The Connectivity–Based Parcellation of The Angular Gyrus: Fiber Dissection And MR Tractography Study

The angular gyrus (AG) wraps the posterior end of the superior temporal sulcus (STS), so it is considered as a continuation of the superior/middle temporal gyrus and forms the inferior parietal lobule (IPL) with the supramarginal gyrus (SMG). The AG was functionally divided in the literature, but there is no fiber dissection study in this context. This study divided AG into superior (sAG) and inferior (iAG) parts by focusing on STS. Red blue silicone injected eight human cadaveric cerebrums were dissected via the Klingler method focusing on the AG. White matter (WM) tracts identified during dissection were then reconstructed on the Human Connectome Project 1065 individual template for validation. According to this study, superior longitudinal fasciculus (SLF) II and middle longitudinal fasciculus (MdLF) are associated with sAG; the anterior commissure (AC), optic radiation (OR) with iAG; the arcuate fasciculus (AF), inferior frontooccipital fasciculus (IFOF), and tapetum (Tp) with both parts. In cortical parcellation of AG based on STS, sAG and iAG were found to be associated with different fiber tracts. Although it has been shown in previous studies that there are functionally different subunits with AG parcellation, here, for the first time, different functions of the subunits have been revealed with cadaveric dissection and tractography images.

Evaluation of Brain Structure Based on Voxel and Surface Morphology in Adults with MRI Negative Temporal Lobe Epilepsy

Background MRI-negative TLE (TLE-N) is a manifestation lacks visible MRI findings yet with detectable electrophysiological changes. In this study, differences of gray matter in drug-controlled MRI negative temporal lobe epilepsy (cTLE-N) and drug-resistant MRI negative temporal lobe epilepsy (rTLE-N) patients were calculated and analyzed by voxel-based morphology (VBM) and surface-based morphology (SBM), to discover the brain structural changes of TLE-N patients. Materials and methods Consecutive resident patients with 30 cTLE-N and 21 rTLE-N were recruited into respective groups, and 30 healthy controls’ structural MRI (sMRI) data collected as a control group. Open-source software based on VBM and SBM was deployed as gray matter volume (GMV) and cortical thickness (CT) analytic tools. Results VBM analysis showed that GMV of bilateral thalamus and right lingual gyrus of cTLE-N group, and left hippocampus, left fusiform gyrus and left thalamus of rTLE-N group were smaller compared to HC group(FDR corrected, P<0.05), while right cerebellum, inferior temporal gyrus, hippocampus, parahippocampal gyrus, amygdala, fusiform gyrus, orbital middle frontal gyrus, and left posterior central gyrus in cTLE-N group, and bilateral cerebellum and middle temporal gyrus, right fusiform gyrus, amygdala, hippocampus, and left middle occipital gyrus of rTLE-N group were greater than HC group(FDR corrected, P<0.05). SBM analysis showed that CT of the left medial orbitofrontal cortex and lateral occipital cortex in cTLE-N group, and thickness of the left medial orbitofrontal, temporal pole, middle temporal gyrus and right anterior superior cingulate cortex in rTLE-N group were thinner, compared to HC group. Correlation analysis showed that GMV and CT of different structures were correlated with age of onset, disease duration, and MoCA score. Conclusion This study utilized two different sMRI analytic tools and discovered several brain morphological changes in TLE-N. These morphological changes were also correlated with clinical variables. Further study may indicate the potential of these findings on the recognition of the TLE-N epilepsy network.

Brain morphometry points to emerging patterns of psychosis, depression, and anxiety vulnerability over a 2-year period in childhood

Background Gray matter morphometry studies have lent seminal insights into the etiology of mental illness. Existing research has primarily focused on adults and then, typically on a single disorder. Examining brain characteristics in late childhood, when the brain is preparing to undergo significant adolescent reorganization and various forms of serious psychopathology are just first emerging, may allow for a unique and highly important perspective of overlapping and unique pathogenesis. Methods A total of 8645 youth were recruited as part of the Adolescent Brain and Cognitive Development study. Magnetic resonance imaging scans were collected, and psychotic-like experiences (PLEs), depressive, and anxiety symptoms were assessed three times over a 2-year period. Cortical thickness, surface area, and subcortical volume were used to predict baseline symptomatology and symptom progression over time. Results Some features could possibly signal common vulnerability, predicting progression across forms of psychopathology (e.g. superior frontal and middle temporal regions). However, there was a specific predictive value for emerging PLEs (lateral occipital and precentral thickness), anxiety (parietal thickness/area and cingulate), and depression (e.g. parahippocampal and inferior temporal). Conclusion Findings indicate common and distinct patterns of vulnerability for varying forms of psychopathology are present during late childhood, before the adolescent reorganization, and have direct relevance for informing novel conceptual models along with early prevention and intervention efforts.

