A research team, including senior author David Glanzman of the Integrative Biology and Physiology and Neurobiology departments at UCLA, has found that early Alzheimer’s patients may be able to restore lost memories by reestablishing connections between neurons in the brain.
Neurons are long cells that are essentially weaved together in a neural network. Messages are sent from one neuron to another, and throughout the body through synaptic gaps, or synapses. In relation to memory, the nature of their complex connections allows for a single memory to be provoked by various stimuli, making them accessible by various routes. This allows some memories to remain despite brain damage in certain areas of the brain.
Previously, scientists believed that memories were stored in the synapses. Now, there’s reason to believe that they may be stored in the nucleus of neurons. This is because dementia and Alzheimer’s are caused by the decay of synaptic connections between neurons; if memories were truly stored in the synapses, they would be unrecoverable. However, studies of a marine snail called Aplysia that has a similar brain function to humans showed that it is possible to trigger the regrowth of lost neural connections and recover lost memories.
Image Source: Andrew Brookes
The research team analyzed synaptic growth and long-term memory in the snails. They sent electric shocks through the tails, prompting defense mechanisms, and found that the resulting release of serotonin encourages memory formation. While observing the synaptic growth, they found that inhibiting protein synthesis prevented proper storage of long-term memories. To verify these observations, they added serotonin and then, shortly after, a protein synthesis inhibitor to a snail’s synaptic connections in a petri dish. When serotonin was added, neural connections were formed, whereas the inhibitor substance stopped growth from occurring. The interrupted growth resulted in the snails’ inability to remember their learned defense mechanism (a long-term memory); memories were not stored. When the protein inhibitor was injected 24 hours after the behavior was learned, the snails retained the memories. Therefore, even if memory formation is temporarily stopped, the already-established memories remain.
The scientists used these experiments to conclude that memories were preserved despite damage to the synapses.
As long as the neurons are still alive, the memory will still be there, which means you may be able to recover some of the lost memories in the early stages of Alzheimer’s.
-David Glanzman
Since Alzheimer’s consists of damage to synapses and not the nerve cells themselves, this study yields a possibility for the prevention of Alzheimer’s when detected in early stages.
Featured Image Source: memory game by jessica wilson
