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Neuroscientists have discovered that restricting a person's sight for as little as a week may improve the brain's ability to process sound.
Dr. Hey-Kyoung Lee, researcher at the Zanvyl Krieger Mind/Brain Institute and an associate professor of neuroscience at the Johns Hopkins University, collaborating with biologist Patrick Kanold at the University of Maryland at College Park and three other scientists, recently published a paper on the relationship between hearing and vision in the brain in the journal Neuron.
In a series of experiments using mice, Lee, Kanold, and other researchers discovered how the neural circuits that support hearing and sight work together to support each sense, and to maximize sensory inputs when one or the other of the two senses is deficient.
The scientists placed healthy adult mice in a darkened (although not completely dark) environment for a week and observed their brain activity and behavioral responses to certain sounds. They then compared the brain activity and behaviors of the test mice to a those of a control group of mice that had been kept in normal light conditions.
“Our result would say that not having vision allows you to hear softer sounds and better discriminate pitch,” Dr. Lee said in a Johns Hopkins University press release.
The researchers also found that deafening, placing the mice in a very quiet environment, increased the strength of neural circuits in the visual cortex. When the mice were deprived of sound, their vision became more acute.
How would these findings apply to humans?
Dr. Lee gave the example of trying to listen to a familiar song over a lot of background noise. Dur to the background noise, some of the notes and some of the rhythms may be lost. It may be possible to hear the melody but not the harmony, or it may not be possible to feel the rhythm due to the interference of ambient sound.
Most of us lose some of our sensitivity to sights and sounds later in life, even if our eyes and ears are in good shape. The connections between the thalamocortical inputs in our brains are less flexible when we are adults than they were when we were children. But deprivation of one of our senses can restore these circuits so that the brain is able to devote more attention to one sense than another.
Dr. Kanold stated in a Johns Hopkins University press release that he does not know how long a human would have to stay in a darkened room to have heightened sound perception. or if many people would be willing to try. The effect in mice is reversible when they return to normal-light conditions, Kanold said.