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Major depressive disorder (MDD) is one of the most prevalent mental disorders. In the brain, the hubs of the brain network play a key role in integrating and transferring information between different functional modules. However, whether the changed pattern in functional network hubs contributes to the onset of MDD remains unclear. Using resting-state functional magnetic resonance imaging (rs-fMRI) and graph theory methods, we investigated whether alterations of hubs can be detected in MDD. First, we constructed the whole-brain voxel-wise functional networks and calculated a functional connectivity strength (FCS) map in each subject in 34 MDD patients and 34 gender-, age- and education level-matched healthy controls (HCs). Next, the two-sample t-test was applied to compare the FCS maps between HC and MDD patients and identified significant decrease of FCS in subgenual anterior cingulate cortex (sgACC) in MDD patients. Subsequent functional connectivity analyses of sgACC showed disruptions in functional connectivity with posterior insula, middle and inferior temporal gyrus, lingual gyrus and cerebellum in MDD patients. Furthermore, the changed FCS of sgACC and functional connections to sgACC were significantly correlated with the Hamilton Depression Rating Scale (HDRS) scores in MDD patients. The results of the present study revealed the abnormal hub of sgACC and its corresponding disrupted frontal-limbic-visual cognitive-cerebellum functional networks in MDD. These findings may provide a new insight for the diagnosis and treatment of MDD.

Background:Cognitive impairment is a key feature of treatment-resistant depression (TRD) and can be related to the anterior cingulate cortex (ACC) function. Repetitive transcranial magnetic stimulation (rTMS) as an antidepressant intervention has increasingly been investigated in the last two decades. However, no studies to date have investigated the association between neurobiochemical changes within the anterior cingulate and executive dysfunction measured in TRD being treated with rTMS.Methods:Thirty-two young depressed patients with treatment-resistant unipolar depression were enrolled in a double-blind, randomized study [active (n=18) vs. sham (n=14)]. ACC metabolism was investigated before and after high-frequency (15Hz) rTMS using 3-tesla proton magnetic resonance spectroscopy (1H-MRS). The results were compared with 28 age- and gender-matched healthy controls. Executive functioning was measured with the Wisconsin Card Sorting Test (WCST) among 34 subjects with TRD and 28 healthy subjects.Results:Significant reductions in N-acetylaspartate (NAA) and choline-containingCompound levels in the left ACC were found in subjects with TRD pre-rTMS when compared with healthy controls. After successful treatment, NAA levels increased significantly in the left ACC of subjects and were not different from those of age-matched controls. In the WCST, more perseverative errors and fewer correct numbers were observed in TRD subjects at baseline. Improvements in both perseverative errors and correct numbers occurred after active rTMS. In addition, improvement of perseverative errors was positively correlated with enhancement of NAA levels in the left ACC in the active rTMS group.Conclusions:Our results suggest that the NAA concentration in the left ACC is associated with an improvement in cognitive functioning among subjects with TRD response to active rTMS.

The right hemispheric dominance in visuospatial attention in human brain has been well established. Converging evidence has documented that ventral posterior parietal cortex (PPC) plays an important role in visuospatial attention. The role of dorsal PPC subregions, especially the superior parietal lobule (SPL) in visuospatial attention is still controversial. In the current study, we used repetitive transcranial magnetic stimulation (rTMS) and diffusion magnetic resonance imaging (MRI) techniques to test the role of posterior SPL in visuospatial attention and to investigate the potential neuroanatomical basis for right hemisphere dominance in visuospatial function. Transcranial magnetic stimulation (TMS) results unraveled that the right SPL predominantly mediated visuospatial attention compared to left SPL. Anatomical connections analyses between the posterior SPL and the intrahemispheric frontal subregions and the contralateral PPC revealed that right posterior SPL has stronger anatomical connections with the ipsilateral middle frontal gyrus (MFG), with the ipsilateral inferior frontal gyrus (IFG), and with contralateral PPC than that of the left posterior SPL. Furthermore, these asymmetric anatomical connections were closely related to behavioral performances. Our findings indicate that SPL plays a crucial role in regulating visuospatial attention, and dominance of visuospatial attention results from unbalanced interactions between the bilateral fronto-parietal networks and the interhemispheric parietal network.

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Not all highly myopic eyes are deformed. Spheroid was the predominant ocular shape in this series of young patients with high myopia bilaterally. Barrel-shaped and temporally distorted eyes present significant myopic maculopathy, whereas eyes with posterior staphyloma display more severe chorioretinal atrophy. Eyes of more deformed shapes tend to have more severe myopic maculopathy and worse BCVA.

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This work presents an automatically annotated fiber cluster (AAFC) method to enable identification of anatomically meaningful white matter structures from the whole brain tractography. The proposed method consists of 1) a study-specific whole brain white matter parcellation using a well-established data-driven groupwise fiber clustering pipeline to segment tractography into multiple fiber clusters, and 2) a novel cluster annotation method to automatically assign an anatomical tract annotation to each fiber cluster by employing cortical parcellation information across multiple subjects. The novelty of the AAFC method is that it leverages group-wise information about the fiber clusters, including their fiber geometry and cortical terminations, to compute a tract anatomical label for each cluster in an automated fashion. We demonstrate the proposed AAFC method in an application of investigating white matter abnormality in emotional processing and sensorimotor areas in major depressive disorder (MDD). Seven tracts of interest related to emotional processing and sensorimotor functions are automatically identified using the proposed AAFC method as well as a comparable method that uses a cortical parcellation alone. Experimental results indicate that our proposed method is more consistent in identifying the tracts across subjects and across hemispheres in terms of the number of fibers. In addition, we perform a between-group statistical analysis in 31 MDD patients and 62 healthy subjects on the identified tracts using our AAFC method. We find statistical differences in diffusion measures in local regions within a fiber tract (e.g. 4 fiber clusters within the identified left hemisphere cingulum bundle (consisting of 14 clusters) are significantly different between the two groups), suggesting the ability of our method in identifying potential abnormality specific to subdivisions of a white matter structure.