scholarly journals Redundancy Circuits of the Commissural Pathways in Human and Rhesus Macaque Brains

2020 ◽  
Author(s):  
Zulfar Ghulam-Jelani ◽  
Jessica Barrios-Martinez ◽  
Aldo Eguiluz-Melendez ◽  
Ricardo Gomez ◽  
Yury Anania ◽  
...  
Keyword(s):  
Corpus Callosum ◽  
Human Brain ◽  
Rhesus Macaque ◽  
Anterior Commissure ◽  
Brain Disorders ◽  
Commissural Pathways ◽  
Commissural Pathway ◽  
Cortical Regions ◽  
Temporal Redundancy ◽  
First Time

AbstractIt has been hypothesized that the human brain has traded redundancy for efficiency, but the structural existence has not been identified to examine this claim. Here, we report three redundancy circuits of the commissural pathways in primate brains, namely the orbitofrontal, temporal, and occipital redundancy circuits of the anterior commissure and corpus callosum. Each redundancy circuit has two distinctly separated routes connecting a common pair of cortical regions. We mapped their trajectories in human and rhesus macaque brains using individual and population-averaged tractography. The dissection results confirmed the existence of these redundancy circuits connecting the orbitofrontal lobe, amygdala, and visual cortex. The volume analysis showed a significant reduction in the orbitofrontal and occipital redundancy circuits of the human brain, whereas the temporal redundancy circuit had a substantial organizational difference between the human and rhesus macaque. Our overall findings suggest that the human brain is more efficient in the commissural pathway, as shown by the significantly reduced volume of the anterior commissure which serves as the backup connections for the corpus callosum. This reduction of the redundancy circuit may explain why humans are more vulnerable to psychiatric brain disorders stemming from the corpus callosum compared to non-human primates.SignificanceWe report and describe the connection routes of three redundancy circuits of the commissural pathways in human and rhesus macaque brains and compare their volumes. Our tractography and dissection studies confirmed that the human brain has smaller redundancy circuits. This is the first time such redundancy circuits of the commissural pathways have been identified, and their differences quantified in human and rhesus macaque to verify the redundancy-efficiency tradeoff hypothesis. The findings provide new insight into the topological organization of the human brain and may help understand the circuit mechanism of brain disorders involving these pathways.

scholarly journals Tcf4 encodescortical differentiation during development

2018 ◽  
Author(s):  
Simone Mesman ◽  
Reinier Bakker ◽  
Marten P. Smidt
Keyword(s):  
Genetic Counseling ◽  
Corpus Callosum ◽  
Human Brain ◽  
Rna Sequencing ◽  
Neurodevelopmental Disorders ◽  
Disease Development ◽  
Cortical Layers ◽  
Critical Function ◽  
Cortical Regions ◽  
Genetic Counseling Programs

AbstractTcf4 has been linked to autism, schizophrenia, and Pitt-Hopkins Syndrome (PTHS) in humans, however, the mechanisms behind its role in disease development is still elusive. In the present study, we provide evidence that Tcf4 has a critical function in the differentiation of cortical regions during development.We show that Tcf4 is present throughout the developing brain at the peak of neurogenesis. Deletion of Tcf4 results in mis-specification of the cortical layers, malformation of the corpus callosum and hypoplasia of the hippocampus. RNA-sequencing on E14.5 cortex material shows that Tcf4 functions as a transcriptional activator and loss of Tcf4 results in downregulation of genes linked to the emergence of other neurodevelopmental disorders. Taken together, we show that neurogenesis and differentiation are severely affected in Tcf4 mutants, phenocopying morphological brain defects detected in PTHS patients. The presented data identifies new leads to understand the mechanism of human brain defects and will assist in genetic counseling programs.

scholarly journals Callosal morphology in schizophrenia: what can shape tell us about function and illness?

