A diffusion tensor imaging study of the anterior limb of the internal capsule in schizophrenia.
Frontal-subcortical cognitive and limbic feedback loops modulate higher cognitive functioning. The final step in these feedback loops is the thalamo-cortical projection through the anterior limb of the internal capsule (AL-IC). Using diffusion tensor imaging (DTI), we evaluated abnormalities in the AL-IC fiber tract in schizophrenia. Participants comprised 16 chronic schizophrenia patients and 19 male, normal controls, who were group matched for handedness, age, and parental socioeconomic status, and underwent DTI on a 1.5 Tesla GE system. We measured the diffusion indices, fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD), and manually segmented, based on FA maps, AL-IC volume, normalized for intracranial contents (ICC). The results showed a significant reduction in the ICC-corrected volume of the AL-IC in schizophrenia, but did not show diffusion measure group differences in the AL-IC in FA, MD, RD or AD. In addition, in the schizophrenia patients, AL-IC FA correlated positively with performance on measures of spatial and verbal declarative/episodic memory, and right AL-IC ICC-corrected volume correlated positively with more perseverative responses on the Wisconsin Card Sort Test (WCST). We found a reduction in AL-IC ICC-corrected volume in schizophrenia, without FA, MD, RD or AD group differences, implicating the presence of a structural abnormality in schizophrenia in this subcortical white matter region which contains important cognitive, and limbic feedback pathways that modulate prefrontal cortical function. Despite not demonstrating a group difference in FA, we found that AL-IC FA was a good predictor of spatial and verbal declarative/episodic memory performance in schizophrenia.
Clinical Neuroscience Division, Laboratory of Neuroscience, Department of Psychiatry, VA Boston Healthcare System, Brockton Division, Brockton, MA 02301 and Harvard Medical School, Boston, MA 02115, United States. james_levitt@hms.harvard.edu
James J
JJ
Levitt
Marek
M
Kubicki
Paul G
PG
Nestor
Hal
H
Ersner-Hershfield
C-F
CF
Westin
Jorge L
JL
Alvarado
Ron
R
Kikinis
Ferenc A
FA
Jolesz
Robert W
RW
McCarley
Martha E
ME
Shenton
D000328:Adult; D000704:Analysis of Variance; D016880:Anisotropy; D001931:Brain Mapping; D056324:Diffusion Tensor Imaging; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D020772:Internal Capsule / Q000503:physiopathology*; D008032:Limbic System / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology; D009483:Neuropsychological Tests; D012559:Schizophrenia / Q000473:pathology*; D013223:Statistics as Topic