Implantation of retina stimulation electrodes and recording of electrical stimulation responses in the visual cortex of the cat

Hesse, Lutz; Schanze, Thomas; Wilms, Marcus; Eger, Marcus

doi:10.1007/s004170000197

Cited by 92 publications

(61 citation statements)

References 11 publications

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“…This stimulation current corresponds to 10 nC injected per pulse and a maximum electrode charge density of 0.8 mC/cm 2 . Since this charge density exceeds the safe limit for platinum electrodes (0.4 mC/cm 2 [18,19]) we use activated iridium oxide film (AIROF) electrodes, which have a safe charge-injection limit of 1-9 mC/cm 2 [20].…”

Section: System Designmentioning

confidence: 99%

Progress towards a high-resolution retinal prosthesis

et al. 2007

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Electronic retinal prostheses represent a potentially effective approach for restoring some degree of sight in blind patients with retinal degeneration. Functional restoration of sight would require hundreds to thousands of electrodes effectively stimulating remaining neurons in the retina. We present a design of an optoelectronic retinal prosthetic system having 3mm diameter retinal implant with pixel sizes down to 25 micrometers, which allows for natural eye scanning for observing a large field of view, as well as spatial and temporal processing of the visual scene to optimize the patient experience. Information from a head mounted video camera is processed in a portable computer and delivered to the implanted photodiode array by projection from the LCD goggles using pulsed IR (810 nm) light. Each photodiode converts pulsed light (0.5 ms in duration) into electric current with efficiency of 0.3 A/W using common biphasic power line. Power is provided by the inductively-coupled RF link from the coil on the goggles into a miniature power supply implanted between the sclera and the conjuctiva, and connected to subretinal implant with a thin 2-wire trans-scleral cable.3-dimensional structures in the subretinal prosthesis induce retinal migration and thus ensure close proximity between stimulating electrodes and the target retinal neurons. Subretinal implantations of the 3-dimentional pillar and chamber arrays in RCS rats with 2 and 6 week follow-up demonstrate achievement of intimate proximity between the stimulation cites and the inner nuclear layer. In some instances formation of a fibrotic seal has been observed.

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Section: System Designmentioning

confidence: 99%

Progress towards a high-resolution retinal prosthesis

et al. 2007

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“…Various efforts toward implementation of visual prosthetic device have involved development of suitable electrodes, circuitry, packaging, and surgical implantation techniques (Hesse et al, 2000;Kazemi et al, 2004;Seo et al, 2004;Sivaprakasam et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Electrically-evoked Neural Activities of rd1 Mice Retinal Ganglion Cells by Repetitive Pulse Stimulation

Ryu

Lee

et al. 2009

Korean J Physiol Pharmacol

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For successful visual perception by visual prosthesis using electrical stimulation, it is essential to develop an effective stimulation strategy based on understanding of retinal ganglion cell (RGC) responses to electrical stimulation. W e studied RGC responses to repetitive electrical stimulation pulses to develop a stimulation strategy using stimulation pulse frequency modulation. Retinal patches of photoreceptor-degenerated retinas from rd1 mice were attached to a planar multi-electrode array (MEA) and RGC spike trains responding to electrical stimulation pulse trains with various pulse frequencies were observed. RGC responses were strongly dependent on inter-pulse interval when it was varied from 500 to 10 ms. Although the evoked spikes were suppressed with increasing pulse rate, the number of evoked spikes were ＞ 60% of the maximal responses when the inter-pulse intervals exceeded 100 ms. Based on this, we investigated the modulation of evoked RGC firing rates while increasing the pulse frequency from 1 to 10 pulses per second (or Hz) to deduce the optimal pulse frequency range for modulation of RGC response strength. RGC response strength monotonically and linearly increased within the stimulation frequency of 1∼ 9 Hz. The results suggest that the evoked neural activities of RGCs in degenerated retina can be reliably controlled by pulse frequency modulation, and may be used as a stimulation strategy for visual neural prosthesis.

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“…The corresponding charge per area is 0.2mC/cm 2 when delivering a 2ms pulse. This is below but in the same order of magnitude as the charge limit of Platinum-Iridium electrodes (0.4mC/cm 2 [8]) that are commonly used in retinal implants.…”

Section: Resultsmentioning

confidence: 82%