Most people are familiar with the idea that people who are blind have better hearing than those with normal vision. It was formerly thought that this compensation for lack of vision could only develop in the brains of the very young. However, new research conducted at the University of Maryland and Johns Hopkins University suggests that the brain may be more flexible than previously believed.
In the study, researchers kept one group of healthy mice in total darkness for a week, and exposed the other group to natural light for a week. Then the team used electrodes to measure activity in neurons in the mice’s primary auditory cortex. This is the part of the brain that processes how loud a sound is and its source. By analyzing this data, researchers found that the mice who were exposed to a week of darkness had much better hearing than the control mice.
This suggests that the circuits that process sensory information can be re-wired in the brains of adult mice, even after the early critical period for hearing. These findings seem to contradict the idea that once the critical period for hearing is past, the auditory system doesn’t respond to changes in an individual’s soundscape.