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
• Noradrenaline > Inactive metabolite
  
  • Monoamine oxidase (MAO)

Question 6

What converts Noradrenaline to an Inactive metabolite?

Answer 6

Monoamine oxidase (MAO)

Question 7

What does the norepinephrine do?

Answer 7

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

Question 8

What is the part of releasing norepinephrine?

Answer 8

Locus Coeruleucs (LC)

Question 9

Properties of Lcous Coeruleus (LC)?

Answer 9

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

Question 10

One thing noradrenalien is MOST known for?

Answer 10

Arousal. More NA = more arousal

Question 11

During REM sleep, is NA released?

Answer 11

Silent = Little NA

Question 12

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

Answer 12

Highest rates rapidly follow a transient noxious or extremely positive stimulus/event (lots of NA released)

Question 13

4Fs in NA?

Answer 13

Fight, Flight, Freeze or Fornicate

Question 14

What is state of hyperarousal of NA adapted for?

Answer 14

Evolutionary aspect is NA important for individual or sexual fitness

Question 15

What can high level of LC/NA lead to?

Answer 15

• Stress
  
  • Sustained LC/NA due to environmental factor
• Anxiety
  
  • Uncontrollable irrational worry for 6 months
• Panic Attacks
  
  • Brief intense episodes reflecting LC/NA Spikes triggered by
    
    • Apparently random thoughts
    • Internal thoughts
    • Learned Associations (PTSD)

Question 16

What is the shape of stress? Explain.

Answer 16

Inverted U shape. Optimal performance requires a balance.

Question 17

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

Answer 17

Consolidate decisions

• Tradeoff between
  
  • exploiting known sources of reward
  • exploring the environment for alternative sources of reward (food, water, sex etc).

Question 18

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

Answer 18

Can do one thing at once

• Indecision(Exploring): Constantly changing decisions
• Inflexible (Exploiting): Repetitive behaviour
  
  • is bad because we need balance

Question 19

How does brain decide 2 behaviour?

Answer 19

• Burst of NA release “tips the balance” in favor of winner
  
  • increases strength of activating signal
  • inhibition of other signals

Question 20

When do LC neurons fire? What happens after?

Answer 20

• When behavioural response selected & exectued (burst)
• Neurons are inhibit after to allow selected behaviour to be ‘exploited’

Question 21

What affects the strength of burst of LC neurons?

Answer 21

More Importance, Salience, or Arousing alternatives the bigger the LC burst and NA released

Question 22

LC Neurons during high arousal?

Answer 22

• Larger neuronal response
  
  • More NA + Longer inhibition
• In high arousal, chosen focus of attention dominates longer

Question 23

LC Neurons during low arousal?

Answer 23

• Smaller neuronal response
  
  • Less NA + Shorter inhibition. Neurons start firing more to add variability to decision
• In low arousal, increased NA promotes a switch to a new decision, promoting “exploration” of alternative behaviors

Question 24

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

Answer 24

• Low LC activity and NA release
  
  • Tired, poor performance
    
    • Inattentive non-alert
• High LC activity and NA release
  
  • Restless, stressed, poor performance
    
    • Distractible
• Optimal performance requires moderate activity with large intermittent bursts.

Question 25

How does LC reflect pupil dilation?

Answer 25

In the dark, dilation reflects NA level

Question 26

How does NA solve perceptual ambiguity (depth perception)?

Answer 26

NA consolidates information and tips balance in favour of winner * Points to which one is the correct percept

Question 27

What has been used to measure pupil dilation in task? What did participants do in the task?

Answer 27

1000Hz Infrared Camera * Pupil diameter recorded during stimulus presentation * Subjects reported their perceptual switch with an immediate button press

Question 28

Is there a r/s between pupil diameter and timing of perceptual switch? Describe the peak timing.

Answer 28

Pupil dilates at the time of new percept * Dilation begins before reported switch * Peak at 1 sec

Question 29

Results of pupil dilation reflecting motor and cognitive decision?

Answer 29

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

Question 30

Experiments using an adapted version of rock-paper-scissors showed that..?

Answer 30

Pupil dilation accompanies a decision and it is possible to see this pupil diameter without any fancy equipment

Question 31

What are the theoretical implications of research on pupils and perception?

Answer 31

_NA and LC_ * Play the same role in perceptual and cognitive decisions, as * Play a role in behaviour as they are believed to play in behaviour * optimizing a balance between exploitation and exploration

Question 32

Clinical use of pupil dilation?

Answer 32

Using pupil dilation, can communicate with people thatare minimally conscious or are suffering locked-in-syndrome

Question 33

What are the conclusion of pupil dilation and perception?

Answer 33

* Pupil dilation accompanies perceptual switches during perceptual rivalry * Pupil dilation can also be used as an index of cognitive decisions