Reward and Addiction Flashcards
Where does motivation originate in the brain?
Coordinated communication between the hypothalamus, reward circuitry, and prefrontal cortex
Primary rewards
Needed for survival
Secondary rewards
Derive their value from attainting primary rewards: money
Intercranial Self-Stimulation
Using pleasure centers, the brain can withhold electrical signals to certain regions to reinforce behaviors
Two areas of mesotelencephalic dopamine pathway
- substantial nigra: to dorsal stratium
- ventral tengmentum: to cortical and limbic sites – the mesotelecephalic pathway which is responsible for reward
How doe the VTA inspire dopamine?
The prefrontal cortex and lateral hypothalamic area, which handle motivation, excite glutamate, while the ventral tegmental area interneurons and nucleus accumbens , which triggers the VTA to provide dopamine to targets, such as the prefrontal and nucleus accumbens (NAc).
Nucleus accumbens
anticipatory reward
receives dopamine from VTA, and then excites the PFC via the ventral palladium (of the basal ganglia) and the dorsomedial nucleus of the thalamus
How does tobacco affect the brain?
Nicotine binds to acetylcholine receptors on dopoingertic neurons in the VTA, causing action potentials that relate dopamine in the NAc
How does alcohol affects the brain?
Reduces neural flaring (less glutamate, increased GABA)
Allows VTA APs to fire more often increasing dopamine in the NAc
How does Marijuana affect the brain?
Reduced Short term memory
THC binds to the GABAergic inputs in the VTA, reducing calcium influx and thus increasing APs for dopamine in the NAc
How do amphetamines affect the brain?
Reduces short term working memory and executive control
Competes with dopamine for uptake in the NAc. Reverses operations in the terminal, increasing dopamine in the NAc.
How does cocaine affect the brain?
A TRI, norepinephrine-serotonin-dopamine inhibitor, cocaine prevents dopamine reuptake in the NAc allowing high levels to persist.
How do opiates affect the brain?
Opiates bind to the GABAergic receptors in the VTA, enhancing potassium efflux, increasing dopamine by disinhibiting VTA dopamine neurons
