Fig. 9. Summed responses of salivary neurones (SN1 and SN2) to peppermint (hatched bars) or vanilla (shaded bars) odour 1 day after five sets of P+V- forward-pairing or backward-pairing trials. The responses are shown as means ± s.e.m. The results of statistical comparisons are shown above the bars (NS, P>0.05, ^**P<0.01; t-test).