Word: hippocampus
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...most used) synapses. How you spend your time may be critical. Research shows, for instance, that practicing piano quickly thickens neurons in the brain regions that control the fingers. Studies of London cab drivers, who must memorize all the city's streets, show that they have an unusually large hippocampus, a structure involved in memory. Giedd's research suggests that the cerebellum, an area that coordinates both physical and mental activities, is particularly responsive to experience, but he warns that it's too soon to know just what drives the buildup and pruning phases. He's hoping his studies...
There's evidence on both sides. The systems that are involved in adding emotional content include a brain structure called the amygdala, which gets activated when we experience strong emotions, particularly negative emotions, and it does influence memory systems - in particular, a structure known as the hippocampus. So there's opportunity there to influence how strongly memories get laid down. But the hippocampus is involved in both the storage as well as the retrieval of memory. Things that are emotionally charged may simply be memories that are more likely to be accessed or used...
Small and his colleagues 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...
...even if you, like the mouse, are low in RbAp48, don't pin all the blame for your memory loss on your hippocampus. As people get older, their attention starts to flicker, and that plays a role of its own. The prefrontal cortex, which controls planning, organization, abstraction and forethought, is the same region that allows us to concentrate, and it starts to diminish in size well before middle age. It also begins to use the brain's fuel, glucose, less efficiently and loses about half the neurotransmitter dopamine it once had. The result of all this, says Amy Arnsten...
...born with a fixed number of brain cells that die off as we age, 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...