LECTURE 4

Question 1

A conditional stimulus (CS) elicits fear because it activates the memory of the aversive unconditional stimulus (US) it was paired with. Describe the two behavioral observations that support this mechanism.

Answer 1

Rat doesn’t react with freezing to the shock but startle. So the freezing displayed in classic conditioning experiments emerges from the pairing of tone and shocks.

Fear conditioned rat → give rat decreasing shocks without tone → if you then on a separate test fase present a tone again the rat will show no fear. Now the tone is associated with a weak shock.

Question 2

Describe the critical experiment that showed involvement of glutamate NMDA receptors in the formation of CS-noUS memories during fear extinction.

Answer 2

WALKER (2002) used rodents and conducted fear conditioning followed by fear extinction training. One group received a placebo, while the other group received an NMDA receptor antagonist in the amygdala. The control group showed a decrease in fear responses during extinction, indicating successful formation of CS-noUS memories. However, the experimental group with NMDA receptor blockade showed impaired fear extinction and failed to form robust CS-noUS memories. This experiment suggests that NMDA receptors play a crucial role in the formation of new memories during fear extinction.

Question 3

Explain why the effects of d-cycloserine (DCS) on fear extinction represent a novel treatment paradigm for anxiety disorders

Answer 3

The effects of d-cycloserine (DCS) on fear extinction represent a novel treatment paradigm for anxiety disorders due to its ability to enhance and accelerate fear extinction during exposure therapy, promote long-term effects, and complement psychological interventions. While being able to only administer the substance when you had a good session.

Question 4

Describe the behavioral and neural findings of the fear extinction study that compared patients with post-traumatic stress disorder (PTSD) to healthy individuals (TENC) and highlight why these findings are relevant.

Answer 4

PTSD patients don’t show fear extinction to context.
Lower activation in ventro medial prefrontal cortex and hippocampus. Which have been shown in rat research to be involved in fear exticiton. And hyperactivation in the ACC which also has been shown to be involved in fear reaction

Question 5

Does d-cycloserine (DCS) enhance the encoding, the consolidation, or the retrieval of CS—noUS extinction memories? Describe the experimental evidence.

Answer 5

DCS augments memory consolidation.
You can give DCS even after the fear extinction paradigm and it will show significant affects.