Word: gyrus
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...have been trying to understand this difference. Small's hunch--now proven--was that a node of the hippocampus different from the one affected in Alzheimer's was breaking down in normal memory loss. "In humans, monkeys and rats," he says, "normal aging targets a node called the dentate gyrus, while a different node--the entorhinal cortex--is relatively spared. But in Alzheimer's disease, it's almost exactly reversed." Small has gone deeper, pinpointing a protein molecule known as RbAp48 that is lower in the brains of people suffering ordinary age-related memory loss. He and his colleagues...
...making us, well, dimmer. That, however, is not the case. It is now known that the brain continues to produce neurons throughout the life cycle, but only in two places: the olfactory bulb and the hippocampus. And not just anywhere in the hippocampus but in the dentate gyrus, the very node that Small has identified as the site of impairment in normal memory loss. So why should memory fade at all? The answer may come from...
...scientists have long known, as belly fat--which disrupts body chemistry more than less reactive fat elsewhere on the body--increases, blood glucose rises along with it. Some of Small's most recent animal studies show that rising glucose levels in turn disrupt the function of the dentate gyrus. That doesn't draw a straight and conclusive line between waistline and memory, but it does suggest one. "It's possible," Small says, "that blood glucose, which tends to drift upward as we get older, is one of the main contributors to age-related memory decline...
...with clear paths left from sofa to kitchen to bathroom, and the rest piled high with debris. When Saxena scanned the brains of these highly particular people, he found that they had equally particular abnormalities. Instead of hyperactivity in any area, they had reduced activity in the anterior cingulate gyrus, the part of the brain that helps you focus your attention and make decisions. "Those are things that compulsive hoarders have a lot of trouble with," he says...
While these images were viewed, the researchers used functional magnetic resonance imaging (fMRI) to monitor brain activity. The researchers paid special attention to activation of the amygdala and the fusiform gyrus, the region of the brain known to be involved in processing human faces...