Skip to main content
. 2015 Aug 15;117:40–55. doi: 10.1016/j.neuroimage.2015.05.039

Fig. 2.

Fig. 2

Illustration of fixel–fixel connectivity and smoothing. a) A group-average FOD template colour-coded by direction (red: left–right, blue: inferior–superior, green: anterior–posterior). b) Zoomed in region from a, showing individual FODs within the group-average FOD template. c) The direction and number of fixels in each voxel was computed by segmenting each FOD in a (coloured by fixel orientation). d) A single exemplar fixel f (blue arrow, belonging to the superior longitudinal fasciculus), with associated probabilistic streamlines. e) Fixels colour-coded by ‘connectivity’ to fixel f. The connectivity, cfi, between exemplar fixel f and fixel i is defined as the proportion of streamlines traversing fixel f that also traverse fixel i. f) A spatial Gaussian kernel centred on fixel, f, is multiplied with fixel connectivity in d to estimate the fixel-specific smoothing neighbourhood weights shown in f. g) Smoothing neighbourhood weights for fixel, f, used to smooth fixel data prior to analysis.