Cold-evoked activity remains unaltered in non-nociceptive class 1 neurons following PAG stimulation. A, Typical examples of a class 1 neuron response to acetone and EC [recorded from the same neuron; peristimulus time histograms (spikes per 1 s bin) are shown] before and after PAG stimulation. B, The effect of VL-PAG stimulation on class 1 neuronal responses to acetone (n = 3) and EC (n = 4). Data are expressed as mean ± SEM of normalized spike counts in response to acetone or EC. Statistical analysis compared post-DLH (PAG) and recovery (PAG+5 min, PAG+10 min, PAG+15 min) groups with baseline responses using Kruskal–Wallis test followed by Dunn's multiple comparison test; ns, p > 0.05. C, Injection sites in the PAG from which the effects of PAG stimulation on acetone- and/or EC-evoked responses were tested; coordinates are relative to bregma (Paxinos and Watson, 2005). DM, Dorsomedial; DL, dorsolateral; L, lateral; VL, ventrolateral.