The Unique Fiber Anatomy of Middle Temporal Gyrus Default Mode Connectivity

2021 ◽  
Author(s):  
Robert G Briggs ◽  
Onur Tanglay ◽  
Nicholas B Dadario ◽  
Isabella M Young ◽  
R Dineth Fonseka ◽  
...  
Keyword(s):  
White Matter ◽  
Language Processing ◽  
Ex Vivo ◽  
Diffusion Imaging ◽  
Middle Temporal Gyrus ◽  
Middle Temporal ◽  
Default Mode ◽  
Linear Sequence ◽  
Human Connectome Project ◽  
Association Fibers

Abstract BACKGROUND The middle temporal gyrus (MTG) is understood to play a role in language-related tasks such as lexical comprehension and semantic cognition. However, a more specific understanding of its key white matter connections could promote the preservation of these functions during neurosurgery. OBJECTIVE To provide a detailed description of the underlying white matter tracts associated with the MTG to improve semantic preservation during neurosurgery. METHODS Tractography was performed using diffusion imaging obtained from 10 healthy adults from the Human Connectome Project. All tracts were mapped between cerebral hemispheres with a subsequent laterality index calculated based on resultant tract volumes. Ten postmortem dissections were performed for ex vivo validation of the tractography based on qualitative visual agreement. RESULTS We identified 2 major white matter bundles leaving the MTG: the inferior longitudinal fasciculus and superior longitudinal fasciculus. In addition to long association fibers, a unique linear sequence of U-shaped fibers was identified, possibly representing a form of visual semantic transfer down the temporal lobe. CONCLUSION We elucidate the underlying fiber-bundle anatomy of the MTG, an area highly involved in the brain's language network. Improved understanding of the unique, underlying white matter connections in and around this area may augment our overall understanding of language processing as well as the involvement of higher order cerebral networks like the default mode network in these functions.

scholarly journals Anatomy and white matter connections of the orbitofrontal gyrus

2018 ◽  
Vol 128 (6) ◽  
pp. 1865-1872 ◽  
Author(s):  
Joshua D. Burks ◽  
Andrew K. Conner ◽  
Phillip A. Bonney ◽  
Chad A. Glenn ◽  
Cordell M. Baker ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Diffusion Imaging ◽  
Internal Capsule ◽  
Ground Truth ◽  
Outcome Evaluation ◽  
Anterior Cingulate ◽  
Anatomical Dissection ◽  
Visual Spatial ◽  
Human Connectome Project

OBJECTIVEThe orbitofrontal cortex (OFC) is understood to have a role in outcome evaluation and risk assessment and is commonly involved with infiltrative tumors. A detailed understanding of the exact location and nature of associated white matter tracts could significantly improve postoperative morbidity related to declining capacity. Through diffusion tensor imaging–based fiber tracking validated by gross anatomical dissection as ground truth, the authors have characterized these connections based on relationships to other well-known structures.METHODSDiffusion imaging from the Human Connectome Project for 10 healthy adult controls was used for tractography analysis. The OFC was evaluated as a whole based on connectivity with other regions. All OFC tracts were mapped in both hemispheres, and a lateralization index was calculated with resultant tract volumes. Ten postmortem dissections were then performed using a modified Klingler technique to demonstrate the location of major tracts.RESULTSThe authors identified 3 major connections of the OFC: a bundle to the thalamus and anterior cingulate gyrus, passing inferior to the caudate and medial to the vertical fibers of the thalamic projections; a bundle to the brainstem, traveling lateral to the caudate and medial to the internal capsule; and radiations to the parietal and occipital lobes traveling with the inferior fronto-occipital fasciculus.CONCLUSIONSThe OFC is an important center for processing visual, spatial, and emotional information. Subtle differences in executive functioning following surgery for frontal lobe tumors may be better understood in the context of the fiber-bundle anatomy highlighted by this study.

scholarly journals A Connectomic Atlas of the Human Cerebrum—Chapter 13: Tractographic Description of the Inferior Fronto-Occipital Fasciculus

2018 ◽  
Vol 15 (suppl_1) ◽  
pp. S436-S443 ◽  
Author(s):  
Andrew K Conner ◽  
Robert G Briggs ◽  
Goksel Sali ◽  
Meherzad Rahimi ◽  
Cordell M Baker ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
White Matter ◽  
Magnetic Resonance ◽  
Language Processing ◽  
White Matter Tract ◽  
Resonance Imaging ◽  
Large White ◽  
Human Cortex ◽  
Human Connectome Project ◽  
And Function

ABSTRACT The inferior fronto-occipital fasciculus (IFOF) is a large white matter tract of the human cerebrum with functional connectivity associated with semantic language processing and goal-oriented behavior. However, little is known regarding the overall connectivity of this tract. Recently, the Human Connectome Project parcellated the human cortex into 180 distinct regions. In our other work, we have shown these various regions in relation to clinically applicable anatomy and function. Utilizing Diffusion Spectrum Magnetic Resonance Imaging tractography coupled with the human cortex parcellation data presented earlier in this supplement, we aim to describe the macro-connectome of the IFOF in relation to the linked parcellations present within the human cortex. The purpose of this study is to present this information in an indexed, illustrated, and tractographically aided series of figures and tables for anatomic and clinical reference.

