Priyanka Bhat¹, S Senthil Kumaran², Vinay Goyal³, and Achal K Srivastava^2
1IIT Delhi, Delhi, India, ²All India Institute of Medical Sciences, Delhi, India, ³Neuroscience Institute, Medanta-The Medicity, Delhi, India

Repetitive transcranial magnetic stimulation is known to render clinical benefits in subjects with Parkinson’s Disease. Because of dopaminergic depletion the cortical connectivity patterns are affected in PD. This study aimed to inhibit the primary motor area which is an important node in the movement control pathway. The effect was studied using clinical scales and task based functional connectivity. The results reveal the ability of rTMS to facilitate the movement by inducting cortical as well as subcortical brain regions.

Mukesh Kumar¹, S Senthil Kumaran¹, Pankaj Pankaj¹, and Rajesh Sagar^2
1Department of NMR & MRI Facility, All India Institute of Medical Sciences, New Delhi, India, ²Department of psychiatry, All India Institute of Medical Sciences, New Delhi, India

The whole-brain effective connectivity (EC) was estimated to interpret the brain dynamics, time-dependent communicability and propagation of neuronal activity within the brain state in patients with early onset schizophrenia. We observed decreased effective connectivity (p<0.05) and global integration of local endogenous events in early onset schizophrenia (EOS) as compared to controls. EOS suffer decreased propagation of neuronal activity and responsiveness to events. 

Hui Sun¹, Wenjing Zhang¹, Chengmin Yang¹, Qiyong Gong¹, and Su Lui^1
1Huaxi MR Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, China

Schizophrenia is characterized by abnormal functional integration between distinct brain regions but whether a common deficit in functional connectivity in relation to both clinical symptoms and cognitive impairments would present in drug-naïve first-episode patients remains elusive. A connectome-wise analysis on resting-state functional MRI in never-treated patients with first-episode schizophrenia. Using the principal component analysis, we found a trans-symptomatic pattern of functional connectivity associated with both psychopathological and cognitive manifestations in never-treated first-episode schizophrenia characterized as the dysconnections involving frontal and visual cortices, suggesting a core deficit of brain functional connectivity that might underpin the psychopathology of schizophrenia.

CHENGMIN YANG¹, WENJING ZHANG¹, JIAJUN LIU², ZHIPENG YANG², and SU LUI^1
1Huaxi MR Research Center (HMRRC), Functional and Molecular Imaging Key Laboratory of Sichuan Province, Department of Radiology, West China Hospital of Sichuan University, Chengdu, China., Chengdu, China, ²College of Electronic Engineering, Chengdu University of Information Technology, Chengdu, P.R. China., Chengdu, China

To characterize the connectome gradient changes of subcortical system in drug-naive first-episode schizophrenia and the longitudinal treatment effect, we calculated the functional gradient and conducted the group comparisons. The principal gradient of subcortex demonstrated the fundamental functional segregation differences between patients at baseline and healthy controls, and the longitudinal analyses indicated that the treatment would gradually normalize the altered gradients with significant improvement of symptoms. This study provided the new perspective on the abnormal subcortical hierarchy organization in schizophrenia and its longitudinal gradient changes could be sensitive to reflect the antipsychotic treatment effect.

Paola Magioncalda^1,2, Chun-Hung Yeh³, Hsiang-Yuan Lin⁴, Rung-Yu Tseng³, Mario Amore⁵, and Matteo Martino^1,2
1Graduate Institute of Mind, Brain, and Consciousness, Taipei Medical University, Taipei, Taiwan, ²Brain and Consciousness Research Centre, Taipei Medical University - Shuang Ho Hospital, New Taipei City, Taiwan, ³Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital, Taoyuan, Taiwan, ⁴Azrieli Adult Neurodevelopmental Centre, Campbell Family Mental Health Research Institute, and Adult Neurodevelopmental and Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, ON, Canada, ⁵Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Section of Psychiatry, University of Genoa, Genoa, Italy

The recent unified model of the pathophysiology of bipolar disorder (BD) proposed that micro/macrostructural disturbance in limbic white matter (WM) fibers is important in the pathophysiological mechanism of BD. To gain more insights into this model, preprocessed diffusion MRI data of 67 BD and 125 healthy participants were analyzed using fixel-based analysis. We found a reduction of fiber density and/or cross-section of tracts, including the fornix and cingulum bundle that are core elements of the limbic system. These findings robustly support an association of BD with a specific spatial pattern of WM alterations.

Zhifeng Zhou¹, Long Qian², Wentao Lai¹, Wentao Jiang¹, Gangqiang Hou¹, and Yingli Zhang^1
1Shenzhen Mental Health Center/Shenzhen Kangning Hospital, Shenzhen, China, ²MR Research, GE Healthcare, Beijing, China

Previous DTI studies have revealed widespread increased radial diffusivity, which tend to be associated with myelin alteration, in patients with bipolar disorder (BD). This study utilizes a surrogate measure of myelin content termed inhomogeneous magnetization transfer (ihMT) to investigate myelin abnormalities in patients with BD. Our results demonstrate that regions with myelin deficits are mainly concentrated in the premiddle corpus callosum and left anterior white matter tracts, suggesting that interhemispheric communication and information transmission of left anterior brain areas may be most affected in patients with BD.  Overall, this study provides new insight into the neuropathological mechanisms underlying BD.

