Figure 2. PDCP expression correlated with caudate DAT binding.

A. A single cluster was identified in a voxel-wise whole brain search of the FPCIT PET images for regions with significant correlations between DAT binding and PDCP activity (see text). This region was localized to the left caudate nucleus (x=−14, y=20, z=−2 mm; Z_max=4.06, p<0.05, corrected). A smaller cluster (arrow) was identified in the right caudate nucleus at the less stringent hypothesis-testing threshold of p=0.005, uncorrected. [The display was superimposed onto a single-subject MRI brain template and thresholded at t=2.95, p<0.005). L indicates the left cerebral hemisphere.]

B. Display of individual data from a spherical volume-of-interest centered at the peak voxel of the left caudate cluster (p<0.001, top) and from a mirror volume placed at the same coordinates on the right cerebral hemisphere (p<0.01, bottom).

C. The results were validated using an independent correlation analysis that employed anatomically defined regions-of-interest to define the boundaries of the left and right caudate nucleus (see text). DAT binding measurements in these hypothesis-testing regions (presented as percent of the normal mean) were found to correlate significantly with PDCP expression values (left caudate: p<0.004; right caudate: p<0.02). [The best fitting regression line for each correlation is depicted by a solid line; the 95% confidence intervals by broken curves.]