Neurobiology of Addiction

Question 1

what are the criteria for dependence

Answer 1

a strong desire to take the substance 
difficulties in controlling substance use 
a physiological withdrawal state 
tolerance 
neglect of alternative pleasures 
persistence despite evidence of harm

Question 2

what is incentive salience

Answer 2

attributing want to a stimulus

Question 3

what are the parts of the motivational pathway

Answer 3

originates in VTA (ventral tegmental area)

• > nucleus accumbens
• > prefrontal cortex

Question 4

what is the role of dopaminergic activity in the mesolimbic pathway

Answer 4

is a motivating signal, incentivises behaviour, is involved in normal pleasurable activities

Question 5

what do drugs cause in motivational pathway

Answer 5

release of dopamine in the nucleus accumbens

Question 6

how is tolerance seen in MRI

Answer 6

less blood flow to the striatum upon rewarding stimulus

Question 7

what receptors are decreased in addiction and why

Answer 7

dopamine D2 receptors

due to repeated dopamine release- receptors down regulate

Question 8

what does decreased D2 receptors in addiction mean

Answer 8

threshold for reward during abstinence is increased- normal experiences don’t evoke adequate reward response

these changes persists even after prolonged abstinence from abuse

Question 9

what happens to the positive reinforcement of taking a drug in addiction

Answer 9

becomes negative reinforcement (removal of adverse stimulus - a thirst for the drug)

Question 10

what is the role of the pre frontal cortex

Answer 10

helps intention guide behaviour
modulates the powerful effects of the reward pathway
sets goals, focuses attention
makes sound decisions
keeps emotions and impulses under control to achieve long term goals
involved in executive function

Question 11

when does the prefrontal cortex stop developing

Answer 11

early 20s

Question 12

what happens to the PFC in addiction

Answer 12

reduced activity and glucose metabolism

Question 13

why does an earlier age of drug experimentation lead to a longer relationship with drugs

Answer 13

as PFC still developing until 20s

• synaptic plasticity
• long term potentiation and depression

Question 14

what is the role of the hippocampus, striatum and amygdala in addiction

Answer 14

acquisition, consolidation and expression of drug stimulus learning
Learned drug associations can cue internal states of craving (the sight of cigarettes/ rolling them releases dopamine making you want to smoke more)

Question 15

what is the role of the orbito-frontal cortex in addiction

Answer 15

provides internal representation of salience of events and assigns value to them
key creator of motivation to act
addicts show increased activation here when presented with drug cues

is influenced by both the nucleus accumbens and the prefrontal cortex, decides whether or not you do it

Question 16

what is the role of the nucleus accumbens

Answer 16

involves in wanted substance/ behaviour
where dopamine is release
influences OFC

Question 17

what is the role of the prefrontal cortex

Answer 17

stops actions, tries to make sound decisions

Question 18

how much of addiction risk is genetic

Answer 18

40-60%

Question 19

how do genetics influence out addiction risk

Answer 19

the way we respond to drugs metabolically
behavioural traits that predispose up to take drugs
how rewarding we find taking drugs

Question 20

how levels of what receptors increases your addiction risk

Answer 20

DRD2

Question 21

how does stress influence addiction

Answer 21

acute stress trigger the release of dopamine in neural reward pathway
rapid increase can motivate drug seeking in dependent individuals
chronic stress leads to dampening of dopaminergic activity through the down regulation of D receptors
this reduces sensitivity to normal rewards, encourages exposure to highly sensitive rewarding behaviours

Question 22

what are the core features of addictive behaviour

Answer 22

salience (importance, dominance)
mood modification (rush and escape)
tolerance (escalation for effect, increasing intensity, recklessness, destructiveness)
withdrawal
conflict (interpersonal, intrapsychic, loss of control)
relapse

Question 23

what is the moral model of addiction

Answer 23

where individual is primary causal factor- result of human weakness
wilful violation of societal rules

Question 24

what part of brain is involved with the withdrawal/ negative effects

Answer 24

amygdala

Question 25

what is conditioning

Answer 25

the process of behaviour modification whereby an individual comes to associate a desired behaviour with a previous unrelated stimuli

Question 26

what group of people are at very high risk of overdose

Answer 26

those who have just been released from prison (loose tolerance)

Question 27

what is instrumental value

Answer 27

learning by connecting the consequences of actions with the preceding behaviour

Question 28

what is positive and negative reinforcement

Answer 28

positive applies stimulus
negative removes stimulus
both increase the frequency of the behaviour that produces them

Question 29

what is associative learning

Answer 29

through repeated pairing with a cue a previously neutral stimuli will come to elicit the same response

Question 30

what is habit formation

Answer 30

an acquired behaviour pattern regularly followed until it becomes almost involuntary

Question 31

how is attention and memory bias involved in addiction

Answer 31

selective recall (forget bad things)
bias towards detection of addiction related cues