Neuropsychopharmocology

Question 2

Ion channel receptor

Answer 2

neurotransmitter binds to the receptor outside the neuron, this causes the gate to open and ions to flow through e.g calcium ion channel

Question 3

G-protein receptor

Answer 3

When the neurotransmitter binds to the receptor it activates a “second messenger system” that can either open a channel or cause other things to change within the cell (e.g. DNA being transcribed and new proteins being made).

Question 4

Neuromodulator

Answer 4

released from neuron that affects a group pf neurons or effector cells/ may not be released at synaptic sites as often acts as second messengers (slower + alter subsequent responsiveness of neurons)

Question 5

NMDA Receptors: Alcohol

Answer 5

-Alcohol is an NMDA antagonist/ GABA agonist
-Reduction in glutamate is believed to contribute both to general sedative effects and memory effects of alcohol

Question 6

NMDA Receptors: PCP and Ketamine

Answer 6

-Both are NMDA antagonists
-Both cause dissociative hallucinations/ risk of psychosis

Question 7

GABA and seizure disorders

Answer 7

-Seizure= sudden excessive activity of neurons
-Epilepsy is believed to be linked to abnormality of the GABA neurons or receptors

Question 8

Dopamine pathways

Answer 8

Substantial Nigra- motor control
Ventral Tegmental Area- Motivation and emotional response/ reward, desire and addiction
Dopamine Synthesis
Tyrosine (tyrosine hydroxylase)  L-DOPA (amino acid decarboxylase)  dopamine (dopamine beta-hydroxylase)  noradrenaline

Question 9

Reward prediction error

Answer 9

-If an unexpected reward occurs DA neurons become more active and release a burst of DA
-If a reward is repeatedly given after a stimulus (such as a beep) then the reward will be “expected” & no DA will be released with the reward but will now be released at the time of the beep
-If a reward is “expected” & not provided, DA neurons will be suppressed

Question 10

DA Drugs- Cocaine

Answer 10

Synthesis  Release from synaptic vesicles  Bind to receptors  +/- influence on post-synaptic neuron  broken down by enzymes  reuptake by transmitter (BLOCKED)  formation and storage in synaptic vesicles

Question 11

Amphetamine

Answer 11

-Reverses uptake transporter actively expelling DA and NA out of the neuron which also prevents DA uptake
N.B- the faster dopamine is released the more addictive it will be

Question 12

Noradrenaline

Answer 12

Synthesis
Tyrosine (tyrosine hydroxylase)  DOPA (amino acid decarboxylase)  Dopamine (dopamine beta-hydroxylase)  Noradrenaline
Noradrenaline Roles
-Sympathetic nervous system, arousal and vigilance, anxiety, reward and addiction, memory consolidation, exploitation vs. exploration

Question 13

Locus Coeruleus- Neuron Firing

Answer 13

-Highest rates rapidly follow a transient noxious or extremely positive stimulus/ event (lots of NA released)

Question 14

LC neurons and behavioural selection

Answer 14

-Neurons in the LC fire when a behavioural response is selected and executed
-After they fire the neurons are inhibited allowing the selected behaviour to be ‘exploited’
-Competition in high-arousal context: LARGER burst of NA release ‘tips the balance’ in favour of the winner with MORE STRENGTH
-The larger the response of neurons in the Locus Coeruleus (LC), the more NA released & and the longer the following period of inhibition.
-Increased NA promotes a switch to a new decision, promoting “exploration” of alternative behaviors

Question 15

Serotonin

Answer 15

-Acts as a neuromodulator influencing the activity of a variety of neurons in the brain
-Important in functions such as sleep, arousal, appetite, temperature, working memory, mood

Question 16

Serotonin synthesis

Answer 16

Tryptophan (tryptophan hydroxylase)  Serotonin  Monoamine oxidase (breakdown enzyme)

Question 17

Selective Serotonin Reuptake Inhibitors (SSRI’s)

Answer 17

-Inhibit reuptake of the neurotransmitter
-Very slow acting, THEREFORE improved mood can not result directly from increased serotonin around the synapse
-In clinical populations: reduces symptoms of depression
-In healthy people: increases empathy and prosocial behaviour

Question 18

Monoamine Oxidase Inhibitors (MAOIs)

Answer 18

-Blocks the breakdown of serotonin
-Power antidepressant drug

Question 19

Peptides

Answer 19

-Most peptides serve as modulators, but can also act as neurotransmitters
E.g- Opioids
-Most known for their pain relief and euphoric properties (heroin, morphine)

Question 20

Lipids

Answer 20

Endocannabinoids
-2 cannabinoid receptors (CB1 AND CB2)
-CB1 is found in the brain and is believed to be responsible for the main psychological effects (shortens the duration of action potentials  decreasing amount of neurotransmitter released)

Question 21

Nucleosides

Answer 21

E.g- Adenosine
-Forms from the breakdown of ATP/ when you are awake adenosine levels rise to promote sleep and suppresses arousal
-High post-synaptic firing leads to sleepiness
E.g- Caffeine
-Acts as adenosine-receptor antagonist and blocks natural action of adenosine
-Caffeine increases alertness but reducing firing of adenosine neurons

Question 22

Gases

Answer 22

Nitric Oxide
-It is involved in learning and memory through effects on synaptic plasticity
-Dilates blood vessels in regions of the brain that become metabolically active