A new study that was reported in the journal Nature has challenged conventional wisdom on the effect Alzheimer’s disease has on the brain. Furthermore the technique used in the study may provide a pathway for a new form of treatment which can one day retrieve some of the memories that have already been lost.
Researchers working out of the Institute of Technology at Cambridge, and led Nobel Prize laureate Susumu Tonegawa, began by modifying genes in one group of mice that are linked to development of plaques in the brain. By doing this they induced memory loss in the mice in the same way that Alzheimer’s would.
The researchers modified another set of genes within the mice so that they would produce light sensitive proteins inside the neurons of the hippocampus. The hippocampus is the part of the brain responsible for creating short term memories and is usually the part of the brain which the disease attacks first.
For the experiment, the researchers used a control group which they would place into an enclosed box that administered an electric shock. Quickly the control mice would begin to associate the box with the shock and would respond with fear.
With the experimental group they would do the same, however, because the modified mice were not able to form memories anymore they would not learn to associate the box with the shock and wouldn’t show any signs of fear. When the researchers repeatedly exposing the hippocampus of the experimental mice to a blue light and then placed them back within the box the mice would freeze up out of fear.
By pulsing the hippocampus with light they were mimicking the natural process of memory formation within the brain. This strengthened the connection between the hippocampus and the entorhinal cortex, the region responsible for forming long term memories.
The study has shown that the memories which are previously thought to be erased entirely through the progression of the disease may actually still exist. Concerns have been raised over whether or not the findings will translate from mice’s brains to human’s. Additionally researchers have not yet figured out how to stimulate a human brain with light, though they say they may be able to do it with electrical pulses and early trials have already begun.