Figure 2. Δe4–22^−/− mice display additional ASDs-related and comorbid behaviours.

(a–f) Abnormal USV communication. P4 Δe4–22^−/− (−/−) pups emitted significantly fewer USVs (a) (F_(2,32)=7.29, P<0.003) and of shorter duration (b) (F_(2,29)=4.59, P<0.02), than the other genotypes (ps<0.01). (c) Representative spectrographs of P4 USVs; n=8–13/genotype. Upon exposure to females, adult −/− males emitted fewer USVs (d) (F_(2,38)=6.15, P<0.01) that were of significantly shorter duration (e) (F_(2,34)=7.12, P<0.01) than the other genotypes (ps<0.02). (f) Representative spectrographs of adult USVs; n=10–18/genotype. (g,h) Impaired motor performance. (g) On the accelerating rotarod (left) −/− mice had shorter latencies to fall (RMANOVA: genotype effect F_(2,27)=5.33, P<0.02) than the other genotypes (ps<0.01). On the steady-speed rotarod (right), −/− mice also fell sooner (RMANOVA: genotype effect F_(2,27)=15.86, P<0.001) than the other genotypes (ps<0.005); n=9–12/genotype. (h) Hypoactivity in the open field. −/− mice had reduced locomotion (F_(2,23)=6.04, P<0.01) relative to the other genotypes (ps<0.001); n=6–10/genotype. (i,j) Escape behaviours in different environments. (i) No mice escaped from new home cages. However, six out of 13 −/− mice escaped from a novel environment (χ²_{(1, N=24)}=6.77, P<0.01); n=11–13/genotype. (j) In the MWM, −/− mice escaped from the hidden platform on significantly more trials than the other genotypes (χ²_{(2, N=1,680)}=314.01, P<0.001); n=11–13/genotype. (k) Impaired instrumental learning. −/− mice had difficulty learning to press a lever for food reward (RMANOVA: genotype effect F_(2,102)=4.7, P<0.05, genotype × session F_{(12, 102)}=3.0, P<0.001) relative to the other genotypes (ps<0.001); n=4–8/genotype. For all panels, *P<0.05 from +/+, ⁺P<0.05 from +/− for post hoc comparisons; ^&P<0.05 for χ² analyses. All data are expressed as means±s.e.m. MWM, Morris water maze.