November 24, 2010

Jet lagged and forgetful? It’s no coincidence

(November 24, 2010)  Chronic jet lag alters the brain in ways that cause memory and learning problems long after one’s return to a regular 24-hour schedule, according to research by University of California, Berkeley, psychologists.

Twice a week for four weeks, the researchers subjected female Syrian hamsters to six-hour time shifts – the equivalent of a New York-to-Paris airplane flight. During the last two weeks of jet lag and a month after recovery from it, the hamsters’ performance on learning and memory tasks was measured.

As expected, during the jet lag period, the hamsters had trouble learning simple tasks that the hamsters in the control group aced. What surprised the researchers was that these deficits persisted for a month after the hamsters returned to a regular day-night schedule.

What’s more, the researchers discovered persistent changes in the brain, specifically within the hippocampus, a part of the brain that plays an intricate role in memory processing. They found that, compared to the hamsters in the control group, the jet-lagged hamsters had only half the number of new neurons in the hippocampus following the month long exposure to jet lag. New neurons are constantly being added to the adult hippocampus and are thought to be important for hippocampal-dependent learning, Kriegsfeld said, while memory problems are associated with a drop in cell maturation in this brain structure.

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