Study of Brain Structure and Function in Chronic Mountain Sickness Based on fMRI

Objective: Headache and memory impairment are the primary clinical symptoms of chronic mountain sickness (CMS). In this study, we used voxel-based morphometry (VBM) and the amplitude of the low-frequency fluctuation method (ALFF) based on blood oxygen level-dependent functional magnetic resonance imaging (BOLD-fMRI) to identify changes in the brain structure and function caused by CMS.Materials and Methods: T1W anatomical images and a resting-state functional MRI (fMRI) of the whole brain were performed in 24 patients diagnosed with CMS and 25 normal controls matched for age, sex, years of education, and living altitude. MRI images were acquired, followed by VBM and ALFF data analyses.Results: Compared with the control group, the CMS group had increased gray matter volume in the left cerebellum crus II area, left inferior temporal gyrus, right middle temporal gyrus, right insula, right caudate nucleus, and bilateral lentiform nucleus along with decreased gray matter volume in the left middle occipital gyrus and left middle temporal gyrus. White matter was decreased in the bilateral middle temporal gyrus and increased in the right Heschl's gyrus. Resting-state fMRI in patients with CMS showed increased spontaneous brain activity in the left supramarginal gyrus, left parahippocampal gyrus, and left middle temporal gyrus along with decreased spontaneous brain activity in the right cerebellum crus I area and right supplementary motor area.Conclusion: Patients with CMS had differences in gray and white matter volume and abnormal spontaneous brain activity in multiple brain regions compared to the controls. This suggests that long-term chronic hypoxia may induce changes in brain structure and function, resulting in CMS.

Pattern and component responses of primate MT neurons recorded with multi-contact electrodes, stimulated with 1D and 2D noise patterns.

Direction selective neurons in primary visual cortex (area V1) are affected by the aperture problem, i.e., they are only sensitive to motion orthogonal to their preferred orientation. A solution to this problem first emerges in the middle temporal (MT) area, where a subset of neurons (called pattern cells) combine motion information across multiple orientations and directions, becoming sensitive to pattern motion direction. These cells are expected to play a prominent role in subsequent neural processing, but they are intermixed with cells that behave like V1 cells (component cells), and others that do not clearly fall in either group. The picture is further complicated by the finding that cells that behave like pattern cells with one type of pattern, might behave like component cells for another. We recorded from macaque MT neurons using multi-contact electrodes while presenting both type I and unikinetic plaids, in which the components were 1D noise patterns. We found that the indices that have been used in the past to classify neurons as pattern or component cells work poorly when the properties of the stimulus are not optimized for the cell being recorded, as is always the case with multi-contact arrays. We thus propose alternative measures, which considerably ameliorate the problem, and allow us to gain insights in the signals carried by individual MT neurons. We conclude that arranging cells along a component-to-pattern continuum is an oversimplification, and that the signals carried by individual cells only make sense when embodied in larger populations.

Exploration of the Mechanism Underlying the Association of Incident Microinfarct and Motor Deficit: A Preliminary Functional MRI Study

Background: Cerebral microinfarcts (CMIs) might cause measurable disruption to brain connections and are associated with cognitive decline, but the association between CMIs and motor impairment is still unclear. Objective: To assess the CMIs effect on motor function in vivo and explore the potential neuropathological mechanism based on graph-based network method. Methods: We identified 133 non-demented middle-aged and elderly participants who underwent MRI scanning, cognitive, and motor assessment. The short physical performance battery (SPPB) assessed motor function, including balance, walking speed, and chair stand. We grouped participants into 34 incident CMIs carriers and 99 non-CMIs carriers as controls, depending on diffusion-weighted imaging. Then we assessed the independent CMIs effects on motor function and explored neural mechanisms of CMIs on motor impairment via mapping of degree centrality (DC) and eigenvector centrality (EC). Results: CMIs carriers had worse motor function than non-carriers. Linear regression analyses showed that CMIs independently contributed to motor function. CMIs carriers had decreased EC in the precuneus, while increased DC and EC in the middle temporal gyrus and increased DC in the inferior frontal gyrus compared to controls (p < 0.05, corrected). Correlation analyses showed that EC of precuneus was related to SPPB (r = 0.25) and balance (r = 0.27); however, DC (r = –0.25) and EC (r = –0.25) of middle temporal gyrus was related with SPPB in all participants (p < 0.05, corrected). Conclusion: CMIs represent an independent risk factor for motor dysfunction. The relationship between CMIs and motor function may be attributed to suppression of functional hub region and compensatory activation of motor-related regions.

