Motivation & Reward

What is behaviour?

It’s how an animal or person acts in response to a situation or stimulus.

Is behaviour always the same for the same stimulus?

No—behaviour is flexible. It can change depending on motivation.

What is internal motivation?

It's driven by needs like hunger, thirst, or curiosity inside the body.

What is external (incentive) motivation?

It’s driven by things outside the body, like rewards or goals.

What is instrumental learning?

Learning through rewards and consequences—behaviour changes depending on results.

What is the difference between appetitive and consummatory behaviour?

Appetitive = searching or working for a goal.
Consummatory = actually getting or using the goal (e.g., eating, drinking).

What is goal-directed behaviour?

Actions aimed at reaching a goal, not just reacting to discomfort.

What affects how motivated we are?

1. How much we want something (deprivation)
2. How good we think it is (value)
3. Its natural appeal (intrinsic properties)

What is the difference between a reward and a reinforcer?

Reward = something pleasant.
Reinforcer = anything that increases the chance a behaviour will happen again.

What is positive reinforcement?

Adding something good to increase behaviour (e.g. giving a treat).

What is negative reinforcement?

Taking away something bad to increase behaviour (e.g. stopping a shock).

What is punishment?

Adding something bad to reduce behaviour (e.g. scolding).

What is extinction in learning?

Behaviour stops when it no longer gets a reward.

What does Thorndike's Law of Effect say?

We repeat actions that feel good and avoid ones that feel bad.

What brain system is involved in reward and motivation?

The dopamine system—especially the mesolimbic pathway.

What is neuromodulation?

When brain chemicals adjust how neurons respond to things like rewards, effort, or risks.

What is Brain Stimulation Reward (BSR)?

BSR is electrical stimulation of the brain that acts as a powerful reinforcer, often linked to "pleasure centres" (Olds & Milner, 1954)

What did rats learn to do in Olds & Milner's (1954) experiment?

Rats learned to press a lever or run a maze to self-administer brain stimulation, even ignoring food.

Is BSR an example of classical or instrumental conditioning?

Instrumental conditioning.

What brain pathway is most involved in BSR?

The medial forebrain bundle (MFB), which connects the VTA to the nucleus accumbens.

What system is involved in reward, motivation, and learning?

The mesolimbic dopamine system.

What is the nucleus accumbens often described as?

The interface between motivation and action (Mogenson, 1980).

Which areas provide input to the nucleus accumbens?

The amygdala, hippocampus, anterior cingulate cortex, and ventral frontal cortex

What happens if dopamine receptors in the nucleus accumbens are blocked?

The reinforcing effect of BSR is reduced.

What effect do dopamine-enhancing drugs like amphetamine have on BSR?

They increase the potency of BSR.

What does Wise’s dopamine theory of reward suggest?

All rewards—including BSR, food, and drugs—are mediated by the mesolimbic dopamine system.

What types of learning are reinforced by the dopamine system?

Stimulus-stimulus, stimulus-response, and response-outcome learning.

What kinds of stimuli activate midbrain dopamine neurons?

Unexpected rewards, reward predictors, and addictive drugs.

What behaviours can medial forebrain bundle (MFB) stimulation trigger?

Eating, drinking, grooming, sex, and digging—energising behaviour in general.

What does dopamine do in relation to reward?

It energises behaviour and is key for appetitive (motivated) actions, not the actual consumption.

Does dopamine depletion affect all reward behaviours?

No, it mostly impairs energised, goal-seeking behaviour, not consumption (e.g., rats may still eat).

What is incentive motivation?

Motivation driven by external stimuli (like goals or rewards); dopamine loss in the nucleus accumbens reduces this kind of behaviour

How does dopamine enhance incentive motivation?

Activation of mesolimbic dopamine increases the significance of external stimuli, directing behaviour towards them

What does dopamine activity help with in learning?

Learning to respond to both reward stimuli and reward-predictive stimuli.

Schultz (1998, 2000) – What key role does dopamine play?

Dopamine neurons fire for rewards and for signals that predict rewards.

What happens in brain stimulation reward (BSR) or drug use?

The brain's reward system is tricked, so things like levers feel very important. The animal keeps going back to them, like they're a real reward.

