Anatomy and White Matter Connections of the Superior Parietal Lobule

Abstract BACKGROUND The superior parietal lobule (SPL) is involved in somatosensory and visuospatial integration with additional roles in attention, written language, and working memory. A detailed understanding of the exact location and nature of associated white matter tracts could improve surgical decisions and subsequent postoperative morbidity related to surgery in and around this gyrus. OBJECTIVE To characterize the fiber tracts of the SPL based on relationships to other well-known neuroanatomic structures through diffusion spectrum imaging (DSI)-based fiber tracking validated by gross anatomical dissection as ground truth. METHODS Neuroimaging data of 10 healthy, adult control subjects was obtained from a publicly accessible database published in Human Connectome Project for subsequent tractographic analyses. White matter tracts were mapped between both cerebral hemispheres, and a lateralization index was calculated based on resultant tract volumes. Post-mortem dissections of 10 cadavers identified the location of major tracts and validated our tractography results based on qualitative visual agreement. RESULTS We identified 9 major connections of the SPL: U-fiber, superior longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, middle longitudinal fasciculus, extreme capsule, vertical occipital fasciculus, cingulum, and corpus callosum. There was no significant fiber lateralization detected. CONCLUSION The SPL is an important region implicated in a variety of tasks involving visuomotor and visuospatial integration. Improved understanding of the fiber bundle anatomy elucidated in this study can provide invaluable information for surgical treatment decisions related to this region.

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Anatomy and white matter connections of the orbitofrontal gyrus

Journal of Neurosurgery ◽

10.3171/2017.3.jns162070 ◽

2018 ◽

Vol 128 (6) ◽

pp. 1865-1872 ◽

Cited By ~ 17

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.

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Different neural substrates for executive functions in youths with ADHD: a diffusion spectrum imaging tractography study

Psychological Medicine ◽

10.1017/s0033291715002767 ◽

2016 ◽

Vol 46 (6) ◽

pp. 1225-1238 ◽

Cited By ~ 19

Author(s):

H.-L. Chiang ◽

Y.-J. Chen ◽

C.-Y. Shang ◽

W.-Y. I. Tseng ◽

S. S.-F. Gau

Keyword(s):

White Matter ◽

Executive Functions ◽

White Matter Tracts ◽

Fibre Tract ◽

Diffusion Spectrum Imaging ◽

Cingulum Bundle ◽

Microstructural Property ◽

Wide Range ◽

Spectrum Imaging ◽

Microstructural Integrity

BackgroundThe relationship between white-matter tracts and executive functions (EF) in attention deficit hyperactivity disorder (ADHD) has not been well studied and previous studies mainly focused on frontostriatal (FS) tracts. The authors explored the microstructural property of several fibre tracts hypothesized to be involved in EF, to correlate their microstructural property with EF, and to explore whether such associations differ between ADHD and typically developing (TD) youths.MethodWe assessed 45 youths with ADHD and 45 individually matched TD youths with a computerized test battery for multiple dimensions of EF. From magnetic resonance imaging, FS tract, superior longitudinal fasciculus (SLF), arcuate fasciculus (AF) and cingulum bundle (CB) were reconstructed by diffusion spectrum imaging tractography. The generalized fractional anisotropy (GFA) values of white-matter tracts were computed to present microstructural property of each tract.ResultsWe found lower GFA in the left FS tract, left SLF, left AF and right CB, and poorer performance in set-shifting, sustained attention, cognitive inhibition and visuospatial planning in ADHD than TD. The ADHD and TD groups demonstrated different association patterns between EF and fibre tract microstructural property. Most of the EF were associated with microstructural integrity of the FS tract and CB in TD youths, while with that of the FS tract, SLF and AF in youths with ADHD.ConclusionsOur findings support that the SLF, AF and CB also involve in a wide range of EF and that the main fibre tracts involved in EF are different in youths with ADHD.

