Fig. 4. Serotonin application resulted in reversible enhancement of the optical responses in both the macroglomerular complex (MGC) and the ordinary glomeruli (Gs). The average peak percentage increase in the optical response in the MGC was 48.7±8.7% (N=7) and in the Gs was 40.0±8.0% (N=5). These both represent significant increases from the control values (P<0.001 and P<0.005, respectively). The enhancing effects reversed significantly with washing in both the MGC and Gs (P<0.05). Scale bar, 200 µm. OL, optic lobe; Oe, oesophagus; PC, protocerebrum; SOG, suboesophageal ganglion. Error bars represent S.E.M.