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PSYC20006 -Theme 3: Drugs (W8-10) > W9L2 - Noradrenaline > Flashcards

W9L2 - Noradrenaline Flashcards

1
Q

Noradrenaline Synthesis

A

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

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2
Q

What does Tyrosine Hydroxylase do

A

Synthesize tyrosine into DOPA

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3
Q

What does Amino Acid decarboxylase do

A

Synthesize DOPA into Dopamine

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4
Q

What does Dopamine β-hydroxylase do

A

Synthesize and break down Dopamine enzyme

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5
Q

Noradrenaline Breakdown

A

1 additional synthesis:

  • Noradrenaline > Adrenaline
  • Noradrenaline > Inactive metabolite
    • Monoamine oxidase (MAO)
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6
Q

Noradrenaline > Inactive metabolite

A

Monoamine oxidase (MAO)

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7
Q

What does the norepinephrine do

A
  • Sympathetic nervous system (flight/fight)
    • Arousal/vigilance
  • Exploitation vs Exploraton
  • Reward/Addiction (as in dopamine)
  • Memory
  • Anxiety
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8
Q

What is the part of releasing norepinephrine

A

Locus Coeruleucs (LC)

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9
Q

Properties of Lcous Coeruleus (LC)

A

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

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10
Q

One thing noradrenalien is MOST known for

A

Arousal. More NA = more arousal

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11
Q

During REM sleep, is NA released?

A

Silent = Little NA

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12
Q

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

A

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

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13
Q

4Fs in NA

A

Fight, Flight, Freeze or Fornicate

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14
Q

What is state of hyperarousal of NA adapted for:

A

Evolutionary aspect is NA important for individual or sexual fitness

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15
Q

What can high level of LC/NA lead to

A
  • 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)
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16
Q

What is the shape of stress. Explain

A

Inverted U shape. Optimal performance requires a balance.

17
Q

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

A

Consolidate decisions

  • Tradeoff between
    • exploiting known sources of reward
    • exploring the environment for alternative sources of reward (food, water, sex etc).
18
Q

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

A

Can do one thing at once

  • Indecision(Exploring): Constantly changing decisions
  • Inflexible (Exploiting): Repetitive behaviour
    • is bad because we need balance
19
Q

How does brain decide 2 behaviour

A
  • Burst of NA release “tips the balance” in favor of winner
    • increases strength of activating signal
    • inhibition of other signals
20
Q

When do LC neurons fire. What happens after?

A
  • When behavioural response selected & exectued (burst)
  • Neurons are inhibit after to allow selected behaviour to be ‘exploited’
21
Q

What affects the strength of burst of LC neurons

A

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

22
Q

LC Neurons during high arousal

A
  • Larger neuronal response
    • More NA + Longer inhibition
  • In high arousal, chosen focus of attention dominates longer
23
Q

LC Neurons during low arousal

A
  • 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
24
Q

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

A
  • 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.
25
Q

How does LC reflect pupil dilation

A

In the dark, dilation reflects NA level

26
Q

How does NA solve perceptual ambiguity (depth perception)

A

NA consolidates information and tips balance in favour of winner

  • Points to which one is the correct percept
27
Q

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

A

1000Hz Infrared Camera

  • Pupil diameter recorded during stimulus presentation
  • Subjects reported their perceptual switch with an immediate button press
28
Q

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

A

Pupil dilates at the time of new percept

  • Dilation begins before reported switch
  • Peak at 1 sec
29
Q

Results of pupil dilation reflecting motor and cognitive decision:

A
  • Could predict based on pupil dilation alone which number they were going to pick.
  • Pupil response by tracking
30
Q

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

A

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

31
Q

What are the theoretical implications of research on pupils and perception

A

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
32
Q

Clinical use of pupil dilation

A

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

33
Q

What are the conclusion of pupil dilation and perception

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

PSYC20006 -Theme 3: Drugs (W8-10) (6 decks)

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