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Identification of a distinct association fiber tract “IPS-FG” to connect the intraparietal sulcus areas and fusiform gyrus by white matter dissection and tractography

Scientific Reports ◽

10.1038/s41598-020-72471-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Tatsuya Jitsuishi ◽

Atsushi Yamaguchi

Keyword(s):

White Matter ◽

Posterior Parietal Cortex ◽

Structural Connectivity ◽

Temporal Cortex ◽

Fusiform Gyrus ◽

Intraparietal Sulcus ◽

Visuomotor Integration ◽

Fiber Tract ◽

Fiber Tracts ◽

Human Connectome Project

Abstract The intraparietal sulcus (IPS) in the posterior parietal cortex (PPC) is well-known as an interface for sensorimotor integration in visually guided actions. However, our understanding of the human neural network between the IPS and the cortical visual areas has been devoid of anatomical specificity. We here identified a distinctive association fiber tract “IPS-FG” to connect the IPS areas and the fusiform gyrus (FG), a high-level visual region, by white matter dissection and tractography. The major fiber bundles of this tract appeared to arise from the medial bank of IPS, in the superior parietal lobule (SPL), and project to the FG on the ventral temporal cortex (VTC) in post-mortem brains. This tract courses vertically at the temporo-parieto-occipital (TPO) junction where several fiber tracts intersect to connect the dorsal-to-ventral cortical regions, including the vertical occipital fasciculus (VOF). We then analyzed the structural connectivity of this tract with diffusion-MRI (magnetic resonance imaging) tractography. The quantitative tractography analysis revealed the major streamlines of IPS-FG interconnect the posterior IPS areas (e.g., IP1, IPS1) with FG (e.g., TF, FFC, VVC, PHA2, PIT) on the Human Connectome Project multimodal parcellation atlas (HCP MMP 1.0). Since the fronto-parietal network, including the posterior IPS areas, is recruited by multiple cognitive demands, the IPS-FG could play a role in the visuomotor integration as well as the top-down modulation of various cognitive functions reciprocally.

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White matter microstructural alterations in amblyopic adults revealed by diffusion spectrum imaging with systematic tract-based automatic analysis

British Journal of Ophthalmology ◽

10.1136/bjophthalmol-2017-311733 ◽

2018 ◽

Vol 103 (4) ◽

pp. 511-516 ◽

Cited By ~ 3

Author(s):

Tzu-Hsun Tsai ◽

Hsien-Te Su ◽

Yung-Chin Hsu ◽

Yao-Chia Shih ◽

Chien-Chung Chen ◽

...

Keyword(s):

White Matter ◽

Visual Processing ◽

Audiovisual Integration ◽

Automatic Analysis ◽

Middle Temporal Gyrus ◽

Whole Brain ◽

White Matter Tracts ◽

Microstructural Alterations ◽

Diffusion Spectrum Imaging ◽

Spectrum Imaging

Background/aimWe investigated the microstructural changes in white matter of adults with amblyopia using diffusion spectrum imaging with systematic tract-based automatic analysis of the whole brain.MethodsTen adults with amblyopia (six women and four men, 33.6±10.6 years old on average) and 20 age- and sex-matched normal-sighted controls were enrolled. The mean generalised fractional anisotropy (GFA) was measured in 76 white matter tracts and compared between the experimental and control groups using a threshold-free cluster-weighted method and t-test. A 2-percentile cut-off was used to identify segments with the greatest differences between the two groups.ResultsParticipants with amblyopia had significantly lower GFA values than the controls in 11 segments located in nine white matter tracts, which included the following: left arcuate fasciculus, left frontal aslant tract, left fornix and left inferior fronto-occipital fasciculus of the association fibres; left thalamic radiations of the auditory nerve and bilateral optic radiations of the projection fibres; and genu and middle temporal gyrus of the callosal fibres. Amblyopic participants had statistically higher GFA values in the bilateral uncinate fasciculus than those of the controls.ConclusionThis preliminary study using whole-brain tractographic analysis of white matter reveals association between abnormal early visual processing and alterations in brain architecture, which may be related to various higher-level deficits, such as audiovisual integration and hand−eye coordination in patients with amblyopia.

