Lecture 22 - Noradrenaline, Arousal, Decisions and Anxiety

Question 1

Can dopamine-producing neurones produce noradrenaline?

Answer 1

No. Only noradrenaline-producing neurones are able to synthesise noradrenaline from dopamine (via the enzyme dopamine beta-hydroxylase).

Question 2

Where is noradrenaline produced in the brain?

Answer 2

Locus Coeruleus

Question 3

Why has studying the role and production of noradrenaline been difficult?

Hint: 30,000 neurones

Answer 3

The LC is very small and it is difficult to actually find it and measure it.

Question 4

What role does noradrenaline play in memory consolidation and why is this the case?

Hint: we remember things to a greater extent if we are in a heightened state of arousal

Answer 4

Noradrenaline plays a key role in arousal. When we are hyper-aroused we tend to remember things more clearly. This is why noradrenaline is associated with memory consolidation for memories we acquired during high arousal scenarios.

Question 5

What are the 4 F’s and how do these correlate with NA activity?

Answer 5

The four F’s associated with noradrenaline activity are Flight, Fight, Freeze and Fornicate.

Question 6

What role does NA play in explore and exploit decision making?

Answer 6

Noradrenaline is thought to play a key role in decision making, especially explore/exploit decision making. It is thought that release of NA leads to us choosing a certain option and then the inhibition of noradrenaline activity that follows is thought to allow us to maintain focus on the decision/option we have chosen.

Question 7

What is the function of the noradrenaline neurons being inhibited after they fire when making decisions?

Answer 7

Inhibition of NA neurons/activity is thought to allow us to maintain our focus on the decision we have made. This allows us to commit to the decision and not become stuck in indecision, which is evolutionarily bad.

Question 8

NA is important for the allocation of attention to a decision that has been made.
True or false?

Answer 8

True.

Question 9

The more arousing a stimulus/decision, such as getting away from a predator, the bigger the spike in Locus Coeruleus activity and….

Answer 9

The longer the period of inhibition of the noradrenaline-producing neurones in the Locus Coeruleus.

Question 10

Where are noradrenaline-producing neurones found in the brain?

Answer 10

Noradrenaline-producing cells are found in the Locus Coeruleus.

Question 11

What is the “inverted U” idea regarding optimal performance and Locus Coeruleus activity?

Answer 11

It is thought that optimal cognitive functioning occurs when we have a balance of NA activity/inhibition. Hyper NA activity or not enough NA activity lead to both stress/anxiety and lethargy/demotivation respectively.

Question 12

What is the “inverted U” idea regarding optimal performance and Locus Coeruleus activity?

Question 13

Can dopamine neurons also synthesise noradrenaline?

Answer 13

No.
Even though noradrenaline is synthesised from dopamine, only noradrenaline specialised neurons synthesise noradrenaline.

Question 14

What is mono-amine oxidase and what does it do?

Answer 14

Monoamoine oxidase is an enzyme that breaksdown three important neuromodulators: noradrenaline, dopamine, and serotonin.

Question 15

Where in the brain is noradrenaline produced?

Answer 15

The Locus Coeruleus and it is made up only about 30,000 neurons.

Question 16

What are some of the functions/roles noradrenaline is involved in?

Answer 16

Noradrenaline is involved in the function of the sympathetic nervous system - flight or fight, arousal/vigilance, anxiety, and memory consolidation (more likely to remember emotion-laden experiences).

Question 17

When are locus coeruleus neurons “almost silent”?

Answer 17

During REM sleep.

Question 18

What are the four Fs that are associated with high locus coeruleus/Noradrenaline activity?

Answer 18

Fight
Flight
Freeze
Fornicate
Noradrenaline is released in states of high arousal.

Question 19

In regards to noradrenaline, what is stress?

Answer 19

Sustained activity of loecus coeruleus/noradrenaline due to environmental factors that lead to prolonged arousal, which can become exhausting and limiting.

Question 20

High levels/prolonged activity of LC and release of noradrenaline are also associated with….

Answer 20

Anxiety and panic attacks.

Question 21

Noradrenaline is often associated with the four F’s. Outside of these high arousal states, what Noradrenaline thought to do?

Answer 21

Noradrenaline is thought to help consolidate choices. This means it helps us commit to a decision and take action. Adaptive behaviour involves a trade off between EXPLOITATION and EXPLORATION.

Question 22

Once we make a decision what do we see in noradrenaline release/activity of LC?

Answer 22

We see an inhibition/ceasing of NA/LC activity.

Question 23

When in a more arousing situation where decision making is between more important/survival centred decisions, what do we see in noradrenaline/LC activity?

Answer 23

The more arousing/important a decision is the more NA activity we see when we make a decision and the longer NA activity is inhibited.

Question 24

Noradrenaline function can be understood as allowing us to focus our attention on a given activity/decision.
True?

Answer 24

True.

Question 25

Noradrenaline helps with the allocation of….

Answer 25

Attention.

Question 26

Noradrenaline activity can also cause…

Answer 26

Restlessness.

Question 27

What is the association between noradrenaline and pupil dilation? And what experiments were done around pupil dilation and decision making and what did these experiments suggest about noradrenaline?

Answer 27

Noradrenaline release/LC activity is associated with pupil dilation.
Experiments looking at pupil dilation found that when we make a decision the pupil dilates. This work brought about the understanding that NA is involved in cognitive decisions, not just motor decision.

Question 28

What has pupil dilation done for communication in people with locked-in syndrome?

Answer 28

Pupil dilation may provide another way individuals with locked-in syndrome can communicate.