According to a study of rats published in the June issue of Behavioral Neuroscience, activation of different parts of the brain may depend on the presence or absence of estrogen. Rats treated with the hormone learned a place-oriented task faster than rats not getting it, but those not on estrogen were faster completing a response-driven task. These tasks are believed to be controlled by different neural or memory systems.

What we found is that given these analogous tasks that require different cognitive strategies, estrogen biased the rats to use a place, or spatial, strategy, said Donna L. Korol, a psychology professor at the University of Illinois at Urbana-Champaign. Those not given estrogen are better using a response, or non-spatial, strategy. This suggests that estrogen isnt just good for all kinds of memory. Rather, it is very specific in dictating what strategy one takes. Estrogen may enhance some and impair other forms of learning.

In the National Science Foundation-funded study, Korol and Lacy L. Kolo (St. Louis University School of Medicine) used young rats whose ovaries had been removed to decrease circulating estrogen levels. Three weeks later, some of them received injections of estrogen, while others got a placebo, before learning to find food in two similar four-arm mazes.

In the place-training test, food always was at the same place, but the required turn changed, depending on the rats starting point. Rats on estrogen learned the task faster than the untreated group. For the response-training test, the rats always found food by turning right (or left) at the first opportunity regardless of where they had started. Rats without estrogen learned this task quicker than the estrogen-tre
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Contact: Jim Barlow
b-james3@uiuc.edu
217-333-5802
University of Illinois at Urbana-Champaign
15-May-2002