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Hugues Duffau - One of the best experts on this subject based on the ideXlab platform.
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Composition and organization of the sagittal stratum in the human brain: a fiber dissection study.
Journal of neurosurgery, 2021Co-Authors: Igor Lima Maldonado, Christophe Destrieux, Eduardo Carvalhal Ribas, Bruna Siqueira De Abreu Brito Guimarães, Patrícia Pontes Cruz, Hugues DuffauAbstract:Objective The sagittal stratum is divided into two layers. In classic descriptions, the stratum sagittale internum corresponds to optic radiations (RADs), whereas the stratum sagittale externum corresponds to fibers of the Inferior Longitudinal Fasciculus. Although advanced for the time it was proposed, this schematic organization seems simplistic considering the recent progress on the understanding of cerebral connectivity and needs to be updated. Therefore, the authors sought to investigate the composition of the sagittal stratum and to detail the anatomical relationships among the macroscopic fasciculi. Methods The authors performed a layer-by-layer fiber dissection from the superolateral aspect to the ventricular cavity in 20 cadaveric human hemispheres. Results Diverse bundles of white matter were observed to contribute to the sagittal stratum and their spatial arrangement was highly consistent from one individual to another. This was the case of the middle Longitudinal Fasciculus, the Inferior fronto-occipital Fasciculus, the RADs, and other posterior thalamic radiations directed to nonvisual areas of the cerebral cortex. In addition, small contributions to the sagittal stratum came from the anterior commissure anteriorly and the Inferior Longitudinal Fasciculus Inferiorly. Conclusions A general model of sagittal stratum organization in layers is possible, but the composition of the external layer is much more complex than is mentioned in classic descriptions. A small contribution of the Inferior Longitudinal Fasciculus is the main difference between the present results and the classic descriptions in which this bundle was considered to entirely correspond to the stratum sagittale externum. This subject has important implications both for fundamental research and neurosurgery, as well as for the development of surgical approaches for the cerebral parenchyma and ventricular system.
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Functional Anatomy of the Inferior Longitudinal Fasciculus: From Historical Reports to Current Hypotheses.
Frontiers in neuroanatomy, 2018Co-Authors: Guillaume Herbet, Ilyess Zemmoura, Hugues DuffauAbstract:The Inferior Longitudinal Fasciculus (ILF) is a long-range, associative white matter pathway that connects the occipital and temporal-occipital areas of the brain to the anterior temporal areas. In view of the ILF’s anatomic connections, it has been suggested that this pathway has a major role in a relatively large array of brain functions. Until recently, however, the literature data on these potential functions were scarce. Here, we review the key findings of recent anatomic, neuromodulation, and neuropsychological studies. We also summarize reports on how this tract is disrupted in a wide range of brain disorders, including psychopathologic, neurodevelopmental, and neurologic diseases. Our review reveals that the ILF is a multilayered, bidirectional tract involved in processing and modulating visual cues and thus in visually guided decisions and behaviors. Accordingly, sudden disruption of the ILF by neurologic insult is mainly associated with neuropsychological impairments of visual cognition (e.g., visual agnosia, prosopagnosia, and alexia). Furthermore, disruption of the ILF may constitute the pathophysiologic basis for visual hallucinations and socio-emotional impairments in schizophrenia, as well as emotional difficulties in autism spectrum disorder. Degeneration of the ILF in neurodegenerative diseases affecting the temporal lobe may explain (at least in part) the gradual onset of semantic and lexical access difficulties. Although some of the functions mediated by the ILF appear to be relatively lateralized, observations from neurosurgery suggest that disruption of the tract’s anterior portion can be dynamically compensated for by the contralateral portion. This might explain why bilateral disruption of the ILF in either acute or progressive disease is highly detrimental in neuropsychological terms.
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Functional compensation of the left Inferior Longitudinal Fasciculus for picture naming.
