Figure 6. FTD vs AD.

Top: Group difference P-map

Bottom: Percentage difference map

The statistical maps are displayed in two formats. Group difference P-maps show the surface of the object such that the color scale represents the P-value at each point on the surface. The Percentage maps display the degree of shape difference between groups as a percentage of the larger group's mean radial size. The color scale shows the percentage difference, with negative values representing atrophy.

In the maps displayed, the superior surface refers to the dorsal anatomical aspect, whilst the inferior surface refers to the ventral aspect. The medial aspect of right and left hemisphere models face each other, and the lateral aspect faces the outside of the image. For example, in Figure 3, the images are, clockwise from left: group difference P-map superior (dorsal) aspect of putamen, with the anterior (rostral) aspect towards the top of the image; group difference P-map inferior (ventral) aspect of putamen, with the rostral aspect towards the bottom of the image; percentage difference map ventral aspect of the putamen, with the rostral aspect towards the bottom of the image; percentage difference map dorsal aspect of the putamen, with the rostral aspect towards the top of the image.

HD: Huntington's disease; FTD: Frontotemporal dementia; AD: Alzheimer's disease; CTL: Healthy controls

R:right

L:left

Put: putamen

Anterior: anterior (rostral) end

Posterior: posterior (caudal) end

Med: medial aspect