It would be completely misleading to say that our memories are filed neatly in our brains, ready to be pulled out whenever we feel nostalgic. Thanks to advances in neuroscience, we now know that making and recalling memories is a process that uses your whole brain and involves cells being triggered and fired, which essentially re-wires the circuitry of your brain.
Scientists theorized that this complicated process is facilitated, at least partially, by specific proteins. They first tested the theory on fish. In the study, they gave fish drugs that prevented the proteins from being made, which resulted in fish that were unable to recall what took place after the protein-inhibitors were administered. From here, scientists discovered that they could target long-term memories and delete them.
Whenever you try to recall something, you’re actually physically changing that memory in your mind. The more you try to reflect on old memories, the less accurate they become because they are rebuilt every single time you try to remember them. Given that, if the protein-inhibitor was administered as you recalled a particular memory, the memory might be erased — just like how it worked with the fish.
The theory was tested on lab mice, which were placed in a chamber that played a specific tone before administering an electric shock through the floor. The mice learned to associate the chamber and sound with an electric shock. Even months later, the mice would freeze up and show stress whenever the sound was played. But when the researchers place the mice in a different chamber, played the tone, and administered a protein-inhibitor, the mice showed no fear in relation to the sound. Placed back in the old chamber, the mice showed the classic fear response.
The whole experiment demonstrated that researchers were able to selectively erase a part of the mice's memories (the ones associated with sound), while leaving the memory of the shocking chamber intact. And scientists who conducted the study believe that someday a similar technique could be used for humans dealing with post traumatic stress disorder (PTSD) or addiction.