Cognitive neuropsychology, 2018Co-Authors: Guillaume Herbet, Sylvie Moritz-gasser, Anne-laure Lemaitre, Fabien Almairac, Hugues DuffauAbstract:The role of the left Inferior Longitudinal Fasciculus (ILF) in language processing has been called into question by recent studies showing that disruption of this tract in glioma patients did not necessarily lead to detrimental effects on spoken language, especially on picture naming. Here we show that disruption of the left ILF with axonal stimulation in patients undergoing an "awake" surgery for a slow-growing tumour systematically induces pure anomia, but only when the temporal pole (TP) is not infiltrated by the tumour. This finding not only confirms that the ILF plays a role in lexical retrieval in normal circumstances but also suggests that the information conveyed by this tract can be rerouted to alternative pathways when the TP is widely lesioned and abandons its function. This conclusion is further supported by the case of a patient who developed a long-lasting anomic aphasia after a surgically preplanned interruption of the ILF.
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Converging evidence for a cortico-subcortical network mediating lexical retrieval.
Brain : a journal of neurology, 2016Co-Authors: Guillaume Herbet, Sylvie Moritz-gasser, Morgane Boiseau, Sophie Duvaux, Jérôme Cochereau, Hugues DuffauAbstract:See Hope and Price (doi:[10.1093/aww240][1]) for a scientific commentary on this article . Neurological insults that damage the left hemisphere are frequently associated with a variety of language disorders. Of these, lexical retrieval impairments are the most commonly observed, and often constitute the residual but lasting disturbance in patients with good functional outcomes. The current study was specifically designed to understand the anatomical factors that prevent full recovery of lexical retrieval in patients having undergone a neurosurgery for a left diffuse low-grade glioma, with a special focus on white matter disconnection. One hundred and ten patients operated on under local anaesthesia with intraoperative language mapping were included in this study. All benefited from an examination of language in the chronic phase using a picture-naming task. We derived from this task two well-controlled regressed measures of lexical retrieval based on the number of anomic responses and response times. We mapped the resection cavities and the postoperative residual lesion infiltrations (mainly located along the white matter tracts), and used a combination of voxelwise and tractwise lesion-deficit analyses to process the data. All results were corrected for multiple comparisons. For the purpose of comparison, 105 neurologically healthy control participants were further enrolled. At the cortical level, lexical retrieval impairments were mainly associated with resection of the mid-to-posterior part of the left Inferior temporal gyrus, as revealed by standard voxel-based lesion–symptom analyses. Multilevel tractwise analyses, including correlations, ridge multiple regressions and group analyses, showed a strong involvement of the left Inferior Longitudinal Fasciculus and, to a lesser extent, of the posterior superior Longitudinal Fasciculus. Further regression analyses indicated that lasting lexical retrieval impairments were better predicted by considering together both resection-related volume loss in the posterior Inferior temporal gyrus and postoperative residual lesion volume in the left Inferior Longitudinal Fasciculus. We conclude that the mid-to-posterior Inferior temporal cortex and its underlying connections, especially the left Inferior Longitudinal Fasciculus, are critical structures in the lexical retrieval network. Beyond this new insight, our data have important implications for both intraoperative language monitoring and rehabilitation strategies. * Abbreviations : DLGG : diffuse low-grade glioma IFOF : Inferior fronto-occipital Fasciculus ITG : Inferior temporal gyrus ILF : Inferior Longitudinal Fasciculus MTG : middle temporal gyrus Resid-anomia/TS/PS : standardized residuals from multiple regressions for the dependent variables anomia, total score and semantic paraphasia SLF : superior Longitudinal Fasciculus VLSM : voxel-based lesion-symptom mapping [1]: /lookup/doi/10.1093/brain/aww240
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Evidence for an occipito-temporal tract underlying visual recognition in picture naming.
Clinical neurology and neurosurgery, 2009Co-Authors: Emmanuel Mandonnet, Peggy Gatignol, Hugues DuffauAbstract:A 24-year-old male underwent awake surgery for a lesion in the left dominant basal temporo-occipital junction. During the intraoperative functional mapping using picture naming, cortical stimulation near the visual word form area led to visual paraphasia. These visual paraphasias were also elicited axonally by subcortical stimulation at the anterior wall of the cavity. We propose to discuss the existence of this "visual object form area", devoted to the visual recognition of object, and its links with the closely related "visual word form area". We suggest that its afference, whose stimulation also induced visual paraphasias, may be one part of the U-shaped fibers distributed along the posterior part of the occipito-temporal connection system (Inferior Longitudinal Fasciculus). Preservation of this white matter tract is essential for visual recognition. Thus, it should be mapped intraoperatively more systematically.
