Fear and the amygdala - week 11 (Chris)

Question 1

Complex emotions

Answer 1

Combinations of basic emotions
May be socially or culturally learned
Requires cognitive processing
E.g. regret (also grief, jealousy)

Question 2

Basic emotions

Answer 2

Unique characteristics
Developed through evolution
Reflected in facial expressions
Relatively automatically generated
E.g. Fear, sadness, happiness, anger, disgust, suprise

Question 3

The amygdala

Answer 3

The neural structure that plays the central role in this theory is the amygdala

Two small almond shaped structures in the medial temporal lobe on the end of the hippocampus.

Question 4

Learning, Emotion and the amygdala: Fear Conditioning

Answer 4

Much of what we know about the amygdala comes from the fear conditioning paradigm

First present 2 different stimuli alone – tone (conditioned stimulus) which elicits no response, and shock which elicits a startle response,

Next train the mouse to associate the tone with a shock

Then after training present the tone alone and this now elicits a startle response (conditioned response)

Question 5

Extinction

Answer 5

In extinction, you just get rid of the association of the light with the footshock.

So you just present the tone alone repeatedly, and after a while the mouse unlearns the association

Question 6

Lateral amygdala cells – patterns of firing during fear conditioning

Answer 6

Quirk et al (1995)
On the left are cells that fire in response to the tone (the conditioned stimulus). As you can see, after training they increase their firing especially in the very early phase after tone delivery. The plasticity goes away after extinction

Question 7

Role of the amygdala in fear conditioning

Answer 7

LeDoux (1996)
Amygala lesions block fear learning
Rats with amygdala lesions do not learn to associate the noise (CS) with the shock (US) to produce a fear response (CR)

Question 8

3 patients with bilateral amygdala lesions due to Urbach-Wiethe disease

Answer 8

Feinstein et al. (2013)

Consistent with earlier suggestions that panic is a false biological alarm, the affective response to CO2 may be part of a protective system triggered by suffocation and acute metabolic distress.

Researchers gave patients with bilateral amygala damage co2 inhalation

Found they actually had an elevated panic response
Compared CO2 response in patients and controls

All the amygdala patients had panic attacks, only 25% of healthy controls did.

Also tested subjective response to CO2.

Amygdala patients and controls who did have panic attacks had similar levels of subjective panic.

Question 9

Conscious or unconscious learning in the amygdala?

Answer 9

Bechara et al. (1995) studied 3 patients – one with amygdala lesion, one with hippocampal lesion, one with damage to both structures
Conditioned Stimulus (CS): coloured slide/tone
Unconditioned Stimulus (US): Boat horn
Measured Skin Conductance Response (SCR)
Also asked patients to report explicit knowledge of which CS predicted the US
Patient with amygdala damage showed impaired SCR to the conditioned stimulus but intact factual learning

Patient with hippocampus damage showed normal SCR to the conditioned stimulus but impaired factual learning

Patients with both amygdala and hippocampus damage showed impaired SCR to conditioned stimulus and impaired factual learning.

Question 10

LeDoux – Two emotion systems

Answer 10

High road:
Slow
Conscious experience
Full sensory analysis of threat

Low road:
Fast
Unconscious
Immediate response (run away)