(A) percentage signal change in visual cortex (V1, top), optic radiata (OR, middle) and splenium of corpus callosum (SCC, bottom) at flicker frequency 4Hz (blue), 8Hz (red) and 12Hz (green). The dotted steps in the background represents the stimulus on/off cycle during acquisition in seconds. (B) Power spectral density in the corresponding ROIs where color represents the flicker frequency of stimulus (time course of representative voxels after Bonferroni correction).Mean and standard error plot showing percentage volume activated in various white matter ROIs.