Word: hippocampus
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Wilson and his team implanted sensors in the hippocampus of rats, the part of the brain that is responsible for short-term memory in both rats and humans. The team tracked the activity of a dozen to a few dozen of the neurons in the hippocampus--only a tiny fraction of the cells in that part of the brain...
...into any type of brain cell, depending on the chemical signals they receive as they grow. Early studies hint that they may even belong to a more primitive population of stem cells that can form anything from skin to blood to liver. Gage showed that a part of the hippocampus contains actively developing neural-stem cells; he further speculated that this regeneration may eventually be controlled by the timely addition or subtraction of a few key growth factors in the brain's chemical soup...
...1960s seemed to support the belief that the supply of neurons is fixed at birth. Hence the surprise when Elizabeth Gould and Charles Gross of Princeton University reported last year that the monkeys they studied seemed to be minting thousands of new neurons a day in the hippocampus of their brain. Even more jarring, Gould and Cross found evidence that a steady stream of the fresh cells may be continually migrating to the cerebral cortex...
...telling that the spawning ground for the neurons is the hippocampus, which is indisputably crucial to memory. Patients with hippocampal injuries lose their ability to acquire new facts, though they can still recall impressions laid down in the years before the damage occurred. Maybe, Gould speculates, the newly generated hippocampal neurons are especially agile in forming connections with one another. As in the canaries, the new cells would readily join hands to encode a new memory. Then, when they were no longer needed, they would be flushed from the system, and the engram would be transferred elsewhere for safekeeping...
That explanation fits pretty well with the old theories. More puzzling, though, is another of the study's findings: the steady migration of new neurons from the hippocampus to the cerebral cortex. Could these neurons be somehow involved in ferrying information into permanent storage--storing short-term memories for the long term...