Reward and Addiction Flashcards
Motivation
Use goal oriented responses and behavior to change external or internal environments
Reinforcement can be used to cause similar behaviors to occur
Salience
Something important that is worth paying attention to in the environment
“Wanting”
You notice a feature that indicate that good rewarding things can come from it
Reward
Involves
- Hedonic effect of pleasure
- Motivation to obtain reward because of its value(Salience)
- Associated learning
Aversion
Negative reinforcement of behavior to avoid future encounters
Pleasure/ Hedonia
Positive sensation, euphoria or hedonia “Liking”
Reward Production Error (RPE)
Dopamine neurons encode the discrepancy between reward prediction and what you actually get ——> brain regions for reward learning
Positive Prediction Reward Error
- Unpredicted reward is elicited (massive brain stimulation)
No RPE
Fully predicted reward is eliciting no reward(no RPE) so you get the reward you expected
Negative Prediction Error
Don’t get reward you expect —-> depression in stimulation
Drugs vs natural rewards
Drugs: have a continuous negative RPE which increases stimulation of brain and is therefore preferred Natural Rewards(caring for young, food, exercise, mating): they are error-correcting DA-RPE, so you get the reward you expect (you learn to predict the outcome)
Drug abuse increases what NT and where
Dopamine in ECM of the Nucleus Accumbens
Cause 5-10 times higher Dopamine then natural reinforcement like sex and food
Drugs increasing Dopamine directly
Cocaine, Amphetamine, Methamphetamine, and ecstasy ——I dopamine reuptake
——> dopamine release
Drugs indirectly increase Dopamine
drugs bind to neurons that regulate other neurons to release more dopamine
Nicotine, Alcohol, opiates, marijuana
how environment and stimuli elicits behavior change (SALIENCE)
How this works in drugs and the reason people relapse
Drugs release 5-10 times more dopamine = more motivation to find the drug or stimuli then natural reward= you have motivation even if you can’t consciously feel the pleasure (since dopamine still increases)
+
Salience and Dopamine increases with even the sight, sound…. of anything associated with the drug in the environment = elicit desire for the drug
Mesolithic System uses what NT
What 4 parts to it
Uses DOPAMINE
- NA-> GABA
- Ventral Tegmental area -> Opioids
- Limbic System -> Dynorphin
- PFC-> EAA
NA (Nucleus Accumbens) Function
The Basic Circuit
To suppress sensation of pleasure and reward
Is default activated continuously by some EAA(GLUTAMATE) from hippocampus, amygdala, or PFC
Stimulated NA neurons release GABA at the PFC which keeps the brain in a reward neutral state (no pleasure)
The reward circuit
The VTA is activated VTA Neurons release Dopamine on NA NA neurons are inhibited NA doesn’t release GABA on the PFC Sensation and pleasure is felt
What activated the VTA
Due to engaging behavior which results in reward innately
Or due to a drug in innately
EEA GLUTAMATE from the PFC
ACH from the Tegmental Nuclei like Dorsal Tegmental Area
OREXIN from the hypothalamus when eating food
The reward feed back to shut it off
Neurons from the NA go to the VTA releasing GABA ——I VTA
And releasing Dynorphin (opioid) ——I(binds kappa-opioid R) VTA
= inhibit dopamine release
Dopamine hypothesis of reward
Inactivation of NA by the VTA
Dopamine-Independent Reward Pathway
Exercise, alcohol, and other activities increase opioid at all levels= VTA, NA, PFC: (BIND TO mu- receptors)
- VTA = bind/activate VTA dopaminergic inhibiting interneurons to allow VTA to release Dopamine
- NA = bind/activate to NA GABA releasing interneurons to inhibit NA form releasing GABA
- PFC= activate it directly
Uses endogenous opioids, a lot of pleasure
Reward from drug
Causes dopamine signal to the NA that is not proportional to a stimuli
REWARD= enhanced euphoria and exaggerated reward to a mild stimulus
Not learned behavior
Reward from natural thing like exercise
Dopamine release from VTA to inhibit NA due to a specific stimulus like running
To promote healthy living that may not have immediate benefits
REWARD= sense of pleasure
Learned behavior
Chronic Drug use alters neurons at a cellular level
Changes expression of TF and proteins involved in neurotransmission to regulate dopamine release
