Discriminative Fear Conditioning

Discriminative fear conditioning trains subjects to differentiate between a CS+ (paired with footshock) and a CS- (explicitly unpaired), assessing the ability to form selective threat associations while inhibiting fear responses to safety signals. This paradigm taxes lateral amygdala circuits for CS-US association, prefrontal mechanisms for safety signal processing, and the discrimination between threat and safety at the level of amygdala-prefrontal interactions. Impaired discrimination, characterized by generalized fear to both CS+ and CS-, models pathological fear generalization observed in post-traumatic stress disorder and generalized anxiety disorder.

The discrimination ratio is calculated as (CS+ freezing minus CS- freezing) divided by (CS+ freezing plus CS- freezing), with values near +1 indicating perfect discrimination and values near 0 indicating complete generalization. Absolute freezing levels to each CS are reported alongside the discrimination ratio to distinguish between high-fear discriminators and low-fear discriminators. Within-session acquisition curves for both CS+ and CS- track the development of differential responding. Generalization gradients can be mapped by testing intermediate stimuli that share features with both CS+ and CS-.

ConductMaze delivers precisely timed CS+ and CS- stimuli with pseudorandom presentation order to prevent temporal prediction. The software independently scores freezing during each CS type, computing discrimination ratios and acquisition slopes in real time. The platform supports multiple CS modalities including tones of different frequencies, light stimuli, and white noise. Automated pseudorandomization ensures balanced CS ordering without immediate repetitions, and the system flags sessions where CS- freezing exceeds user-defined generalization thresholds.