Psychology 2020A/B Lecture Notes - Lecture 3: Nucleus Accumbens, Transdermal Patch, Nicotine Patch
22 May 2018
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Psychology 2020
Lecture 3
Behavioural Tolerance and Drug Overdose
- Tolerance is the capacity of a drug to have a gradually diminished effect over repeated
administrations; in effect, a greater dose has to be taken to maintain the original effect of the
drug.
- Tolerance effects can be quite dangerous, because experienced drug users often end up taking
potentially lethal dose levels.
Addiction and the Brain
- Olds and Miller (1953) – Mistakenly placed an electrode into a rats hypothalamus
- Started repeating the previous activity in hopes of receiving the stimulation again
- So they put electrodes in the brain of rats and shocked them and saw that rats would learn to
not press the lever
o But they accidently put the electrode in the hypothalamus and this rat LIKED pressing
the lever, even though it shocked the rat
o When the electrode would go off, the rat wouldn’t experience pain and discomfort, it
would experience pleasure
Olds and Miller
- Further testing showed that some rats would press a lever thousands of times an hour in order
to receive the electrical stimulation
o Sometimes, this rat would starve themselves to be able to press the lever or even walk
across a floor that was electrically shocking them to press the lever
- Olds & Miller found was something they called the Pleasure centre of the brain →Nucleus
Accumbens
o Drugs can also stimulate the nucleus accumbens
o So when we do things that are pleasurable (have sex, eat fav food etc), the nucleus
accumbens is involved
o You can become addicted to the pleasure from the nucleus accumbens
VIDEO: brain mechanisms of pleasure and addiction
- Ppl started testing this on humans with depression
- Stimulation of the nucleus accumbens caused happiness
- This is not a solution to depression bc:
o The more she presses the button, the less it could work?
o There are other things that could trigger depression
CHAPTER 3
How Drugs Work in the Body and on the Mind
How Drugs Enter the Body
- There are four basic ways to administer drugs into the body: oral administration, injection,
inhalation, and absorption through the skin or membranes.
- Each of these imposes constraints on which kinds of drugs will be effectively delivered into the
bloodstream.
- Injection of a drug bypasses the digestive process entirely and delivers the drug more directly
into the bloodstream
o Intravenous (IV)
o Intramuscular (IM)
o Subcutaneous (sub-Q)
find more resources at oneclass.com
find more resources at oneclass.com
- Injection has a danger of acute toxicity bc it bypasses the GI tract
- Absorption of a drug through the skin or membranes dissolves into the bloodstream
o Intranasal
o Sublingual
o Transdermal patch
▪ Ex: nicotine patch was used for ppl to stop smoking
▪ Ex: phentanoyl patch →it was marketed as a patch for people suffering from
chronic pain or chemotherapy could have pain relief for 3 days
How Drugs Exit the Body
- Most drugs are eliminated from the body through urinary excretion.
- Drugs are broken down for elimination by the action of enzymes in the liver.
- An index of how long this process takes is called the elimination half-life
o How quickly does the drug get out of our system on avg?
o Ex: caffeine has short half life
o Ex: nicotine has a short half life
o Ex: alcohol has a short half life
o Ex: marijuana has a long half life
- Biotransformation:
o the process of changing the molecular structure of a drug into forms that make it easier
for the body to excrete it.
- A metabolite is a by-product resulting from the biotransformation process
Factors Determining the Behavioral Impact of Drugs
- The factors that can make the physiological effect of a drug vary include:
o the time elapsed since its administration
o drug interactions when it is administered with other drugs at about the same time
o the personal characteristics of the individual consuming the drug.
▪ individual’s weight
▪ gender
▪ ethnic background.
- Synergism:
o the property of a drug interaction in which the combination effect of two drugs exceeds
the effect of either drug administered alone.
- Potentiation:
o the property of a synergistic drug interaction in which one drug combined with another
drug produces an enhanced effect when one of the drugs alone would have had no effect
o the 2nd drug causes the 1st drug that usually doesn’t have an effect to have an effect
- Cross-tolerance:
o a phenomenon in which the tolerance that results from the chronic use of one drug
induces a tolerance effect with regard to a second drug that has not been used before
o effects the same brain areas or neurotransmittesr
o the impact may be a little lessened bc of your tolerance for another drug
o ex: taking an antianxiety drug and taking another type
- Cross-dependence:
o a phenomenon in which one drug can be used to reduce the withdrawal symptoms
following the discontinuance of another drug
o someone suffering from withdrawal effects tries to alievate those symptoms by taking a
second drug
o ex: methadone clinics use methadone to try to treat their heroin addiction
find more resources at oneclass.com
find more resources at oneclass.com
Introducing the Nervous System
- Understanding the organization of the nervous system helps us to understand where
psychoactive drugs are working in our bodies.
- The nervous system consists of the peripheral nervous system and the central nervous system,
with the latter divided into the brain and the spinal cord.
- Autonomic nerves control our cardiac and smooth muscles to respond either to stress
(sympathetic activation) or to demands for nurturance and renewal (parasympathetic
activation).
Understanding the Brain
- Within the brain are three major divisions:
o Hindbrain
▪ coordinator of the basic life-support systems in our body.
o Midbrain
▪ center for the control of important sensory and motor reflexes, as well as for the
processing of pain information
o forebrain
▪ most recently evolved region of the brain
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Tolerance is the capacity of a drug to have a gradually diminished effect over repeated administrations; in effect, a greater dose has to be taken to maintain the original effect of the drug. Tolerance effects can be quite dangerous, because experienced drug users often end up taking potentially lethal dose levels. Olds and miller (1953) mistakenly placed an electrode into a rats hypothalamus. Started repeating the previous activity in hopes of receiving the stimulation again. Accumbens accumbens is involved: you can become addicted to the pleasure from the nucleus accumbens. Ppl started testing this on humans with depression. This is not a solution to depression bc: Stimulation of the nucleus accumbens caused happiness: the more she presses the button, the less it could work, there are other things that could trigger depression. How drugs work in the body and on the mind.
