Scientists have had a breakthrough in retrieving lost memories.     

 In the latest experiment, scientists analyzed mice to understand what happens to lost memories. The question: Are they wiped out permanently or still there?

Researchers in the lab of Susumu Tonegawa at Picower Institute for Learning and Memory at MIT published their recent findings published in the journal, Science. They used a series of studies using latest light-based brain tracking techniques.

This shows memories in certain forms of amnesia that aren’t erased but remain intact and are potentially retrievable. Studied mice and trained them to remember getting a shock in a certain chamber. Scientists then used protein labels to tag specific cells in the hippocampus of the brain. Area is activated and responsible for making that memory .  Found 3-5% of the cells in a portion of the hippocampus are recruited to form a memory §  Mice were then placed into same room again and froze because they recalled and anticipate the shock.   Animals were given a drug that interrupts the memory, making the process immediately after the shock, they no longer remembered the shock and didn’t free if placed in the room .

Researchers also tried to retrieve the lost memory by activating the circuit of cells that were responsible for memory without the shock.   Used a technique called optogenetics: laser lights stimulate tagged cells in the hippocampus. Circuit was activated, animals froze again, even if they were in a neutral room that they didn’t associate with shock.  Scientists stressed that this type of amnesia in general is due to inaccessibility of a memory. 

However the memory itself is still present.   Findings could have implications for humans    Results suggest:

• Memories lost after traumatic brain injury, concussion, car accident or stressful event, or some forms of dementia — MAY BE RETRIEVABLE
• The success of this attempt majorly relies on how soon after the memory loss occurs
• Scientists predict its more likely to retrieve memories soon after the traumatic event, before the memory is completely stored in the brain   
• These results mainly establish that those memories may still be there, even if thought to be lost

The Debate of Amnesia

Scientists have long debated how it happens.   Many studies point to the problem being due to storage of memory rather than the inability to retrieve it from long-term memory banks of the brain . 

Retrograde amnesia, when memory loss occurs after traumatic injury, stress or diseases such as Alzheimer’s, is probably caused by damage to the brain cells involving memory retrieval rather than memory storage.