Empathy Is Moderated by Genetic Background in Mice
Figure 2
Freezing responses of test mice during direct presentation of the CS-only or the paired CS-UCS.
(a) When mice were not pre-exposed to objects or conditioned themselves, there was no strain difference in freezing to the CS (N = 12 mice/genotype; age = 6–7 wks). (b) BALB mice expressed longer freezing responses than B6 mice on trials 5-10 when they had not been pre-exposed to objects, but were directly exposed to the CS-UCS contingency (N = 16 mice/genotype; age = 7–8 wks). Asterisks represent significant differences between BALB and B6 mice as assessed by a Bonferroni step-down procedure on a trial-by-trial basis (∝ = 0.005 for each trial). All data were scored in duplicate by 2 independent raters (see the figure legend corresponding to Figure 3 for the inter-rate reliability) and are presented as the mean±s.e.m.