Microsurgical and Tractographic Anatomical Study of Transtemporal-Transchoroidal Fissure Approaches to the Ambient Cistern

2020 ◽  
Author(s):  
Emrah Egemen ◽  
Pinar Celtikci ◽  
Yücel Dogruel ◽  
Fatih Yakar ◽  
Defne Sahinoglu ◽  
...  
Keyword(s):  
White Matter ◽  
Anterior Commissure ◽  
Temporal Cortex ◽  
Anatomical Study ◽  
Middle Temporal Gyrus ◽  
Detailed Knowledge ◽  
Fiber Tractography ◽  
Human Connectome Project ◽  
Fiber Dissection ◽  
Ambient Cistern

Abstract BACKGROUND Approaching ambient cistern lesions is still a challenge because of deep location and related white matter tracts (WMTs) and neural structures. OBJECTIVE To investigate the white matter anatomy in the course of 3 types of transtemporal-transchoroidal fissure approaches (TTcFA) to ambient cistern by using fiber dissection technique with translumination and magnetic resonance imaging fiber tractography. METHODS Eight formalin-fixed cerebral hemispheres were dissected on surgical corridor from the temporal cortex to the ambient cistern by using Klingler's method. The trans-middle temporal gyrus, trans-inferior temporal sulcus (TITS), and trans-inferior temporal gyrus (TITG) approaches were evaluated. WMTs that were identified during dissection were then reconstructed on the Human Connectome Project 1021 individual template for validation. RESULTS The trans-middle gyrus approach interrupted the U fibers, arcuate fasciculus (AF), the ventral segment of inferior frontoocipital fasciculus (IFOF), the temporal extensions of the anterior commissure (AC) posterior crura, the tapetum (Tp) fibers, and the anterior loop of the optic radiation (OR). The TITS approach interrupted U fibers, inferior longitudinal fasciculus (ILF), IFOF, and OR. The TITG approach interrupted the U fibers, ILF, and OR. The middle longitudinal fasciculus, ILF, and uncinate fasciculus (UF) were not interrupted in the trans-middle gyrus approach and the AF, UF, AC, and Tp fibers were not interrupted in the TITS/gyrus approaches. CONCLUSION Surgical planning of the ambient cistern lesions requires detailed knowledge about WMTs. Fiber dissection and tractography techniques improve the orientation during surgery and may help decrease surgical complications.

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

2021 ◽  
Author(s):  
Lu Liu ◽  
Di Chen ◽  
Fang Huang ◽  
Tianye Jia ◽  
Meirong Pan ◽  
...  
Keyword(s):  
Attention Deficit Hyperactivity Disorder ◽  
Attention Deficit ◽  
Middle Temporal Gyrus ◽  
Healthy Controls ◽  
Attention Networks ◽  
Middle Temporal ◽  
Default Mode ◽  
Hyperactivity Disorder ◽  
Functional Connections ◽  
Potential Biomarker

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.

scholarly journals Supramodal Sentence Processing in the Human Brain: Fmri Evidence for the Influence of Syntactic Complexity in More Than 200 Participants

2019 ◽  
Author(s):  
Julia Uddén ◽  
Annika Hultén ◽  
Jan-Mathijs Schoffelen ◽  
Nietzsche Lam ◽  
Karin Harbusch ◽  
...  
Keyword(s):  
Language Processing ◽  
Sentence Processing ◽  
Parietal Lobe ◽  
Inferior Frontal Gyrus ◽  
Middle Temporal Gyrus ◽  
Syntactic Complexity ◽  
Input Modality ◽  
Middle Temporal ◽  
Left Posterior ◽  
Brain Fmri

ABSTRACTThis study investigated two questions. One is to which degree sentence processing beyond single words is independent of the input modality (speech vs. reading). The second question is which parts of the network recruited by both modalities is sensitive to syntactic complexity. These questions were investigated by having more than 200 participants read or listen to well-formed sentences or series of unconnected words. A largely left-hemisphere fronto-temporoparietal network was found to be supramodal in nature, i.e. independent of input modality. In addition, the left inferior frontal gyrus (LIFG) and the left posterior middle temporal gyrus (LpMTG) were most clearly associated with left-branching complexity. The left anterior middle temporal gyrus (LaMTG) showed the greatest sensitivity to sentences that differed in right-branching complexity. Moreover, activity in LIFG and LpMTG increased from sentence onset to end, in parallel with an increase of the left-branching complexity. While LIFG, bilateral anterior and posterior MTG and left inferior parietal lobe (LIPL) all contribute to the supramodal unification processes, the results suggest that these regions differ in their respective contributions to syntactic complexity related processing. The consequences of these findings for neurobiological models of language processing are discussed.

