Reward - Drug Abuse

Question 1

Function in reward and reinforcement as part of a neural circuit that interfaces between limbic emotional-motivational information and extrapyramidal regulation of motor behavior.

Answer 1

Ventral Tegmental Area (VTA) and nucleus accumbens:

Question 2

____________ is Central to Reward

Answer 2

Dopamine

Question 3

Critical integrative structure projecting to the VTA and the nucleus accumbens. Thought to be important to the formation of stimulus-reward associations (i.e., remembering the pairing of stimulus with reward).

Answer 3

Amygdala

Question 4

Drugs of abuse usually:

Answer 4

Affect DA

Question 5

Certain regions are critical for executive function in providing control over impulses from destructive behavior. Their impairment in humans following chronic drug abuse appears to be an important mediator in the loss of control over drug intake (addiction).

Answer 5

Prefrontal cortex:

Question 6

a stimulus that the brain interprets as intrinsically positive or something to be approached.

Answer 6

reward

Question 7

A _____________ is one that increases the probability that behaviors paired with it will be repeated

Answer 7

reinforcing stimulus

Question 8

Central Role of Dopamine Release from VTA into NA: Final common pathway of reinforcement and reward is hypothesized to be the mesolimbic dopamine pathway AKA ___________

Answer 8

– ventral tegmental area to nucleus accumbens.

Question 9

VTA releases DA into

Answer 9

Nucleus Accumbens

Question 10

Reactive Reward System: Consists of the VTA (dopamine cell bodies), the nucleus accumbens (where DA neurons project) and the amygdala (which connects to both the VTA and NA).

Answer 10

x

Question 11

Physiologic Role of Reward Pathway

Normal function

Answer 11

Mediate pleasure perception (reward) and strengthen behaviors (reinforcement) associated with natural reinforcers

Produces motivational states that modulate physiological-behavioral responses ensuring survival and reproduction

Complementary pathway to networks for learning about dangerous stimuli (fear)

Question 12

Physiologic Role of Reward Pathway Reward:

Answer 12

Stimulus interpreted as intrinsically positive – something to be approached

Question 13

Drug-induced pleasurable states are strong motivators of initial drug use

Answer 13

Hijack normal Physiologic Role of Reward Pathway

Question 14

Reactive Reward System: Consists of the VTA (dopamine cell bodies), the nucleus accumbens (where DA neurons project) and the amygdala (which connects to both the __________).

Answer 14

VTA and NA

Question 15

Major components of reward and reinforcement circuitry

Function as interface between limbic emotional-motivational information and extrapyramidal regulation of motor behavior

Answer 15

Ventral Tegmental Area [VTA]–> Nucleus Accumbens [NA]

Question 16

Memory circuit that mediates associations between biologic stimuli (or drugs) and environmental cues

Answer 16

Hippocampus

Question 17

Integrative structure that is critical to formation of stimulus-reward associations

Answer 17

Amygdala

Usues Glu at NA

Question 18

Critical for executive function in providing control over impulses from destructive behavior - impairment important mediator of loss of control

Answer 18

Prefrontal Cortex

Question 19

Prefrontal output to Na

Answer 19

Glu

Question 20

NA projects to ____ using GABA

Answer 20

Thalamus

Question 21

The more intense and more direct this effect on DA release –> ___________

Answer 21

greater the addiction potential of the drug

Question 22

Amygdala to VTA functions to signal prospect of pleasure-reward (relevance detection) from ________ and provides motivational state to achieve it

Answer 22

natural reinforcers

Question 23

Drug-induced DA release (__________) is more explosive (pleasurable) than with natural reinforcers

Answer 23

VTA to NA

Drugs skip the learning natural pathway

Question 24

Repeated drug exposures result in __________ to trigger drug-seeking behavior when presented with drug cues

Answer 24

pathologic learning (VTA to amygdala)

Question 25

Amygdala to NA signals triggering of emotional memories by drug cues that then initiates ________

Answer 25

behavior to seek and take drugs

Question 26

Drug Addiction thus “hijacks” the ______________

Answer 26

normal reward circuitry

Question 27

Prefrontal cortex to nucleus accumbens

Orbitofrontal

Answer 27

regulating impulses

Question 28

Prefrontal cortex to nucleus accumbens

Dorsolateral

Answer 28

analysis of situation

Question 29

Prefrontal cortex to nucleus accumbens

Ventromedial

Answer 29

integration with emotions

Question 30

Variables Influencing Drug Abuse Pharmacokinetics
Rate of Onset of Action
~highly addictive

Answer 30

Abuse liability increased with faster of onset of action

Inhalation
Intravenous

Question 31

Onset of effects within 15-30 sec

Answer 31

IV

Question 32

Onset of effects within 7 sec

Answer 32

Inhalation

Question 33

Most dangerous route

Answer 33

IV

Question 34

Easiest route of administration – onset of effects delayed 20-30 minutes
Difficult to obtain rush feelings via this route

Answer 34

Oral

Question 35

Most commonly via insufflation – effects within 3-5 minutes

More rapid and intense than oral (bypasses liver)

Answer 35

Mucous membrane absorption

Question 36

Termination of Effects

Answer 36

Withdrawal effects more severe for drugs with short half-lives

Leads to continued drug administration simply to prevent withdrawal

Heroin (short t1/2) more addicting than methadone (long t1/2)

Question 37

For a drug-dependent individual, the more rapidly the target-receptor becomes __________, the more severe the withdrawal effects

Answer 37

unoccupied by drug