It turns out that the auditory centers in the brains of the congenitally deaf process information provided by the sense of touch
Yanai Ofran
Legend has it that when Beethoven's ears got heavy he sawed off the legs of his piano and placed it on the floor. When he pressed his cheek to the floor while playing, he felt the music. These vibrations were the only sensory cue he used to write the Ninth Symphony. This, of course, was also the only way in which the composer "heard" the most popular of his works. This week it turns out that there is scientific logic in the story about the piano that saw off the legs.
Dr. Dean Shibata from the University
Washington discovered that the brains of deaf people use the auditory centers to process vibrations that are reported to the brain by the sense of touch. It's possible, Shibata said this week, that these findings could be used to develop revolutionary hearing aids for the congenitally deaf.
Researchers from Dr. Shibata's team discovered in the past that deaf people have a high sensitivity to vibrations caused by music in the air. Many congenitally deaf also seem to be aware of this sensitivity. When Heather Wheatstone McCallum won the Miss America pageant in 1995, many television viewers were amazed by the way she danced to the background music. McCallum is deaf from birth. In the US, in recent years, concerts for the deaf have been held where the listeners hold balloons to increase the vibrations, and these events are a great success.
Shibata wanted to test how the brains of deaf people process such vibrations. He asked ten congenitally deaf students and ten hearing students to hold a plastic tube in their hand. Occasionally the pipe was shaken. A functional MRI machine looked at what was going on in the subjects' brains at the time.
In the listeners, as expected, active activity was recorded in the area that processes information from the sense of touch. But in the deaf, in addition to this area, activity was also observed in the area of the cerebral cortex that normally processes auditory information. The brain of the deaf processed the vibrations of the pipe with the tools that a normal brain processes sounds. "According to this finding," Shibata said this week at the American Society of Radiology conference, "the experience deaf people go through when they 'feel' music is similar to what other people go through when they hear music."
How does it happen that the role of an area in the brain changes? Shibata defines this as a "struggle for real estate". The cerebral cortex is the brain's supercomputer. The most complex information that reaches the brain is transmitted from the sensory organs, through several relay stations, to cells in the cerebral cortex. The intricate cell networks of the cerebral cortex process this information and dictate behavior accordingly. These prodigious computational and processing capabilities make the cerebral cortex a valuable resource. Normally, the nerves coming from the ears are wired to the auditory cortex, a special area of the brain that specializes in processing sounds. But in the deaf, these wires do not transmit any information. A precious piece of cerebral cortex may be left without employment. Between the senses there is a fierce competition for the free area, with each sense trying to recruit these cells to improve the processing of the information it transmits to the brain. According to the new findings, it seems that the brain prefers to allocate this group of cells in favor of the sense of touch. With this extra computational resource, the deaf's ability to distinguish vibrations is improved.
Shibata's experiment was conducted on congenitally deaf. Babies' brains are very plastic and a process of rewiring can easily occur in them. In people who became deaf at a later age, such as Beethoven, the process is probably slower, but it is likely that even in them, in the end, the auditory cortex is allocated in favor of the sense of touch.
Shibata's conclusion is that deaf people's sensitivity to vibration is similar to hearing people's sensitivity to sounds. He proposes to develop an assistive device for the deaf that will be attached to the skin and turn syllables and sounds into vibrations. The special processing ability in the auditory cortex will allow, he claims, the deaf to distinguish between different syllables and sounds based on these vibrations. For such a device to work, says Shibata, you need special practice that will increase the sensitivity of the auditory cortex to vibration. Therefore, he claims, it may be worthwhile to expose deaf children to music from a very young age, when the brain's wiring process is still at its peak.
Beethoven. The story about the piano with its legs sawn off has scientific logic
