addiction

Question 1

Symptoms of addiction

Answer 1

Compulsivity
cravings
intrusive thoughts
mood swings
neglect of responsibilities
secrecy

Question 2

Neuroanatomy of reward

Answer 2

Electrical stimulation of rats found the nucleus accumbens (but also many other regions) primarily mediated reward system. Further reinforced by lesions in the VTA and nucleus accumbens abolishing reward system.

DA system has very large role. Predominantly mediated by mesolimbic and mesocoritcal pathways. DA agonists increase motivation and exploration, while antagonists cause anhedonia and avolition. L-DOPA seen to increase compulsive/impulsive behaviour.

Hedonic hotspots in the nucleus accumbens have been identified with opioids and cannabinoids. They are plastic - not same in everyone, and can change

Question 3

Different types of rewards and associative learning

Answer 3

Intrinsic or extrinsic.

Intrinsic directly causes pleasure (e.g., sex), while extrinsic is indirectly linked to pleasure (e.g., money)

Associative learning associates a stimuli with a reward, e.g., pavlovian conditioning (bell ring signals food)

Question 4

Different effects of different NTs in reward and euphoria

Answer 4

DA drives reward prediction and associative learning - motivates reward seeking

endorphins and endocannabinoids mediate the euphoria and gratification of the reward.

Question 5

Changes to DA system in addiction

Answer 5

Changes from reward recognition to reward anticipation. This promotes reward seeking behaviour -> addiction.

When this is continually reinforced, compulsions, cravings, tolerance, and intrusive thoughts emerge indicating the development of addiction

Question 6

Prefrontal cortex control over addiction

Answer 6

The prefrontal cortex can feedback to the nucleus accumbens to halt reward seeking behaviour.

This is seen with the ontogenic activation of rats prefrontal cortex leading to decreased time in chambers that increased the rats midbrain DA. Was able to override the reward seeking.

Question 7

Behavioural/psychological addictions and supernormal stimuli

Answer 7

Compulsive behaviours linked to reward seeking without physical addiction, e.g., gambling, eating, sex, etc…

Supernormal stimuli are stimuli that are not considered ‘natural’, ones that provide a heightened reward cue, e.g., social media, porn, highly processed high sugar/fat foods.

Question 8

Endogenous negative reinforcement of addictions

Answer 8

Hormonal influences, such as rising cortisol with continued drug abuse

Dynorphin, an endogenous peptide acts as a k-opioid agonist, and decrease DA release - drug abuse becomes less rewarding.