Figure 2: Three-dimensional structure of pallial inputs.

Three-dimensional renderings of the chickadee brain, showing pallial regions projecting to HF. First view is from the anterior direction, last view is from the left, and the two intermediate views are rotations by 30° around the DV axis. In all cases the brain is vertically tilted toward the viewer by 10°. A random jitter between −50 μm and +50 μm was added to all AP coordinate for visualization only, since the actual coordinate is discretized by the 100 μm thickness of brain sections. The HD label pools all cells that were retrogradely labeled by three injections in one bird, at locations 2, 3, and 4 (Table 1). The three nidopallial regions are from a separate bird with injections at locations 4 and 7 (Table 1).