Manzar Ashtari - One of the best experts on this subject based on the ideXlab platform.
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Anatomy and functional role of the Inferior Longitudinal Fasciculus: a search that has just begun.
Developmental medicine and child neurology, 2011Co-Authors: Manzar AshtariAbstract:The Inferior Longitudinal Fasciculus (ILF) was classically defined as a direct connection from the occipital cortex to the temporal lobe. But even after the advent of diffusion tensor imaging (DTI) this view was challenged by several authors. Using DTI and tractography, which allows for a non-invasive assessment of the microstructural organization of white matter pathways, Catani et al. elegantly confirmed the direct pathway between the occipital cortex and temporal lobe in a group average, as well as in eleven individual normal controls. The ILF fiber bundle connects the occipital lobe with the anterior part of the temporal lobe, running laterally and Inferiorly above optic radiation fibers. However, in addition to the ILF there is a second major fiber bundle connecting the occipital cortex to the frontal brain known as the Inferior fronto-occipital Fasciculus (IFOF) that runs medially and above the optic pathways and spatially overlaps with the ILF along part of their pathways. The IFOF is known as a direct pathway, one that connects the occipital, posterior temporal, and the orbitofrontal areas. The ILF, on the other hand, is considered to be an indirect pathway essentially connecting similar brain areas and anteriorly joins the uncinate Fasciculus to relay information to the orbito-frontal brain. In a recent report, Wahl et al. studied whether specific patterns of correlation and overlap among the major brain fibers bundles exist, using DTI scalar parameters such as fractional anisotropy, and axial, radial, and mean diffusivity. The only significant overlaps they found were between the IFOF and the ILF, and between the IFOF and the uncinate Fasciculus. Such overlap may indeed reflect functional similarity as well as spatially sharing overlapping paths. The ability to track white matter bundles and access detailed anatomical information about white matter broadens our investigative ability to uncover disease-related abnormalities. However, even though advances in DTI have enabled us to better study the anatomy of the ILF, the understanding of the functional role of the ILF is still poorly understood. Thus the study by Ortibus et al. is of great importance as it broadens our knowledge of ILF functionality. This study is the first to report compromised ILF integrity in children with visualperceptual impairment and found correlations between decreased fractional anisotropy of the ILF with impaired object recognition. Although the authors clearly showed the relationship between ILF integrity and object recognition, based on strong correlations between the ILF and IFOF, it is likely that the IFOF also plays a role in the execution of such processes. As stated by Ortibus et al., when comparing mean fractional anisotropy values in impaired versus non-impaired patients, decreased fractional anisotropy in the ILF should not be considered a biomarker for visual perception, as the ILF has been shown to be involved in multiple functions and various diseases. For example, lower fractional anisotropy in the ILF was also reported in a group of adolescent patients with schizophrenia with visual hallucinations. A recent review by Chanraud et al. provides a comprehensive review of diseases with ILF involvement and other major white matter fiber bundles. As discussed by Chanraud et al., the ILF has functionally been correlated with thought disorders, visual emotion, cognitive impairments, and other symptoms. As a whole, our knowledge of the functional influences of white matter pathways continues to progress rapidly by virtue of the non-invasive nature of DTI and the insight it provides into the brain’s white matter microstructures. It is important, however, to bear in mind that abnormality in a specific fiber bundle may also be reflected in other fiber bundles integrating or sharing the functions of multiple affected cortical regions.
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Disruption of white matter integrity in the Inferior Longitudinal Fasciculus in adolescents with schizophrenia as revealed by fiber tractography.
