Squares on brain diagrams on the right show approximate areas of imaging, and dashed lines represent approximate brain midlines. a, Cerebellar region from shallow to deep imaging. At 60 μm, some skin is visible (red asterisk) due to the curvature of the brain, as well as several blood vessels (red triangles) under the skin and above the skull. At 120 μm, skull features are evident. Deeper into the brain, fiber tracts predominate (red arrows). b, Optic tectal region from shallow to deep. At 147 μm, some skull is evident (green square) as well as some brain. Tectal fiber tracts are evident (green asterisk) at multiple depths (see 147, 245 and 378 μm) with a thick commissural fiber tract present (green triangle) at 490 μm. At deeper layers fiber tracts predominate (green arrows). CB N=10, OT N=16.