The fact that visually impaired or blind people hear much sharper and better than sighted people has long been known. However, the specific processes occurring in the brain of such people have not been studied until now. Some of the questions were answered by researchers from Oxford and the University of Washington.
A team of scientists have published a paper in the peer-reviewed journal JNeurosci, in which they describe the results of their research. To visualize the processes occurring in the brains of the subjects, the method of functional magnetic resonance imaging was used, which makes it possible to assess the blood flow in various areas of the brain. Depending on its volume, it is possible to determine which part of this organ is more involved in current activities.
The subjects were divided into two groups, the control group - the sighted group, and the most interesting group - the blind group. Of the nine blind people, four lost the ability to see at an early age, and the rest had congenital defects in development. To assess hearing, the researchers alternately reproduced pure tones of different frequencies and pitches. Simultaneously, the brain activity of the test subjects was monitored in real time.
On the left side of the illustration, there is a visualization of the brain with marked areas of the auditory cortex: those highlighted in red are sensitive to low sounds, the blue part of the spectrum is - to high. On the right is a graph of sensitivity to nearby sounds, the results of the blind group are highlighted in red.
It turned out that the auditory cortex of the brain of blind people is more excited to separate tones in a series of similar ones in frequency - in other words, the blind are better at distinguishing similar sounds. The auditory centers of the brain are divided into areas "responsible" for the processing of different frequency spectra, but in subjects who are guided in life not by sight, but by hearing, this division is more pronounced. Despite the small sample, the scientists note that the new study is an accurate starting point for further work in this area.
Vasily Parfenov