When downloading files of the IIT Human Brain Atlas make sure you realize that there is a mean and a median DTI template available. The mean DTI template is constructed from the mean of tensors from multiple subjects. The median DTI template contains the median tensors from the group of subjects used in the construction of these templates. If you are not sure which one to use, then you probably want to use the mean DTI template. Use the median DTI template only if you are sure you are interested in the median tensors. The mean DTI template is more appropriate for use as a reference for spatial normalization (the median DTI template is more noisy).