W9L2 - Noradrenaline

Question 1

Noradrenaline Synthesis

Answer 1

Tyrosine > Dopa > Dopamine > Noradrenaline (Same as Dopamine)

Question 2

What does Tyrosine Hydroxylase do

Answer 2

Synthesize tyrosine into DOPA

Question 3

What does Amino Acid decarboxylase do

Answer 3

Synthesize DOPA into Dopamine

Question 4

What does Dopamine β-hydroxylase do

Answer 4

Synthesize and break down Dopamine Enzyme

Question 5

Noradrenaline Breakdown

Answer 5

1 additional synthesis:

Noradrenaline > Adrenaline (driven by hormone adrenaline)
Noradrenaline > Inactive metabolite

Question 6

Noradrenaline > Inactive metabolite

Answer 6

Monoamine oxidase (MAO)

Question 7

Noradrenaline alternative name

Answer 7

Norepinephrine

Question 8

What does the norepinephrine do

Answer 8

• Sympathetic nervous system (flight/fight)
• Arousal/vigilance
• Anxiety
• Exploitation vs Exploraton
• Reward/Addiction (as in dopamine)
• Memory

Question 9

What is the part of releasing norepinephrine

Answer 9

Locus Coeruleucs (LC)

Question 10

Properties of Lcous Coeruleus (LC)

Answer 10

Very small area of brain with very few neurons (about 30,00)

Question 11

One thing noradrenalien is MOST known for

Answer 11

Arousal. More NA = more arousal

Question 12

During REM sleep, is NA released?

Answer 12

Silent = Little NA

Question 13

Following a noxious/super positive event, is NA released?

Answer 13

Highest rates of NA released

Question 14

4Fs in NA

Answer 14

Fight, Flight, Free or Fornicate

Question 15

What is state of hyperarousal of NA adapted for:

Answer 15

Evolutionary aspect is NA important for individual or sexual fitness

Question 16

What can high level of LC/NA lead to

Answer 16

• Stress and Anxiety
  (Stress: sustained NA due to environmental factor)
  (Anxiety: uncontrollable irrational worry for 6 months)

Panic Attacks: Brief intense episodes reflecting LC/NA Spikes

Question 17

What is the function of stress. Explain

Answer 17

Inverted U shape. Optimal performance requires a balance.

Question 18

At moderate levels of LC/NA activity, what does NA do

Answer 18

Consolidate decisions.

Question 19

Explain moderate levels of LC/NA and its utility in evolution

Answer 19

Adaptive behaviour = Tradeoff between (1) EXPLOITING known sources of reward (2) EXPLORING environment for alternative reward sources

Question 20

What is exploitation vs exploration. What kind of behaviour is best?

Answer 20

• Can choose one.

- Indecision / Inflexible is bad because we need balance

Question 21

How does brain decide 2 behaviour

Answer 21

Burst of NA release “tips the balance” in favor of winner - increases strength of activation & inhibition of signals

Question 22

When do LC neurons fire

Answer 22

When behavioural response selected & exectued (burst)

Question 23

What happens after LC neurons

Answer 23

After response, neurons are inhibited (suppressed) to allow selected behaviour to be “exploited”

Question 24

What affects the strength of burst of LC neurons

Answer 24

More Importance/Salience/Arousal = More NA burst

Question 25

LC Neurons during high arousal

Answer 25

Bigger neuronal response = More NA + Longer inhibition

• In high arousal, chosen focus of attention dominates longer

Question 26

LC Neurons during low arousal

Answer 26

Smaller neuronal response = Less NA + Shorter inhibition

• In low arousal, increased NA promotes a switch to a new decision, promoting “exploration” of alternative behaviors (firing more to add variability after)

Question 27

How does LC release affect performance. What is the optimal performance. Compare low and high

Answer 27

Low levels of LC activity and NA release = tired, vague & poor performance (inattentive non-alert)

High levels of LC activity and NA release = restless, stressed & poor performance (distractible)

Optimal performance requires moderate activity with large intermittent bursts.

Question 28

How does LC reflect pupil dilation

Answer 28

Pupil dilation is caused by Atropine and NA Causes Dilation.

Question 29

How does NA solve perceptual ambiguity (depth perception)

Answer 29

NA consolidates information and tips balance in favour of winner

Question 30

Is there a r/s between pupil diameter and timing of perceptual switch

Answer 30

Pupil dilates at the time of new percept (dilation begins before reported switch & pick at 1 sec)

Question 31

How to measure pupil diameter in task

Answer 31

• Pupil diameter recorded during stimulus presentation.
• Subjects reported their perceptual switch with an
  immediate button press

Question 32

Task to distinguish pupil dilation between motor and cognitive decision: Results

Answer 32

Could predict based on pupil dilation which one they were going to pick. Pupil response by tracking.

Question 33

What are the conclusion of pupil dilation and perception

Answer 33

1.) Pupil dilation accompanies a switches during
perceptual rivalry
2.) Pupil dilation can also be used as an index of cognitive decisions

Question 34

What are the theoretical implications of research on pupils and perception

Answer 34

NA and LC likely play the same role in perceptual and cognitive decisions, as they are believed to play in behaviour (optimizing a balance between exploitation and exploration)

Question 35

Clinical use of pupil dilation

Answer 35

Using pupil dilation, can communicate with people that

are minimally conscious or are suffering locked-in-syndrome