5.3—drugs and conscious experience

Question 1

Short Term Effects of Drugs

Answer 1

1. altering the amount of the neurotransmitter being released into the synapse,
2. preventing the reuptake (i.e., reabsorption back into the cell that released it) of the neurotransmitter once it has been released, thereby allowing it to have a longer influence on neurons,
3. blocking the receptor that the neurotransmitter would normally bind to,
4. or binding to the receptor in place of the neurotransmitter.

• different drugs influence different neurotransmitter systems.
• the brain chemical that is most often influenced by drugs is dopamine, a neurotransmitter that is involved in responses to rewarding, pleasurable feelings.
  
  • dopamine release in two brain areas: nucleus accumbens and the ventral tegmental area.
  • is likely related to the “high” associated with many drugs
• the effects of drugs involve biological, psychological, and social mechanisms.
  
  • e.g. think about the effects of alcohol.
  • drinking half a bottle of wine at a party often leads people to be more outgoing, whereas drinking half a bottle at home might cause them to fall asleep on the couch.
  • overdoses of some drugs are more common when they are taken in new environments than when they are taken in a setting that the person often uses for drug consumption.

Question 2

Long Term Effects of Drugs

Answer 2

• tolerance: when repeated use of a drug results in a need for a higher dose to get the intended effect.
  
  • when receptors are overstimulated by neurotransmitters, as often happens during drug use, the neurons fire at a higher rate than normal.
  • in order to counteract this effect and return the firing rate to normal, some of the receptors move further away from the synapse so that they are more difficult to stimulate, a process known as down-regulation.
• physical dependence: the need to take a drug to ward off unpleasant physical withdrawal symptoms.
  
  • psychological dependence occurs when addiction develops without any physical symptoms of withdrawal (warding off negative feelings with drug use).

Question 3

Psychoactive Drugs

Answer 3

substances that affect thinking, behaviour, perception, and emotion.

Question 4

Stimulants

Answer 4

• stimulants: a category of drugs that speed up the nervous system, typically enhancing wakefulness and alertness.
• e.g. cocaine, caffeine, crystal meth

Question 5

Cocaine

Answer 5

• cocaine is synthesized from coca leaves.
• it influences the nervous system by blocking the reuptake of dopamine in reward centres of the brain, although it can also influence serotonin and norepinephrine levels as well.

Question 6

Amphetamines

Answer 6

• amphetamines come in a variety of forms.
• some are prescription drugs, such as methylphenidate (Ritalin) and modafinil (Provigil).
• methamphetamine stimulates the release of dopamine in presynaptic cells.
  
  • also causes significant neurological as well as external physical problems.
  • people who have a history of abusing methamphetamine have been shown to have structural abnormalities of cells in the frontal lobes, which reduces the brain’s ability to inhibit irrelevant thoughts.

Question 7

Ecstasy

Answer 7

• ecstasy: (3,4-methylenedioxy N -methylamphetamine or MDMA) a drug that is typically classified as a stimulant, but also has hallucinogenic effects.
• stimulates the release of massive amounts of the neurotransmitter serotonin
• also blocks serotonin reuptake, ensuring that neurons containing serotonin receptors will fire at levels much greater than normal can produce unique damage in several areas of the cortex in the left hemisphere.

Question 8

Hallucinogens

Answer 8

• hallucinogenic drugs: substances that produce perceptual distortions.
• depending on the type of hallucinogen consumed, these distortions may be visual, auditory, and sometimes tactile in nature, such as the experience of crawling sensations against the skin.
• e.g. LSD, mescalin, and psilocybin

Question 9

LSD

Answer 9

• LSD (lysergic acid diethylamide): a laboratory made (synthetic) drug.
• acts on the transmission of serotonin.

Question 10

Marijuana

Answer 10

• marijuana: a drug comprising the leaves and buds of the Cannabis plant that produces a combination of hallucinogenic, stimulant, and relaxing (narcotic) effects.
• these buds contain a high concentration of a compound called tetrahydrocannabinol (THC).
• THC mimics anandamide, a brain chemical that occurs naturally in the brain and the peripheral nerves.
• both anandamide and THC bind to cannabinoid receptors and induce feelings of euphoria, relaxation, reduced pain, and heightened and sometimes distorted sensory experiences impairments to memory processes.
• marijuana also affects a number of cognitive abilities: executive functions, such as decision making and the control of attention.

Question 11

Opiates

Answer 11

• opiates: (also called narcotics) drugs such as heroin and morphine that reduce pain and induce extremely intense feelings of euphoria.
• bind to endorphin receptors in the nervous system.
• endorphins (“endogenous morphine”) are neurotransmitters that reduce pain and produce pleasurable sensations.
• opiate drugs are very common in medical and emergency room settings.
• e.g. fentanyl is used in emergency rooms to treat people in extreme pain.
  
  • a street version of fentanyl, known as “China White,” can be more than 20 times the strength of more commonly sold doses of heroin.
• physical dependence: the need to take a drug to ward off unpleasant physical withdrawal symptoms.
• psychological dependence: when addiction develops without any physical symptoms of withdrawal (warding off negative feelings with drug use).

Question 12

Sedatives | Legal Drugs

Answer 12

• sedative drugs: (sometimes referred to as “downers”) depress activity of the central nervous system.
• e.g. barbiturates were an early form of medication used to treat anxiety and promote sleep.
  
  • have a high potential for abuse, typically by people who want to lower inhibitions, relax, and try to improve their sleep.
• newer forms of sedative drugs, called benzodiazepines, include prescription drugs such as Xanax, Ativan, and Valium.
  
  • increase the effects of gammaaminobutyric acid (GABA), an inhibitory neurotransmitter that helps reduce feelings of anxiety or panic.

Question 13

Alcohol | Legal Drugs

Answer 13

• initially targets GABA receptors, and subsequently aff ects opiate and dopamine receptors.
• the stimulation of opiate and dopamine receptors accounts for the euphoria associated with lower doses as well its rewarding effects.
• the release of GABA, an inhibitory neurotransmitter, reduces the activity of the central nervous system.
• alcohol also inhibits the frontal lobes of the brain.