Ear-y Noise The cochlea, pictured super-magnified, is a spiralling tunnel that leads deep inside our ear. It acts as a funnel, feeding sound from the outside world through a ‘lawn’ of sensory hair cells which line the organ of corti, highlighted here in red. As noise floods in, the sensory hairs wave around, opening up electrical channels that take speedy messages to the brain. Our auditory hair cells are intricate and fragile, making them prone to damage by diseases and infections. The World Health Organization (WHO), promoting today as International Day for Ear and Hearing, supports immunization schemes worldwide in efforts to prevent hearing loss. They also advise on safety for people with noisy jobs – after all, constant exposure to loud noises can rip out our sensitive ear hair cells. Such damage is irreparable; we are born with just 30,000 of these precious hairs and once they’re gone, they’re gone for good. Written by John Ankers — Bechara Kachar NIDCD, National Institutes of Health, USA
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Ear-y Noise

The cochlea, pictured super-magnified, is a spiralling tunnel that leads deep inside our ear. It acts as a funnel, feeding sound from the outside world through a ‘lawn’ of sensory hair cells which line the organ of corti, highlighted here in red. As noise floods in, the sensory hairs wave around, opening up electrical channels that take speedy messages to the brain. Our auditory hair cells are intricate and fragile, making them prone to damage by diseases and infections. The World Health Organization (WHO), promoting today as International Day for Ear and Hearing, supports immunization schemes worldwide in efforts to prevent hearing loss. They also advise on safety for people with noisy jobs – after all, constant exposure to loud noises can rip out our sensitive ear hair cells. Such damage is irreparable; we are born with just 30,000 of these precious hairs and once they’re gone, they’re gone for good.

Written by John Ankers

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Source: bpod.mrc.ac.uk

Drumming Sound Have you ever experienced that uncomfortable feeling in your ears as an aeroplane takes off? The pressure change as we climb higher into the sky causes unpleasant sensations because our ears have not had time to adjust. Other than deep sea diving, flying is one of the few occasions when we’re aware of our eardrums. Known as the tympanic membrane by scientists, the eardrum separates the middle and inner ear from the environment and converts sound into vibrations that are further processed for our brain to register. Explosions and physical trauma to the ear can cause rupture of the membrane that may lead to infections and hearing difficulty. Some World War II pilots intentionally ruptured their eardrums to stop air pressure problems when flying and the Bajau tribe of the South Pacific do the same to facilitate deep sea diving, albeit often with severe consequences for their hearing. Written by Georgina Askeland — Image originally published under Creative Commons (CC-BY-NC-ND); Courtesy of Wellcome Images
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Drumming Sound

Have you ever experienced that uncomfortable feeling in your ears as an aeroplane takes off? The pressure change as we climb higher into the sky causes unpleasant sensations because our ears have not had time to adjust. Other than deep sea diving, flying is one of the few occasions when we’re aware of our eardrums. Known as the tympanic membrane by scientists, the eardrum separates the middle and inner ear from the environment and converts sound into vibrations that are further processed for our brain to register. Explosions and physical trauma to the ear can cause rupture of the membrane that may lead to infections and hearing difficulty. Some World War II pilots intentionally ruptured their eardrums to stop air pressure problems when flying and the Bajau tribe of the South Pacific do the same to facilitate deep sea diving, albeit often with severe consequences for their hearing.

Written by Georgina Askeland

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  • Image originally published under Creative Commons (CC-BY-NC-ND); Courtesy of Wellcome Images

Source: bpod.mrc.ac.uk

Deaf Disconnect Dogs and cats hear better than us, but there is one household pet with which we are on a par – the gerbil. This rodent is therefore ideal for studying deafness. Over a million people in the UK are deaf due to a condition called auditory neuropathy, where nerve cells connecting the ear to the brain break down. Scientists studying gerbils have shown how stem cells could help patch up this broken link. Auditory nerves carry sound messages from the ear to the brain. Damaging these nerves in gerbils led to significant hearing loss. To repair this, human embryonic stem cells were transformed, using a cocktail of factors, into early auditory nerve cells. These cells were then transplanted into the gerbil’s ears. Some grew extensions into the brain, so mending the damaged link and partially restoring hearing. These findings bring us one step closer to stem cell therapy for human deafness. Written by Lux Fatimathas — Image originally published under Creative Commons (CC-BY-NC-ND); Courtesy of Wellcome Images
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Deaf Disconnect

