Fig. 3. The optical response in the antennal lobe (AL) in response to electrical stimulation of the antennal nerve (AN) was greater and longer lasting following serotonin application. (A) The normalized control optical response is first in the macroglomerular complex (MGC) and, in later frames, throughout the AL. The time given in each frame represents the time (ms) following the stimulus; the same values apply to the corresponding frames in (B) and (C). (B) After 12 min bath application with serotonin (10^-4 mol l^-1), the normalized optical response is stronger throughout the AL and longer lasting. (C) The serotonin-effect images show that the enhancing effects are non-homogenously distributed throughout the AL. Arrows indicate two glomerulus-sized regions of the ordinary glomeruli (Gs) in which the enhancing effects of serotonin were particularly strong. Scale bar, 200 µm.