Biological Basis of Fear and Anxiety

Question 1

What are the distinctive features of the fear emotion?

Answer 1

Its universal, is a non-social emotion and has a distinctive facial expression

Question 2

What is the definition of anxiety?

Answer 2

Sustained fear due to the release of Corticotropin releasing factor, from the amygdala to the Bed nucleus stria terminalis

Question 3

What is a fear potentiated state?

Answer 3

When an animal is already primed with a fear reaction and then reacts to a scary stimulus e.g. when the rat is already anxious and then has an exaggerated jump from a startle

Question 4

What is the function of Valium in these studies?

Answer 4

In a sense the Valium, “takes away” the effect of the anxiety

Question 5

How fast is a startle reflex?

Answer 5

5-8ms

Question 6

If the amygdala was damaged, what would happen to the startle reflex?

Answer 6

There would be no change in the rats jump

Question 7

If the amygdala was damaged, what would happen to the fear potentiated state?

Answer 7

The rat couldn’t form the connection between the stimulus and the response so when the light comes on the rat would not be anxious and so doesn’t have the fear enhancement

Question 8

What is an anterograde tracer?

Answer 8

An anterograde tracer is a tracker that travels down a neuron to the end of the pathway

Question 9

What is special about the pathways of the BNST and CA?

Answer 9

They are parallel – when you stimulate one, they stimulate the same areas as each other

Question 10

Why do the BNST and CA have parallel pathways?

Answer 10

The BNST is not involved in the conditioning of fear, only involved in unconditioned responses e.g. light in rats – so if the BNST is damaged, it doesn’t affect the ability of the fear conditioned component

Question 11

What cues are the BNST in charge of?

Answer 11

Diffuse cues e.g. long term, unconditioned, less predictable

Question 12

What cues are the CA in charge of?

Answer 12

Explicit cues e.g. short term, conditioned, highly predictable

Question 13

What are the two main differences in the tests of conditioned and unconditioned fear responses?

Answer 13

Conditioning – fear potentiated startle vs no conditioning

Timing – short term activation (fear potentiated startle) vs long term activation (light or CRF enhanced startle)

Question 14

When is the CA crucially needed for the reaction to fear?

Answer 14

Cruically needed in minutes 1-4 because in mins 5-8, the area is inactive but the rat still jumps the same height but earlier on, the rat doesn’t jump as high when CA isn’t active

Question 15

When is the BNST crucially needed for the reaction to fear?

Answer 15

BNST is needed in minutes 5-8 because the rat hardly jumps at all in this second time frame when it jumps a lot in the first few minutes

Question 16

What effect does blocking the Basolateral amygdala have on both the CA and BNST

Answer 16

If the BaN is inactive then it prevents both functions because it is the crucial pathway for both areas

Question 17

What is the role of CRF in the fear pathway?

Answer 17

CRF can bypass the basolateral amygdala and come straight from the cortex and facilitates anxiety so using an antagonist would only work if places after the lateral CA – using an antagonist could stop the feeling of anxiety

Question 18

What is extinction?

Answer 18

Extinction is a form of inhibitory learning – facilitated by D-cycloserine (NMDA agonist)

Question 19

What can the conditioned stimulus do after extinction?

Answer 19

Activates the amygdala to produce a fear reaction or can activate another unknown area that inhibits the amygdala

Question 20

What effects does D-cycloserine have on anxiety to promote extinction?

Answer 20

If given cycloserine then extinction can happen twice as fast – you want to be able to inhibit the amygdala so you don’t cause anxiety, so people who had cycloserine recovered from their anxieties quicker