Researchers from Colombia University have successfully restored the memories of mice with Alzheimer’s disease that were previously regarded as being lost. The successful technique saw the team of researchers focus a laser on the part of the brain used for memory storage.
It was widely accepted by scientists that when a person develops the disease, memories are lost due to the memory encoding neurons being destroyed by clumps of a protein called Amyloid beta. As a result of this, memories have always been regarded as being lost and never to be restored. This study has given new hope that access to memories are blocked as opposed to being forgotten in people suffering from Alzheimer’s disease.
During the study researchers genetically engineered neurons in 2 groups of mice. The first group were engineered to emit a yellow glow when activated as part of memory storage, and the second to emit a red glow when activated as part of memory retrieval. One group of mice were also engineered to develop a condition similar to Alzheimer’s with the other group acting as a control.
To test memory skills, the team gave the mice a lemon scent and then followed this with a small electric shock. The following week when exposed to the same lemon scent as expected the healthy mice remembered the smell and froze immediately, with the Alzheimer’s group forgetting their fear of the scent. The groups of mice were then assessed using an MRI and the subjects with the disease had little activity in the part of their brain used to recall the fear memories. Some mice were actually experiencing incorrect memories - a symptom commonly displayed in humans with the disease.
To test if the memories were lost or if access was being blocked to them, researchers attempted to stimulate the yellow neurons with focussed laser light using a technique known as Optogenetics. Using fiber optics, the scientists were able to effectively reactivate the neurons which they believe facilitated the mice in regaining their memories associated to the fear of the lemon scent.
Whilst Optogenetics sadly cannot be translated into a human-friendly treatment at the moment, knowing that memories may not be lost could lead to novel ways of how to approach managing the condition.