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White matter endophenotype candidates for ADHD: a diffusion imaging tractography study with sibling design

Psychological Medicine ◽

10.1017/s0033291719001120 ◽

2019 ◽

Vol 50 (7) ◽

pp. 1203-1213 ◽

Cited By ~ 1

Author(s):

Huey-Ling Chiang ◽

Yung-Chin Hsu ◽

Chi-Yuan Shang ◽

Wen-Yih Isaac Tseng ◽

Susan Shur-Fen Gau

Keyword(s):

White Matter ◽

Fractional Anisotropy ◽

Diffusion Imaging ◽

Familial Risk ◽

Mean Diffusivity ◽

Control Group ◽

White Matter Tracts ◽

Spatial Span ◽

Diffusion Spectrum Imaging ◽

The Right

AbstractBackgroundBrain structural alterations are frequently observed in probands with attention-deficit/hyperactivity disorder (ADHD). Here we examined the microstructural integrity of 76 white matter tracts among unaffected siblings of patients with ADHD to evaluate the potential familial risk and its association with clinical and neuropsychological manifestations.MethodsThe comparison groups included medication-naïve ADHD probands (n = 50), their unaffected siblings (n = 50) and typically developing controls (n = 50, age-and-sex matched with ADHD probands). Whole brain tractography was reconstructed automatically by tract-based analysis of diffusion spectrum imaging (DSI). Microstructural properties of white matter tracts were represented by the values of generalized fractional anisotropy (GFA), fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD).ResultsCompared to the control group, ADHD probands showed higher AD values in the perpendicular fasciculus, superior longitudinal fasciculus I, corticospinal tract, and corpus callosum. The AD values of unaffected siblings were in the intermediate position between those of the ADHD and control groups. These AD values were significantly associated with ADHD symptoms, sustained attention and working memory, for all white matter tracks evaluated except for the perpendicular fasciculus. Higher FA and lower RD values in the right frontostriatal tract connecting ventrolateral prefrontal cortex (FS-VLPFC) were associated with better performance in spatial span only in the unaffected sibling group.ConclusionsAbnormal AD values of specific white matter tracts among unaffected siblings of ADHD probands suggest the presence of familial risk in this population. The right FS-VLPFC may have a role in preventing the expression of the ADHD-related behavioral phenotype.ClinicalTrials.gov numberNCT01682915

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Association of dorsal inferior frontooccipital fasciculus fibers in the deep parietal lobe with both reading and writing processes: a brain mapping study

Journal of Neurosurgery ◽

10.3171/2014.2.jns131234 ◽

2014 ◽

Vol 121 (1) ◽

pp. 142-148 ◽

Cited By ~ 26

Author(s):

Kazuya Motomura ◽

Masazumi Fujii ◽

Satoshi Maesawa ◽

Shunichiro Kuramitsu ◽

Atsushi Natsume ◽

...

Keyword(s):

White Matter ◽

Parietal Lobe ◽

Diffusion Tensor ◽

Inferior Parietal Lobule ◽

White Matter Tracts ◽

Reading And Writing ◽

Writing Processes ◽

Subcortical Stimulation ◽

Parietal Lobule ◽

Cortical Regions

Alexia and agraphia are disorders common to the left inferior parietal lobule, including the angular and supramarginal gyri. However, it is still unclear how these cortical regions interact with other cortical sites and what the most important white matter tracts are in relation to reading and writing processes. Here, the authors present the case of a patient who underwent an awake craniotomy for a left inferior parietal lobule glioma using direct cortical and subcortical electrostimulation. The use of subcortical stimulation allowed identification of the specific white matter tracts associated with reading and writing. These tracts were found as portions of the dorsal inferior frontooccipital fasciculus (IFOF) fibers in the deep parietal lobe that are responsible for connecting the frontal lobe to the superior parietal lobule. These findings are consistent with previous diffusion tensor imaging tractography and functional MRI studies, which suggest that the IFOF may play a role in the reading and writing processes. This is the first report of transient alexia and agraphia elicited through intraoperative direct subcortical electrostimulation, and the findings support the crucial role of the IFOF in reading and writing.

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How Many Streamlines are Required for Reliable Probabilistic Tractography? Solutions for Microstructural Measurements and Neurosurgical Planning

10.1101/2020.01.26.920397 ◽

2020 ◽

Author(s):

Lee B. Reid ◽

Marcela I. Cespedes ◽

Kerstin Pannek

Keyword(s):

