Brain keeps tabs on arbitrary patterns. (Behavior).

Several parts of the frontal brain cooperatively identify apparent regularities in random sequences of events and detect breaks in those patterns, neuroscientists have found.

These brain regions, previously implicated in the noting of novel stimuli and in keeping related information in mind, generate expectations about upcoming events by continuously scrutinizing incoming information, theorize Scott A. Huettel of Duke University Medical Center in Durham, N.C., and his colleagues.

The researchers used functional magnetic resonance imaging to measure blood flow throughout the brains of 16 adults. Each volunteer viewed random sequences of circles and squares presented one at a time on a computer screen. Surges in blood flow provide an indirect sign of increased neural activity.

Brief but substantial rises in frontal-brain activity followed two types of pattern breaks, Huettel's group reports in an upcoming Nature Neuroscience. These consisted of a break in a repeated pattern, such as three circles followed by a square, or in an alternating pattern, such as three circle-square pairs followed by two circles.

Frontal-brain activation was greatest after breaches of patterns in an eight- image sequence, the longest one analyzed by the scientists. These new results coincide with evidence that a limited working memory may actually aid recognition of all sorts of regularities in the world, some useful and others not (SN: 11/22/97, p. 334). That's because it's easier to detect positive correlations in smaller batches of information than in larger ones. --B.B.