Memory Molecules

There are still a great many mysteries about memory:

• The molecules in neurons are constantly changing, as are many of the connections between cells. So how can memory be maintained for a lifetime in an environment that is in a constant state of flux?
• Why is it that you can remove large regions of the brain yet memories are not lost? Even in the late stages of Alzheimer’s disease, some long-term memories are maintained even when much of the brain is taken over by plaques and tangles.
• How much memory is there outside the brain and in the body?
• Is some memory maintained not in the brain itself but in fields associated with the body?

Gradually some questions are being answered not just by technology, but by asking new questions and bringing new types of expertise to bear on these problems.

A very interesting new study was published last week in the Journal of Neuroscience. The paper was not by neurologists, but by two mathematicians from the Brain Institute at the University of Utah. Their research suggests that memories are held in our brains because certain proteins serve as anchors, holding other proteins in place to strengthen the connections between nerve cells known as synapses. The anchors keep proteins in place, and these proteins in turn determine how strong a synapse is. And the strength of the synapse is a key to forming and retaining memories.

Synapses function by electrical activity in a neuron releasing a chemical neurotransmitter that affects another neuron or an organ.

One of the primary neurotransmitters involved in learning and memory is called glutamate, that binds to a number of receptors. But the most important for memory are the "AMPA receptors" that are embedded in the receiving ends of neurons. The AMPA receptors are held in place by special scaffolding molecules.

The mathematicians were able to make several predictions about the way in which AMPA receptors stay in place and how repeatedly learning something strengthens the connections between neurons.

The key to learning and remembering is anchoring AMPA receptors on our neurons.

I went into the technical side a bit, because this finding may help us get closer to understanding what goes wrong in Alzheimer’s disease.

It also ties in with some other research out this week in the journal Neuron. A team from the Univesity of Oxford has been trying to work out why adults may find learning more difficult than children. The young learn things more easily, but older brains stiore information more efficiently. They also focused on synapses, and  seem to have found the mechanisms involved.

Young brains have many "silent" synapses that don’t do anything unless called upon to learn something. Older brains have to reuse synapses that have already been used, boosting the strength of connections with increased amounts of neurotransmitters.

So as we get older, our brains adopt different strategies for learning new material, and we should get ever better at organizing and integrating information.

That also fits with the strategies that we have used for improving people’s ability to learn and remember. We use connections as in Mind mapping, multiple sensory associations inclusing music, color and smells, and a sophisticated method for asking constant questions to see if new information fits with material that we have already asimilated.