Figure 1.

Schematic depiction of the experimental paradigm used in the present study. (A) Number and stimuli types presented during the 3 experimental phases. The central hypotheses of the current study focused on the Day 2 recall test, during which EEG and fMRI were recorded simultaneously. CS+E/CS−E, CSs presented during extinction phase; CS+N/CS−N, CSs not presented during extinction phase. CS+ were reinforced with an aversive US (“w/”, contingency of 50%) during acquisition phase, while CS− were never paired with a US (“w/o”). (B) Trial structure and timeline for a single CS trial. All CSs were shown for 4 s. During the acquisition phase, a 500-ms electric shock US coterminated with 50% of all CS+ trials, starting 3.5 s after CS onset. (C) Normalized CS evoked differential (CS+ – CS−) SCRs, (D) subjective CS arousal ratings, and (E) subjective CS negative valence ratings (M ± within-subject standard error of the mean (SEM), O'Brien and Cousineau 2014) for extinguished and nonextinguished stimuli during all experimental stages. *P ≤ 0.05, **P ≤ 0.01 (one-sided, CS+ > CS−).