Spending some time in complete darkness has now been tied to permanent improvements in hearing, confirming the long-held belief that the loss of one sense sharpens another.

Dr. Hey-Kyoung Lee, associate professor of neuroscience at Johns Hopkins University and one of the lead authors of the new study, said in press release that the findings also illuminate a potential therapy method for the hard of hearing. "In my opinion, the coolest aspect of our work is that the loss of one sense — vision — can augment the processing of the remaining sense, in this case, hearing, by altering the brain circuit, which is not easily done in adults," she said. "By temporarily preventing vision, we may be able to engage the adult brain to now change the circuit to better process sound, which can be helpful for recovering sound perception in patients with cochlear implants for example.”

The findings, which are published in the journal Neuron, show that adult mice who spend one week in complete darkness display a significant increase in their ability to respond to sounds. Compared to a control group that spent the same period in a naturally lit environment, these mice developed more complex nerve circuitry in the primary auditory cortex, the brain area that processes sounds. "There is some level of interconnectedness of the senses in the brain that we are revealing here," Patrick Kanold, the paper's second lead author, explained.

Lee, Kanold, and colleagues theorize that the observed rewiring of mice’s brains arises from a temporary increase in the brain’s “malleability.” This state, they say, is akin to a “critical period” that occurs in our early youth, when our brains continuously adapts to the surrounding soundscape. As a result, entirely new nerve connections are formed.

Temporary Blindness To Work Out Your Ears

Although you are welcome to try the experiment on your own, it may take some more research before we can effectively improve our hearing by spending time in the dark. In an email to Medical Daily, Kanold said that the next step is to see how the mice’s improvements can be mapped onto the human brain. After all, we’re dealing with two rather different minds.

“Now we know that in mice it is possible to change the way sound is processed in the adult brain. That gives us hope that eventually there might be the potential for simple treatments for human central hearing problems,” he said. "We don't know how much time people would have to spend in the dark to permanently improve their hearing. But our study shows that it potentially may be possible to develop some crossmodal training exercises that will benefit hearing.”

 

Source: Petrus E, Isaiah A, Lee H, et al. Crossmodal Induction of Thalamocortical Potentiation Leads to Enhanced Information in the Auditory Cortex. Neuron. 2014.