Principles of Neuroscience Lecture 27 Reward

Question 0

Describe ‘Suppression of Behaviour’ with reference to a specific example

Answer 0

Micruration

Humans have the capability to decide when it is appropriate to urinate. We can inhibit the spinal reflex via brain input

Question 1

Describe the divisions in descending control of emotion

Answer 1

Volitional: pyramidal projections

Non volitional, emotional: extra pyramidal

Question 2

What did the Olds-Milner experiment show

Answer 2

There are specific regions associated with pleasure

Rats will press a lever when it causes stimulation of specific areas in the brain

Question 3

Which regions in the brain are important for reward?

Answer 3

Ventral medial forebrain
Median forebrain bundle

Ventral tegmental area

Question 4

Describe the limbic loop pathway

Answer 4

1. Cortical input stimulates
2. Striatum, nucleus accumbens, which inhibits
3. Pallidum, which can no longer inhibit
4. Thalamus, which activates
5. Cortex

Question 5

What is the role of dopamine in the limbic loop pathway?

Answer 5

Increases the activity of the loop by further activating the striatum

Question 6

What is the role of the VTA?

Answer 6

It is the source of dopamine for the basal ganglia

Question 7

Describe the dopaminergic pathway, and the effects of hedonic drugs on this pathway

Answer 7

Dopamine is released by neurons from the VTA terminating on striatum (nucleus accumbens)

Heroin and nicotine: stimulate the VTA to release more dopamine
Cocaine and amphetamines: stop the reuptake of dopamine by the VTA neurons. Dopamine has longer lasting effects

Question 8

What happens to the neurons in the brain when the individual is addicted to drugs?

Answer 8

There is a decrease in basal activity

Question 9

When the olds-Milner experiment was performed on humans, what feeling did the subjects report?

Answer 9

They reported that the effect of dopamine was an anticipation of reward, not reward itself

Question 10

Describe the difference between wanting and enjoying with reference to a particular experiment

Answer 10

In rats who have depleted striatal dopamine, they will not seek sugar.

However, if they are given sugar, they will still enjoy it.

This shows that there are two different areas for wanting and enjoying

Question 11

Which region is important for enjoying?

Answer 11

Ventral striatum

Question 12

Describe the features of stimulus-reward learning

Answer 12

When we receive a reward, there is increased activity of the VTA

When we are conditioned to that reward, there is no longer an increase in activity when we receive it

If we are conditioned, and we receive the conditioned stimulus but no reward follows, there is extinction of the activity of the neurons in the VTA

Question 13

Describe how reward undermines motivation with reference to a particular study

Answer 13

In one study there were two groups. One group received a reward when it performed an activity and the other didn’t

The second time, neither recieved a reward. The group who initially had had no motivation to perform the activityy

Question 14

What are modulatory systems of the brain?

What are the general features?

Answer 14

A neuron regulates diverse populations of CNS neurons with various neurotransmitters

1. Diffuse action
2. Nuclei contain relatively few neurons
3. Nuclei in brain stem and basal forebrain
4. Highly divergent
5. En passant connections

Question 15

What are the four neuromodulatory systems?

Answer 15

Dopamine
Serotonin
Noradrenaline
Acetyl choline

Question 16

Which activities normally elicit the phasic dopamine activations of the limbic loop?

Answer 16

Food
Water
Sex
Micturition
Complex social behaviours