Fig. 6
Nlgn3−/y rats show similar dPAG ERP amplitudes to WT rats during an auditory fear conditioning paradigm. A Schematic of auditory fear conditioning paradigm including tone habituation session. B Approximate locations of recording sites in the PAG. Black dots represent lesion site after electrode removal for an individual animal. C Almost no classic freezing behaviour was seen during the tone habituation session (p = 0.13, F(1, 13) = 2.63, repeated measures two-way ANOVA, WT n = 7, KO n = 8). PT: Pre-tone. D WT and Nlgn3−/y rats display similar levels of freezing behaviour during auditory fear conditioning (p = 0.54, F(1, 13) = 0.74, repeated measures two-way ANOVA, WT n = 7, KO n = 8). E Nlgn3-/y rats display significantly lower freezing behaviour during fear recall in comparison with WT cage-mates (p = 0.032, F(1, 13) = 1.96, three-way ANOVA, WT n = 7, KO n = 8). Grey boxes represent tone-responses that have been averaged for panels (H–K).F When analysed as “immobility response” (all four paws unmoving but allowing for movement of head and neck) Nlgn3-/y rats show no difference in this behaviour during fear recall (p = 0.001, F(1, 7) = 29.75, three-way ANOVA, KO n = 8) in comparison with WT controls (p = 0.12, F(1, 6) = 3.39, three-way ANOVA, WT n = 7). (p = 0.014, F(1, 13) = 8.036 (analysis method x genotype), p = 0.28, F(12, 156) = 1.21 (tone x analysis method), p = 0.093, F(12, 156) = 1.62 (tone x genotype), three-way ANOVA, WT n = 7, KO n = 8). G No significant difference in z-scored ERP peak-to-trough amplitude during fear recall in WT and Nlgn3-/y rats (p = 0.42, F(1, 13) = 0.73, repeated measures two-way ANOVA, WT n = 7, KO n = 8). H No significant ERPs during tone habituation for WT (n = 7, p = 0.25, paired t-test) or Nlgn3-/y (n = 8, p = 0.093, paired t-test) rats. Data represented as mean (solid line) ± SEM (translucent shading). I–L Significant ERPs were observed in both WT and Nlgn3−/y z-scored average ERP waveforms after CS onset for tones 1–3 (WT: p = 0.0032, KO: p = 0.0099), 4–6 (WT: p = 0.0030, KO: p = 0.0084), 7–9 (WT: p = 0.029, KO: p = 0.004) and 10–12 (WT: p = 0.0158, KO: p = 0.0046, paired t-tests, WT n = 7, KO n = 8). Data represented as mean (solid line) ± SEM (translucent shading). Dotted lines represent tone onset. Data represented as mean ± SEM, dots represent individual animals.