Reward And Addiction Flashcards
What is motivation?
A process that mediates goal directed responses or goal seeking behavior to changes in the external or internal environment
What is reinforcement?
The consequences of operant (learned) behaviors that alters the probability that a behavior will be repeated under similar conditions each time
What is salience?
Something important in the surrounding environment worth paying attention to
The attention grabbing feature of rewarding objects (think of it as wanting)
Describe salience
Heightens perception and focuses attention toward the particular sights, sounds and smells associated with these rewards in a way that normally promotes well being and survival
Typically triggered by encounters with reward related cues and experienced as surges of motivation to obtain and consume the reward that can last beyond the time the individual is exposed to the cue
Something having salience = something has value to the individual so that they want it
What is reward?
Involves hedonic effect of pleasure, motivation to obtain the reward because of its value (salience) and associated learning
What is aversion?
A negative reinforcement of behavior that the individual will learn to avoid in future encounters
What is pleasure/hedonia?
A subjectively positive sensations often referred to as euphoria or hedonia
Think of it as liking
What is anhedonia?
Lack of interest in something (no longer liking something you used to)
What is the physiologic purpose of pleasure?
To promote behaviors that are consistent with survival of self and the species
What is reward prediction error (RPE)?
Mismatch between events and reward elicited
An unpredicted reward elicits an activation (positive prediction error)
A fully predicted reward elicits no response
Omission of a predicted reward induces a depression (negative prediction error)
Dopaminergic neurons encode the discrepancy between what?
Reward predictions and information about the actual reward received and broadcast this signal to downstream brain signals involved in reward learning
Describe drugs of abuse
Increase extracellular dopamine concentrations in limbic regions including the NA
Drugs of abuse provide longer and large increases in dopamine than natural reinforcers like food and sex
Some drugs increase dopamine directly (ex. Cocaine, amphetamine, meth and ecstasy)
Other drugs work indirectly via other neuron receptors that modulate dopamine levels (ex. Nicotine, alcohol, opiates and marijuana)
What are the important brain regions for reward and addiction?
The mesolimbic system such as NA, ventral tegmental area (VTA), prefrontal cortex (PFC), limbic system
What is the main function of the nucleus accumbens (NA)?
To suppress sensations of pleasure/reward
Describe the nucleus accumbens
Is constitutively activated by a constant trickle of EAA like glutamate from the hippocampus, amygdala, or even the PFC
NA neurons are GABAergic meaning that activation of these neurons stimulate them to release GABA upon their target and inhibit it
Inhibit the PFC which keeps the brain in a reward neutral state (no pleasure)
What is the reward circuit?
When you do something that elicits a reward the VTA becomes activated which inhibits the NA
- DA neurons from the VTA project to the NA
- DA is released into the NA and inhibits its neurons
- NA activity decreases
- Decreased NA activity results in sensation of pleasure