2014 ◽  
Vol 204 (1) ◽  
pp. 9-11 ◽  
Author(s):  
Mark Walterfang ◽  
Dennis Velakoulis
Keyword(s):  
Corpus Callosum ◽  
Psychiatric Disorders ◽  
Microstructural Analysis ◽  
Brain Disorders ◽  
Cortical Regions ◽  
Brain Change

SummaryExamination of the corpus callosum provides a window to cortical brain change in brain disorders. Combining volumetric with microstructural analysis allows a greater understanding of the biology underpinning change, and examining callosal structure alongside the structure of the cortical regions it interconnects may allow us to understand the true significance of callosal change in psychiatric disorders.

scholarly journals Myeloarchitectonic Asymmetries of Language Regions in the Human Brain

2021 ◽  
Author(s):  
Di Yuan ◽  
Daiyi Luo ◽  
Veronica P Y Kwok ◽  
Yulong Zhou ◽  
Haoyue Tian ◽  
...  
Keyword(s):  
Human Brain ◽  
Hemispheric Specialization ◽  
Middle Temporal Gyrus ◽  
Planum Temporale ◽  
Quantitative Magnetic Resonance Imaging ◽  
Pars Opercularis ◽  
Two Measures ◽  
Cortical Regions ◽  
Mixed Pattern ◽  
First Time

Abstract One prominent theory in neuroscience and psychology assumes that cortical regions for language are left hemisphere lateralized in the human brain. In the current study, we used a novel technique, quantitative magnetic resonance imaging (qMRI), to examine interhemispheric asymmetries in language regions in terms of macromolecular tissue volume (MTV) and quantitative longitudinal relaxation time (T1) maps in the living human brain. These two measures are known to reflect cortical myeloarchitecture from the microstructural perspective. One hundred and fifteen adults (55 male, 60 female) were examined for their myeloarchitectonic asymmetries of language regions. We found that the cortical myeloarchitecture of inferior frontal areas including the pars opercularis, pars triangularis, and pars orbitalis is left lateralized, while that of the middle temporal gyrus, Heschl’s gyrus, and planum temporale is right lateralized. Moreover, the leftward lateralization of myelination structure is significantly correlated with language skills measured by phonemic and speech tone awareness. This study reveals for the first time a mixed pattern of myeloarchitectonic asymmetries, which calls for a general theory to accommodate the full complexity of principles underlying human hemispheric specialization.

scholarly journals Shape Profile of Corpus Callosum As a Signature to Phenotype Different Dementia

2020 ◽  
Author(s):  
Sandhya Mangalore ◽  
Shiva Shanker Reddy Mukku ◽  
Sriharish Vankayalapati ◽  
Palanimuthu Thangaraju Sivakumar ◽  
Mathew Varghese
Keyword(s):  
Corpus Callosum ◽  
Frontotemporal Dementia ◽  
Corticobasal Degeneration ◽  
Lewy Body Dementia ◽  
Clinical History ◽  
The Body ◽  
Cortical Atrophy ◽  
Alzheimer Dementia ◽  
Geriatric Clinic ◽  
Cortical Regions

Abstract Background Phenotyping dementia is always a complex task for a clinician. There is a need for more practical biomarkers to aid clinicians. Objective The aim of the study is to investigate the shape profile of corpus callosum (CC) in different phenotypes of dementia. Materials and Methods Our study included patients who underwent neuroimaging in our facility as a part of clinical evaluation for dementia referred from Geriatric Clinic (2017–2018). We have analyzed the shape of CC and interpreted the finding using a seven-segment division. Results The sample included MPRAGE images of Alzheimer’ dementia (AD) (n = 24), posterior cortical atrophy- Alzheimer’ dementia (PCA-AD) (n = 7), behavioral variant of frontotemporal dementia (Bv-FTD) (n = 17), semantic variant frontotemporal dementia (Sv-FTD) (n = 11), progressive nonfluent aphasia (PNFA) (n = 4), Parkinson’s disease dementia (PDD) (n = 5), diffuse Lewy body dementia (n = 7), progressive supranuclear palsy (PSP) (n = 3), and corticobasal degeneration (CBD) (n = 3). We found in posterior dementias such as AD and PCA-AD that there was predominant atrophy of splenium of CC. In Bv-FTD, the genu and anterior half of the body of CC was atrophied, whereas in PNFA, PSP, PDD, and CBD there was atrophy of the body of CC giving a dumbbell like profile. Conclusion Our study findings were in agreement with the anatomical cortical regions involved in different phenotypes of dementia. Our preliminary study highlighted potential usefulness of CC in the clinical setting for phenotyping dementia in addition to clinical history and robust biomarkers.

scholarly journals The Right Hemisphere Is Responsible for the Greatest Differences in Human Brain Response to High-Arousing Emotional versus Neutral Stimuli: A MEG Study

