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Drug Addiction and the Reward Pathway of the Brain – Consciousness (PSY)

by Tarry Ahuja, MD
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    00:01 Let’s talk about drug addiction and what that actually looks like and why that’s happening.

    00:04 So there are two sides of the coin.

    00:07 The first side is psychological dependence.

    00:09 So we know that this is impacting the mind and that people who take these can fall into sort of two categories, so first category being you’re predisposed to psychological dependence.

    00:20 So what does that mean in English? Well, that means that you have been prewired due to your genes from your parents to have the potential to be addicted or have dependence towards, it could be anything.

    00:33 So people can have an addictive or dependent personality and you might know yourself that, “Oh, when I get into something, I really get into it.” It could be something as benign as when I really get into cooking, I’m all in, or if I start drinking coffee, now I’m a coffee drinker, as opposed to somebody who might try it and say, “I’ll have it if it’s there, but I’m not really addicted or need it.” Okay? So psychologically, your brain is prewired to have that type of what we call psychological disposition or psychological characteristic.

    01:03 And so, psychological dependence is sort of one side of the coin.

    01:07 Now, the other side of the coin is actual physical dependence, and this is irrelevant to what your mind is doing.

    01:13 This is more of your actual body.

    01:15 And so we say the definition is refers to a state that has produced tolerance and withdrawal with physical symptoms.

    01:21 So, again, in English what that means is your body has now gotten accustomed to or dependent upon that drug and it’s actually caused changes in the receptors, it’s caused changes in your physical makeup that says, “Hey, if you don’t give me that drug, I’m actually going to go through withdrawals and I’m going to express my displeasure with the fact that you haven’t given me my,” you know, for exact, “cocaine today.” So you can have cocaine addiction, your body changes and when you don’t take your cocaine, it’s withdrawal that you experience.

    01:52 And a lot of times, people will continue the drug taking behavior not because they’re getting high and they’re feeling amazing.

    01:58 They do it because they don’t want to suffer the withdrawal symptoms or the physical dependence that they’re experiencing.

    02:04 So if you ask them, saying, you know, “Listen, you know that it’s addictive. You know that it’s killing you. You know that you’ve lost your job, your wife, your house, yet you still continue to take the drug. Why?” “Oh, man, I can’t deal with the withdrawal symptoms.” You know I hear that all the time.

    02:16 They say, “I take it just so I don’t have to go through that dip.” So that’s them taking the drug or containing the drug taking behavior because they don’t want to deal with the withdrawal symptoms due to the physical dependence, different than the psychological dependence.

    02:31 Now, what is mediating this? What is making us to continue to take this drug behavior? And we’re going to focus on a very key pathway and this is called the dopamine reward pathway, which is found in the limbic system.

    02:43 Okay? So there’s a couple of structures within the limbic system that you need to know.

    02:47 We’re going to highlight some of them here.

    02:49 So typically, we have the VTA or the ventral tegmental area, we have the nucleus accumbens, and we have the prefrontal cortex.

    02:55 So typically, we say addiction is linked to changes in dopamine.

    02:58 I had mentioned dopamine as an excitatory, pleasure-reinforcing transmitter in the nucleus accumbens.

    03:05 So the nucleus accumbens belongs and is part of this pathway of the limbic system, which includes the VT and the dopamine, and collectively, this is called the dopamine reward pathway.

    03:16 So if you take a drug and we activate the nucleus accumbens and we cause this increase in dopamine release, that pathway will get activated.

    03:25 And like the name implies, it’s being rewarded.

    03:27 It’s quite happy.

    03:27 It’s quite happy.

    03:28 It’s saying, “Mmm, me like this cocaine,” and you’re going to want to take more.

    03:32 So we say that’s behaviorally reinforcing and it’s being reinforced by the increase in dopamine.

    03:37 Okay? So any drug you take, anything you do that activates the dopamine reward pathway means you’ll continue to want to do that behavior, and if the release of the dopamine is high enough, it will become addictive.

    03:51 So as you can see there’s a whole bunch of different types of drugs that you can take, each of them impacting your brain in a different way.

    03:58 At the end of the day, we’re looking at drugs that are reinforcing.

    04:02 They’re reinforcing the dopamine reward pathway, which is found in the limbic system.


    About the Lecture

    The lecture Drug Addiction and the Reward Pathway of the Brain – Consciousness (PSY) by Tarry Ahuja, MD is from the course Making Sense of the Environment.


    Included Quiz Questions

    1. It causes tolerance.
    2. It can be genetically determined.
    3. It has motivational and emotional components.
    4. It is a component of drug addiction.
    5. It is increased through reinforcement.
    1. People are motivated to use drug for emotional reasons.
    2. Increasing doses are needed to achieve same effect.
    3. Sedative drugs can cause physical dependence.
    4. People are motivated to use drug in order to stop withdrawal symptoms.
    5. In order to avoid rebound symptoms, drug must be slowly tapered.
    1. Dopamine
    2. Serotonin
    3. GABA
    4. Norepinephrine
    5. Glutamate
    1. Nucleus accumbens, ventral tegmental area, prefrontal cortex
    2. Substantia niagra, basal ganglia, dorsal striatum
    3. Infundibular nucleus, pituitary gland
    4. Limbic cortex, amygdala, hippocampus
    5. Ventral tegmental area, nucleus accumbens

    Author of lecture Drug Addiction and the Reward Pathway of the Brain – Consciousness (PSY)

     Tarry Ahuja, MD

    Tarry Ahuja, MD


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