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http://story.news.yahoo.com/news?tmpl=story&u=/nm/20020917/hl_nm/brain_action_dc_1

Monkeys' Brain Activity Predicts Future Action

Tue Sep 17, 1:44 PM ET

NEW YORK (Reuters Health) - A new study in monkeys shows that a burst of brain activity can predict the order of certain behaviors before the activity takes place. What's more, researchers also can tell if a monkey is going to make a mistake before it actually happens by looking at the pattern of brain activity, according to the report.

In an experiment involving monkeys trained to draw several shapes, researchers detected specific patterns of brain activity linked to the drawing even before the monkeys picked up a pen, or in this case, a joystick used to draw on a computer screen.

The researchers were studying a concept called serial order, which is used in many activities, according to a team led by Dr. Apostolos P. Georgopoulos of the University of Minnesota in Minneapolis. Speech is a good example of an action that depends on serial order, Georgopoulos and colleagues point out in the online early edition of the journal Proceedings of the National Academy of Sciences ( news - web sites).

Sounds called "phonemes are uttered serially to make a syllable, syllables are strung serially to complete a word, words are emitted serially to make a sentence, etc.," the authors write.

Now, Georgopoulos and his team report that brain patterns related to a specific serial action are present even before any of the individual steps take place. It seems like the steps that make up serial order--used in everything from typing to reaching and grasping--are mapped out ahead of time.

The study involved two monkeys who were trained to use a joystick to draw a series of shapes on a computer screen. Using electrodes implanted in the neocortex--a part of the brain known to play a role in serial order--the researchers monitored the activity of several hundred neurons.

For each segment the monkeys drew--each of three sides of a triangle, for example--the researchers observed a specific pattern of neuron activity in the prefrontal neocortex. What's more, these specific patterns were detectable before the monkeys started to draw.

Brain activity before drawing was also a good predictor of whether a monkey would make an error in drawing, according to the report. Monkeys' mistakes often occurred when they got ahead of themselves. For example, in the case when a monkey was supposed to draw segment A first, then segment B, but accidentally drew B first, the pre-drawing activity pattern for B tended to be greater than usual.

Although this code was discovered in the prefrontal cortex, the authors note that the various brain areas may also play a role in serial order information.

SOURCE: Proceedings of the National Academy of Sciences Early Edition 2002;10.1073/pnas.162485599.

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