Figure 14. Performance of PV-M₁KO mice in T-maze, novel object recognition and Morris water maze tasks.

A, examples of correct and incorrect choices in the spontaneous alternation T-maze. B, in a T-maze spontaneous alternation task there was no significant difference in alternation rates between PV-M₁KO mice and WT mice (F_(1,52) = 0.99; P = 0.32). However, there was a significant interaction in time (F_(1,52) = 10.24; P = 0.0023). Representative track plots of a (C) WT mouse and (D) PV-M₁KO mouse during the 5 min test novel object recognition task. E, as a population, WT (n = 12) but not PV-M₁KO (n = 13) mice spent significantly more time with the novel than familiar object (object time: F_(1,23) = 12.44, P = 0.0018, two-way ANOVA, Bonferroni multiple comparisons test). Representative track plots are shown for a WT mouse on (F) training day 1 and (G) training day 3 in Morris water maze; (H) and (I) are corresponding plots for a PV-M₁KO mouse. J, population data indicate that both WT (P < 0.05, n = 12) and PV-M₁KO (P > 0.05, n = 13) mice exhibited a significant reduction in latency to escape between days 1 and 3 (time effect: F_(2,69) = 6.64, P = 0.0023, two-way ANOVA, Bonferroni multiple comparisons test). No significant differences were found on days 1–3 between WT and PV-M₁KO mice (genotype effect: F_(1,69) = 1.15, P = 0.29, two-way ANOVA, Bonferroni multiple comparisons test). M₁KO, M₁ muscarinic acetylcholine receptor knockout; PV, parvalbumin; WT, wild-type.