Fig. 5.
Odor habituation tests to discriminate behavioral phenotypes toward novel and familiar odorants. Behavioral familiarity with the odorants was assessed by duration of odorant investigation time. (A) Representative images of rat body traces from groups 6 through 10 during the 15-min acclimation phase without odorants in the central cartridge. (B) Snout traces generated within the first 100 s after initial approach to the odorant zone during the test. (C) Time course of 7-day repeated behavioral tests of odor habituation, attenuation, and discrimination showing that odorant habituation occurs after a single exposure. Plotted are odorant investigation times of animals in groups 2 and 3 over the repeated training and test days. * indicates significant difference (P < 0.05, repeated-measures ANOVA with Bonferroni post hoc test). (D) Time course of smelling responses on the acclimation, single-session training, and testing trials. Smelling duration was determined by the time during which snout was within the odorant zone scored automatically for the first 30 s after initial approach to the zone. (E) Data on the testing day in (D) are summarized in bar graph representation. All symbols and colors are identical to those in figure 3, G and H and table 1 for easy comparison. Data were derived from the same animals as in figure 3, G and H. * Significant difference (P < 0.01) relative to a novel odorant exposure without anesthesia (blue bar); † significant effect (P < 0.01) relative to a novel odorant exposure given 24 h after anesthesia (purple bar) or to the second exposure to the anesthesia-paired odorants (gray bar). Notice that the gray bar is not different from the blue and purple bars, in sharp contrast to the histology results in figure 3, G and H. ANES = anesthesia.