In the September 18th issue of the journal Neuron, results of research conducted at the Massachusetts Institute of Technology (MIT) revealed a gene that appears to be important to the process of “memory extinction.” Memory extinction is the natural process of older memories being “overridden” by newer experiences. In the process, our conditioned responses to stimuli can change: what once elicited a fearful response doesn’t always need to if the danger has ceased. In patients with post-traumatic stress disorder (PTSD), it is often very difficult to override a traumatic memory and change the conditioned response.
2010 NARSAD Grantee, Andrii Rudenko, Ph.D., and a research team at MIT found that the activation (or de-activation) of a gene known as Tet1 in mice was linked to how well they were able to integrate new memories and “let go” of bad memories, and how much their conditioned behavioral responses changed accordingly.
When the researchers “knocked out” (or de-activated) the Tet1 gene in some of the mice, they observed that while they were able to form memories and learn new tasks, they lagged behind the “control” mice (with normal Tet1 levels) in learning that a situation was no longer “dangerous” (and adapting behavior accordingly). To test this, the researchers conditioned the mice to fear a particular cage where they received a mild shock and then once the memory was formed, put the mice in the cage but did not deliver the shock. After a while, the control mice lost their fear of the cage as new memories replaced the old ones, but the mice lacking Tet1 remained fearful.
“They don’t re-learn properly,” said Dr. Rudenko, an MIT post-doctoral scholar. “They’re kind of getting stuck, and cannot extinguish the old memory."
The researchers are now looking to see if increasing Tet1 levels may be a way to boost memory extinction and help de-traumatize patients that seem to get “stuck” in fearful memories and associations.
Read the official press release from MIT.
Read an article about this research from the Huffington Post.