highly significantp < 0.0001
Comparison of the MO versus MO breathing histogram ( Figure S3B ; Figure 4A , gray trace) with the odor discrimination tasks revealed a highly significant difference ( Figure 4 ; Kolmogorov-Smirnov [K-S] test, p < 0.0001 for all odor pairs), indicating that increased sniffing occurred only when mice were conditioned to discriminate odors.