The Concept of Neuroplasticity

This is my first excerpt from Chapter Two, “How We Learn Addiction.” It’s an introduction to the concept of neuroplasticity, and discusses why I chose to use this concept to explain not only the process of addiction, but also the process of recovery.

Nearly every recovery self-help book explains the mechanism of addiction, if they address it at all, by discussing the chemical changes that take place in the brain during the various phases of the addiction process, some of which are irreversible. Explaining addiction in that manner merely feeds into the disease and powerlessness model, when we are not powerless over our addictions at all. I’m not denying that some of these chemical changes are, in fact, irreversible, but they do not effect our ability to overcome our addictions by changing our thoughts, beliefs, and actions. Fortunately there is an entirely different way to look at both the process, and the effects of addiction that is not only equally valid, but also does a much better job of explaining not only how we become dependent upon substances, but also how most of us manage to recover, on our own, from this “irreversible” condition.

Our brains have the ability to rewire themselves, changing structurally and functionally, in response to changes in our environment and our experiences. For most of the twentieth century, the general consensus among neuroscientists was that the brain was relatively fixed and immutable after a certain critical period during early childhood. This belief has been challenged by new findings and evidence, especially detailed brain imaging that has conclusively proven that our brains retain a significant ability to change, which is called “plasticity,” into adulthood, and even old-age. Neurological research indicates that experience can actually change both the brain’s physical structure and functional organization from top to bottom. It was also once believed that our brains can never grow new neurons, but this has also been proven to be false, for at least two areas of the brain having to do with learning can indeed grow new neurons. In fact, it’s happening to you right now as you read this page! This characteristic of the brain, called “Neuroplasticity,” not only is responsible for our ability to learn and unlearn, but also for the ability of some people to recover from serious injuries, strokes, and diseases that disable or disrupt some of their brain functions.

Why am I talking about this when most other books on addiction discuss the chemistry that drives the process? I do it for two important reasons:

  1. Understanding that we learn to become addicted is an important key to overcoming it, and the underlying chemistry, fascinating though it may be, that drives the addiction learning process, doesn’t really matter. In fact, the chemistry varies from drug-to-drug, while the learning process remains the same.
  2. We don’t recover from addiction chemically; we recover by changing our thoughts, feelings, beliefs, and therefore our actions. This is an unlearning and a learning process, and in the context of neuroplasticity happens in the same way as addiction itself, making the whole process much easier to explain.

To draw a sports analogy, if you were teaching your son or daughter to hit a baseball, would you talk about contracting this muscle or that, at what time, and to what degree, for a hundred different muscles? Of course not! You would just tell them to keep their eye on the ball, their shoulders level, take a good swing, and follow-through. As we go through this discussion, I think you will understand why I chose to go this way – at least I hope you do!

At birth, our brains contained approximately 100,000,000,000, that’s one hundred billion nerve cells, called neurons. Each and every neuron has the ability to connect to anywhere from a few thousand to as many as 100,000 other neurons.

The neurons connect to one another through what is called a synapse. The synapse is nothing but a gap, one-millionth of a centimeter wide. Through these tiny gaps flow all of our thoughts, emotions, and sensory perceptions. The scientific consensus is that at the peak, around age three, the average neuron makes about 15,000 connections with other neurons, before some of them begin to die off in a process called pruning. In the adult brain, we can estimate the number of connections, or synapses to be somewhere between 100 and 1,000 trillion!

Many of the connections we are born with are indeed dictated by our genes, but as the human genome has something on the order of 35,000 different operative genes, and only half or so of those are involved in the brain, it seems clear that most of the connections that are active in our brains right now are the result of our environment and experiences, not heredity. Synapses that are not used are pruned-away. By one estimate, we lose about 20 billion a day between childhood and early adolescence. Connections we don’t use wither and die, while at the same time we are continually forming new connections as we learn about the world around us and interact with others.

As Jeffrey M. Schwartz puts it in his book, “The Mind and the Brain:”

“Here is where the power of genes falls off rapidly: genes may lead neurons to make their initial, tentative connections and control the order in which different regions of the brain (and thus physical and mental capacities) come on line, but it’s the environmental inputs acting on the plasticity of the young nervous system that truly determine the circuits that will power the brain. Thus, from the earliest stages of development, laying down brain circuits is an active rather than a passive process, directed by the interaction between experience and the environment. The basic principle is this: genetic signals play a large role in the initial structuring of the brain. The ultimate shape of the brain, however, is the outcome of an ongoing active process that occurs where lived experience meets both the inner and the outer environment.”

One additional concept is necessary in order to understand neuroplasticity, and that is the issue of synaptic strength. In 1949 it was proposed, and later confirmed by studies, that when two connected neurons are simultaneously active a good deal of the time, the synapse itself changes in such a way that makes the activation of one cell more likely to cause the other cell to fire. This has become known by the maxim “cells that fire together, wire together.” Picture the concept as being similar to a well-used dirt road in the country, with deep ruts worn by generations of traffic, making it easy to stay on the path, or like a school child learning the multiplication tables, repeating them over and over, until constant use allows us to remember that seven-times-seven is forty-nine without having to do any conscious computation. That’s the concept of synaptic strength.

In order to communicate with each other, neurons synthesize chemicals called neurotransmitters. These are released from one side of the synaptic gap and attach to receptors on the other side. They have the dual function of transmitting a signal and modulating signals that are already present. Communication between neurons takes place through this exchange of neurotransmitters. Information flows from one end of a neuron to the other because of a difference in electrical potential between the two ends of the neuron. This difference in potential produces an electrical current, and when it reaches a sufficient magnitude, it forces a release of neurotransmitters from one neuron to the other.

So, we have these billions of neurons with trillions of connections, all talking with one-another. How do they work together in the process of learning? Why do we remember some things, forget others, learn new things, and most of all, form what we come to know as “habitual behavior patterns?”

My next post will answer these questions, as it explains the learning (and unlearning) process in terms of neuroplasticity.

(Excerpted from Chapter 2 of the forthcoming book: “Powerless No  Longer” Copyright© 2011, Pete Soderman)

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