brain substrates

Question 1

what is synaptic transmission?

Answer 1

presynaptic neuron releases vesicles of neurotransmitters into synaptic cleft, which are picked up by post-synaptic neuron via receptors or transporter receptors

Question 2

how do drugs interfere with synaptic transmission?

Answer 2

hijack neurotransmitter systems

Question 3

what are catecholamines?

Answer 3

play key roles in body’s stress response, regulation of blood pressure, heart rate and various metabolic processes

Question 4

what are examples of catecholamines?

Answer 4

dopamine

noradrenalin

serotonin

acetylcholine

neurotransmitters and hormones derived from amino acid tyrosine (involved in dopamine synthesis)

Question 5

what is dopamine associated with?

Answer 5

reward/excitement

Question 6

what drugs affect dopamine?

Answer 6

amphetamines

cocaine

Question 7

what is noradrenalin associated with?

Answer 7

alertness/excitement

Question 8

what drugs affect noradrenalin?

Answer 8

amphetamines

cocaine

Question 9

what is serotonin associated with?

Answer 9

happiness

“love”

Question 10

what drugs affect serotonin?

Answer 10

“ecstasy” (MDMA)

Question 11

what is acetylcholine associated with?

Answer 11

focus

learning/memory

Question 12

what drugs affect acetylcholine?

Answer 12

nicotine

Question 13

how are catecholamines hacked?

Answer 13

things that aren’t dopamine, fit in receptor, blocking it from activating

Question 14

what illegal drugs hack catecholamines?

Answer 14

cocaine = blocks DA and NA transporters

amphetamines = increased DA and NA release

Question 15

what legal drugs hack catecholamine?

Answer 15

risperidone = blocks DA receptors (used in schizophrenia and bipolar treatments)

ritalin = blocks DA and NA uptake (i.e. ADHD)

Question 16

what drugs hack catecholamines?

Answer 16

some antidepressants inhibit monoamines (enzymes that breakdown catecholamines), prolonging catecholamine action

reserpine = general catecholamine antagonist - inhibits VMAT, protein responsible for moving them back into vesicles (i.e. less to use)

Question 17

what are indirect agonists of catecholamines?

Answer 17

Bloomfield et al (2016) - THC promotes DA release through cannabinoid receptors, long term DA system dulling

Reigel et al (2007) - same results as Bloomfield

Question 18

what are dopamine pathways?

Answer 18

neural circuits through which dopamine travels to regulate various physical and psychological functions

pathways are critical for processes like movement, reward, motivation, emotion and hormonal control

Question 19

what are specialised dopamine neurons called?

Answer 19

chains

Question 20

what is the mesocorticol dopamine pathway?

Answer 20

biggest pathway

regulates cognition, decision-making, emotion and social behaviour

originates in VTA but projects to PFC

when low levels of dopamine, depression and apathy

Question 21

what is dysfunction in the mesocortical pathway associated with?

Answer 21

dysfunction or underactivity associated with negative symptoms of schizophrenia (e.g. apathy, lack of motivation) and cognitive impairments

Question 22

what drugs affect the mesocortical pathway?

Answer 22

drugs that target primarily aim to modulate dopamine activity in prefrontal cortex

drugs used to address cognitive dysfunction, emotional regulation and negative symptoms

Question 23

what is the mesolimbic pathway?

Answer 23

main pathway associated with addiction and reward

originates in VTA and projects to nucleus accumbens and other limbic areas (like amygdala and hippocampus)

involved in reward motivation and feelings of pleasure

plays central role in reinforcing behaviours and development of addiction

Question 24

what is overactivity in the mesolimbic pathway linked with?

Answer 24

addiction

positive symptoms of schizophrenia (e.g. hallucinations)

other disorders involving reward-processing

Question 25

what does high dopamine in the mesolimbic pathway result in?

Answer 25

psychosis addiction mania

Question 26

what does low dopamine in the mesolimbic pathway result in?

Answer 26

depression anhedonia apathy

Question 27

what drugs affect the mesolimbic pathway?

Answer 27

drugs that modulate dopamine activity in the reward and motivation system of the brain commonly used to treat schizophrenia, addiction, depression and Parkinson's disease

Question 28

what is the nigrostriatal pathway?

Answer 28

mainly involved in motor behaviour

Question 29

what does high dopamine levels in the nigrostriatal pathway result in?

Answer 29

uncontrolled movement tardive dyskinesia Huntingdon's chorea

Question 30

what does low dopamine levels in the nigrostriatal pathway result in?

Answer 30

complete lack of movement Parkinson's disease drug-induced Parkinsonism

Question 31

what drugs affect the nigrostriatal pathway?

Answer 31

drugs crucial for motor control and drugs that target it primarily used for Parkinson's disease, drug-induced movement disorders and Huntingdon's disease

Question 32

what is the tuberoinfundibular pathway?

Answer 32

associated with hormone release and pituitary gland originates in hypothalamus (arcuate nucleus) and projects to the pituitary gland regulates secretion of prolactin from anterior pituitary gland, playing a role in hormonal control

Question 33

what does increased prolactin (hyperprolactinemia) result in?

Answer 33

infertility menstrual irregularities decreased libido galactorrhoea

Question 34

what does decreased prolactin result in?

Answer 34

rare usually not clinical significant unless in conditions like hypopituitarism

Question 35

what drugs affect the tuberoinfundibular pathway?

Answer 35

dopamine acts as a prolactin antagonist

Question 36

what receptors does dopamine have?

Answer 36

D1-like (D1, D5) and D2-like (D2, D3, D4) multiple locks for the same key some activate easily (D3) and others less so (D1) some excite neurons (D1-like) while others calm it down (D2-like) located in different regions