Fiber tracking of white matter integrity connecting the mediodorsal nucleus of the thalamus and the prefrontal cortex in schizophrenia: A diffusion tensor imaging study

Abstract

The goal of this study was to detect abnormalities in white matter integrity connecting the mediodorsal nucleus of the thalamus and the prefrontal cortex using fiber-tracking technique. Diffusion tensor imaging was acquired in 20 patients with schizophrenia and 20 normal comparison subjects. Fiber tracking was performed on the anterior thalamic peduncle, and the tractography was used to determine the cross-sectional area, mean fractional anisotropy, and standard deviation of fractional anisotropy for every step separately in the right and left hemispheres. Compared with normal subjects, patients showed a significant reduction in the cross-sectional area of the left anterior thalamic peduncle. There were no significant differences for the mean fractional anisotropy bilaterally between the two groups, but significant differences for the standard deviation of fractional anisotropy in both hemispheres. Reduction in the cross-sectional area of the left anterior thalamic peduncle suggests the presence of the failure of left-hemisphere lateralization. In schizophrenic patients a significant increase of the standard deviation of fractional anisotropy raise the possibility that the inhomogeneity of white matter integrity, which is densely or sparsely distributed by site. These findings might provide further evidence for disruption of white matter integrity between the thalamus and the prefrontal cortex in schizophrenia.

Anterior thalamic radiation integrity in schizophrenia: A diffusion-tensor imaging study

“…Previous DTI studies in schizophrenia have also found decreased anisotropy and/or increased mean diffusivity of the ALIC (Oh et al, 2009; Sussmann et al, 2009; Munoz Maniega et al, 2008; Zou et al, 2008; Mitelman et al, 2007). Other studies have reported smaller volumes (Wobrock et al, 2009; Brickman et al, 2006; Lang et al, 2006; Zhou et al, 2003; Kito et al, 2009), or tract length (Buchsbaum et al, 2006), of the ALIC in schizophrenia, which were not found in our study. Altered myelin- and axonal-associated proteins have also been noted in the ALIC in schizophrenia (Beasley et al, 2009), which further suggests that impaired ALIC integrity is linked to disorder pathology.…”

Thalamocortical Disconnection in the Orbitofrontal Region Associated With Cortical Thinning in Schizophrenia

“…We did not detect a significant association between the FA value for each pathway and duration of illness, dose of medication, or clinical symptoms. In line with our results, Kito et al 21 found no significant correlation between the FA for the thalamocortical pathway and antipsychotic dosage, and Marenco et al 22 reported no significant correlation between connectivity for the thalamolateral prefrontal pathway and medication dosage or duration of illness. One possible explanation is that the alteration in the thalamocortical pathway is not a "state" marker of schizophrenia but rather a "trait" marker.…”

“…18,19 The prefrontal cortex can be divided according to its various functions, 20 and previous studies have suggested that thalamocortical integrity of the lateral, medial, and orbitofrontal regions may be disrupted in schizophrenia. 18,19,21,22 Furthermore, recent studies have provided evidence that GM reduction and WM disruption in schizophrenia are connected, 23,24 suggesting that WM pathology is related to GM pathology. To our knowledge, however, no study has investigated the relationship between impaired thalamocortical pathway integrity and cortical thickness reduction in schizophrenia.…”

Altered Interhemispheric and Temporal Lobe White Matter Microstructural Organization in Severe Chronic Schizophrenia

“…However, other studies contradict FA reductions in schizophrenia and report no significant FA difference in the genu but only in the splenium (Agartz et al, 2001;Foong et al, 2000), and no FA difference in any WM region (Foong et al, 2002;Kito et al, 2009;Levitt et al, 2010;Wang et al, 2003). Discrepancies in these findings could be attributed to methodological differences, subjective rater-based variation between studies such as region of interest (ROI) placement, and clinical heterogeneity including stage of illness and medication exposure.…”