Lecture 1 - Transmission

Question 1

Neurons

Answer 1

• The building blocks of the CNS
• Responsible for receiving, processing and transmitting information throughout the body
• Roughly 86 billion in the average human brain, all interconnected with each other
• Responsible for cognition, sensory processing, motor control and coordination, reflexes, heartbeat regulation, breathing, decision making

Question 2

Neurotransmitters

Answer 2

• Chemical messengers that transmit signals between neurons to other neurons across a synaptic cleft
• Vesicles in axon hold neurotransmitters and push down to the edge of the neuron
• Presynaptic axon -> synaptic cleft -> postsynaptic cell
• Neuropeptides are a subset of neurotransmitters (typically more complex and have longer lasting effects compared to traditional neurotransmitters)

Question 3

Two types of postsynaptic receptors

Answer 3

• (1) Neurotransmitter transporters = take through into next neuron
• (2) Receptors = take transmitter and recognise that they are in cleft (take recognition into electrical into postsynaptic neuron)

Question 4

Dopamine

Answer 4

– indirectly released by amphetamines, cocaine – reward/excitement

Question 5

Noradrenaline

Answer 5

indirectly released by amphetamines, cocaine – alertness/excitement

Question 6

Serotonin

Answer 6

(5-hydroxtryptamine, 5-HT) – increased by ‘ecstasy’ (MDMA) – happiness and ‘love’

Question 7

Acetylcholine

Answer 7

receptors activated by nicotine – focus, learning/memory

Question 8

Relationship between drugs and neurotransmitters

Answer 8

• Distinction between the internal transmitter and the drugs that trick that system
• Drugs trick system into being more active (hijack neurotransmitter systems which already exist in the brain)

Question 9

Agonist

Answer 9

typically involves binding to a receptor and activating it (mimicking a neurotransmitter)

Question 10

Antagonist

Answer 10

typically involves binding to a receptor and not activating it (blocking a neurotransmitter)

Question 11

Agonists and antagonists

Answer 11

Can be full or partial

Question 12

Autoreceptors

Answer 12

Allow the neuron to self-regulate or not releasing so things don’t get flooded (keep things in a normal range – homeostasis)
- Drugs don’t only act on a receptor on the postsynaptic cell, they can also be used for synthesis of the transmitter

Question 13

Evidence of neurochemicals in addiction

Answer 13

• Gerra et al. (2000)
• PRL = prolactin (pituitary hormone) – the more PRL, the more serotonin
• Fenfluramine promotes 5-HT (serotonin) release (used clinically to treat obesity, here to test 5-HT function, 5-HT regulates PRL)
• Part 2: the drug itself is no longer present, but long-term effects are found (less likely to feel happiness effects)
• However, self-report used and little dose knowledge from MDMA users (tend to underreport)
• Ethics: can’t give people MDMA (use pre-existing users)

Question 14

Evidence of psychology (stress) in addiction

Answer 14

• Miczek & Mutschler (1996)
• Rats trained to respond for cocaine or food reward
• ‘Social stress’ – 60 min as an intruder in the cage of the resident rat (protected from attack by wire mesh)
• Found that when introduced to stress, rats sought out cocaine over food (even when you half the dose)
• Incredibly addictive – forego basic needs
• (+) Animal study – know what the exact doses are
• Drug users report stress, but there are problems with correlational evidence (does the drug cause stress or does the stress cause the drug taking)
• Suggests selective effect of social stress on cocaine-reinforced responding
• Clinical reports suggest role of stressful life events in relapse, but these are correlational. Controlled animal studies can show cause and effect