Archives of general psychiatry, 2007Co-Authors: Manzar Ashtari, John Cottone, Babak A. Ardekani, Kelly L. Cervellione, Philip R. Szeszko, Steven Xi Chen, Sanjiv KumraAbstract:Introduction: There is increasing evidence that schizophrenia is characterized by abnormalities in white matter. The authors investigated the integrity of white matter tracts in adolescents with schizophrenia. Methods: Cross-sectional, case-control, whole-brain, voxel-based analysis and fiber tractography using diffusion tensor magnetic resonance imaging conducted at a university research institute. Forty-four individuals (age range, 11-18 years), 23 with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder and 21 demographically similar healthy controls participated in the study. Results: Voxelwise analysis revealed that adolescents with schizophrenia had reduced fractional anisotropy within the left Inferior temporal (P < 0.001) and occipital (P < 0.001) regions. Tractography was performed to extract the left and the right Inferior Longitudinal fasciculi (ILF). Measuring the mean diffusion indices along the left ILF, patients had significantly reduced fractional anis otropy (P < 0.001) as well as significantly increased radial diffusivity (P < 0.001) and trace (P = 0.003) after adjusting for differences in a measure thought to reflect premorbid intelligence, Wide Range Achievement Test 3 reading scores. Exploratory analyses revealed that patients with a history of visual hallucinations had lower fractional anisotropy in the left ILF (P = 0.02) than patients without visual hallucinations. Conclusions: Our findings, which benefited from greater image resolution and methodological control than previous studies conducted in adolescents with schizophrenia, provide strong evidence for lower white matter integrity in the left ILF, particularly for patients with a history of visual hallucinations.
Mieke Van De Sandt-koenderman - One of the best experts on this subject based on the ideXlab platform.
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Change in Right Inferior Longitudinal Fasciculus Integrity Is Associated With Naming Recovery in Subacute Poststroke Aphasia.
Neurorehabilitation and neural repair, 2020Co-Authors: Marieke R M A Blom-smink, Marjolein Verly, Kerstin Spielmann, Marion Smits, Gerard M. Ribbers, Mieke Van De Sandt-koendermanAbstract:Background. Despite progress made in understanding functional reorganization patterns underlying recovery in subacute aphasia, the relation between recovery and changes in white matter structure remains unclear. Objective. To investigate changes in dorsal and ventral language white matter tract integrity in relation to naming recovery in subacute poststroke aphasia. Methods. Ten participants with aphasia after left-hemisphere stroke underwent language testing and diffusion tensor imaging twice within 3 months post onset, with a 1-month interval between sessions. Deterministic tractography was used to bilaterally reconstruct the superior Longitudinal Fasciculus (SLF), Inferior fronto-occipital Fasciculus (IFOF), Inferior Longitudinal Fasciculus (ILF), middle Longitudinal Fasciculus (MdLF), and uncinate Fasciculus (UF). Per tract, the mean fractional anisotropy (FA) was extracted as a measure of microstructural integrity. Naming accuracy was assessed with the Boston Naming Test (BNT). Correlational analyses were performed to investigate the relationship between changes in FA values and change in BNT score. Results. A strong positive correlation was found between FA change in the right ILF within the ventral stream and change on the BNT (r = 0.91, P < .001). An increase in FA in the right ILF was associated with considerable improvement of naming accuracy (range BNT change score: 12-14), a reduction with limited improvement or slight deterioration. No significant correlations were found between change in naming accuracy and FA change in any of the other right or left ventral and dorsal language tracts. Conclusions. Naming recovery in subacute aphasia is associated with change in the integrity of the right ILF.
Kazuo Yagi - One of the best experts on this subject based on the ideXlab platform.
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Damage to the left ventral, arcuate Fasciculus and superior Longitudinal Fasciculus-related pathways induces deficits in object naming, phonological language function and writing, respectively.
The International journal of neuroscience, 2013Co-Authors: Nobusada Shinoura, Yusuke Tabei, Akira Midorikawa, Toshiyuki Onodera, Ryozi Yamada, Seiko Saito, Masanobu Tsukada, Chisato Itoi, Kazuo YagiAbstract:The anatomic localization of brain functions can be characterized via diffusion tensor imaging in patients with brain tumors and neurological symptoms. The goal of the present study was to evaluate the function of the ventral, arcuate Fasciculus (AF) and the superior Longitudinal Fasciculus (SLF)-related language pathways using these techniques by analyzing 9 patients treated in our hospital between 2007 and 2011. In cases 1–3, the left ventral pathways, namely, the Inferior Longitudinal Fasciculus, uncinate Fasciculus or Inferior fronto-occipital Fasciculus, were mainly damaged, and the common dysfunction experienced by these patients was a deficit in object naming. In cases 4–6, the left SLF was mainly damaged, and the common deficit was dysgraphia. In cases 7–9, the left AF was mainly damaged, and almost all language functions related to phonology were abnormal. These results suggest that the left ventral, AF and SLF-related pathways are closely related to visual, auditory and hand-related language fun...
