What You Hear Depends on What Your Hands Are Doing: Sudy
A study by researchers from Georgetown University Medical Center has linked motor skills and perceptions and also relates it to an understanding of what the left and right hemispheres of the brain "hear."
According to the researchers, the study results may help stroke patients recover their language abilities, and could help improve speech recognition in dyslexic children.
"Language is processed mainly in the left hemisphere, and some have suggested that this is because the left hemisphere specializes in analyzing very rapidly changing sounds," says the study's senior investigator, Peter E. Turkeltaub, M.D., Ph.D., a neurologist in the Center for Brain Plasticity and Recovery.
This newly created center is a joint program of Georgetown University and MedStar National Rehabilitation Network.
For the study, the researchers hid rapidly and slowly changing sounds in background noise and 24 volunteers were asked to simply indicate whether they heard the sounds by pressing a button, medical Xpress reported.
"We asked the subjects to respond to sounds hidden in background noise," Turkeltaub explained. "Each subject was told to use their right hand to respond during the first 20 sounds, then their left hand for the next 20 second, then right, then left, and so on."
The findings revealed that when the volunteers used their right hand, they were more likely to hear the rapidly changing sound than when they used their left hand. The vice versa was applicable for the slowly changing sounds.
"Since the left hemisphere controls the right hand and vice versa, these results demonstrate that the two hemispheres specialize in different kinds of sounds-the left hemisphere likes rapidly changing sounds, such as consonants, and the right hemisphere likes slowly changing sounds, such as syllables or intonation," Turkeltaub explains.
"These results also demonstrate the interaction between motor systems and perception. It's really pretty amazing. Imagine you're waving an American flag while listening to one of the presidential candidates. The speech will actually sound slightly different to you depending on whether the flag is in your left hand or your right hand."
Turkeltaub hopes that an understanding of the basic auditory systems and their interaction with motor systems could help explain why language resides in the left hemisphere of the brain, could also lead to new treatments for language disorders.
"If we can understand the basic brain organization for audition, this might ultimately lead to new treatments for people who have speech recognition problems due to stroke or other brain injury. Understanding better the specific roles of the two hemispheres in auditory processing will be a big step in that direction. If we find that people with aphasia, who typically have injuries to the left hemisphere, have difficulty recognizing speech because of problems with low-level auditory perception of rapidly changing sounds, maybe training the specific auditory processing deficits will improve their ability to recognize speech," Turkeltaub concludes.
The study was presented at Neuroscience 2012, the annual meeting of the Society for Neuroscience.