White Matter ◽

Diffusion Mri ◽

Scientific Community ◽

Image Resolution ◽

Regions Of Interest ◽

Probabilistic Tractography ◽

White Matter Tracts ◽

Factors Influencing ◽

Neurosurgical Planning ◽

Human Connectome Project

AbstractDiffusion MRI tractography is commonly used to delineate white matter tracts. These delineations can be used for planning neurosurgery or for identifying regions of interest from which microstructural measurements can be taken. Probabilistic tractography produces different delineations each time it is run, potentially leading to microstructural measurements or anatomical delineations that are not reproducible. Generating a sufficiently large number of streamlines is required to avoid this scenario, but what constitutes “sufficient” is difficult to assess and so streamline counts are typically chosen in an arbitrary or qualitative manner. This work explores several factors influencing tractography reliability and details two methods for estimating this reliability. The first method automatically estimates the number of streamlines required to achieve reliable microstructural measurements, whilst the second estimates the number of streamlines required to achieve a reliable binarised trackmap than can be used clinically. Using these methods, we calculated the number of streamlines required to achieve a range of quantitative reproducibility criteria for three anatomical tracts in 40 Human Connectome Project datasets. Actual reproducibility was checked by repeatedly generating the tractograms with the calculated numbers of streamlines. We found that the required number of streamlines varied strongly by anatomical tract, image resolution, number of diffusion directions, the degree of reliability desired, the microstructural measurement of interest, and/or the specifics on how the tractogram was converted to a binary volume. The proposed methods consistently predicted streamline counts that achieved the target reproducibility. Implementations are made available to enable the scientific community to more-easily achieve reproducible tractography.

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Dorsal-to-ventral imbalance in the superior longitudinal fasciculus mediates methylphenidate’s effect on beta oscillations in ADHD

10.1101/2020.09.23.309526 ◽

2020 ◽

Author(s):

C. Mazzetti ◽

C. G. Damatac ◽

E. Sprooten ◽

N. ter Huurne ◽

J.K. Buitelaar ◽

...

Keyword(s):

White Matter ◽

Diffusion Tensor ◽

Structural Connectivity ◽

Superior Longitudinal Fasciculus ◽

Beta Oscillations ◽

Double Blind ◽

Attention Task ◽

White Matter Tracts ◽

Fiber Tracts ◽

Beta Power

AbstractBackgroundWhile pharmacological treatment with Methylphenidate (MPH) is a first line intervention for ADHD, its mechanisms of action have yet to be elucidated. In a previous MEG study, we demonstrated that MPH in ADHD normalizes beta depression in preparation to motor responses (1). We here seek to identify the white matter tracts that mediate MPH’s effect on beta oscillations.MethodsWe implemented a double-blind placebo-controlled crossover design, where boys diagnosed with ADHD underwent behavioral and MEG measurements during a spatial attention task while on and off MPH. Results were compared with an age/IQ-matched typically developing (TD) group performing the same task. Estimates of white matter tracts were obtained through diffusion tensor imaging (DTI). Based on aprioristic selection model criteria, we sought to determine the fiber tracts associated with electrophysiological, behavioral and clinical features of attentional functions.ResultsWe identified three main tracts: the anterior thalamic radiation (ATR), the Superior Longitudinal Fasciculus (‘parietal endings’) (SLFp) and Superior Longitudinal Fasciculus (‘temporal endings’) (SLFt). ADHD symptoms severity was associated with lower fractional anisotropy (FA) within the ATR. In addition, individuals with relatively higher FA in SLFp compared to SLFt showed faster and more accurate behavioral responses to MPH. Furthermore, the same parieto-temporal FA gradient explained the effects of MPH on beta modulation: subjects with ADHD exhibiting higher FA in SLFp compared to SLFt also displayed greater effects of MPH on beta power during response preparation.ConclusionsBased on MPH’s modulatory effects on striatal dopamine levels, our data suggest that the behavioral deficits and aberrant oscillatory modulations observed in ADHD depend on a structural connectivity imbalance within the SLF, caused by a diffusivity gradient in favor of temporal rather than parietal, fiber tracts.

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Advanced white matter mapping in the subconcussive brain

Neurology ◽

10.1212/01.wnl.0000550693.00184.ee ◽

2018 ◽

Vol 91 (23 Supplement 1) ◽

pp. S15.2-S15

Author(s):

Bradley Caron ◽

Nicholas Port ◽

Franco Pestilli

Keyword(s):

