How the Brain Makes Sense of the Senses

Study offers new information about how it processes sound, sight and touch

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MONDAY, Feb. 23, 2004 (HealthDayNews) -- Theories about the way the brain processes touch, sight and sound may need revision, suggest results from a new study in this week's issue of the Proceedings of the National Academy of Sciences.

Researchers from Wake Forest University Baptist Medical Center and the University of California at San Francisco recorded cell activity in the brains of 31 adult rats to test two conflicting theories about brain organization.

"One theory is that individual senses have separate areas of the brain dedicated to them," lead investigator Mark Wallace, an associate professor of neurobiology and anatomy at Wake Forest, says in a prepared statement.

"In this view, information is processed initially on a sense-by-sense basis and doesn't come together until much later. However, this view has recently been challenged by studies showing that processing in the visual area of the brain, for example, can be influenced by hearing and touch," Wallace says.

In this study, Wallace and his colleagues created a map of the rat cerebral cortex, the brain area believed to be responsible for perception. The scientists created the map to illustrate how different areas of the cerebral cortex respond to touch, sound and sight.

The study found that while large areas of the cerebral cortex are mostly devoted to processing information from a single sense, cells along the borders between these areas can share information from more than one sense.

"This represents a new view of how the brain is organized," Wallace says, and may explain how a person who suffers the loss of a sense early in life can develop greater acuity with their remaining senses.

"Imaging studies in humans show that when sight is lost at a young age, a portion of the brain that had been dedicated to sight begins to process sound and touch. It is possible that this change begins in the multi-sensory border regions, where cells that are normally responsive to these different senses are already found," Wallace says.

More information

The American Rhinologic Society has more about the loss of taste and smell.

SOURCE: Wake Forest University, news release, Feb. 23, 2004

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