2021 ◽  
Vol 11 (8) ◽  
pp. 960
Author(s):  
Mina Kheirkhah ◽  
Philipp Baumbach ◽  
Lutz Leistritz ◽  
Otto W. Witte ◽  
Martin Walter ◽  
...  
Keyword(s):  
Human Brain ◽  
Right Hemisphere ◽  
Emotional Stimuli ◽  
Brain Response ◽  
Whole Brain ◽  
Brain Responses ◽  
Cortical Regions ◽  
The Right ◽  
Healthy Participants

Studies investigating human brain response to emotional stimuli—particularly high-arousing versus neutral stimuli—have obtained inconsistent results. The present study was the first to combine magnetoencephalography (MEG) with the bootstrapping method to examine the whole brain and identify the cortical regions involved in this differential response. Seventeen healthy participants (11 females, aged 19 to 33 years; mean age, 26.9 years) were presented with high-arousing emotional (pleasant and unpleasant) and neutral pictures, and their brain responses were measured using MEG. When random resampling bootstrapping was performed for each participant, the greatest differences between high-arousing emotional and neutral stimuli during M300 (270–320 ms) were found to occur in the right temporo-parietal region. This finding was observed in response to both pleasant and unpleasant stimuli. The results, which may be more robust than previous studies because of bootstrapping and examination of the whole brain, reinforce the essential role of the right hemisphere in emotion processing.

A role for the corpus callosum in visual area V4 of the macaque

1993 ◽  
Vol 10 (1) ◽  
pp. 159-171 ◽  
Author(s):  
Robert Desimone ◽  
Jeffrey Moran ◽  
Stanley J. Schein ◽  
Mortimer Mishkin
Keyword(s):  
Visual Field ◽  
Corpus Callosum ◽  
Anterior Commissure ◽  
Color Constancy ◽  
Receptive Fields ◽  
Optic Tract ◽  
Complete Suppression ◽  
Central Visual Field ◽  
Field Representation ◽  
Area V4

AbstractThe classically defined receptive fields of V4 cells are confined almost entirely to the contralateral visual field. However, these receptive fields are often surrounded by large, silent suppressive regions, and stimulating the surrounds can cause a complete suppression of response to a simultaneously presented stimulus within the receptive field. We investigated whether the suppressive surrounds might extend across the midline into the ipsilateral visual field and, if so, whether the surrounds were dependent on the corpus callosum, which has a widespread distribution in V4. We found that the surrounds of more than half of the cells tested in the central visual field representation of V4 crossed into the ipsilateral visual field, with some extending up to at least 16 deg from the vertical meridian. Much of this suppression from the ipsilateral field was mediated by the corpus callosum, as section of the callosum dramatically reduced both the strength and extent of the surrounds. There remained, however, some residual suppression that was not further reduced by addition of an anterior commissure lesion. Because the residual ipsilateral suppression was similar in magnitude and extent to that found following section of the optic tract contralateral to the V4 recording, we concluded that it was retinal in origin. Using the same techniques employed in V4, we also mapped the ipsilateral extent of surrounds in the foveal representation of VI in an intact monkey. Results were very similar to those in V4 following commissural or contralateral tract sections. The findings suggest that V4 is a central site for long-range interactions both within and across the two visual hemifields. Taken with previous work, the results are consistent with the notion that the large suppressive surrounds of V4 neurons contribute to the neural mechanisms of color constancy and figure-ground separation.

scholarly journals The zebrafish as a promising tool for modeling human brain disorders: A review based upon an IBNS Symposium

2018 ◽  
Vol 85 ◽  
pp. 176-190 ◽  
Author(s):  
Soaleha Shams ◽  
Jason Rihel ◽  
Jose G. Ortiz ◽  
Robert Gerlai
Keyword(s):  
Human Brain ◽  
Brain Disorders ◽  
Promising Tool

scholarly journals Non-local means based Rician noise filtering for diffusion tensor and kurtosis imaging in human brain and spinal cord

2020 ◽  
Author(s):  
Zhongping Zhang ◽  
Dhanashree Vernekar ◽  
Wenshu Qian ◽  
Mina Kim
Keyword(s):  
Spinal Cord ◽  
Corpus Callosum ◽  
Human Brain ◽  
Healthy Subjects ◽  
Diffusion Tensor ◽  
Mean Diffusivity ◽  
Chi Square ◽  
Lateral Column ◽  
Diffusion Weighted Images ◽  
The Brain

