Figure 4: Overview of ICD analysis.
From: Weak functional connectivity in the human fetal brain prior to preterm birth
For any voxel in the gray matter, the voxel’s time course is correlated with every other voxel’s time course. This procedure is repeated for every voxel, resulting in a voxel-by-voxel correlation matrix. From this matrix, a single row is extracted (representing all correlation to a voxel) and converted to a histogram to estimate the distribution of connectivity for that voxel. From this distribution, a survival function is constructed and parameterized with a stretch exponential with unknown parameters α and β. For our purposes, α controls the rate of decay of the survival function with a larger α indicating a slower decay and larger global connectivity. The α ICD maps can then be thresholded to reveal putative hubs of the fetal connectome.
