Biopsychology Chapter 15

Front 1

Psychoactive Drugs

Back 1

drugs that influence subjective experience and behaviour by acting on the nervous system

Front 2

Administration and Absorption

Back 2

1. Oral – absorbed from stomach and small intestine, easy and relatively safe, unpredictable absorption
2. Injection – bypasses digestion process and administers drug directly into bloodstream, intravenously or intramuscularly, subcutaneously (*intravenously is the quickest and most intense method, also irreversible)
3. Inhalation – easiest after ingestion by mouth, reaches brain in 5-8 seconds, produces lung damage
4. Absorption – (through mucous membranes) intranasal sniffing, sublingual absorption, rectal suppository, transdermal patch

Front 3

Drug tolerance

Back 3

larger amounts of drug is necessary to produce the same effects
-body tries to compensate for the effects of the drug (e.g. increase heart rate, body compensates by trying to decrease heart rate)

Front 4

Cross tolerance

Back 4

for drugs that act via similar mechanisms (e.g. Alcohol and benzodiazepines)
-tolerance leads to withdrawal symptoms if drug taking stops: withdrawal symptoms are typically opposite to what the drug produced

Front 5

2 types of drug tolerance

Back 5

1. Metabolic tolerance – less of the drug is getting to site of action
2. Functional tolerance –decreased responsiveness at the site of action (fewer receptors, decreased efficiency of binding at receptors, receptors are less responsive)

Front 6

Conditioned drug tolerance

Back 6

drug tolerance that is cued when the drug is administered in the presence of same environmental cues as the past. Ex: contextual induced hypothermia

Front 7

Tobacco

Back 7

nicotine is the major psychoactive ingredient
-about 70% of all people who experiment with smoking become addicted (vs. 10% for alcohol and 30% for cocaine)
-only ~20% of attempts to stop smoking are successful (for 2+ years)

Front 8

“smoker’s syndrome”

Back 8

chest pain, wheezing, coughing, etc.

Front 9

Alcohol

Back 9

-a depressant
-heritability is about 55%
-functional tolerance develops
-affects almost every tissue in the body (fat and water soluble)
-crosses placenta easily

Front 10

fetal alcohol syndrome

Back 10

brain damage, mental retardation, poor muscle tone, low birth weight, physical deformity

Front 11

3 Phases of Chronic Alcohol Consumption

Back 11

5-6 hours: tremors, nausea, sweating
15-30 hours: convulsions
24-48 hurs: delirium tremens (hallucinations, delusions, hyperthermia, etc)

Korsakoff’s syndrome
-cirrhosis
-erodes heart muscle
-irritates lining of digestive tract

Front 12

Marijuana

Back 12

Cannabis sativa (common hemp plant)
THC- major psychoactive ingredient although there are 80 others present
-high doses impair short term memory and interferes with tasks involving multiple steps
-addiction potential is low
-young adults who smoked >5 joints/week lost on average about 4 IQ points

Front 13

Medicinal Uses

Back 13

-treats nausea, blocks seizures, dilates bronchioles of asthmatics, decreases severity of glaucoma, reduces some forms of pain
-immune system has widespread modulatory effects on diverse physiological processes
-anandamide and 2-AG are the most common endocannabinoids
-delta 9 THC stimulates cannabinoid receptors

Front 14

Cannabinoids and Nausea

Back 14

-anti-nausea and anti-emetic effects shown in humans, cats, ferrets, pigeons and shrews

Front 15

Cocaine

Back 15

-increase neural and behavioral activity
-blocks dopamine transporters
-commonly abused
-“crack” is the potent, cheap, smoke-able form of cocaine
-cocaine is an effective local anesthetic

-cocaine sprees lead to cocaine psychosis-which looks like schizophrenia
-while tolerance may develop to most effects, the user becomes more responsive to motor and convulsive effects
-highly addictive but withdrawal symptoms are relatively mild

Front 16

Opiates: Heroin and Morphine

Back 16

morphine and codeine are obtained from the opium poppy, heroin is synthesized from morphine
-opiates act on the CNS receptors that normally bind to endogenous opiates
-there are 2 classes: endorphins and enkephalins

Front 17

Effects of Opiates

Back 17

the effects of opiates are: analgesics (painkiller), treatment of cough and diarrhea, hypnotic, and euphoria
-high risk of addiction
-heroin is dangerous because it produces intense pleasurable effects since it crosses the Blood brain barrier easily and rapidly
-user may be unaware of drugs purity
-tolerance develops rapidly =leads to overdose

Front 18

Natural Rewards

Back 18

(water, food, sex, nurturing) = reward = reinforced behaviour, repeated for survival

Front 19

Positive-incentive value

Back 19

anticipated amount of pleasure from stimulus

Front 20

Hedonic value

Back 20

actual amount of pleasure experienced

Front 21

Intracranial self stimulations

Back 21

administer brief bursts of weak electrical stimulation to specific brain sites in themselves

Front 22

Drug Self-Administration

Back 22

– rat presses lever to self inject a drug into the brain or general circulation

Front 23

Conditioned Place Preference

Back 23

rat repeatedly receives drug in one of two compartments. The tendency of the rat to prefer the drug compartment is measured, and usually the rater prefers the drug compartment.

Front 24

Nucleus Accumbens and Drug Addiction

Back 24

-animals self administer microinjections of addictive drug into nucleus Accumbens
-microinjections of drugs in the nucleus Accumbens produced a conditioned place preference
-lesions to the nucleus Accumbens or ventral tegmental area blocked self-administration of drugs into general circulation or CPP
-both self administration of drugs and the experience of natural reinforcers were found to be associated with elevated levels of extracellular dopamine in nucleus accumbens

Front 25

mesocorticolimbic dopamine pathway

Back 25

major pathway in the brain

Front 26

Why do addicts seek drugs?

Back 26

-drug taking is motivated by the desire to avoid withdrawal consequences
-drug taking is motivated by the cravings for the pleasurable effects of the drug

Front 27

The physical theory of dependence does not explain addiction because:

Back 27

inconsistent with evidence

positive incentive theories are more relevant

Front 28

Sensitization and Neural Changes

Back 28

-change in how the striatum reacts to drug and drug associated cues
-striatal control of addiction spreads from NA to the dorsal striatum, which is known to play a role in habit formation and retention
-at the same time, the role of prefrontal cortex is controlling drug related behaviors declines, stress circuits in hypothalamus interact with dorsal striatum