Figure 2.

Two-photon imaging of antennal lobe projection neurons. (A) Based on the good optical resolution of the images obtained with the two-photon microscope, single glomeruli could be discriminated, some landmark glomeruli could be identified and neuronal activity could be measured selectively. (B) 3D reconstruction of single glomeruli in the antennal lobe based on in vivo morphological data. Individual glomeruli, in this case the three glomeruli that are putatively innervated by the receptor neuron axons of the sensilla coeloconica (Sc), could be identified (solid glomeruli). (C) The average image (100 frames) of a Ca²⁺ imaging trial was used to select regions of interest (ROI, encircled by dotted lines). The relative fluorescence change (ΔF/F) in single glomeruli (ROIs) was measured upon stimulation. (D) In this optical section (depth = 45 μm), one glomerulus (purple ROI) responded to odor stimulation (two air puffs of a mixture of 10⁻² citral and 10⁻² octanol at second 5 and 15 of the recording) with a drop in ΔF/F of about 11%. Other glomeruli, e.g., the orange ROI did not respond to the odor stimulation. D, dorsal; L, lateral; M, medial; V, ventral. Scale: 10 μm.