Functional MR imaging of confounded hypofrontality

Comparatively reduced blood flow to frontal brain regions in patients with schizophrenia (hypofrontality) has been frequently observed in the last 25 years. However, there is an inconstant quality to hypofrontality, suggestin g either confounded observation of a static (trait-like) abnormality, or th at it is a genuinely dynamic (state-like) phenomenon. Possible confounds in functional magnetic resonance imaging (fMRI) studies of hypofrontality are classified. Methods for assessment and correction of stimulus correlated m otion (an extracerebral confound) are reviewed in the context of fMRI data acquired from five schizophrenic patients and five comparison subjects duri ng performance of a verbal fluency task. Factorial analysis of these and ot her data, acquired from the same subjects during a semantic decision task, is used to exclude a number of possible intracerebral confounds. By analogy to the historical controversy concerning the appearance of the planet Satu rn viewed through early telescopes, understanding the inconstancy of hypofr ontality in schizophrenia is likely to progress more by theoretically drive n experiments that exploit the repeatability of fMRI than by further techno logical development alone. (C) 1999 Wiley-Liss, Inc.