FIGURE 1. AWC responds to odour removal.

a, AWC sensory neurons and downstream interneurons. b, Low magnification and c, d, high magnification view of the PDMS imaging chip, with worm nose exposed to buffer (c, streams 1–3 are open; stream 2 reaches the nose) or odour (d, streams 2–4 are open; stream 3 reaches the nose). e–g, Representative G-CaMP responses from AWC^ON. e, f, AWC^ON responses on addition (e) or removal (f) of isoamyl alcohol odour (coloured traces) or buffer (black traces) at 10 s. Grey shading denotes presence of odour; yellow intervals are analysed in h and i. g, AWC^ON responses on removal of bacterial-conditioned medium at 10 s. h, i, Average fluorescence change in AWC^ON during the 10 s after odour addition (h) or removal (i) (n = 30). Error bars indicate standard error of the mean (s.e.m.).