Uncinate fasciculus findings in schizophrenia: a magnetic resonance diffusion tensor imaging study.
OBJECTIVE
Disruptions in connectivity between the frontal and temporal lobes may explain some of the symptoms observed in schizophrenia. Conventional magnetic resonance imaging (MRI) studies, however, have not shown compelling evidence for white matter abnormalities, because white matter fiber tracts cannot be visualized by conventional MRI. Diffusion tensor imaging is a relatively new technique that can detect subtle white matter abnormalities in vivo by assessing the degree to which directionally organized fibers have lost their normal integrity. The first three diffusion tensor imaging studies in schizophrenia showed lower anisotropic diffusion, relative to comparison subjects, in whole-brain white matter, prefrontal and temporal white matter, and the corpus callosum, respectively. Here the authors focus on fiber tracts forming temporal-frontal connections.


METHODS
Anisotropic diffusion was assessed in the uncinate fasciculus, the most prominent white matter tract connecting temporal and frontal brain regions, in 15 patients with chronic schizophrenia and 18 normal comparison subjects. A 1.5-T GE Echospeed system was used to acquire 4-mm-thick coronal line-scan diffusion tensor images. Maps of the fractional anisotropy were generated to quantify the water diffusion within the uncinate fasciculus.


RESULTS
Findings revealed a group-by-side interaction for fractional anisotropy and for uncinate fasciculus area, derived from automatic segmentation. The patients with schizophrenia showed a lack of normal left-greater-than-right asymmetry seen in the comparison subjects.


CONCLUSIONS
These findings demonstrate the importance of investigating white matter tracts in vivo in schizophrenia and support the hypothesis of a disruption in the normal pattern of connectivity between temporal and frontal brain regions in schizophrenia.
Kubicki
Marek
M
Department of Psychiatry, Harvard Medical School and VA Boston Healthcare System-Brockton Division, MA 02301, USA.
Westin
Carl-Fredrik
CF
Maier
Stephan E
SE
Frumin
Melissa
M
Nestor
Paul G
PG
Salisbury
Dean F
DF
Kikinis
Ron
R
Jolesz
Ferenc A
FA
McCarley
Robert W
RW
Shenton
Martha E
ME
D000328:Adult; D001931:Brain Mapping / Q000379:methods; D002908:Chronic Disease; D005625:Frontal Lobe / Q000033:anatomy & histology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D009434:Neural Pathways / Q000033:anatomy & histology*; D009483:Neuropsychological Tests; D012559:Schizophrenia / Q000175:diagnosis*; D013702:Temporal Lobe / Q000033:anatomy & histology*