Measuring learning in human classical threat conditioning: Translational, cognitive and methodological...

Area of Science:

• Neuroscience
• Psychology
• Behavioral Science

Background:

• Threat conditioning is a key model for understanding anxiety disorders.
• Numerous conditioned responses (CR) exist for quantifying learning in humans.
• Existing literature offers varied insights into CR's relation to threat learning.

Purpose of the Study:

• To review and analyze various CR used in human threat conditioning.
• To assess if CR indicate amygdala-dependent threat learning.
• To relate CR to formal learning models and infer threat learning.

Main Methods:

• Narrative review of existing literature on threat conditioning CR.
• Analysis of CR based on their relation to amygdala function, learning models, and inferential validity.
• Consideration of specific CR including heart period, skin conductance, startle eye-blink, and pupil size.

Main Results:

• Heart period, startle eye-blink, and Pavlovian-to-instrumental transfer are strongly linked to amygdala-dependent threat learning.
• Skin conductance responses (SCR) are most studied in relation to formal learning models, reflecting threat prediction and uncertainty.
• Startle eye-blink and pupil size show promise in differentiating conditioned stimuli (CS+/CS-), though direct comparisons are limited.

Conclusions:

• Not all CR equally inform about amygdala-dependent threat learning or formal learning models.
• Specific CR like heart period and startle eye-blink offer robust measures for threat learning research.
• Future research should focus on improving the quantification and comparative analysis of CR in threat conditioning.