Figure 6

Unilateral CCI results in deficits in olfactory avoidance behavior that recover at a rate proportional to CCI severity. The duration of investigative behavior to a noxious acetic acid stimulus in relation to an odorless water control was recorded for each mouse within an open field apparatus during a 3-min testing period at 1, 10 and 29 days post-procedure. The data is plotted as the total time each mouse spent investigating the water-scented paper subtracted from the value obtained with the acetic-acid odorant to give the relative avoidance time (negative values indicate higher preference for the water control odor). The results reveal an acute effect of CCI on olfactory preference. At 1 day post-procedure, CCI mice (but not shams or naïve) show no preference for water over acetic acid (* p < 0.05 versus naïve). Lack of olfactory discrimination in this test persists in CCI mice at 10 days post-procedure (** p < 0.01 moderate CCI versus naïve, ** p < 0.01 mild CCI versus sham). At 29 days post-procedure, moderate CCI mice continue to show no preference in this test (** p < 0.01 moderate CCI versus naïve), whereas mild CCI mice show a preference for water over acetic acid similar to sham and naïve controls). Data shown as mean ± SEM with n = 10/group.