Volumetric Changes of the Caudate. The plots show the significant caudate volumetric differences in the high vs. low frequency migraine subjects (left: p < 0.025 and right: p < 0.006). The volumes have been normalized to the total intracranial volume to scale for the brain volume for each subject. Bar heights represent the mean value for each volumetric measurement. Error bars represent the 95% confidence interval of the mean. * denotes significance.