Memories Are Made of What? Part 2

In my last post I began describing how memory or learning might occur in the brain of a mammal, as described by Dennis Bray in his wonderful book, Wetware. 

         It seems that learning and memory are somehow encoded in synapses between neurons.  The more often a synapse is used, the stronger and more developed it becomes.  But this strengthening depends on neuron A sending a signal to neuron B at the same moment that neuron B is also sending a signal.

         Here’s how the chemistry may work.  When A sends a signal to B, B may not be aware of the signal because its receptors are plugged up.  But if B is also signaling, B’s electrical change may unplug its receptors.  Then it can receive the signal from A.

         If the signal from A to B is repeated, a protein called Cam II kinase starts changing itself in permanent ways, so that the synapse between A and B becomes permanently stronger and more sensitive.  The changed protein is “…like a toggle switch that, once thrown, remains on forever.”  This switch then turns neuron B on at the slightest twitch from neuron A.

         But how is it possible for this situation to last a lifetime?  For this is how long many memories and much learning do last.  More on this next time.