Even neurons have favori...( At least a third of the communicating c...)

Activity of neurons in the prefrontal cortex of monkeys trained to judge the number of dots on a computer screen reflected changes in quantity -- peaking for a preferred number and then dropping off progressively as the discrepancy between numbers of dots increased, the researchers found. The study adds to mounting evidence showing how the prefrontal cortex categorizes information from the senses. Drs. Andreas Nieder, David Freedman and Earl Miller, Massachusetts Institute of Technology, report on their findings in the September 6 2002 Science.

"Judging the difference between the number of items we see is one way of categorizing and making sense of them," explained Miller. "This capacity to quickly glean concepts and meaning from experience underlies the "executive" functions of the prefrontal cortex, which are disturbed in disorders like schizophrenia and autism."

"The ability to judge the relative quantity of items in the visual field is highly adaptive," note the researchers. "Social animals such as primates can make decisions to fight or flee by judging the relative number of friends versus foes; in foraging, choosing a larger alternative can contribute to survival."

Although much more highly developed, the human brain's capacity to represent numbers likely involves many of the same properties as discovered in the monkey brain, say the researchers. They suggest that future studies may lead to a better understanding of such numerical competence, with possible applications in education and in the treatment of cognitive deficits.

Miller and colleagues are finding that visual categories are represented in the cortex at the level of indivi
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Contact: Jules Asher
NIMHpress@nih.gov
301-443-4536
NIH/National Institute of Mental Health
5-Sep-2002