Mesolimbic Reward System

Question 1

Describe the organization and function of the ventral striatopallidal system

Answer 1

Function:
Functions as the interface between the limbic and motor systems and the hypothalamus; involved in goal directed behavior (appetitive motor behavior; motivated drive or reason to move the body); about reinforcing the movement (to eat or drink)

Organization:

• below the anterior commissure
• ventral striatum contains Nucleus Accumbens
• ventral pallidum has GABA-ergic projections that fire spontaneously

Question 2

Relate the internal nucleus accumbens (NAc) circuit to the dorsal striatum and note similarities in function and structural anatomical equivalents between ventral
and dorsal striatal networks

Question 3

Explain how dopamine is supplied to the ventral striatum

Answer 3

called up from LHA

Question 4

Explain how the lateral hypothalamus generates appetitive motor behaviors in the mesostriatal reward system

Question 5

Explain the effect of dopamine delivery to the ventral striatum on reward and addiction

Question 6

Summarize the roles played by different neural systems for reinforcement of drug addiction

Answer 6

BLA (conditioned reinforcement) and hippocampus (context) - input to NAc

CeA & BNST - processes Negative emotional states and stress

Ventral striatopallido system - goal directed behaviors

The habits depend on engagement of dorsal striatum

Executive control and subjective states (cravings, presumably feelings) associated with drugs depend on the prefrontal cortex

Question 7

Contrast proactive and reactive mechanisms for inhibiting movement

Answer 7

dlfpc vs vmpfc

Question 8

Explain how the lateral habenula is involved in the acquisition of avoidance response

Answer 8

overactive habenula plays a role in major depression

Active when we experience negative valence; perceive a cue to be rewarding, but in the end it is not

Question 9

Explain how the brain’s reward circuitry regulates immunity

Answer 9

VTA activation before bacterial infection has been shown to prime the immune response via sympathetic nervous system, which amplifies the activation of immune cells

Question 10

Describe the function of the mesolimbic system

Answer 10

To reinforce and automate behaviors in the presence of certain cues that we’ve trained our brain to believe lead to rewarding outcomes

Question 11

What are the consequences of vmPFC damage

Answer 11

Low affect (apathy)
Abulia (lacking drive; if bilateral)

Question 12

What are the inputs (& pathways & neurotransmitters if applicable) to the Ventral Striatum? (Nucleus Accumbens)?

Answer 12

Amygdala (via ventro-amygdalofugal pathway; GLU)
Hippocampus (via fornix; GLU)
vmPFC (GLU)
Lateral hypothalamus (wakefulness and eating; Orexin)

Question 13

What are the three DA pools we have learned about so far?

Answer 13

• VTA for motivated drive of rewarding behaviors
• Substantia Nigra Pars Compacta for motor system in basal ganglia to make movements occur
• Arcuate Nucleus for regulating prolactin levels for sexual behaviors

Question 14

list the three stages of the addiction cycle

Answer 14

1. Binge/Intoxication
2. Withdrawal/Negative Affect
3. Preoccupation/Anticipation