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Deficits in the left Inferior Longitudinal Fasciculus results in impairments in object naming.
Neurocase, 2009Co-Authors: Nobusada Shinoura, Y Suzuki, Yusuke Tabei, Kuniaki Saito, Ryozi Yamada, Masanobu Tsukada, Mizuho Yoshida, Tomoyuki Koizumi, Kazuo YagiAbstract:The functional characteristics of the left Inferior Longitudinal Fasciculus (ILF) remain unclear. The present study describes a case of a right-handed 74-year-old woman with a brain tumor who showed marked deterioration in object naming ability after invasion of the tumor into the medial region of the left posterior (middle and Inferior) temporal lobe just beside the atrium of the lateral ventricle. Diffusion tensor imaging showed possible interruption of the left ILF after invasion of tumor at this site. By contrast, the left superior Longitudinal Fasciculus (SLF) remained intact after invasion of tumor, and the Inferior fronto-occipital Fasciculus (IFOF) was already disrupted prior to tumor invasion. These observations indicate that intact ILF function may be required for object naming ability.
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damage to the right superior Longitudinal Fasciculus in the Inferior parietal lobe plays a role in spatial neglect
Neuropsychologia, 2009Co-Authors: Nobusada Shinoura, Y Suzuki, Ryoji Yamada, Yusuke Tabei, Kuniaki Saito, Kazuo YagiAbstract:Functional neurological changes after surgery combined with data from diffusion tensor imaging (DTI) studies can provide direct evidence of anatomical localization of brain function. The goal of the present study was to characterize mechanisms of spatial neglect using these techniques by analyzing two patients with development or worsening of left neglect after surgery at our hospital in 2008. In both cases, the surgical approach was via the right Inferior parietal lobes, and damage to the superior Longitudinal Fasciculus (SLF) was demonstrated after surgery by DTI tractography. By contrast, neither the Inferior Longitudinal Fasciculus (ILF) nor the Inferior fronto-occipital Fasciculus (IFOF) was damaged. These results suggest that damage to the right SLF in the Inferior parietal lobe plays a critical role in the development of spatial neglect.
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Impairment of Inferior Longitudinal Fasciculus plays a Role in Visual Memory Disturbance
Neurocase, 2007Co-Authors: Nobusada Shinoura, Y Suzuki, Yusuke Tabei, Kuniaki Saito, Ryozi Yamada, Masanobu Tsukada, Shizuka Katsuki, Kazuo YagiAbstract:Function of the Inferior Longitudinal Fasciculus (ILF), which connects the anterior temporal and occipital lobes, has not been clearly demonstrated in the human brain. A 47-year-old woman with visual memory disturbance as demonstrated by the Wechsler Memory Scale-Revised presented with possible brain tumor in the right temporal lobe. Diffusion tensor imaging showed partial disconnection of the right ILF, indicating that function of the ILF is highly involved in visual memory.
Miet De Letter - One of the best experts on this subject based on the ideXlab platform.
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The white matter architecture underlying semantic processing: A systematic review.
Neuropsychologia, 2019Co-Authors: Elissa-marie Cocquyt, Ellen Lanckmans, Arnaud Szmalec, Wouter Duyck, Pieter Van Mierlo, Patrick Santens, Miet De LetterAbstract:Abstract From a holistic point of view, semantic processes are subserved by large-scale subcortico-cortical networks. The dynamic routing of information between grey matter structures depends on the integrity of subcortical white matter pathways. Nonetheless, controversy remains on which of these pathways support semantic processing. Therefore, a systematic review of the literature was performed with a focus on anatomo-functional correlations obtained from direct electrostimulation during awake tumor surgery, and conducted between diffusion tensor imaging metrics and behavioral semantic performance in healthy and aphasic individuals. The 43 included studies suggest that the left Inferior fronto-occipital Fasciculus contributes to the essential connectivity that allows semantic processing. However, it remains uncertain whether its contributive role is limited to the organization of semantic knowledge or extends to the level of semantic control. Moreover, the functionality of the left uncinate Fasciculus, Inferior Longitudinal Fasciculus and the posterior segment of the indirect arcuate Fasciculus in semantic processing has to be confirmed by future research.