Friday, February 7, 2014

Therapy for hearing loss?

"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."

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


Visual deprivation improves frequency selectivity of A1 neurons
Visual deprivation improves sound discrimination performance by A1 neurons
Visual deprivation strengthens thalamocortical synapses in A1, but not in V1
Crossmodal changes are more effectively recruited than unimodal changes in adult

The full study is below:

Though these scientific findings have only been with mice, there seems to be potential consequences for humans. Until the findings are verified with further research, what might we make of the results, do with them?

In zazen, sitting, we are not in the dark, our eyes are not closed. Nevertheless, if you sit zazen, if you sit for extended periods, for sesshin of days or even longer training periods, what do you notice about your senses both during those times and afterwards?

(c) 2014 Elihu Genmyo Smith