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

2022 ◽  
Author(s):  
Fatih Yakar ◽  
Pınar Çeltikçi ◽  
Yücel Doğruel ◽  
Emrah Egemen ◽  
Abuzer Güngör
Keyword(s):  
Anterior Commissure ◽  
Angular Gyrus ◽  
Middle Temporal Gyrus ◽  
Supramarginal Gyrus ◽  
Middle Temporal ◽  
Fiber Tracts ◽  
Human Connectome Project ◽  
Cortical Parcellation ◽  
Fiber Dissection ◽  
First Time

Abstract 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.

scholarly journals Indirect White Matter Pathways Are Associated With Treated Naming Improvement in Aphasia

2021 ◽  
pp. 154596832199905
Author(s):  
Janina Wilmskoetter ◽  
Julius Fridriksson ◽  
Alexandra Basilakos ◽  
Lorelei Phillip Johnson ◽  
Barbara Marebwa ◽  
...  
Keyword(s):  
White Matter ◽  
Treatment Outcomes ◽  
Inferior Frontal Gyrus ◽  
Brain Regions ◽  
Angular Gyrus ◽  
Middle Temporal Gyrus ◽  
Middle Temporal ◽  
Pars Opercularis ◽  
Left Hemisphere Stroke ◽  
Linear Regressions

Background White matter disconnection of language-specific brain regions associates with worse aphasia recovery. Despite a loss of direct connections, many stroke survivors may maintain indirect connections between brain regions. Objective To determine (1) whether preserved direct connections between language-specific brain regions relate to better poststroke naming treatment outcomes compared to no direct connections and (2) whether for individuals with a loss of direct connections, preserved indirect connections are associated with better treatment outcomes compared to individuals with no connections. Methods We computed structural whole-brain connectomes from 69 individuals with chronic left-hemisphere stroke and aphasia who completed a 3-week-long language treatment that was supplemented by either anodal transcranial direct current stimulation (A-tDCS) or sham stimulation (S-tDCS). We determined differences in naming improvement between individuals with direct, indirect, and no connections using 1-way analyses of covariance and multivariable linear regressions. Results Independently of tDCS modality, direct or indirect connections between the inferior frontal gyrus pars opercularis and angular gyrus were both associated with a greater increase in correct naming compared to no connections ( P = .027 and P = .039, respectively). Participants with direct connections between the inferior frontal gyrus pars opercularis and middle temporal gyrus who received S-tDCS and participants with indirect connections who received A-tDCS significantly improved in naming accuracy. Conclusions Poststroke preservation of indirect white matter connections is associated with better treated naming improvement in aphasia even when direct connections are damaged. This mechanistic information can be used to stratify and predict treated naming recovery in individuals with aphasia.

Surgical Approaches to the Temporal Horn: An Anatomic Analysis of White Matter Tract Interruption

2016 ◽  
Vol 13 (2) ◽  
pp. 258-270 ◽  
Author(s):  
Paulo A. S. Kadri ◽  
Jean G. de Oliveira ◽  
Niklaus Krayenbühl ◽  
Uğur Türe ◽  
Evandro P. L. de Oliveira ◽  
...  
Keyword(s):  
White Matter ◽  
Anterior Commissure ◽  
Anterior Segment ◽  
Clinical Manifestations ◽  
Fiber Bundles ◽  
Surgical Approaches ◽  
Middle Temporal Gyrus ◽  
Uncinate Fasciculus ◽  
Middle Temporal ◽  
Temporal Horn