Abstract Background: To investigate the effect of using an Rician nonlocal means (NLM) filter on quantification of diffusion tensor (DT)- and diffusion kurtosis (DK)-derived metrics in various anatomical regions of the human brain and the spinal cord, when combined with a constrained linear least squares (CLLS) approach.Methods: Prospective brain data from 9 healthy subjects and retrospective spinal cord data from 5 healthy subjects from a 3T MRI scanner were included in the study. Prior to tensor estimation, registered diffusion weighted images were denoised by an optimized blockwise NLM filter with CLLS. Mean kurtosis (MK), radial kurtosis (RK), axial kurtosis (AK), mean diffusivity (MD), radial diffusivity (RD), axial diffusivity (AD) and fractional anisotropy (FA), were determined in anatomical structures of the brain and the spinal cord. DTI and DKI metrics, signal-to-noise ratio (SNR) and Chi-square values were quantified in distinct anatomical regions for all subjects, with and without Rician denoising. Results: The averaged SNR significantly increased with Rician denoising by a factor of 2 while the averaged Chi-square values significantly decreased up to 61 % in the brain and up to 43% in the spinal cord after Rician NLM filtering. In the brain, the mean MK varied from 0.70 (putamen) to 1.27 (internal capsule) while AK and RK varied from 0.58 (corpus callosum) to 0.92 (cingulum) and from 0.70 (putamen) to 1.98 (corpus callosum), respectively. In the spinal cord, FA varied from 0.78 in lateral column to 0.81 in dorsal column while MD varied from 0.91 × 10−3 mm2/s (lateral) to 0.93 × 10−3 mm2/s (dorsal). RD varied from 0.34 × 10−3 mm2/s (dorsal) to 0.38 × 10−3 mm2/s (lateral) and AD varied from 1.96 × 10−3 mm2/s (lateral) to 2.11 × 10−3 mm2/s (dorsal).Conclusions: Our results show Rician denoising NLM filter incorporated with CLLS significantly increases SNR and reduces estimation errors of DT- and KT-derived metrics, providing the reliable metrics estimation with adequate SNR levels.

scholarly journals Two Pools of ATP Detected in the Brains of Pediatric Patients with Myelin Oligodendrocyte Glycoprotein Antibody Disorders (MOGAD) by 3D 31P MR Spectroscopic Imaging (MRSI) at 7T

2022 ◽  
Author(s):  
Jimin Ren ◽  
Fang Yu ◽  
Benjamin M. Greenberg
Keyword(s):  
Human Brain ◽  
Pediatric Patients ◽  
Simultaneous Detection ◽  
Myelin Oligodendrocyte Glycoprotein ◽  
Free Radical Damage ◽  
The Central Nervous System ◽  
31P Mrsi ◽  
First Time ◽  
Radical Damage ◽  
Mr Spectroscopic Imaging

Over the past four decades, ATP, the obligatory energy molecule for keeping all cells alive and functioning, was thought to contribute only one set of 31P MR signals in the human brain. Here we report for the first time the simultaneous detection of two pools of ATP in the human brain by high-resolution 3D 31P MRSI at ultrahigh field 7T. These two ATP pools differ in cytosolic Mg2+ concentration (1:0.5 ratio), with a resonance separation of 0.5 ppm at beta-ATP, a well-established imaging marker of intracellular Mg2+ concentration. Mg2+ is a cofactor of ATPase and its deficiency is associated with immune dysfunction, free radical damage, perturbations in Ca2+ homeostasis, development of atherosclerosis and dyslipidemia, and a number of neurological disorders, such as cerebral vasospasm, stroke, migraine, Alzheimer's disease, and Parkinson's disease. Our study documents reduced Mg levels in the brain of patients with myelin oligodendrocyte glycoprotein antibody disorders (MOGAD), which is an idiopathic, inflammatory, demyelinating condition of the central nervous system (CNS) more common in pediatric patients. Low-Mg2+ ATP signals in MOGAD were detected mostly in the white matter regions, which may suggest Mg2+ deficiency in oligodendrocytes, which are primarily responsible for maintenance and generation of the axonal myelin sheath. This preliminary study demonstrates the utility of the 7T 3D 31P MSRI for revealing altered energy metabolism with reduced Mg availability at a normal ATP level. The potential correlation between [Mg2+] and disease progression over time should be assessed in larger cohorts.

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