11. Dopamine Hypothesis Theory Flashcards
1
Q
The law of effect
A
- selection of behaviours determined by law of effect (Thorndike, 1898)
- responses leading to pleasant stimuli occur more often, those leading to unpleasant stimuli less often
- tendancy to carry out a response is adjusted according to its immediate consequences
2
Q
how do stimuli effect behaviour
A
- Reinforcement = stimulus increases frequency of responses leading to its delivery
- Positive = occurrence of pleasant stimuli increases probability of response leading to delivery
- Negative = probability of responses leading to termination/reduction of unpleasant stimuli
- Punishment = decreases frequency of responses leading to its delivery
3
Q
what is reward?
A
- nothing inherently rewarding about a stimulus
- its the neural action of the mind that determines the stimulus’ value
4
Q
what makes a stimulus rewarding
A
- almost all rewarding/pleasurable stimuli can be explained in evolutionary terms (gene propagation)
- natural (primary) rewards required to maintain the survival of a species (food/water/sex)
- Conditioned reinforcer = previously neutral stimuli can be paired with a primary reinforcer, neutral stimulus then acquires reinforcement properties previously associated with primary reward (socialisation, clothes = sex)
5
Q
conditioning
A
- conditioned stimulus (CS) - may affect behaviour
- for behaviour to change, follow a CS with an unconditional stimulus (US)
- CS can either be rewarding or aversive
- CS = associations are learnt
- Operant conditioning = learnt through reward
- operant = responses have consequences (reinforcement or punishment/increase or decrease probability of response)
6
Q
how does the brain process reward?
supports dopamine hypothesis
A
Olds and Milner (1954)
- specialised centres in the brain
Wise (1996)
- changes in dopamine
7
Q
Olds and Milner (1954)
A
- brain has specialised centres for reward function
- implanted rats with deep brain stimulating electrodes
- whenever rats entered a specific corner of the box the NAc was electrically stimulated
- rats kept running to the same corner
- when a lever is introduced that delivers shocks
- rats prefer this to any other stimulus (food or sex)
- will run across an electric grid to stimulate themselves
8
Q
Wise (1996)
A
- drug induced changes in dopamine availability alter the potency of stimulation
- using DA antagonists (reduction) reduces amount of dopamine, rat processes level more times more quickly
9
Q
Excitatory Neurotransmitters
A
- glutamate
- acetylcholine (Ach - main)
10
Q
Inhibitory Neurotransmitters
A
- GABA
- Glyicine
11
Q
Modulatory Neurotransmitters
A
- Dopamine (depends where it is in the brain)
- Serotonin
- many more
12
Q
Valente et al (2012)
A
- classical and operant conditioning in other animals
- early stages of brain (pre cortex = basal ganglia, nucleus accumbens) must have something to do with learning
- also means we can study in other animals (less ethical in humans)
- focus on brain regions present in studies
13
Q
two main dopaminergic regions
A
- nucleus accumbens (NAc)
- Ventral Tegmental area (VTA)
- rats have really strong preservation of areas in the mammalian brain (thalamus/hypothalamus)
- just gets bigger with more cortical regions in human midbrain region similar, just larger in humans
14
Q
human reward model
A
- lots of neurotransmitters merge at the NAc (has a shell and core)
- GABA taken and DA given between VTA and NAc
- GABA also responsible as output from NAc as motor response
- Glutamate comes from many other regions (PFC, HPC, BLS [basolatoral amygdala])
