Figure 2.

Intervening sleep promoted generalization of extinction of conditioned fear in comparison of two groups: Wake (trained in the morning and tested in the evening, upper panels) and Sleep (trained in the evening and tested in the morning, lower panels). A. Average trial by trial SCR during Fear Conditioning and Extinction Learning. There were no differences between the Sleep and Wake group. B. Schematic of the acquisition of conditioned fear (upper panel) and extinction learning (lower panel). Note that although acquisition of fear is schematically depicted as an ascending curve, actual SCR responses in humans tend to decrease across conditioning trials. C. Average trial by trial SCR to the extinguished (CS+E) and un-extinguished (CS+U) CS+ in the two groups during each trial of the Extinction Recall phase occurring 12 hours after Fear Conditioning and Extinction Learning phases. D. Schematic interpretation of results in C., i.e., because groups did not initially differ (A.), sleep promoted generalization of extinction learning. μS1/2, square-root transformed SCR in micro-Siemens,** p < 0.01, bars are SEM.