A preliminary study carried out on mice who suffered from amnesia shows that in the case of retrograde amnesia – which is considered a loss of memory access, the patients don’t actually lose their memories but they simply become inaccessible for recall, which is a very different thing.
The study, published in the journal Science, on Thursday, the 28th of May 2015, focused on the use of an innovative technique called optogenetics.
By employing this technique, the researchers were able to select certain neurons and insert a protein in them via an engineered virus. After the protein was introduced, the cells showed an increased sensitivity to blue light, which made it easy for researchers to turn certain neurons on and off whenever they wanted to.
At first, they created a bad memory for the mice by using shocking devices. While doing this, they identified the neurons that were stimulated whenever the mice experienced the memory.
Afterwards, they had the mice suffer from retrograde amnesia by injecting them with anisomycin – which alters memory formation. When blue light was used, the researchers saw that their response returned.
Therefore, they concluded that memories that were previously regarded as lost could actually leave engram cells that remain active in the brain.
“Our conclusion is that in retrograde amnesia, past memories may not be erased, but could simply be lost and inaccessible for recall. These findings provide striking insight into the fleeting nature of memories, and will stimulate future research on the biology of memory and its clinical restoration,” said Susumu Tonegawa, who is the director of the RIKEN Brain Science Institute in Saitama in Japan and also the lead study author.
However promising this study might sound, it will not be available for humans very soon for ethical reasons. The method is invasive and it tags memories before they have been recorded in the brain.
Even so, the importance of their study cannot be neglected. This is mainly due to the fact they made the discovery that memories are not lost but just inaccessible. Thus, it is very likely that one day, a method suitable for humans is found.
Image Source: minibeatboxx