Over at Telic Thoughts, I introduced the concept of Encapsulated Evolution. The idea here is that a process that occurs within an organism or cell might reflect a condensed version of evolution itself. Thus, an understanding of a physiological or cellular process, and envisioning this process expanded over time and space, could conceivably allow us a novel perspective on the process of evolution.

Recently, a study by Paul Bressloff, from the University of Utah, was conducted that shed more light on the process of learning. Learning is, of course, a neurological process that boils down to the molecular events that occur within the synapse, a 20 nm gap that separates neurons. What is remarkable is that in the days before Watson and Crick solved the DNA puzzle, a psychologist, Donald Hebb, correctly identified the basis of learning:

When an axon of cell A is near enough to excite B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased

This called strengthening the synapse and it is a biological explanation that connects learning with experience. When you learn, your brain is physically changed. But in what way? Bressloff's study supplies part of the answer.

One way a synapse is strengthened after repeated stimulation is to alter the membrane channels of the pre-synaptic neuron, causing it to release more neurotransmitter as a result. Bressloff's study focuses on changes in the post-synaptic neuron. And as the article (provided in the link above) explains, the change involves the receptors that bind the neurotransmitter. In this case, we simply increase the density of receptors on the post-synaptic membrane. But how?

The receptors, like so many other components of the cell, are in a constant state of flux. As a population, they are constantly being inserted into the membrane and then taken back out. This is called trafficking. As the article asks, "So how can an ever-changing synapse help retain learning and memories?"

Bressloff argues The simulation's answer: The strength of a synapse – and thus its ability to hold what we learn and remember – changes when there is a change in the number of scaffolding proteins that keep AMPA receptors in place in the synapse, specifically on the surface or cap of the mushroom-shaped dendritic spine. In other words, the most important factor in strengthening synapses was the presence of scaffolding proteins that hold AMPA receptor proteins in place so they can receive nerve signals from neurotransmitter chemicals. For synapses between nerves to grow stronger, "you can't just shove a bunch of new AMPA receptors to the surface because they will just go away again," Bressloff says. "You need to keep them there."

So how does this all relate to Encapsulated Evolution? According to Bressloff's model, the learning process can be viewed as an interplay between the flux of the receptors, the anchoring ability of the scaffold proteins, and experience (the distal cause of the neurotransmitter release). This sounds like evolution, where we substitute random mutations for flux, the genotype/phenotype for the scaffold proteins, and the environment for experience. If I was a non-teleologist, I would tease that intelligence is just condensed natural selection. But from the teleological perspective, I tease that evolution is just learning expanded.

So how might a front-loading designer design such a learning process? Perhaps you begin by designing your cells to be in a constant state of flux and find the equivalent of those anchor proteins.