White Matter ◽

Structural Changes ◽

Diffusion Tensor ◽

Division I ◽

Football Players ◽

Tensor Model ◽

White Matter Tracts ◽

Tissue Properties ◽

Research Fields ◽

Fiber Tracts

The topic of behavioral and structural deficits caused by concussions is an increasingly important 1 in the related research fields. With an incidence rate of 2.9 competition concussions per 1,000 athlete exposures (NCAA 2013) in collegiate football, the concussion risk to athletes is significant. However, even subconcussive blows, or blows that do not lead to a concussion diagnosis, appear to create health risks for athletes. These impacts appear to lead to significant neural changes, the severity of which may depend on the number of hits (McAllister et al., 2014). An anatomically informed, personalized-medicine tractography approach was used to determine which major white matter tracts showed the greatest degree of difference in white matter tensor measures between 17 Division I upperclassmen football players, 15 Division I upperclassman cross-country runners, and 9 socioeconomically-matched non-athlete controls. We determined the underlying microstructural white matter biomarkers, using a classic diffusion-tensor model (Pierpaoli and Basser, 1999) as well as Neurite Orientation Dispersion and Density Imaging (NODDI; Zhang et al., 2012), that predict differences across different white matter tracts in the groups of athletes. Results show widespread differences in white matter tissue properties in multiple tracts and among the 3 athletes groups, including decreased FA, increased ICVF, and OD in the football players vs the 2 control groups. These differences occurred more often in longer fiber tracts compared to shorter fiber tracts, suggesting a differential effect of head impacts based on the geometric properties of these tracts. We developed a fully automated processing pipeline for this study, available as open source code as well as open service at brainlife.io. These results support the hypothesis that multiple subconcussive blows can result in white matter structural changes, with differential effects based on the length of the fiber tract being investigated, that are detectable with diffusion MRI and tractography.

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WHITE MATTER TRACTS IN FRONTO-STRIATO-THALAMIC CIRCUIT IN THE HUMAN BRAIN: A DIFFUSION SPECTRUM IMAGING STUDY

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s1016237211002542 ◽

2011 ◽

Vol 23 (03) ◽

pp. 215-222

Author(s):

Yu-Chun Lo ◽

Fu-Shan Jaw ◽

Su-Chun Huang ◽

Yu-Yang Yeh ◽

Wen-Yih Isaac Tseng

Keyword(s):

White Matter ◽

Water Molecule ◽

Imaging Study ◽

Brain Structures ◽

White Matter Tract ◽

White Matter Tracts ◽

Diffusion Mr ◽

Diffusion Spectrum Imaging ◽

Significant Difference ◽

Spectrum Imaging

Gender and handedness differences in cognitive functions and brain structures are well recognized. Recent research has reported different white matter structures between male and female subjects. Yet it is unknown whether the gender and handedness effects on different white matter tracts are comparable or disparate. In this study, we focus on three main tracts in the fronto-striato-thalamic circuit, namely, the cingulum bundles (CG), fornices (FXs) and anterior thalamic radiations (ATR). These are the primary connections among the frontal lobe, the limbic system, and the thalamus, integrating functions of emotion control, memory, and decision-making. A total of 40 healthy adults were recruited in this study. There was no significant difference in demographic variables between males and females. Images were acquired on a 3-T Magnetic resonance imaging (MRI) system with an eight-channel head coil. The diffusion spectrum imaging (DSI) experiment was performed by applying 203 diffusion gradient vectors. DSI maps the angular distribution of water molecule displacement by acquiring diffusion MR signals in a more comprehensive way. The theory of DSI is based on the Fourier transform relationship between diffusion MR signals and the average propagator of water molecule displacement. Isotropic spatial resolution was obtained by setting both in-plane and through-plane resolutions as 2.7 mm. A total of 45 trans-axial slices were acquired encompassing the whole brain. DSI analysis was computed based on the Fourier relationship between diffusion echo signals and the probability density function (PDF). Fiber tracking was used to define the targeted tracts. All fiber orientations of the nearest voxels were used to decide the proceeding orientation for the next step. Tracking stopped if there was no coinciding orientation in the nearest voxels. Mean path analysis, a method that projected the anisotropy of PDF [generalized fractional anisotropy (GFA)] onto a single mean path of the specific white matter tract bundle, was used to analyze subtle changes in microstructure coherence along individual tract bundles. The asymmetric differences of targeted tracts were assessed statistically by calculating GFA values and lateralization indices (LIs). The handedness factor of the LI values in CG and ATR showed a trend for significance. The gender factor of the LI values was investigated in FX also. Different white matter tract bundles manifested different degrees of gender effect on GFA distributions. Our results suggest that the gender and handedness factors should be considered when one evaluates the impairment of the fronto-striato-thalamic circuit.

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