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Scientists can use light to switch on a neuron.
In the film Amèlie,
the main character is a young eccentric woman who attempts to change the lives of those around her for the better. One day Amèlie finds an old rusty tin box of childhood mementos in her apartment, hidden by a boy decades earlier. After tracking down Bretodeau, the owner, she lures him to a phone booth where he discovers the box. Upon opening the box and seeing a few marbles, a sudden flash of vivid images come flooding into his mind. Next thing you know, Bretodeau is transported to a time when he was in the schoolyard scrambling to stuff his pockets with hundreds of marbles while a teacher is yelling at him to hurry up.
We have all experienced this: a seemingly insignificant trigger, a scent, a song, or an old photograph transports us to another time and place. Now a group of neuroscientists have investigated the fascinating question: 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 a part 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.