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Factual brains, uneventful lives.

Beth, Jon, and Kate lose track of their lives every day. Since childhood, each Of them--now age 14, 19, and 22, respectively--has found it nearly impossible to remember what just happened. School ,buildings and other familiar places always look new and prove easy to get lost in; the youngsters need frequent reminders of the times of class meetings, scheduled appointments, and even major holidays; and each day's telephone conversations, messages, and visitors drain quickly into a well of forgotten incidents.

Everyday memory losses such as these make life so difficult and potentially dangerous that Beth, Jon, and Kate's parents must provide them with constant supervision.

But there's a kicker: The three memory-deprived young people have attended mainstream schools, where they attained good speech and language skills, read and spelled as well as most of their peers, and acquired loads of factual knowledge.

A study of these unusual individuals in the July 18 SCIENCE indicates that fact (or semantic) memory and event (or episodic) memory derive largely from separate areas of the brain. The hippocampus, a small brain structure that has long been tied to memory, regulates recall of personal experiences but plays only a minor role in the accumulation of factual knowledge, concludes a research team headed by neuroscientist Faraneh Vargha-Khadem of University College London Medical School.

Severe brain seizures afflicted Beth shortly after birth, Jon by age 4, and Kate at age 9. Brain scans show that each of them has incurred extensive damage to the hippocampus, with surrounding regions having been spared, the scientists report.

Hippocampal destruction in monkeys stifles memory in ways similar to the episodic evaporation noted in humans, they add. After such damage, for example, monkeys lose their way in familiar surroundings but recognize experimental stimuli that yielded rewards in prior training sessions.

Parts of the brain's outer layer, or cortex, may formulate contextfree semantic memories, Vargha-Khadem and her coworkers theorize. Context-rich, episodic memories require additional interventions by the hippocampus and adjacent neural tissue, they suggest.
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Title Annotation:Behavior; semantic and episodic memory dependent on different brain areas
Publication:Science News
Article Type:Brief Article
Date:Aug 2, 1997
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