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. Author manuscript; available in PMC: 2008 Oct 20.
Published in final edited form as: Pharmacol Biochem Behav. 2007 Apr 13;87(1):81–89. doi: 10.1016/j.pbb.2007.04.006

Figure 4.

Figure 4

Summary histograms of motion parameters from 29 scans during marijuana or placebo marijuana smoking. A) shows the distribution of the maximum displacement from the initial head position due to any of the six measured motion parameters over the entire timecourse in voxel units (NOTE: rotation values were converted to displacement by calculating displacement at a radius of 75 mm due to the rotation). Subjects with a maximum displacement of >2 voxels are considered to have excessive motion. B) shows the distribution of the maximum change in displacement over a single timepoint in voxel units. Subjects with a single point displacement > 0.5 voxels have excessive motion. In this subject group, six subjects exceeded one or both thresholds.