Quantitative Tract-Specific Measures of Uncinate and Cingulum in Major Depression Using Diffusion Tensor Imaging

Abstract

Previous findings suggested the role of the prefrontal cortex, hippocampus, and cingulate gyrus in major depressive disorders (MDD), but the white matter microstructural abnormalities of the fibers connecting these brain structures are not known. The purpose of this study was to test the hypothesis that white matter abnormalities are present in association fibers of the uncinate fasciculus (UF) and cingulum bundle (CB) among MDD subjects. A total of 21 MDD subjects aged between 30 and 65 years and 21 age-matched healthy controls (HC) were recruited. All subjects were right-handed and without history of diabetes or other cardiac diseases. We extracted quantitative tract-specific measures based on diffusion tensor imaging tractography to examine both diffusivity and geometric properties of the UF and CB. Significantly decreased fractional anisotropy (FA) and increased radial diffusivity of the right UF were observed in MDD patients compared with HC (po0.05), while their geometric characteristics remained relatively unchanged. Among MDD subjects, depression severity had a significant negative correlation with normalized number of fibers (NNF) in the right UF (r ¼ À0.53, p ¼ 0.02). We also found significant age effect (oldoyoung) in HC group and laterality effect (L4R) in both groups in the FA measure of the CB. Our study demonstrates novel findings of white matter microstructural abnormalities of the right UF in MDD. In the MDD group, the severity of depression is associated with reduced NNF in the right UF. These findings have implications for both clinical manifestations of depression as well as its pathophysiology.

The cerebral isthmus: fiber tract anatomy, functional significance, and surgical considerations

“…20,27,30,51,70,71 Furthermore, human studies using electrical stimulation have indicated reciprocal connections between the anterior limb of the internal capsule and the dorsolateral and ventrolateral prefrontal cortex, findings consistent with anatomical tracing research in nonhuman primates. 32 The genu of the internal capsule in turn contains pyramidal fibers that connect the precentral gyrus to the motor nuclei of the cranial nerves, and also the anterior part of the superior thalamic peduncle.…”

“…Additionally, we consider incising the proximal superior isthmus less destructive than the anterior corpus callosum, since the former is mainly related to the ability of set shifting while the latter participates in the vital functions of memory and learning. 20,27,30,37,38,41,43,51,70,71 Undoubtedly, approaching the frontal horn through the proximal part of the superior isthmus is not an easy and straightforward procedure. It requires thorough neuroanatomical knowledge of the insular anatomy, flawless microneurosurgical technique, and proper planning of the surgical trajectory.…”

Lithium and GSK3-β Promoter Gene Variants Influence White Matter Microstructure in Bipolar Disorder

“…The cingulum bundle integrates disparate modular brain systems involved in attention, memory, and emotion regulation, and in mood disorders, a higher directionality of water diffusion in the cingulum bundle associates with better hedonic tone (Keedwell et al, 2012), better cognitive performance (Schermuly et al, 2010), and less psychomotor slowing (Walther et al, 2012). The number of fibers within the uncinate fasciculus inversely correlated with depression severity (Zhang et al, 2012). Executive function and processing speed were correlated with anisotropy of the anterior thalamic radiation and uncinate fasciculus in late life depression (Sexton et al, 2011).…”

White Matter Tract Integrity of Anterior Limb of Internal Capsule in Major Depression and Type 2 Diabetes

“…All diffusion weighted images (32 gradient directions) were first coregistered onto the b0 images by using the automatic image registration (AIR) algorithm with affine transformation to minimize eddy currents and remove any potential small bulk motions that occurred during the scans (Zhang et al, 2012;. The diffusion directions in the diffusion gradient table were transformed by the rotation matrix calculated by AIR, to correct changes in section angulation due to coregistration.…”