Spending a Week in the Dark Could Boost Hearing

By Tia Ghose Live science

Spending a week in the dark may boost the ability to hear, at least in mice, a new study suggests.
The research, published today (Feb. 5) in the journal Neuron, showed that mice that lived in total darkness for a week developed stronger connections between neurons, or brain cells, in the part of the brain that processes sounds.
"Even in adults, when you actually lose vision for a few days, you can improve auditory processing," said study co-author Hey-Kyoung Lee, a neuroscientist at Johns Hopkins University in Maryland.The new results suggest that sensory deprivation could be a viable way to train adults with hearing loss to better process sounds coming from cochlear implants, the researchers said.

In the dark
Many studies have found that people who are born blind have heightened hearing, and can even navigate using a kind of echolocation. But it isn't clear how exactly this super sensing developed. [Inside the Brain: A Photo Journey Through Time]
To find out, Lee and her colleagues subjected mice that were a few weeks old to a week of total darkness. The researchers then put the animals back into the light, and tested their response to sound.
"Once you put the animals in the dark for about a week, the neurons in the auditory part of the brain start processing sound better," Lee told Live Science. "They can respond to much softer and weaker sound," and have a better sense of pitch, she said.
Electrodes placed in the mice's auditory cortex, which processes sound, also showed stronger connections between the neurons.
Though the findings are in mice, the same process could be at work in humans, and may explain why blind people have stronger hearing, Lee said.
Human treatment
It's still too soon to say whether spending prolonged time in the dark could give people better hearing and, if so, how long they would have to be in the dark. But if sensory deprivation was found to work, it could provide a way to help adults with hearing loss regain that sense.
For instance, cochlear implants, which are devices that translate sound into signals sent directly into the brain, don't work as well for older people, whose brains are less changeable than those of young children.
But the new research suggests that a bout of sensory deprivation could help adult brains process sound signals from cochlear implants better, Lee said.
The findings are interesting because the hearing improvements were seen even in grown animals, other experts said.
"It's surprising how quickly these effects can be observed (after just a week of deprivation), and that this takes place in animals that had normal vision for the first few weeks of life," when the mice are essentially "teenagers," Robert Froemke, an otolaryngology (ear, nose and throat) researcher at New York University who was not involved in the study, wrote in an email to Live Science.
Still, it's too soon to say whether sensory deprivation could help humans regain their hearing, Froemke said, adding that "more is not necessarily better, especially in the case of hearing."
If the connections between brain cells are too strong, it could also lead to other problems, such as tinnitus, a condition that brings a constant ringing in the ears, Froemke said.
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