Females Learn Some Things Better Than Males, Keep New Brain Cells Longer, Rutgers Psychologist Discovers

Shors wanted to know whether sex differences in learning influence the survival of new neurons – cells that process and transmit information by electrochemical signaling -- located in the hippocampus. She discovered that differences between male and female brains continue throughout life. Shors discovered that female rats subjected to conditioned-response training learned their responses better and preserved more neurons than the male rats subjected to the same conditioning. Specifically, females preserved a greater proportion of newly formed cells in the hippocampus.

Scientists have long known that learning physically changes the brain – that, for example, learning preserves new cells formed in the hippocampus.

“It’s a use-it-or-lose-it situation,” said Shors, “These new neurons are being produced all the time, but learning keeps them around for the future.”

Scientists have long known that male and female brains work differently. Among humans, for example, women tend to do better in tasks involving verbal communications and men in tasks involving the manipulation of complex spatial information.

Like many researchers studying the brain, Shors used rats for her study, titled Females Learn Trace Memories Better than Males, and Consequently Retain a Greater Proportion of New Neurons in their Hippocampus. But unlike previous researchers, Shors and her co-authors used male and female rats in equal numbers. They trained half the rats of each sex to blink after hearing a tone, and used the other half as a control group.

Their training method should be familiar to anyone who remembers reading about Ivan Pavlov’s work on classical conditioning in the early 20th century. Pavlov discovered that dogs could be taught to associate a stimulus, such as a sound, with food and would, therefore, salivate whenever they received the stimulus, whether food was forthcoming or not.

 In their work, Shors and her co-authors also used sound.

“The animal hears a tone, and then some time later receives a stimulus that causes it to blink,” Shors said. After a while, just hearing the tone causes the animal to blink. This is the sort of learning we do all the time, where we have to associate things together that aren’t necessarily happening together in time.”

Shors discovered that the male and female rats subjected to the conditioned response training preserved more neurons than their counterparts not subjected to the conditioning. Among the trained rats, females learned the responses better than the males, and preserved more neurons in their hippocampi.

“To me, what this demonstrates is not only that male and female brains are different, but by virtue of how they work, they continue to differentiate,” Shors said. ”Males and females act differently, and that has consequences for the anatomy of their brains.”

Shors coauthors are Christina Dalla, a postdoctoral scholar at the time the work was done and now an assistant professor at the University of Athens, in Greece; Efstathios Papachristos, a graduate student at the time and since awarded his Ph.D; and Abigail Whetstone, an undergraduate who received her bachelor’s degree from Rutgers in 2008.

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