. From these results one can assert that visual field representation with retinotopic relation exists in the extrastriate visual cortex.

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