Lost memories could one day be restored, according to new research, offering hope for people with Alzheimer's.
The new study, carried out by scientists at the University of California (UCLA), casts doubt on the assumptions of neuroscientists that memories are stored at the synapses - connections between brain cells that are destroyed by Alzheimer's.
It is hoped that people in the early stages of the condition could have their memories restored one day.
"Long-term memory is not stored at the synapse," said David Glanzman, a senior author of the study, and a UCLA professor of integrative biology and physiology and of neurobiology.
"That's a radical idea, but that's where the evidence leads. The nervous system appears to be able to regenerate lost synaptic connections. If you can restore the synaptic connections, the memory will come back. It won't be easy, but I believe it's possible."
The team studied a type of marine snail called Aplysia to understand the animal's learning and memory, focusing on its withdrawal reflex and the sensory and motor neurons that produce it.
They enhanced this reflex by administering a series of mild electrical shocks to its tail. The enhancement lasts for days after a series of electric shocks, indicating the snail's long-term memory.
A serotonin and protein inhibitor combination was used to erase the snail's memory of how and when to defend itself. When the snail was given electric shocks, however, the response returned.
This would not have happened if memories were stored at the synapses, as these had been destroyed.
The researchers concluded that memory is not stored in the connections between synapses but elsewhere. Although they are unsure, they think they may be located in the nucleus of the neurons.
Professor Glanzman said this means memories will still be there as long as neurons are present, meaning it may be possible to restore memories lost in the early stages of Alzheimer's.
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