The Addictive Brain as taught by Professor Thad A. Polk

I recently purchased some courses from The Great Courses. The subjects were intended to help me in being a better SMART facilitator. The subjects are:

The Addictive Brain taught by Professor Thad A. Polk

Cognitive Behavioral Therapy taught by Professor Jason M. Satterfield

The Science of Mindfulness: A Research Based Path to Well Being taught by Professor Ronald Siegel and

Practicing Mindfulness: An Introduction to Meditation taught by Professor Mark W. Muesse

In learning, I always do better when I take notes, do outlines, highlight important parts and try to communicate what I’ve learned to others. I’ve decided to do blogs on these subjects as I am learning them. So hopefully my readers, which number in the single digits, can learn this material without having to buy the courses. To learn more go to You can put any of these courses in their search.

The first course I’ll do is The Addictive Brain. It’s a course given in 12 lectures. The first lecture is titled: Addiction 101.

Lecture 1: Addiction 101 is basically an introduction to the subject along with some definitions. Polk uses the term “addiction” with the meaning that you have pathological abuse of psychoactive substances. He notes that the DSM 5 now uses the term Substance Use Disorder instead of addiction. The new DSM also has 11 criteria now used to define the disorder. When 2 to 3 criteria met there is a Mild disorder, 4 to 5 is Moderate and 6 or more is Severe Substance Use Disorder. Although the 11 criteria weren’t in the lecture I post them here. You can substitute any drug for alcohol in this example.

The Eleven Symptoms of Alcohol Use Disorder

1.Alcohol is often taken in larger amounts or over a longer period than was intended.

2.  There is a persistent desire or unsuccessful efforts to cut down or control alcohol use.

3. A great deal of time is spent in activities necessary to obtain alcohol, use alcohol, or recover from its effects.

4. Craving, or a strong desire or urge to use alcohol.

5. Recurrent alcohol use resulting in a failure to fulfill major role obligations at work, school, or home.

6. Continued alcohol use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of alcohol.

7. Important social, occupational, or recreational activities are given up or reduced because of alcohol use.

8. Recurrent alcohol use in situations in which it is physically hazardous.

9. Alcohol use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by alcohol.

10. Tolerance, as defined by either of the following: a) A need for markedly increased amounts of alcohol to achieve intoxication or desired effect b) A markedly diminished effect with continued use of the same amount of alcohol.

11. Withdrawal, as manifested by either of the following: a) The characteristic withdrawal syndrome for alcohol, b) Alcohol (or a closely related substance, such as a benzodiazepine) is taken to relieve or avoid withdrawal symptoms.

The teacher then briefly discusses behavioral addictions such as gambling and the parallels with substance abuse. The last two lectures in this series covers those issues.

Lecture 2: The Psychology and Neuroscience of Reward

Dr Polk makes the claim that addictions “hijack” the brain’s reward system. The lecture breaks down the reward system into 2 factors one is the Psychology of Reward Processing and next the Neuroscience of Reward Processing.

For psychology he starts with basic Pavlovian conditioning then adds the concept that learning is based on “prediction error”. As long as Pavlof’s dog knew food was coming with the bell ringing the dog didn’t need to learn anything new in order to eat. Prediction error learning leads to changing our behavior to achieve a reward. He then talks about Reinforcement Learning, or figuring out how to behave in order to maximize short and long term rewards. He mentions a technique used in Artificial Intelligence programing called Temporal Difference Learning. Temporal difference learning is simply a series of learned behavior based on prediction error learning that can result in rewards such as winning a chess match. He also talks about the phenomenon of “backing up”. In the case of Pavlov’s dog anticipating the reward of eating is “backed up” to the sound of a bell. Has important implications for triggering urges.

Next he discusses some early neuroscience studies which show an area of the brain called the septal area gives people pleasure when stimulated. He notes how both people and rats will forgo basic survival like eating in order to stimulate these areas electrically.

He states there are 3 major brain areas associated with reward processing. The Nucleus Accumbens, the Prefrontal Cortex and the Ventral Tegmental Area.

Nucleus Accumbens – The Pleasure Center. What was stimulated in the early experiments. Major center involved in pleasure from drug stimulation. The Pleasure Center constantly urges us to seek rewards such as food, sex etc.

Prefrontal Cortex – Plays central role in controlling urges arising from reward center. Used to plan and make decisions about future behavior. Central role in controlling addiction. Can exert self control and considers the consequences of continued indulgence of the Pleasure Center.

Ventral Tegmental Area (VTA). The function of the VTA is more difficult to understand but I’ll try me best to convey what this does. This area of the brain is more primitive than the Nucleus Accumbent and the Prefrontal Cortex. The VTA has neural connections to both and is mainly involved in learning. The VTA neurons start firing when a prediction error occurs and results in a reward. Monkeys had their VTAs monitored when they were exposed to a lever that delivered a reward. However, the lever would only deliver a reward if a light was also on. When the monkey would randomly press the lever with the light on a reward would be delivered and the VTA would be activated. Once the monkey learned the association with the light and lever the VTA would not fire when a reward was delivered. In short the VTA is very effective in helping us learn new ways to seek rewards. Also now the light is backed up to the learned behavior.

Lecture 3: How Addiction Hijacks the Brain

The lecturer pointed out 3 ways the brain is altered as addiction progresses. 1) Numbed pleasure response. 2)  increased cravings as associations between drug use and cues evolve and 3) reduced self control.

1) In drug use the Nucleus Accumbens gets repeated overstimulation. Drugs stimulate the Nucleus Accumbens much more than normal activities. Your brain compensates by suppressing the Nucleus Accumbens. Hence more drugs are needed for the same effect. This is the mechanism of tolerance for drugs. This suppression also results in the addict not being able to get pleasure from activities that used to satisfy the pleasure center. The addict may reach a point where they need the drug just to feel normal.

2) Increased associations and cravings. This is a little more abstract and difficult to understand. I think it can help answer the question of why addicts use when they claim they no longer get pleasure from using – a common complaint. The Nucleus Accumbens pleasure activation is mediated by endorphins. They way it compensates by overstimulation is by making dynorphin, which makes it more resistant to endorphins, and opiates in general. For cravings, and satisfaction from indulging them, the neurotransmitter dopamine is involved. Dopamine has been described as the “addiction molecule”. The lecturer makes the distinction between wanting and liking. Wanting is craving the drug. Liking is enjoying the effects of the drug. Addicts always want the drug, even when the drug gives little pleasure.

We need to turn to the Ventral Tegmental Area (VTA). The VTA is responsible for the associations between drug use and drug related cues resulting in increased cravings. The VTA releases dopamine in response to associations such as the light with the monkeys in lecture 2. Thus dopamine is linked to craving or wanting the drug. Neuroscientists believe that as addiction progresses we develop “incentive sensitization”. We become more sensitive to the cravings induced by dopamine. Sort of the opposite of tolerance. Also, scientists believe, the dopamine itself is that “reward prediction error” and it produces learning, or in the case of addiction, increasing obsession with the drug.

3) Reduced Self Control. Remember that the Prefrontal Cortex is involved in inhibiting undesirable behavior. The rational brain center. Chronic drug use leads to abnormalities of the prefrontal cortex. Neuroimaging studies show diminished function and animal studies show neural damage to the prefrontal area. All this results in lessened ability to suppress the self destructive behaviors of drug abusers.

That’s it for the blog today. I’ll listen to these lectures and blog about them as the days go on.

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