X-Message-Number: 23583
From: "Basie" <>
Subject: New evidence in animals suggests 
Date: Tue, 9 Mar 2004 15:21:22 -0500

            New evidence in animals suggests that theories about how the
brain processes sight, sound and touch may need updating. Researchers from
Wake Forest University Baptist Medical Center and colleagues report their
findings in the current issue of the Proceedings of the National Academy of
Sciences.

            Using electrodes smaller than a human hair, researchers from
Wake Forest Baptist and the University of California at San Francisco
recorded individual cell activity in the brains of 31 adult rats. Their goal
was to test two conflicting ideas about brain organization.


            "One theory is that individual senses have separate areas of the 
            brain

            dedicated to them," said Mark Wallace, Ph.D., the study's lead 
            investigator.

            "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 and colleagues created a map of the rat cerebral cortex, the
            
            part of the brain believed responsible for perception. The map was 
            created

            to show how different areas respond to sight, sound and touch.  They
            found

            that while large regions are overwhelming devoted to processing 
            information
            from a single sense, in the borders between them, cells can share
            information from both senses.

            "This represents a new view of how the brain is organized," said
            Wallace, an associate professor of neurobiology and anatomy at
            Wake Forest Baptist.

            He said these multisensory cells might also help explain how
            individuals who suffer a loss of one sense early in their life 
            often develop greater acuity in 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 
            these

            multisensory border regions, where cells that are normally 
            responsive to
            these different senses are already found."

            Wallace said the finding is also important because it suggests that

            the process of integrating sensory information might happen faster 
            in the

            cerebral cortex than was previously thought. Wallace said that the 
            ultimate

            goal of this research is to understand how the integration of 
            multiple
            senses results in our behaviors and perceptions.

            "It should come as no surprise when I say that we live in a

            multisensory world, being constantly bombarded with information from
            many

            senses. What is a bit of a surprise is that although we now know a 
            great

            deal about how the brain processes information from the individual 
            senses to

            form our perceptions, we're still in the early stages of 
            understanding how
            this happens between the different senses. "





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