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Family income kindles brighter sparks in the brain's judgment and attention regions

December 9, 2008 |  5:14 pm

The injustices of growing up poor start early, and even before adolescence, may leave their mark on the brain's prefrontal cortex -- the area known as the seat of higher reasoning and a key node in making comparative judgments, weighing risks and focusing attention amid distractions. Researchers have long observed performance gaps between rich and poor in some tests of cognitive skills and reasoning. They wondered whether poverty not only degraded performance on such tests, but also changed underlying brain structure and function as well.

A small study, soon to be published in the Journal of Cognitive Neuroscience, suggests an answer: By age 10, the prefrontal cortex of a child who has grown up in poverty appears to respond to some test stimuli in ways that are detectably different from the electrical activity shown in the prefrontal region of a more affluent child. And by some measures, the response pattern seen in the brains of poor kids looked very much like that seen in an adult who has suffered a stroke in those regions. Overall, no such similarity was seen in the cortical response patterns of the group in the highest socioeconomic bracket.

A pair of UC Berkeley neuroscientists, joining forces with researchers from UCLA, Stanford and University of British Columbia in Vancouver, rigged up the noggins of 26 kids -- with an average age of 9.5 years -- with probes that sense the ebb and flow of electrical current in different regions of the brain. Then, they put them through a battery of neuropsychological tests. Half of the kids came from families with annual incomes that averaged just over $27,000 and generally had low levels of parental education; the other half came from families where a primary caregiver had completed at least four years of college and in which annual household income averaged a little more than $97,000.

The kids, on the whole, performed roughly evenly on the neuropsych tests, which were meant to be relatively easy. Investigators were not looking at performance, but at how the two groups of kids' brains "lit up" in response to the task. The authors, led by Berkeley neuroscientist Mark M. Kishiyama, speculated that growing up in environments with a narrower range of stimulation -- ranging from books and play groups to the give-and-take of child-parent interaction -- may put poorer kids at an early disadvantage.

Enriched environments such as early preschool, the authors suggest, could erase such differences. With debates expected soon over President-elect Barack Obama's proposal for universal preschool, this preliminary study may get some high-level attention. With only 26 participants, however, it is far from definitive. Stay tuned for more.

-- Melissa Healy

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