Wednesday, April 11, 2012

Can a few neurons trigger a full memory?!!! 
In a new study , published in Nature ,a group of researchers from MIT showed for the first time that it is possible to activate a memory on demand, by stimulating only a few neurons with light, using a technique known as optogenetics. 
Optogenetics is a powerful technology that enables researchers to control genetically modified neurons with a brief pulse of light.

To artificially turn on a memory, researchers first set out to identify the neurons that are activated when a mouse is making a new memory. 
To accomplish this, they focused on apart of the brain called the hippocampus, known for its role in learning and memory, especially for discriminating places. Then they inserted a gene that codes for a light-sensitive protein into hippocampal neurons, enabling them to use light to control the neurons. 
With the light-sensitive proteins in place, the researchers gave the mouse a new memory. They put the animal in an environment where it received a mild foot shock, eliciting the normal fear behavior in mice: freezing in place. The mouse learned to associate a particular environment with the shock. 

Next, the researchers attempted to answer the big question: Could they artificially activate the fear memory?
They directed light on the hippocampus, activating a portion of the neurons involved in the memory,and the animals showed a clear freezing response. Stimulating the neurons appears to have triggered the entire memory.