Feasibility of a visual prosthesis for the blind based on intracortical microstimulation of the visual cortex

Em, Schmidt; Bak, M.; Hambrecht, F. Terry; Kufta, CV; O'Rourke, DK; Vallabhanath, P.

doi:10.1016/s0002-9394(14)72149-x

Cited by 171 publications

(286 citation statements)

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“…Within a few days, current detection thresholds decreased from 5-70 A in the first training session to 2-5 A. These values are comparable with the lowest cortical microstimulation detection thresholds found in humans (Schmidt et al, 1996), monkeys (Bartlett and Doty, 1980;de Lafuente and Romo, 2005;Murphey and Maunsell, 2007), and rats (Butovas and Schwarz, 2007;Houweling and Brecht, 2008). Once animals responded consistently to microstimulation currents Յ5 A, we started single-cell stimulation experiments.…”

Section: Resultssupporting

confidence: 54%

Behavioral Detectability of Single-Cell Stimulation in the Ventral Posterior Medial Nucleus of the Thalamus

Voigt¹,

Brecht²,

Houweling³

2008

J. Neurosci.

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In mammals, most sensory information passes through the thalamus before reaching cortex. In the rat whisker system, each macrovibrissa is represented by ϳ250 neurons in the ventral posterior medial nucleus (VPM) of the thalamus and ϳ10,000 neurons in a cortical barrel column. Here we quantify the sensory impact of individual thalamic neurons in the rat VPM. We first trained animals to report microstimulation of VPM. All animals learned to report microstimulation currents of 2-5 A. We then evoked action potentials (APs) in single thalamic neurons close to the microstimulation site using juxtacellular stimulation, adding on average 17.8 APs to 2.6 spontaneous APs during 200 ms current applications. A population analysis revealed that animals responded equally often in single-cell stimulation trials as in catch trials without stimulation, suggesting that APs of single thalamic cells in VPM lead to either no or only a very weak perceptual effect. These results are surprising given the relatively small number of VPM neurons and our previous observations that single neurons in other parts of the vibrissal system do have an impact on perception or motor output. Our findings therefore suggest that neural representations in whisker thalamus are more distributed than in other whisker-related structures.

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Section: Resultssupporting

confidence: 54%

Behavioral Detectability of Single-Cell Stimulation in the Ventral Posterior Medial Nucleus of the Thalamus

Voigt¹,

Brecht²,

Houweling³

2008

J. Neurosci.

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“…It has been shown that the electrical stimulation of primary V1 could produce phosphenes in monkeys and humans (Brindley and Lewin, 1968;Schmidt et al, 1996;Tehovnik and Slocum, 2007).…”

Section: Electric Pulse-induced Glutamate Release Cortical Phosphenementioning

confidence: 99%

Phosphene perception is due to the ultra-weak photon emission produced in various parts of the visual system: glutamate in the focus

Császár¹,

Scholkmann²,

Salari³

et al. 2016

Reviews in the Neurosciences

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AbstractPhosphenes are experienced sensations of light, when there is no light causing them. The physiological processes underlying this phenomenon are still not well understood. Previously, we proposed a novel biopsychophysical approach concerning the cause of phosphenes based on the assumption that cellular endogenous ultra-weak photon emission (UPE) is the biophysical cause leading to the sensation of phosphenes. Briefly summarized, the visual sensation of light (phosphenes) is likely to be due to the inherent perception of UPE of cells in the visual system. If the intensity of spontaneous or induced photon emission of cells in the visual system exceeds a distinct threshold, it is hypothesized that it can become a conscious light sensation. Discussing several new and previous experiments, we point out that the UPE theory of phosphenes should be really considered as a scientifically appropriate and provable mechanism to explain the physiological basis of phosphenes. In the present paper, we also present our idea that some experiments may support that the cortical phosphene lights are due to the glutamate-related excess UPE in the occipital cortex.

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“…Electrical stimulation currently offers a method to improve the disrupted function in a number of neurological disorders and many new applications are on the horizon [1][2][3][4][5][6]. Historically the rectangular waveform has been the choice for the current or voltage pulses employed in neural stimulators.…”

Section: Introductionmentioning

confidence: 99%

Non-rectangular waveforms for neural stimulation with practical electrodes

2007

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Historically the rectangular pulse waveform has been the choice for neural stimulation. The strength-duration curve is thus defined for rectangular pulses. Not much attention has been paid to alternative waveforms to determine if the pulse shape has an effect on the strength-duration relation. Similarly the charge injection capacity of neural electrodes has also been measured with rectangular pulses. In this study we questioned if non-rectangular waveforms can generate a stronger stimulation effect, when applied through practical electrodes, by minimizing the neural activation threshold and maximizing the charge injection capacity of the electrode. First, the activation threshold parameters were studied with seven different pulse shapes using computer simulations of a local membrane model. These waveforms were rectangular, linear increase and decrease, exponential increase and decrease, Gaussian, and sinusoidal. The chronaxie time was found to be longer with all the non-rectangular pulses and some provided more energy efficient stimulation than the rectangular waveform. Second, the charge injection capacity of titanium nitride microelectrodes was measured experimentally for the same waveforms. Linearly decreasing ramp provided the best charge injection for all pulse widths tested from 0.02 to 0.5 ms. Finally, the most efficient waveform that maximized the charge injection capacity of the electrode while providing the lowest threshold charge for neural activation was searched. Linear and exponential decrease, and Gaussian waveforms were found to be the most efficient pulse shapes.

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Feasibility of a visual prosthesis for the blind based on intracortical microstimulation of the visual cortex

Cited by 171 publications

References 0 publications

Behavioral Detectability of Single-Cell Stimulation in the Ventral Posterior Medial Nucleus of the Thalamus

Behavioral Detectability of Single-Cell Stimulation in the Ventral Posterior Medial Nucleus of the Thalamus

Phosphene perception is due to the ultra-weak photon emission produced in various parts of the visual system: glutamate in the focus

Non-rectangular waveforms for neural stimulation with practical electrodes

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