Fig. 4

The HPC-AON circuit is necessary for context-driven odour recall. a Top: contextually cued odour recall test paradigm. Bottom: control groups in both experiments showed an increased investigation time between Day 9 and 10. Yet, following hM4D- (left) or ArchT-mediated (right) inhibition of hippocampal projections to the AON, mice fail to exhibit this behaviour (hM4D experiment- hM4D-mCherry: n = 10, mCherry control: n = 8; two-way ANOVA main effect of treatment F_(1,32) = 14.85, ***P < 0.0005; main effect of Day F_(1,32) = 34.5, P < 0.0001; interaction between treatment and Day F_(1,32) = 15.19, ***P < 0.0005; ArchT experiment—GFP: n = 14, iHPC-lAON: n = 12, vHPC-mAON: n = 12; two-way ANOVA main effect of treatment F_(2,70) = 7.538, **P < 0.005; main effect of Day F_(1,70) = 31.45, ****P < 0.0001; interaction between treatment and Day F_(2,70) = 7.052, **P < 0.005). b Mice were trained on a context-odour association and tested in a distinct context B in the absence of an applied odour. All animals showed no increase in investigation of the cotton swab despite all aspects of training being equivalent to mice tested in the training context (hM4D experiment—hM4D-mCherry: n = 10, mCherry control: n = 8; two-way ANOVA main effect of treatment F_(1,32) = 0.5035, NS, P = 0.4831; main effect of Day F_(1,32) = 0.0581, NS, P = 0.8111; interaction between treatment and Day F_(1,32) = 0.01156, NS, P = 0.9150; ArchT experiment—GFP: n = 12, iHPC-lAON: n = 12, vHPC-mAON: n = 12; two-way ANOVA main effect of treatment F_(2,66) = 0.4907, NS, P = 0.6144; main effect of Day F_(1,66) = 0.007502, NS, P = 0.9312; interaction between treatment and Day F_(2,66) = 0.2189, NS, P = 0.8040). Data are presented as mean ± SEM