Pei-Ti Lin¹, Huai-Hsuan Tseng^2,3, Po See Chen^2,3, and Jun-Cheng Weng^1,4,5
1Department of Medical Imaging and Radiological Sciences, Graduate Institute of Artificial Intelligence, Chang Gung University, Taoyuan, Taiwan, ²Department of Psychiatry, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ³Institute of Behavioral Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ⁴Department of Psychiatry, Chang Gung Memorial Hospital, Chiayi, Taiwan, ⁵Medical Imaging Research Center, Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan

Bipolar disorder (BD) is a major psychiatric disorder associated with structural and functional brain alterations and cognitive deficits. This study used q-ball imaging and graph theoretical analysis to investigate both neurological structural change and network alterations between BD patients and healthy controls. The results showed the alterations in several brain regions including the corpus callosum and cingulate gyrus, which are associated with executive, cognitive, emotional function, and memory. We found the BD group demonstrated higher global integrity than the HC group, but they remained small-world properties. It indicated that white matter integrity and network alterations were associated with bipolar disorder.

Mengyue Tang¹, Zilin Zhou¹, Lingxiao Cao¹, Yingxue Gao¹, Lianqing Zhang¹, Hailong Li¹, Yingying Wang¹, Qiyong Gong¹, and Xiaoqi Huang^1
1Huaxi MR Research Center (HMRRC), Functional and molecular imaging Key Laboratory of Sichuan Province, Department of Radiology, West China Hospital, Sichuan University, Chengdu, China

Using seed based FC analysis, we investigated alterations in functional connectivity of amygdala subregional networks in a relatively large sample of adolescent MDD. Our findings identified adolescent MDD patients, compared to HC, have anomalous amygdala subregional functional network connections to several brain regions that play a pivotal role in emotional and cognitive processing, which may contribute to revealing the pathophysiology underlying MDD. These findings were not detected when using the whole amygdala as seeds, further verify the significance of analyses at the subregion level.

Tomohisa Okada¹, Yujiro Yoshihara², Manabu Kubota², Taro Suwa², Jun Miyata², Yuhei Takado³, Jamie Near⁴, Masoumeh Dehghani⁴, Thai Akasaka¹, Dinh Ha Duy Thuy¹, Ravi Teja Seethamraju⁵, Sinyeob Ahn⁶, Tadashi Isa¹, and Toshiya Murai^2
1Human Brain Research Center, Kyoto University, Kyoto, Japan, ²Department of Psychiatry, Kyoto University, Kyoto, Japan, ³Department of Functional Brain imaging, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan, ⁴Physical Sciences Platform, Sunnybrook Research Institute, Toronto, ON, Canada, ⁵Siemens Healthcare USA, Boston, MA, United States, ⁶Siemens Healthcare USA, Berkeley, CA, United States

Major depressive disorder (MDD) afflicts up to 20% of the total population. MRS findings are different among studies. One of the reasons is differences in MRS sequences used. This study compared two sequences: sSPECIAL and STEAM, which consistently found significant and marginally significant reduction of taurine in the anterior cingulate cortex in MDD compared with healthy controls, although concentration of neurochemicals in sSPECIAL and STEAM was different. The difference was lost when concentration was normalized by total creatine due to its significant positive correlation to Taurine. Differences between the two sequences did not result in different neurochemical findings for MDD. 

Vishwa Rawat¹, Ritu Tyagi¹, Gagan Hans², Pratap sharan², S Senthil Kumaran¹, and Uma Sharma^1
1Department of NMR, All India Institute of Medical Sciences (AIIMS), New Delhi, India, ²Department of Psychiatry, All India Institute of Medical Sciences (AIIMS), New Delhi, India

Present study investigated volumetric changes in the brain of Indian patients suffering from Major Depressive Disorder (MDD) using Magnetic Resonance Imaging (MRI). These patients were seen to have significantly reduced brain and cerebellar volumes. Volume of caudate, putamen and globus pallidus were seen to be reduced but no significant changes were seen in hippocampus and amygdala. Volume of cerebellum and lobule VI of cerebellum was also reduced. Our results suggest that cerebellum as well as VI lobule of cerebellum may be associated with MDD.

Zilin Zhou¹, Yingxue Gao¹, Weijie Bao¹, Hui Qiu¹, Lianqing Zhang¹, Ruohan Feng^1,2, Yingying Wang¹, Mengyue Tang¹, Qiyong Gong¹, and Xiaoqi Huang^1
1Department of Radiology, Huaxi Magnetic Resonance Research Centre (HMRRC),Functional and Molecular Imaging Key Laboratory of Sichuan Province, Chengdu, China, ²Department of Radiology, the Third Hospital of Mianyang, Sichuan Mental Health Center, Mianyang, China

Through seed-based functional connectivity (SBFC) analysis, we investigated the altered intrinsic connectivity patterns of hippocampus, orbitofrontal cortex (OFC) and insula in adolescents with major depressive disorder(aMDD) comparing to typically developing control(TDC). We found distinct network alterations of those three structures at regional and subregional level. Moreover, we located the aberrant connectivity in hippo-orbitofrontal-insular circuit with family conflict and depressvie symptoms in aMDD which may underline the neural mechanism for depressvie symptoms in adolescents.

Xun Zhang¹, Song Wang¹, and Qiyong Gong^1
1Huaxi MR Research Center (HMRRC), West China Hospital of Sichuan University, Chengdu, China

Social anxiety disorder (SAD) is a prevalent and disabling psychiatric disorder, for which the underlying neurobiological mechanisms remain poorly understood. Herein, whole-brain voxel-based morphometry and coupled functional connectivity analyses were conducted to investigate structural and functional alterations, while correlation and mediation analyses were performed to probe the potential roles of structural-functional couplings in SAD diagnosis. As a result, we observed significant subcortical grey matter atrophy and widespread dysconnectivity in cortico-striato-thalamo-cerebellar circuitry in SAD; functional dysconnectivity could partially mediate the effects of structural atrophy on SAD diagnosis, which may contribute to clarifying the underlying mechanisms of structure-functional couplings for SAD.