Figure 1.

(A) Sample T₂-weighted images at acquired in vivo at P14 and P21. Using CARET software (Van Essen et al. 2001), images were manually segmented at the boundary of gray matter and cerebrospinal fluid, and cortical surface representations were generated. The isocortex is highlighted in blue and allocortex in red. (B) The LACROSS registration approach (Knutsen et al. 2010) was used to determine a point-to-point correspondence between surfaces at different time points. Following the arrows between the surfaces, 1) an initial correspondence is determined between the surfaces the younger and older surfaces. 2) The older surface is then mapped to a sphere, and 3) a partial differential equation is solved on the spherical surface so that distortions between the 2 cortical surfaces are minimized while surface features are matched. The output of the solution is a spherical surface with updated coordinates. 4) These updated spherical coordinates are then mapped back onto the older cortical surface, which 5) provides a smoother mapping between the younger and older cortical surfaces. The solution is implemented on a spherical surface to simplify computations. Importantly, distortions introduced in mapping a cortical surface to a spherical surface are taken into account.