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Neuroscientist working on device to conduct retinal ‘symphony’

Professor E.J. Chichilnisky is aiming to create a device to tackle degenerative eye probls that currently have no cure through a novel approach which he says will revolutionise the way electronic devices interface with the brain.According to Chichilnisky, one of the issues with current retinal implants is that they don’t account for the fact that diseases such as dry age-related macular degeneration and retinitis pigmentosa don’t kill all of the retinal cells within the eye.{{quote-A:R-W:450-I:2-Q: I’m not saying we’ve nailed it, but we certainly now have proof of concept, -WHO:E.J. Chichilnisky, Stanford University}}Retinal ganglion cells – of which there are about 20 different types that transmit various information to the brain – se to survive the culling, which Chichilniksy says creates probls when they interact with visual implants.“Think of the retina as an orchestra. When you try to make music, you need the violins to play one score, the oboes to play a different score and so on,” he explains.“If you instruct all the instruments to play indiscriminately, someone will hear you – but it’s not music.”Instead, the Stanford neuroseurgeon is aiming to get each ganglion cell, or ‘instrument’ to play at the correct moment. The current plan is to achieve this through a specialised, wirelessly powered prosthesis that will be surgically implanted into the eye.However, he says there is still much to be done before they reach that point as getting the right signal to the right cell at the right time is difficult, because the mixture of different types of ganglion cells varies between individuals and may even change over time.{{quote-A:L-W:450-Q: Think of the retina as an orchestra. When you try to make music, you need the violins to play one score, the oboes to play a different score and so on. }}To better understand the patterns of electrical activity in the retina, Chichilnisky and his colleagues have used eye tissue taken from primates and placed it atop microchip arrays capable of measuring neural activity at the cellular level. They then expose those samples to various patterns of light.So far, the team has been able to record and study the distinctive electrical responses of five different types of retinal ganglion cells, which together account for 75% of the visual signals sent to the brain.The next stage of their research has seen th develop techniques to replicate those electrical patterns, in the process artificially stimulating the ganglion cells with a precision that is comparable to the natural signals elicited by the rods and cones.Chichilnisky says the ability to replicate these signals has validated his team’s work and taken th one step closer to their goal of a high-acuity visual prosthesis that can signal the retina’s myriad of neurons to fire in the precisely the right ways at the appropriate times.{{image3-a:r-w:300}}“I’m not saying we’ve got it nailed, but we certainly now have proof of concept for how to make a better device in the future,” he said, while predicting if all goes well, a prototype of the implant could be ready for testing in lab animals in 4–5 years.However, before reaching that stage, the team will need to fit his lab’s expansive computing power onto an implantable electrode array that can autonomously do its job safely inside the eye, without overheating surrounding tissues.“We have to take everything we know and program it effectively into chip that can sense its environment, figure out what’s going on, and do the right thing at right time in the right place, always. And it has to be smart enough to talk to a neural circuit,” Chichilnisky told online tech publication Futurism in a recent interview. “It’s a tall order.”But, with a team of neuroscientists, circuit designers and an eye surgeon all working on the device, Chichilnisky is confident he has the right people in place to eventually produce an implant with the ability to conduct his favourite kind of symphony.

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