Differing degrees of head motion have long been recognized as a
potential confound in functional neuroimaging studies comparing
neuropsychiatric populations to healthy normal volunteers, and studies
often cite excessive head motion as a possible reason for the different
patterns of functional activation frequently observed between groups. We
empirically tested the degree of head motion in 16 patients with chronic
schizophrenia and 16, age- and education-matched controls during the
acquisition of functional magnetic resonance imaging data. We examined the
degree of motion across three different indices (total motion, relative
motion, task-correlated motion) during a complex attentional task and the
effect of entering the motion parameters as additional regressors in a
general linear model analysis. Results indicate that individuals with
schizophrenia did not exhibit more task-correlated or total motion
compared with controls. Moreover, the residual error term from the general
linear model analysis was similar for both groups of subjects. In
conclusion, current results suggest that stable patients with
schizophrenia are capable of controlling head motion compared with matched
normal controls. However, a direct comparison of the motion parameters is
an essential step for any quality assurance protocol to determine whether
additional corrective techniques need to be implemented. (JINS,
2007, 13, 839–845.)