Word: smith
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...This is higher-order learning, and it takes multiple trials to learn," explains Sheryl Smith, a professor of physiology and pharmacology at Downstate. Prepubescent mice mastered the task quickly. Postpubescent mice also did quite well. But mice in the throes of puberty, which occurs at age 5 weeks, couldn't seem to get it through their furry little heads...
...series of elegant experiments, Smith and her collaborators showed that this temporary learning deficit could be traced to a remarkable change that occurs at puberty in the hippocampus, a region of the brain that is involved in remembering places and integrating other kinds of learning. The change affects the GABA neurotransmitter system. GABA, which is present in all mammals, inhibits or down-regulates nerve signals, as opposed to exciting them; this calming, relaxing system is activated by tranquilizers like Valium and the popular sleep drug Ambien, which attach to GABA receptors and act similarly to GABA. But at puberty, female...
...Smith and company found that having this abundance of receptors, which recede later in adolescence, interferes with learning. And just as fascinating, a dose of THP reverses the learning deficit. "We are suggesting that mild stress is advantageous to learning in adolescence," she says. (Smith's current study involved only female mice; she plans to look next at males and females to see if there are gender differences on the learning task...
...might this relate to humans? Actually, mild stress has been shown to improve learning in people; too much does the opposite. Smith wonders whether the discovery may help explain certain learning declines, like the drop-off in the ability to learn to speak a foreign language without an accent, which occurs sometime around puberty...
...learn new things at puberty might merely reflect the fact that teenagers are becoming more attuned to social issues than dull learning tasks: "It may be a shift in what we pay attention to and are motivated to look at that's driving this." But that would not explain Smith's mice or similar biochemical changes she has observed in tissue samples related to learning. (There's no question of motivation in a petri dish...