University of Iowa News Release
Jan. 29, 2004
UI Researcher Says Monkey Brains Process Communication Sounds Like Humans
New research led by a University of Iowa professor has shown for the first time that monkeys listening to calls from other monkeys have the same brain activity pattern seen in humans during language processing, giving scientists a starting point for investigating how communication and language may develop.
The study, led by Amy Poremba (left), assistant professor of psychology in the UI College of Liberal Arts and Sciences, found that monkeys process the sound of vocalizations from within their own species on the left side of the brain, just as humans process language on the left side. Previous studies had used animal behavior to suggest that this might be the case, but Poremba's study is the first to use neural imaging to show left-brain processing of species-specific sounds.
The results are published in the Jan. 29 issue of the journal Nature.
Poremba and her team studied monkeys' responses to several types of sounds including monkey calls, human voices, music, pure tones and scrambled monkey calls. Only during the monkey calls was the sound processed exclusively on the left side of the brain, Poremba said. Further, right-brain sound processing was suppressed during monkey calls, giving scientists the first concrete evidence of one mechanism for how "lateralization"-brain activity on one side or the other-occurs.
Poremba emphasized that while the study does not indicate that monkeys are capable of higher-order language, including grammar and syntax, the fact that they respond differently to sounds from their own species than to other types of sounds clearly demonstrates that communication signals between the animals are of special importance.
Communication is of major importance to our survival and yet we do not understand how the brain encodes this information, Poremba said. Much of human communication and language relies on learning simple auditory associations and rules. The discovery of this similarity in sound processing between monkeys and humans will facilitate further investigation into memory, language, learning problems and communicative disorders that have to do with hearing.
"By finding a specialized mechanism for communication processing in monkeys, we can start to visualize how it might occur in humans," Poremba said. "It has been extremely difficult to study the neural bases of language given that humans seem to have cornered the market on this form of communication. Finding an animal brain model of even simple communication allows for in-depth exploration of the building blocks for human language and communication. It gives us a roadmap to start studying the biological framework of how communication and possibly language evolved."
Poremba collaborated on this research with Mortimer Mishkin, Richard C. Saunders, Megan Malloy, Richard E. Carson, and Peter Herscovitch of the National Institutes of Health. This research was funded by the National Institute of Mental Health and the University of Iowa.
STORY SOURCE: University of Iowa News Services, 300 Plaza Centre One, Suite 371, Iowa City, Iowa 52242-2500.