Inhibitory signals
leptin, insulin, and PYY
Stimulatory signals
ghrelin from the stomach
hypothalamus-pituary complex
command center of the endocrine system
paraventricular zone of the hypothalamus
controls the ANS
Arcuate nucleus
center of energy regulation in hypothalamus`
Satiety neurons
POMC/CART
Hunger neurons
AgRP/NPY
Anoretic peptides
αMSH and CART
Orexigenic peptides
AgRP/NPY
Elevated leptin
- POMC/CART neurons release anoretic peptides
- Activate PVN neurons that release TSH and ACTH from anterior pituary to raise metabolic rate
- Inhibit lateral hypothalamus neurons to inhibit feeding behavior
- Activate sympathetic division of ANS
Decreased leptin
- AgRP/NPY neurons release orexigenic peptides
- Inhibit PVN neurons that release TSH and ACTH from anterior pituary to decrease metabolic rate
- Activate lateral hypothalamus neurons to stimulate feeding behavior
- Activate parasympathetic division of ANS
The timing of reward
- Learn to recognize a reward cue: associating
- Mobilize and go after the reward: wanting
- Savor the reward: liking
Anatomy of reward system
ventral tegmental area, nucleus accumbens,and PFC
What neurotransmitter does the VTA release?
dopamine
Two pathways
mesolimbic and mesocortical
Mesolimbic pathway
VTA to NA
Mesocortical
VTA to PFC
VTA
Learning association between cues and potential reward
NAc
Important for mobilizing effort for reward
Largest recipient of dopamine in the brain
NAc
Involved in decision-making and cost-benefit analysis
PFC
Effect of drugs on the reward system
Prolong dopamine activation or potentiate neuronal activation in NAc and VTA
Net effect of addiction
Chronic decrease in basal activity and increase in phasic activity in presence of abusive drug
PFC addicted brain
decreased activity
