(A) Multiphoton calcium imaging of odor-evoked activity patterns in the developing OB. Left: optical section through the OB of a transgenic zebrafish expressing GFP under the control of dlx4/6 enhancer elements, which target expression to subsets of interneurons. Center: changes in fluorescence intensity of a red-fluorescent calcium indicator (rhod-2-AM) in the same field of view evoked by odor stimulation (nucleotide mix). Right: thresholded overlay. (B) Three-dimensional reconstruction of calcium signal patterns in larvae at 3 and 5 dpf. Red: responses to amino acid mix (AA); green: responses to bile acid mix (BA); yellow: responses to both stimuli. Size of spheres indicates response magnitude. Responses to amino acids and bile acids are spatially segregated already at 3 dpf. Reproduced from (Li et al., 2005).

Reconstruction of four mitral cells with dendritic tufts in the same glomerular precursor from a stack of electron micrographs. Pairs of mitral cells with overlapping dendritic tufts are shown in the same color; dendritic tufts of mitral cells shown in different color are segregated.