Schultz (2006) – What is dopamine neuron firing linked to?

Reward delivery, not movement. They respond to rewards, not to movement itself

What happens to dopamine firing over time in learning?

Neurons stop firing at the reward itself and start firing at the cue that predicts the reward.

What does it mean when dopamine neurons shift their response?

The brain is learning. It expects the reward and reacts to the signal instead.

What did Berns et al. (2001) find about juice rewards?

The brain only reacted when the juice was a surprise — if expected, no strong reaction.

What does Berns et al. (2001) tell us about dopamine and learning?

Dopamine signals that something new or surprising is happening — it's a "learning signal."

What is a reward prediction error?

Dopamine neurons fire more for unexpected rewards – helps learning (Rescorla-Wagner model).

Why is the reward prediction error important?

It activates and strengthens synapses (via synaptic plasticity), supporting learning with glutamate.

What is the mesolimbic dopamine system's role in reinforcement?

Responds to important stimuli and helps organise responses towards them (e.g. levers in BSR)

How does BSR or drug addiction show dopamine system's effects?

The system is artificially activated, making environmental objects like levers the focus of motivated behaviour.

What is amphetamine?

A synthetic compound, chemically similar to catecholamines

What effects does amphetamine have?

Energising, can improve mental efficiency

What are some uses and risks of amphetamine?

Used for weight loss due to appetite suppression; overuse can cause psychosis

How do cocaine and amphetamine work in the brain?

They are indirect agonists for dopamine and noradrenaline neurons.

What do animals do with cocaine in research studies?

Self-administer intravenously, show conditioned place preference, and relapse when exposed to cues.

What is brain stimulation reward (BSR)?

Animals will learn a task (like pressing a lever) to receive electric brain stimulation – this reinforces behaviour

How is BSR similar to drug use?

Animals also learn tasks to receive drugs; both are examples of instrumental conditioning.

What happens when stimulants are self-administered into the nucleus accumbens?

Dopamine levels rise; this area is key to the drug's reinforcing effects.

What effect do dopamine blockers have on cocaine use?

Low doses increase drug-taking (compensation); high doses reduce it.

What do 6-OHDA lesions in the nucleus accumbens do?

They reduce self-administration of cocaine and amphetamine by destroying dopamine.

Do all addictive drugs act on dopamine directly?

No, some act indirectly through other neurotransmitters but still affect dopamine.

How do opiates affect dopamine?

They inhibit GABA neurons, which disinhibits dopamine

How does nicotine affect dopamine?

It acts in the VTA to trigger dopamine release.

How does alcohol affect neurotransmission?

It’s an indirect agonist at GABA_A and antagonist at NMDA (glutamate) receptors.

Do physical withdrawal symptoms fully explain addiction?

No. Addiction can persist without withdrawal symptoms, and relapse can occur long after withdrawal ends.

What triggers relapse?

Re-exposure to the drug, cues (like people or places), and stress.

What does classical conditioning have to do with drug use?

Environmental cues (CS) linked with drugs (US) can trigger drug-like effects (CR), like cravings.

What did Ito et al. (2000) find about conditioned stimuli?

Drug-related cues increase dopamine in the nucleus accumbens core.

What did Volkow et al. (2006) find using PET scans?

Drug cues increase dopamine release in human cocaine addicts.

What is the difference between ‘wanting’ and ‘liking’ in addiction?

‘Wanting’ is the motivational drive (incentive salience); ‘liking’ is the sensory pleasure

What brain system is associated with ‘wanting’?

The mesocorticolimbic dopamine system.

What brain areas are associated with ‘liking’?

Nucleus accumbens shell, ventral pallidum, and orbitofrontal cortex.

What happens to ‘wanting’ after repeated drug use?

It becomes sensitised – drugs and cues become more 'wanted' even if they’re less 'liked'.

What did Berridge et al. (2009) say about drug sensitisation?

'Wanting' can increase even if 'liking' or withdrawal does not change.

What did structural MRI studies show about drug addicts' brains?

Reduced grey matter in dorsal and ventral medial prefrontal cortex.

What functional change occurs in the brain of addicts?

Disrupted glutamatergic pathway from prefrontal cortex to nucleus accumbens – reduces impulse control