Dogs and cats hear better than us, but there is one household pet with which we are on a par – the gerbil. This rodent is therefore ideal for studying deafness. Over a million people in the UK are deaf due to a condition called auditory neuropathy, where nerve cells connecting the ear to the brain break down. Scientists studying gerbils have shown how stem cells could help patch up this broken link. Auditory nerves carry sound messages from the ear to the brain. Damaging these nerves in gerbils led to significant hearing loss. To repair this, human embryonic stem cells were transformed, using a cocktail of factors, into early auditory nerve cells. These cells were then transplanted into the gerbil’s ears. Some grew extensions into the brain, so mending the damaged link and partially restoring hearing. These findings bring us one step closer to stem cell therapy for human deafness.

Written by Lux Fatimathas

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Source: bpod.mrc.ac.uk

Hearing Hairs Deep inside our ears there are thousands of hairs waving around to collect and amplify sound. These hairs sprout from hair cells and are very fragile. Toxic chemicals can damage their foundations leading to hearing loss. Here we see beds of hair cells from the ears of mice, stained red, with their nuclei stained blue. The hair cells in the picture on the left have been damaged by gentamicin, a powerful antibiotic that unfortunately also causes these cells oxidative stress [the potentially damaging situation caused by a cell’s inability to remove toxins] highlighted here by a green stain. A similar chemical called apramycin was fed to identical cells on the right, which show much less stress. Finding out what makes apramycin less toxic to ear hair cells might guide the design of new antibiotics to tackle infections with minimal side effects. Written by John Ankers — Erik Böttger University of Zurich, Switzerland Published in PNAS 109(27): 10984-10989 
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Hearing Hairs

Deep inside our ears there are thousands of hairs waving around to collect and amplify sound. These hairs sprout from hair cells and are very fragile. Toxic chemicals can damage their foundations leading to hearing loss. Here we see beds of hair cells from the ears of mice, stained red, with their nuclei stained blue. The hair cells in the picture on the left have been damaged by gentamicin, a powerful antibiotic that unfortunately also causes these cells oxidative stress [the potentially damaging situation caused by a cell’s inability to remove toxins] highlighted here by a green stain. A similar chemical called apramycin was fed to identical cells on the right, which show much less stress. Finding out what makes apramycin less toxic to ear hair cells might guide the design of new antibiotics to tackle infections with minimal side effects.

Written by John Ankers

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Source: bpod.mrc.ac.uk

Sensing the Vibes Whether the merest whisper or an earth-trembling boom, the delicate apparatus deep within our ear vibrates helping us to perceive sound. Tiny bones rattle and create waves in a fluid-filled compartment, the cochlea. Undulation of the cochlea lining is sensed by thousands of hair cells whose ciliia (the cluster pictured is magnified 75000 times) jostle. This movement in turn morphs into a signal that nerves transmit to our brain, which acknowledges the ‘sound’. Mechanical wear by repeated exposure to loud noise, meningitis, or congenital disorders can cause deafness by damaging hair cells. Many thousands worldwide with profound impairment have had hearing restored by a cochlear implant. Hair cells are replaced with electrodes surgically positioned inside the cochlea and sound is received through a microphone fixed on the scalp. In the future stem cell therapy could supersede this form of treatment. Written by Lindsey Goff — Dr Spiro Comis/WTMPL Originally published under Creative Commons (CC-BY-NC-ND); Courtesy of Wellcome Images
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Sensing the Vibes

Whether the merest whisper or an earth-trembling boom, the delicate apparatus deep within our ear vibrates helping us to perceive sound. Tiny bones rattle and create waves in a fluid-filled compartment, the cochlea. Undulation of the cochlea lining is sensed by thousands of hair cells whose ciliia (the cluster pictured is magnified 75000 times) jostle. This movement in turn morphs into a signal that nerves transmit to our brain, which acknowledges the ‘sound’. Mechanical wear by repeated exposure to loud noise, meningitis, or congenital disorders can cause deafness by damaging hair cells. Many thousands worldwide with profound impairment have had hearing restored by a cochlear implant. Hair cells are replaced with electrodes surgically positioned inside the cochlea and sound is received through a microphone fixed on the scalp. In the future stem cell therapy could supersede this form of treatment.

Written by Lindsey Goff

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  • Dr Spiro Comis/WTMPL
  • Originally published under Creative Commons (CC-BY-NC-ND); Courtesy of Wellcome Images

Source: bpod.mrc.ac.uk