PSYC20006 Lecture 21: Lecture 21 - Noradrenaline (Arousal, Decisions & Anxiety)
12 Jun 2018
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Lecture 21 - Thursday 18 May 2017
PSYC20006 - BIOLOGICAL PSYCHOLOGY
LECTURE 21
NORADRENALINE: AROUSAL, DECISIONS & ANXIETY
TODAY
•Noradrenaline Synthesis & Release
•Noradrenaline in arousal & the 4 F’s
•Noradrenaline in decision making
•Pupil dilation experiments
NORADRENALINE SYNTHESIS & RELEASE
•Tyrosine is translated to dopa, into
dopamine, which can further be changed
into NA. No longer able to activate
dopaminergic neurons.
NORADRENALINE = NOREPINEPHRINE
•Sympathetic nervous system (flight or fight)
•Arousal/Vigilance
•Anxiety
•Exploitation vs Exploration
•Reward/addiction
•memory consolidation
•Very small area of the brain with very few neurons
(~30,000).
•(In contrast the primary visual cortex V1 estimated
to have 280 million neurons).
LOCUS COERULEUS (LC)
•Neuron firing
•Highest rates rapidly follow a transient noxious or extremely positive stimulus/event
(lots of NA released). Highly salient event = more NA.
•Silent during rapid eye movement (REM) sleep (very little NA released).
Lecture 21 - Thursday 18 May 2017
PSYC20006 - BIOLOGICAL PSYCHOLOGY
•High LC/NA activity = 4 F’s
•4F’s (Fight, Flight, Freeze or F...
Fornicate)
•State of Hyper-arousal adapted for
evolutionarily important situations
where “individual” or “sexual fitness” is
involved.
•High LC/NA activity = Stress &
Anxiety
•High levels of LC/NA activity can lead
to the following, depending on the
trigger and duration:
•Stress: often experienced when LC/
NA Activity is sustained due to
environmental Factors (social,
emotional, physical etc).
•Anxiety: excessive, uncontrolled
and often irrational
“worry” (diagnosis requires
symptoms for 6 months).
•Panic attacks: brief intense episodes
believed to reflect spikes of LC/NA
activity triggered by
•apparently random events
•internal thoughts
•learned associations (PTSD)
STRESS & AROUSAL
•Stress response involves intricate interactions between the brain and body.
•Optimal performance requires a balance. Function is impaired with too little or too much stress
(inverted U).
NA FUNCTION BEYOND AROUSAL & THE 4 Fs
•At moderate levels of LC activity, Noradrenaline acts to consolidate decisions.
•Adaptive behaviour represents a tradeoff between exploiting known sources of reward and
exploring the environment for alternative sources of reward (food, water, sex etc).
•An idea that’s been put forward from animal literature is that outside of these highly arousing
moments, what is NA doing? A model
was put forward saying it is balancing
trade off between exploring environment
and exploring opportunities maybe?
•Indecision, inaction or constant changing
decisions is bad. But inflexible, repetitive
behaviour is also bad. We need a balance.
NA & BEHAVIOURAL
SELECTION
•At any given moment there’s parts of the
brain doing different shit. Talking about
food etc. Along with these urges, not only
are certain networks involved in
coordinating the response, it is also
bubbling away in the background for !
Document Summary
Today: noradrenaline synthesis & release, noradrenaline in arousal & the 4 f"s, noradrenaline in decision making, pupil dilation experiments. Noradrenaline synthesis & release: tyrosine is translated to dopa, into dopamine, which can further be changed into na. Noradrenaline = norepinephrine: sympathetic nervous system (flight or fight, arousal/vigilance, anxiety, exploitation vs exploration, reward/addiction, memory consolidation, very small area of the brain with very few neurons (~30,000), (in contrast the primary visual cortex v1 estimated to have 280 million neurons). Locus coeruleus (lc: neuron firing, highest rates rapidly follow a transient noxious or extremely positive stimulus/event (lots of na released). Highly salient event = more na: silent during rapid eye movement (rem) sleep (very little na released). Psyc20006 - biological psychology: high lc/na activity = 4 f"s, 4f"s (fight, flight, freeze or f Fornicate: state of hyper-arousal adapted for evolutionarily important situations where individual or sexual fitness is involved, high lc/na activity = stress &
