University of Iowa News Release
Release: Feb. 19, 2003
UI Researcher Maps Sound Processing Areas In Brain
A study led by a University of Iowa professor offers surprising new information about how sound is processed in the brain. The results of research led by Amy Poremba, an assistant professor of psychology in the UI College of Liberal Arts and Sciences, define precisely which areas of the cortex in a primate brain are associated with hearing. The study also identifies similarities between the auditory processing system and the better-studied visual system including maps that show which areas of the brain process both auditory and visual information.
The results were published in the Jan. 24 issue of the journal Science.
Poremba and her team are the first to use many different complex sounds during whole brain mapping to test which parts of the brain are used to process sound. They monitored the brain activity of monkeys hearing a wide variety of sounds including male and female human voices, music, and primate vocalizations.
Previous studies usually using simple tones of varying frequency from high to low had identified only a small part of the brain used to process sound. Poremba and her team showed that much larger sections of the brain are used to process complex sounds and that there is some overlap between those areas and areas that process visual information.
Now that Poremba and her colleagues have identified where auditory processing takes place in the brain, they can move on to studying how it happens, which will be a key to understanding memory, language, and learning problems that have to do with hearing.
Discovering that the auditory system is organized similarly to the visual system may be very helpful since so much more is already known about how the brain processes visual information, Poremba said.
"With vision we know everything from how we see color to how we differentiate between various objects," she said. "But we don't yet know how the brain separates sounds into discrete auditory events. We want to know how the brain assigns meaning to sound and how it focuses attention on sound."
In addition, identifying areas that are connected to more than one sensory process (in this case hearing and vision) is a significant step toward understanding how the brain seamlessly integrates the five sensory systems.
"Most of our higher cognitive functions require us to integrate sensory information-for example knowing that an apple is red and roundish, makes a crunching sound when being eaten and smells heavenly when baked with cinnamon in a pie," Poremba said. "Yet we don't know very much about how that process occurs in the brain. Now we know where to start looking in the primate brain."
Poremba's research team included Richard C. Saunders, Michelle Cook, Louis Sokoloff and Mortimer Mishkin of the National Institute of Mental Health, and Alison M. Crane of the University of Texas at Austin. This research was funded by the National Institutes of Health and the University of Iowa.
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