SCIENTISTS have found a previously unknown and alternate pathway by which memories are stored in the brain, allowing so-called “second-learning”.
The discovery by Australian and American scientists challenges the orthodox view on how the brain handles its core functions of memory and learning, said molecular neuroscientist Dr Bryce Vissel from Sydney’s Garvan Institute.
The research also revealed a promising new target for drugs or therapy that could one day help people with Alzheimer’s disease, and other brain impairment, to boost their cognition and learn new skills.
“Up till now, memory has long been thought to involve a molecule on nerve cells called the NMDA receptor in the hippocampus (a region of the brain),” Dr Vissel said.
“The NMDA receptor was previously thought to be important not only for forming new memories, but was thought to be essential for all memory formation.
“The way we have been thinking about this is fundamentally correct, however, it is not always true – there is an angle that has been completely missed.”
What was missed was the role played by calcium permeable AMPA receptors, an alternate process now known to handle memory storage during events which are novel but not totally unique experiences.
Dr Vissel, working along with fellow experts at the University of California Los Angeles, conducted a series of experiments in mice that showed how disabling the brain’s NMDA receptor did not always block the ability to learn as would have been previously thought.
They found evidence of the alternate AMPA processes kicking in and allowing the mice to learn completely new things in cases where it had already learned the general “rules” of its environment. “This is `second-learning` involving a completely different mechanism of learning in the brain,” Dr Vissel said.
“… in some circumstances of learning, you don’t need to use the NMDA receptors at all, the system that has been until now thought to be essential for all learning.
“This is a fundamental discovery of a new mechanism underlying how memories can be formed.”
Alzheimer’s sufferers could be helped by discovery of new pathway to storing memories
The discovery is also significant when viewed alongside growing scientific evidence showing the important role NMDA receptors play in the progression of Alzheimer’s disease.
Dr Vissel said new anti-Alzheimer’s drugs, which boost the role played by AMPA receptors, could be developed along with new “iterative, repetitive” teaching programs that could help people with brain impairment learn new skills.
“For a typical Alzheimer’s patient … you could start to teach them a set of rules about how to live, which doesn’t depend on the NMDA receptor,” Dr Vissel said.
“The point is there is an alternative mechanism of learning that can be exploited.”
The research is published in the journal PLoS ONE.