Figure 2.

NE represents a threat prediction error. (A) Prediction error and value representations under forward (difficult to separate) and trace (more separable) conditioning. (B) Behavioral schema. Same as Figure 1A, but with a 15-second waiting period between cue offset and shock. (C) Placement of fibers in frontal cortex. (D) During initial tone/shock pairing, both precue freezing and trace freezing are greater than cue freezing (F_2,20 = 18.95, p < .0001; trace vs. cue freezing: t₂₀ = 5.785, p < .0001, precue vs. cue freezing: t₂₀ = 4.717, p = .0004). (E) Continued tone/shock pairing maintains freezing pattern (F_2,20 = 17.49, p < .0001; trace vs. cue freezing: t₂₀ = 5.720, p < .0001, precue vs. cue freezing: t₂₀ = 4.161, p = .0014). (F) During tone-only presentations, cue and trace freezing are greater than precue freezing (F_2,20 = 40.31, p < .0001, precue vs. cue freezing: t₂₀ = 3.028, p = .0198, precue vs. trace freezing: t₂₀ = 8.835, p < .0001, cue vs. trace freezing: t₂₀ = 5.806, p < .0001). (G–I) Same as Figure 1F–H, but for trace conditioning (n = 11 mice). Lack of NE ramping during trace is notable. (J) NE release during trace period is decreased compared with cue period across acquisition (F_1,10 = 7.270, p = .0225 for cue vs. trace). (K) Shock-evoked NE release (0 to 2 seconds postshock %dF/F minus 2 to 0 seconds preshock %dF/F) decreases across acquisition trials. (L) Forward cue-evoked NE is on average greater than trace cue-evoked NE. ****p < .0001. NE, norepinephrine.