Look at the little light …
When an important document reaches your hands, you will surely file it in a safe place. The same is true of our memories: they first appear in one part of the brain and then move to another for long-term storage in a process known as memory consolidation.
Now, according to a study published in the journal Science, led by Akihiro Goto of the University of Kyoto, mouse brains were used to demonstrate a new optic-neural system for manipulating memories. The technique hinders nerve activity, known as long-term potentiation or LTP, that would otherwise consolidate memory during sleep.
LTP strengthens synapses through neuronal activity and is essential for memory formation. When and where memories are formed in the brain can be determined by examining when and which cells undergo LTP. Drugs can alter it, but they have a general effect and are not good at targeting specific regions of the brain at specific times of memory consolidation.
For inspiration, Goto turned to Hollywood.
«In Men in Black, the agents erase memories with a flash of light. We did something similar, ”he says with a smile. His team uses light to deactivate proteins essential for LTP.
By swapping out black suits and sunglasses for white lab coats and safety glasses, co-author Yasunori Hayashi’s team lit up the brains of mice to inhibit cofilin, a protein essential for synapse function.
Brains are initially injected with the adeno-associated virus, or AAV – commonly used for gene delivery – which then expresses a fused protein made of cofilin and fluorescent SuperNova. When exposed to light, these proteins release reactive oxygen that inactivates nearby compounds like cofilin.
The occurrence of LTP in the hippocampus, where memories are first stored, is significant. When this area of the brain is irradiated, immediately after the mouse learns a task and then again during sleep after learning, memory is lost.
“It was surprising that the removal of local LTP by directed illumination clearly erased the memory,” Goto commented.
Hayashi believes that this new technology provides a method to isolate memory formation both temporally and spatially in the brain at the cellular level.
Synaptic abnormalities related to LTP are implicated in memory and learning disorders such as Alzheimer’s disease and also in psychiatric diseases such as schizophrenia.