Lecture 17 - Emotion Flashcards
What are emotions made up of?
Emotional experience - feelings
Emotional expression - physiological changes
Why would we study fear?
- Adaptive mechanism
- Life long
- Underlie several psychological disorder e.g. anxiety, PTSD
- Observed throughout species - easy to study
Describe the Pavlovian conditioning
- A protocol which causes learned fear
Training:
Tone (CS) + Shock (US) = Freezing (UR)
Memory testing
Tone (CS) = Freezing (CR)
Which brain structure is responsible for responding to fear? State the subregions of the structure which specifically involved in fear response.
Amygdala
- Lateral nucleus
- Central nucleus
Describe the pathway in the amygdala responsible for producing fear response in (1) increased heart rate (2) freezing and (3) increased vigilance
- Lateral nucleus is the major input of the amygdala
- Information is transferred into the central nucleus
- Central nucleus output converge into three structures
- Central grey nucleus: freezing
- Lateral hypothalamus: increased HR
- Paraventricular nucleus: increased vigilance
What happened to the neurons in the central and lateral nucleus of the amygdala following conditioning?
- Lateral: increased their firing rate to tone CS
- Central: previously did not response to tones now respond to tone CS
What happened when lesion to the amygdala (central and lateral lesion) was made to the freezing response?
Decreased freezing to the tone CS in rats
Name three therapeutic strategies to reduce fear
- Extinction
- Cognitive regulation
- Reconsolidation
Explain the concept of extinction: basic principles of it, what sort of experiment proved that amygdala is responsible for the underlying mechanism of fear extinction?
- Extinction learning new association between CS and aversive stimuli
- In extinction, the memory of CS-US association is NOT erased
- If NMDA antagonist which blocks LTP (i.e. blocks new learning) is administered in the amygdala = extinction is impaired in rats
In extinction, if the original memory is not erased why do we stop being afraid? - explain the molecular basis of extinction (incl. what happened to amygdala activation during extinction?), what other brain structure(s) is involved?
- What was known: activation of amygdala is high during fear conditioning but low during extinction - hence, amygdala is inhibited
- Inhibition comes from ventromedial prefrontal cortex - neurons in vmPFC becomes activated during extinction
- This activation inhibits fear response produced by the amygdala
What sort of disorder does extinction treat?
Phobias
Name two structures which actively blocks amygdala in cognitive regulation therapy
- vmPFC
2. dorsolateral prefrontal cortex
Describe the basis of cognitive regulation therapy in one sentence.
Reduced activation of amygdala through cognitive control.
Explain the basis of reconsolidation and how it could be use to treat fear disorder
When a memory is reactivated, it goes through a process of reconsolidation (storing memory again) which required protein synthesis (like in consolidation). During this time frame, the memory is sensitive to change.
The basis of the therapy is administering protein synthesis inhibitor to prevent this reconsolidation event and effectively erasing fear.
What experimental evidence was there to showed that fear memory can be erased through blocking reconsolidation?
RATS experiment:
- Rats are trained to show fear response to CS
- Rats injected with protein synthesis inhibitor AFTER reactivation
- Rats significantly showed diminished freezing response to CS
