Which circuit is known as the reward circuit?
Mesolimbic-dopamine circuit = final common pathway of reward
Name the three methods for receiving chemical reward?
1) natural highs e.g. sex, marathon
2) Behaviour-induced highs e.g. gambling
3) Substance-induced highs e.g. cocaine
Name the brain’s three natural highs and the illegal drug they are similar to.
1) endorphins (heroin)
2) anandamide (cannabis)
3) dopamine (cocaine)
Where is dopamine released?
Nucleus accumbens (NAc)
Psychotropic drugs can…
causeM-DA pathway to release dopamine more explosively + pleasurably than naturally
Any drug capable of affecting the mind, emotions, and behaviour
Name the stages that occur when you first try a psychotropic drug.
1) DA released
2) pleasure experience
3) amygdala learns that this is a rewarding experience = conditioned
Name the stages that occur when after repeated tries of a psychotropic drug.
1) drug cues that predict pleasure cause pleasure (DA release) –> reward circuit has learnt to anticipate reward –> anticipation becomes pleasurable
2) anticipation send signals to VTA to expect reward/relief from withdrawal
3) DA release triggered
4) impulse to take drug transformed into action of finding drug
Describe the mechanism for impulse resistance.
1) drug anticipation occurs
2) signals an impulsive choice to VTA
3) produces output to engage behaviour
4) Orbitofrontal cortex signals signals drug-induced cravings + support ‘vote’ for drugs
5) dorsolateral prefrontal cortex interprets signals + decides whether to take action
6) reflective reward is activated and can prevent impulse decisions
7) outcome can go either way
ventral tegmental area
risk of becoming a substance abuser depends on no. of receptors
~ taking substance doesn’t have much effect at first
~ drug becomes more rewarding as dose increases
~ own internal reward system not working as well = predisposed to keep doing drugs
substance will be aversive/unpleasant so will not want to try again
Low initial response
more likely to abuse substance
High initial response
less likely to abuse substance