Mouse eyeball drug restores light sensitivity

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Mouse eyeball drug restores light sensitivity
John Timmer | July 29 2012 | Ars Technica

Light-sensitive chemical triggers nerves even when rods and cones are absent.

'In some forms of blindness, notably retinitis pigmentosa and macular degeneration, the loss of vision is caused by the death of the rod and cone cells that actually sense light; the rest of the eye and visual system remains largely intact. This allows electrode implants to activate the nerves that relay signals from the eye on towards the brain, providing some hope of restoring vision. Now, researchers have figured out a clever way to get rid of all the hardware. They've tested a light-sensitive chemical that sticks to proteins on nerve cells and causes them to fire off a nerve signal in response to light. When it's injected into the eye of otherwise blind mice, the chemical restores some light sensitivity.

The chemical in question is called AAQ (short for acrylamide-azobenzene-quaternary ammonium), and its activity on nerve cells was first described in 2008. In one of AAQ's forms, it binds to a protein that lets potassium ions into the cell, which makes nerve cells more likely to fire. In an alternate configuration, the molecule allows the ions to flow, causing nerve cells to shut down. The key feature of the molecule is that it's possible to switch AAQ between these two states using light: short wavelengths push it into the form that starts up potassium flow, while longer wavelengths cause it to switch back to shutting ion flows down.'

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Braille Bracelet Keeps Blind On Track
August 2012 | Gajitz

'The Metro Dot is a conceptual product designed by Ho-Yeoul Lee, Jinwoo Kim and Sangyong Choi to help visually impaired people navigate the subway system. The bracelet-like device features a polymer plane that, just like magic, displays braille information to help keep the wearer informed about where she is on the train line.'


Photo: The Metro Dot
Credit: Gajitz

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Stem Cells Restore Hearing In Deaf Gerbils – When Will It Work On Humans?
Peter Murray | September 18th, 2012 | Singularity Hub

'In a new study, scientists were able to restore partial hearing to deaf gerbils by implanting human embryonic stem cells in their ears. The breakthrough offers hope that one day a similar treatment may be developed to cure hearing loss in humans.


Photo: Human embryonic stem cells, induced to become
auditory neurons (yellow), were implanted into gerbils.
Replacing damaged auditory neurons allowed the gerbils
to regain most of their hearing.
Credit: Singularity Hub

One cause of hearing loss is auditory neuropathy, the impairment of auditory neurons that normally transmit sound signals from the ear to the brain. Researchers at the University of Sheffield in the UK sought to restore hearing in 18 gerbils whose auditory nerves had been experimentally damaged, by replacing the nerves with new ones derived from human embryonic stem cells.

The undifferentiated embryonic stem cells were first subject to chemicals to induce them into becoming auditory neurons. These new auditory neurons were then placed into the gerbils’ ears. Ten weeks later, many of the transplanted cells had grown fibers that reached the brainstem where several relay centers necessary for hearing are found. To see if those fibers helped the gerbils to hear, the researchers played sounds to the gerbils of increasing volume, and used electrodes to determine what volume was needed to evoke brain activity. The gerbils showed improved hearing ten weeks after receiving the stem cells, with a 46 percent increase in sensitivity. The improvement, however, was far from consistent. A third responded exceptionally well, with some regaining 90 percent of their hearing, while another third showed almost no recovery at all.'

Study: The study was published recently in Nature

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