CHAMPAIGN, Ill. Next time an older person says that thinking is exhausting, believe it. Concentration, researchers say, drains glucose from a key part of the brains of young and old rats, but dramatically more from older brains, which also take longer to recover. The findings, detailed in two studies published in May, are part of research that eventually may impact how schools schedule classes and meals as well as our understanding of age-related deficits in memory and learning, said lead researcher Paul E. Gold of the University of Illinois. "The brain runs on glucose," said Ewan C. McNay of Yale University. "Young rats can do a pretty good job of supplying all the glucose that a particular area of the brain needs until the task becomes difficult. For an old rat given the same task, the brain glucose supply vanishes out the window. This correlates with a big deficit in performance. A lack of fuel affects the ability to think and remember."
Glucose is a naturally occurring sugar in the blood and the primary source of energy in human brain metabolism. Last year, Gold, a professor of psychology, and McNay broke ground when they reported declines of hippocampal extracellular glucose concentrations in rats as they went through a maze. Their findings challenged conventional thinking about levels and stability of glucose in the brain. It has long been thought that the brain always has an ample supply of glucose short of starvation.
"While this is the case in terms of consciousness, the new findings suggest that glucose is not always present in ample amounts to optimally support learning and memory functions," said Gold, who also is director of the Medical Scholars Program in the UI College of Medicine at Urbana-Champaign.
In the May issue of Neurobiology of Learning and Memory, Gold, McNay and Richard C. McCarty, formerly at the University of Virginia, reported that glucose drainage during a task is site specific. Hippocampal extracellular levels fe
Contact: Jim Barlow
University of Illinois at Urbana-Champaign