Figure 4. Deformation field analysis.

A.Processing of wildtype brain images by reflection around the anterior-posterior axis

B.Horizontal slice through the habenula showing (1) unregistered image, (2) deformation field produced during registration, (3) registered image. Left panels (wildtype) started with unprocessed images, right panels (flipped) with left/right-flipped images. Arrowhead shows voxel-expansion required on left side of image required to match reference brain.

C-E. Number of statistically significant voxels detected in the habenula after comparison of unprocessed and flip-brain images using Holm-Bonferroni correction (C), region-wise permutation testing (D) and cluster analysis (E). Results derived from analysis using voxel-intensity comparisons (grey circles) and deformation-field analysis (black squares)

F-G. False positives (percent of all significant voxels that were outside the habenula) for the experiment in C-E for N=10 (F) and N=15 (G) per group and using voxel-intensity analysis (I) or deformation-field analysis (J).

H. 3D-projection of significant pixels comparing normal and flipped brains, from region-wise permutations with N=15 per group. Arrowhead: habenula

Hb:habenula; MO:medulla oblongata; oe:olfactory epithelium; TeO:optic tectum; Ce:cerebellum