Wednesday, November 4, 2009

Making a Smarter Rat

Overexpressing the NR2B gene lets brain cells communicate just a fraction of a second longer

The bumper sticker reads “My rat is smarter than YOU.” Transgenically-enhanced Hobbie-J –- named after a clever rat in a Chinese cartoon book – may not be smarter than you, but she appears to be smarter than the smartest known breeds of rat.

According to Science Daily, Hobbie-J was able to remember novel objects, such as a toy she played with, three times longer than the average Long Evans female rat, the smartest rat strain. Hobbie-J was also better at remembering which path she last traveled to find a chocolate treat.

Researchers from the Medical College of Georgia and East China Normal University developed Hobbie-J 's superior brainpower by transgenic over-expression of the NR2B gene, which in turn increased communication between NMDA receptor sites maybe a hundred milliseconds longer than normal, just enough to enhance learning and memory. NMDA receptors (and their NR2B subunits) are the controlling molecular structures for synaptic plasticity and memory.

"This adds to the notion that NR2B is a universal switch for memory formation," says Dr. Joe Z. Tsien, co-director of the MCG Brain & Behavior Discovery Institute and co-corresponding author with Dr. Xiaohua Cao of a paper called “Genetic Enhancement of Memory” published recently in PLoS One.

Gene expression is translation of information encoded in a gene into protein or RNA. When done to a very high level, it is known as over-expression. The researchers wanted to determine whether the NR2B gene is “a universal genetic factor that acts as a rate-limiting molecule” across species. Here’s a short video showing the process of gene expression:

Previous studies of mice suggest a common biochemical mechanism at the root of nearly all learning. Tsien and Cao wanted to show that the brain uses the same basic mechanism in rats when it forms associations. Their research supports the hypothesis that NR2B is a key switch that controls the brain’s ability to associate one event with another, critical to learning.

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