Circuit tracing using Brainbow multicolor labeling. (A) The confocal data set of the inner granular layer of the cerebellum was resampled in the y–z orientation to provide this view orthogonal to most axons (A1). In this orientation, each cellular component was traced with Reconstruct (A2). Small spots are axons; enlarged, bright objects are mossy fiber rosettes. (B) Three-dimensional reconstruction of cerebellar mossy fiber axons and granule cells. A mossy fiber contact with a granule cell is visible (indicated by the white arrowhead and enlarged in B2). B1 also shows two different rendering options in Reconstruct: Boissonant surface (top, left) and individual traces (bottom, right). Scale bars, 20 μm (A); 10 μm (B).