Abstract BACKGROUND: Surgical access to the temporal horn is necessary to treat tumors and vascular lesions, but is used mainly in patients with mediobasal temporal epilepsy. The surgical approaches to this cavity fall into 3 primary categories: lateral, inferior, and transsylvian. The current neurosurgical literature has underestimated the interruption of involved fiber bundles and the correlated clinical manifestations. OBJECTIVE: To delineate the interruption of fiber bundles during the different approaches to the temporal horn. METHODS: We simulated the lateral (trans-middle temporal gyrus), inferior (transparahippocampal gyrus), and transsylvian approaches in 20 previously frozen, formalin-fixed human brains (40 hemispheres). Fiber dissection was then done along the lateral and inferior aspects under the operating microscope. Each stage of dissection and its respective fiber tract interruption were defined. RESULTS: The lateral (trans-middle temporal gyrus) approach interrupted “U” fibers, the superior longitudinal fasciculus (inferior arm), occipitofrontal fasciculus (ventral segment), uncinate fasciculus (dorsolateral segment), anterior commissure (posterior segment), temporopontine, inferior thalamic peduncle (posterior fibers), posterior thalamic peduncle (anterior portion), and tapetum fibers. The inferior (transparahippocampal gyrus) approach interrupted “U” fibers, the cingulum (inferior arm), and fimbria, and transected the hippocampal formation. The transsylvian approach interrupted “U” fibers (anterobasal region of the extreme capsule), the uncinate fasciculus (ventromedial segment), and anterior commissure (anterior segment), and transected the anterosuperior aspect of the amygdala. CONCLUSION: White matter dissection improves our knowledge of the complex anatomy surrounding the temporal horn. Identifying the fiber bundles at risk during each surgical approach adds important information for choosing the appropriate surgical strategy.

scholarly journals Extreme Capsule is a Bottleneck for Ventral Pathway

2020 ◽  
Author(s):  
Ehsan Shekari ◽  
Elahe Shahriari ◽  
Mohammad Taghi Joghataei
Keyword(s):  
White Matter ◽  
Language Processing ◽  
White Matter Tract ◽  
Anatomical Position ◽  
Ventral Pathway ◽  
Association Fibers

As neuroscience literature suggests, the extreme capsule is considered a white matter tract. Nevertheless, it is not clear whether the extreme capsule itself is an association fiber pathway or only a bottleneck for other association fibers to pass. Via our review, investigating anatomical position, connectivity, and cognitive role of the extreme capsule, and by analyzing data from the dissection, it can be argued that extreme capsule is probably a bottleneck for the passage of uncinated fasciculus (UF) and inferior fronto occipital fasciculus (IFOF), and its different role of language processing is due to various tracts that pass it through.

scholarly journals Mapping the subcortical connectivity of the human default mode network

2021 ◽  
Author(s):  
Jian Li ◽  
William H. Curley ◽  
Bastien Guerin ◽  
Darin D. Dougherty ◽  
Adrian V. Dalca ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Default Mode Network ◽  
Basal Forebrain ◽  
Ex Vivo ◽  
7 Tesla ◽  
Human Consciousness ◽  
Connectivity Map ◽  
Caudate Nuclei ◽  
Default Mode ◽  
Human Connectome Project

The default mode network (DMN) mediates self-awareness and introspection, core components of human consciousness. Therapies to restore consciousness in patients with severe brain injuries have historically targeted subcortical sites in the brainstem, thalamus, hypothalamus, basal forebrain, and basal ganglia, with the goal of reactivating cortical DMN nodes. However, the subcortical connectivity of the DMN has not been fully mapped and optimal subcortical targets for therapeutic neuromodulation of consciousness have not been identified. In this work, we created a comprehensive map of DMN subcortical connectivity by combining high-resolution functional and structural datasets with advanced signal processing methods. We analyzed 7 Tesla resting-state functional MRI (rs-fMRI) data from 168 healthy volunteers acquired in the Human Connectome Project. The rs-fMRI blood-oxygen-level-dependent (BOLD) data were temporally synchronized across subjects using the BrainSync algorithm. Cortical and subcortical DMN nodes were jointly analyzed and identified at the group level by applying a novel Nadam-Accelerated SCAlable and Robust (NASCAR) tensor decomposition method to the synchronized dataset. The subcortical connectivity map was then overlaid on a 7 Tesla 100 micron ex vivo MRI dataset for neuroanatomic analysis using automated segmentation of nuclei within the brainstem, thalamus, hypothalamus, basal forebrain, and basal ganglia. We further compared the NASCAR subcortical connectivity map with its counterpart generated from canonical seed-based correlation analyses. The NASCAR method revealed that BOLD signal in the central lateral nucleus of the thalamus and ventral tegmental area of the midbrain is strongly correlated with that of the DMN. In an exploratory analysis, additional subcortical sites in the median and dorsal raphe, lateral hypothalamus, and caudate nuclei were correlated with the cortical DMN. We also found that the putamen and globus pallidus are negatively correlated (i.e., anti-correlated) with the DMN, providing rs-fMRI evidence for the mesocircuit hypothesis of human consciousness, whereby a striatopallidal feedback system modulates anterior forebrain function via disinhibition of the central thalamus. Seed-based analyses yielded similar subcortical DMN connectivity, but the NASCAR result showed stronger contrast and better spatial alignment with dopamine immunostaining data. The DMN subcortical connectivity map identified here advances understanding of the subcortical regions that contribute to human consciousness and can be used to inform the selection of therapeutic targets in clinical trials for patients with disorders of consciousness.

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