Not everyone hears the same. Many studies have shown that people who have become blind early in life can experience improved hearing compared to vision, but a new experiment seems to have revealed the neural basis of this phenomenon for the first time.
The common assumption that people without vision have superior hearing is not just an assumption; It is clear from a survey that only shows it, besides other benefits that the condition seems to give.
But even though researchers know for a long time that people with early onset blindness have more nuanced or accurate hearing, the brain is mechanisms that make it possible to stay far away.
"This is the idea that blind people are good at auditory tasks, because they have to do the world without visual information," says neuroscience Ione Fine of the University of Washington.
"We wanted to explore how this happens in the brain."
For this purpose, Fine and her team used functional magnetic resonance imaging (fMRI) imaging to investigate activity in the auditory cortex ̵
In their cohort, four of the blind participants had early onset blindness and five had the condition anophthalmia, where the eyes failed to develop.
In the experiment, these participants played a number of pure tones that resonated at different frequencies, while a fMRI device recorded its brain activity. A control group went through the same procedure.
When the researchers analyzed the results, they found that the blind persons in the trial tended to treat the tones in a narrower and more accurate bandwidth than the visual individuals, suggesting that their sense of frequency response in the auditory cortex was better refined than non-blind group.
"Our study shows that the hearts of blind individuals can better represent frequencies," says one of the team, says Kelly Chang, the psychologist graduate student.
"For a visual person who has an accurate representation of the sound is not as important because they have vision to help them recognize objects, while blind individuals only have hearing information.
This gives us an idea of what changes in the brain explain why blind people are better off picking out and identifying sounds in the environment. "
Left: red colors show b Rain regions respond more to low-toned tones while blue-colored areas responded more to high tones Right: Overall, the frequency setting of blind participants was narrower than that of vision.
It is worth noting that we are only talking about a small group of participants here, which we must always come up with Remember when considering the results of studies.
But the team nevertheless suggests that their results constitute the first evidence of systematic changes in neural testing within the human hearing cortex as a result of blindness.
How the hearing cortex develops this form of neuroplasticity is still unknown, but in their paper, the team speculates that it may be "a development adjustment to early blindness, the ongoing effects of visual t failure and / or differential hearing requirements that result from being blind ".
Future studies can help us get closer to the understanding of the basis of brain hearing changes observed in detail here, but at present researchers have a new goal to investigate, although there is still much left for us to learn.
"In blind individuals, more information must be extracted from sound – and this region seems to develop improved capacity as a result," says Fine.
"This provides an elegant example of how the development of abilities within infant brains is affected by the environment they The results are reported in Journal of Neuroscience .