Localized Task-Invariant Emotional Valence Encoding Revealed by Intracranial Recordings

The ability to distinguish between negative, positive and neutral valence is a key part of emotion perception. Emotional valence has conceptual meaning that supersedes any particular type of stimulus, although it is typically captured experimentally in association with particular tasks. We sought to identify neural encoding for task-invariant emotional valence. We evaluated whether high gamma responses (HGRs) to visually displayed words conveying emotions could be used to decode emotional valence from HGRs to facial expressions. Intracranial electroencephalography (iEEG) was recorded from fourteen individuals while they participated in two tasks, one involving reading words with positive, negative, and neutral valence, and the other involving viewing faces with positive, negative, and neutral facial expressions. Quadratic discriminant analysis was used to identify information in the HGR that differentiates the three emotion conditions. A classifier was trained on the emotional valence labels from one task and was cross-validated on data from the same task (within-task classifier) as well as the other task (between-task classifier). Emotional valence could be decoded in the left medial orbitofrontal cortex and middle temporal gyrus, both using within-task classifiers as well as between-task classifiers. These observations suggest the presence of task-independent emotional valence information in the signals from these regions.

Connectome-wide association analysis identified significant brain functional alteration in adults with attention-deficit/hyperactivity disorder

Adults with attention-deficit/hyperactivity disorder (ADHD), as an extreme-phenotype of ADHD, is still facing problems of inconsistency and undeciphered mechanisms for its neuropathology. To address this matter, our present study performed connecotome-wide voxel-based analyses with the resting-state fMRI data of 84 adults with ADHD and 89 healthy controls. We found that functional connectivity patterns of the left precuneus and the left middle temporal significantly altered in ADHD populations serving as potential neural biomarkers to distinguish ADHD with healthy controls, with subsequent seed-based analysis revealing the dysfunction of functional connections both intra- and inter- default mode and attention networks, among which middle temporal gyrus plays the key role of bridge linking the default mode and attention networks. After cognitive behavioral therapy, two of these ADHD-altered functional connections ameliorated accompanied with improvement of ADHD core symptoms. Additionally, imaging genetic analyses also revealed close relationships between the observed brain functional alterations and ADHD-risk genes. Taken together, our findings suggested the interference of default mode on attention networks in adults with ADHD, which would be severing as a potential biomarker for both ADHD pathogenesis and treatment effects.

Clinical outcome of selective amygdalectomy in a series of patients with resistant temporal lobe epilepsy

Background: Selective amygdalohippocampectomy is one of the main approaches for treating medial temporal lobe epilepsy (TLE). We herewith describe seven cases of amygdala lesions treated with selective amygdalectomy with the hippocampus saving procedure. Furthermore, we explain the trans-middle temporal gyrus transventricular approach for selective amygdalectomy. Methods: We studied patients with TLE who underwent selective amygdalectomy with hippocampal saving procedure between March 2012 and July 2018. We preferred the trans-middle temporal gyrus transventricular approach. We adopted pterional craniotomy with extensive exposure of the base and posterior of the temporal lobe. The posterior margin of resection in the intraventricular part of the amygdala was considered the inferior choroidal point. Medially anterior part of the uncus was resected until reaching the ambient cistern. We applied the transcortical transventricular approach for selective amygdalectomy in all patients. Results: We present 11 cases having an amygdala lesion in our series, seven of whom underwent selective amygdalectomy with hippocampal sparing. Nine patients had neoplastic lesions, and in two of them, gliosis was evident. Total resection of the lesion was achieved in all cases based on postoperative magnetic resonance imaging. No unusual complication or surgically-related new neurological deficit occurred. Conclusion: We consider the resection of the amygdala until the inferior choroidal point sufficient for the disconnection of its circuits, which results in more effective control of seizures and reduction of surgery time and complications.

Resting state functional connectivity in relapsing remitting multiple sclerosis with mild disability – a data driven, whole brain multivoxel pattern analysis study

Multivoxel pattern analysis (MVPA) has emerged as a powerful unbiased approach for generating seed regions of interest (ROIs) in resting-state functional connectivity (RSFC) analysis in a data-driven manner. The aim of the present study was to investigate RSFC differences between persons with relapsing-remitting multiple sclerosis (RRMS) and healthy controls (HCs). We performed a whole-brain connectome-wide MVPA in 50 RRMS patients with expanded disability status scale ≤4 and 50 age and gender-matched HCs. Significant group differences were noted in RSFC in 9 clusters distributed in 7 regions; right middle frontal gyrus, frontal medial cortex, left frontal pole, anterior cingulate gyrus, right middle temporal gyrus, left posterior middle temporal gyrus and right lateral occipital cortex. Whole-brain seed-to-voxel RSFC characterization of these clusters as seed ROIs revealed significantly increased RSFC to the posterior brain regions (bilateral superior lateral occipital cortices, right lingual gyrus and left occipital pole) and reduced connectivity in the anterior and medial regions (right paracingulate gyrus, anterior cingulate gyrus, left amygdala and left frontal orbital cortex) in RRMS compared to HCs. The results of this study agree with the previous reports on abnormalities of RSFC in RRMS, the cognitive and clinical implications of which are discussed herein.