Learning rates and CR latency data for mice trained at trace 50–350 or trace 50–450. Learning rates and CR latency data for mice trained at trace 50–350 or trace 50–450. A, Only 4 of the 8 mice were able to learn trace 50–350 (left graph), and only 3 of 8 mice were able to learn trace 50–450 (right graph) within 12 training sessions (black lines indicate learners and gray lines indicate nonlearners; red markers show median CR rate for learners and light red markers show the median CR rate for all mice). B, Left graphs show probe trials from two example mice from each of the three groups trained at different trace intervals. Numbers on x-axes give the median latency to CR onset and peak for each example mouse. Note that the latencies to onset are similar across these examples, while the latencies to peak shift with the longer training intervals. Right graph shows group data for CR latencies and amplitude for the 3 training groups beginning with initial expression until the last training session (black lines show median latencies, shaded gray region indicates interquartile range). Mice showed CR onsets that did not vary across the different trace intervals on the final training days (trace 50–250 vs 50–350, Wilcoxon rank: U = 26, n = 4 and 12, p = 0.42; trace 50–350 vs 50–450, U = 5, n = 3 and 4, p = 0.69). Latencies to CR criterion and peak were different between trace 50–250 and 50–350 (Wilcoxon rank: U = 45, n = 4 and 12, p < 0.001 and U = 44, p < 0.001, respectively), with the peaks of CRs appropriately timed for the training intervals used. Mice trained to trace 50–450 showed early latencies relative to the training interval, and were not different from mice trained to 50–350 for any parameter (Wilcoxon rank, Onset: U = 5, n = 3 and 4, p = 0.69; Criterion: U = 8, p = 0.31; Peak: U = 6, p = 0.57). CR amplitudes were similar between the three training groups (rightmost graph, black lines show median for each training day, gray shaded area shows interquartile range, dotted line indicates median amplitude of trace 50–250 mice on the first day of expression as reference). Jennifer J. Siegel et al. eneuro 2015;2:ENEURO.0051-14.2015 ©2015 by Society for Neuroscience