Figure 3

Relationship between Ahi1 expression and fear learning across the BXD recombinant inbred strains. (a, b) Bar graphs depicting the expression of the Ahi1 3′UTR (untranslated region) probe (y axis, arbitrary units (log₂)) across the BXD RI and parent strains assessed in the neocortex at postnatal days (a) P3 and (b) P14. Note variability in probe expression across strains (2–3-fold range). (c) Pearson’s product–moment correlation between expression of the Ahi1 3′UTR probe measured at P14 (y axis) vs P3 (x axis). Note that, although significant, it is only modest in strength. (d) Bar graph depicting ‘PC_Owen’, the major principal component (PC) derived from three traits related to contextual fear conditioning reported by Owen et al.⁵³ across adult mice from 23 RI strains. Note that PC trait is highly variable across strains. (e–g) Pearson’s product–moment correlations between ‘PC_Owen’ (y axis) and expression of the Ahi1 3′UTR probes (x axis) measured at (e) P3, (f) P14 and (g) P60. Only strains for which both expression and behavioral data were available were entered into the correlation. Note the strong, highly significant correlation between contextual fear learning in adulthood and Ahi1 expression in neonates. Fear learning was not correlated with Ahi1 expression in adulthood and only marginally correlated with Ahi1 expression in juveniles. (h) Bar graph depicting ‘PC_Philip’, the major PC derived from six traits related to contextual and cued fear conditioning reported by Philip et al.⁵⁴ across adult mice from 60 RI strains. (i–k) Pearson’s product–moment correlations between ‘PC_Philip’ (y axis) and expression of the Ahi1 3′UTR probes (x axis) measured at (i) P3, (j) P14 and (k) P60. Note that cued fear learning in adult mice was moderately correlated with the neonatal expression profile of Ahi1 and weakly correlated with the adult profile. Notice that although the correlations between Ahi1 expression and PC_Philip were negative, the traits reported by Philip et al.⁵⁴ reflect activity upon presentation of the conditioned stimulus, while those reported by Owen et al.⁵³ reflect freezing. Hence, correlations between Ahi1 expression and fear conditioning in these two reports point to the same biological direction, so that strains exhibiting lower neocortical Ahi1 expression tend to perform worse on these associative learning paradigms. The data in the bar graphs depict mean±s.e.m. calculated over samples from each individual RI strain. For sample sizes, please refer to individual reports.^{53, 54}

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