The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Susumu Mori - One of the best experts on this subject based on the ideXlab platform.
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critical role of the right uncinate Fasciculus in emotional empathy
Annals of Neurology, 2015Co-Authors: Kenichi Oishi, Susumu Mori, Andreia V Faria, John Hsu, Donna C Tippett, Argye E HillisAbstract:A coherent hypothesis about the neural network underlying emotional empathy has emerged from various sources: functional MRI of healthy individuals experiencing empathy1–7, resting state functional connectivity studies of individuals with frontotemporal dementia (who have impaired empathy)8, focal lesion studies9–11 and voxel-based morphometry studies12, 13 of individuals with impaired empathy. Together, these studies have identified the important roles of several cortical and limbic areas, including prefrontal cortex, orbitofrontal cortex, amygdala, and temporal pole, particularly in the right hemisphere. Some of components of this network may be especially critical for specific processes underlying emotional empathy14–24. These areas are strongly interconnected with the anterior insula and anterior cingulate cortex1, 25, 26, areas which themselves are clearly engaged when healthy people empathize with others1, 2, 4–7. Seeley and colleagues8 have raised the possibility that Von Economo neurons, found in anterior cingulate and anterior insula, are selectively targeted in behavioral variant frontotemporal dementia (bvFTD), a neurodegenerative disease in which impaired empathy is prominent feature. Loss of Von Economo neurons and fork cells in right anterior anterior insular cortex correlates with severity of clinical disease in bvFTD27. If areas found to be critical for emotional empathy comprise a functional network, then focal lesions to white matter connections between them should disrupt emotional empathy. There is some evidence favoring this hypothesis from patients with FTD. One of the most important white matter connections between orbitofrontal cortex, temporal pole, insula, and amygdala is the uncinate Fasciculus. In a diffusion tensor imaging study of FTD compared to controls, patients with FTD had reduced fractional anisotropy (FA) in uncinate Fasciculus, anterior corpus callosum, and bilateral anterior descending cingulum tracts, compared to controls28. Likewise, even carriers of progranulin mutations (one gene mutation underlying FTD) had reduced FA in the uncinate Fasciculus29; and patients with advanced FTD had reduced FA only in the uncinate Fasciculus in another study30. However, reduced FA in the uncinate Fasciculus in FTD could be a result of degeneration of any of the cortical areas to which the uncinate Fasciculus is connected rather than direct evidence that the “lesion” itself is associated with clinical symptom of impaired empathy in FTD. In the present study, we tested the hypothesis that impaired emotional empathy immediately after acute right hemisphere ischemic stroke is associated with lesions in the (right) uncinate Fasciculus.
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brain white matter anatomy of tumor patients evaluated with diffusion tensor imaging
Annals of Neurology, 2002Co-Authors: Susumu Mori, Kim Frederiksen, Peter C M Van Zijl, Bram Stieltjes, Michael A Kraut, Meiyappan Solaiyappan, Martin G PomperAbstract:We applied multislice, whole-brain diffusion tensor imaging (DTI) to two patients with anaplastic astrocytoma. Data were analyzed using DTI-based, color-coded images and a 3-D tract reconstruction technique for the study of altered white matter anatomy. Each tumor was near two major white matter tracts, namely, the superior longitudinal Fasciculus and the corona radiata. Those tracts were identified using the color-coded maps, and spatial relationships with the tumors were characterized. In one patient the tumor displaced adjacent white matter tracts, whereas in the other it infiltrated the superior longitudinal fasciclus without displacement of white matter. DTI provides new information regarding the detailed relationship between tumor growth and nearby white matter tracts, which may be useful for preoperative planning.
Jill V Hunter - One of the best experts on this subject based on the ideXlab platform.
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the temporal stem in traumatic brain injury preliminary findings
Brain Imaging and Behavior, 2010Co-Authors: Erin D Bigler, Stephen R Mccauley, Ragini Yallampalli, Sanjeev Shah, Marianne Macleod, Zili Chu, Jill V HunterAbstract:The temporal stem (TS) of the temporal lobe is a major white matter (WM) region containing several major pathways that connect the temporal lobe with the rest of the brain. Because of its location, it may be particularly vulnerable to shear-strain effects resulting from traumatic brain injury (TBI). A case vignette is presented in a patient with severe brain injury and focal TS pathology. Also, 12 severe TBI subjects unselected for TS pathology were compared to demographically matched, neurologically-intact controls using diffusion tensor imaging (DTI) to examine white matter tracts associated with the TS, including the inferior fronto-occipital Fasciculus (IFOF), inferior longitudinal Fasciculus (ILF), arcuate Fasciculus (AF), cingulum bundle (CB) and the uncinate Fasciculus (UF). For each tract, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were computed and compared between the two groups and also examined in relationship to memory performance in the TBI subjects. Significant FA and ADC differences were observed in all tracts in the TBI patients compared to controls, with several relationships with memory outcome noted in the IFOF, ILF and AF. Based on these preliminary findings, the potential role of TBI-induced WM disconnection involving the TS is discussed as well as the relationship of TS damage to neurobehavioral outcome. The need for future studies specifically examining the role of TS injury in TBI is emphasized.
Hugues Duffau - One of the best experts on this subject based on the ideXlab platform.
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evidence of a middle longitudinal Fasciculus in the human brain from fiber dissection
Journal of Anatomy, 2013Co-Authors: Igor Lima Maldonado, Nicolas Menjot De Champfleur, S Velut, Christophe Destrieux, Ilyess Zemmoura, Hugues DuffauAbstract:A rostrocaudal pathway connecting the temporal and parietal lobes was described in monkeys using autoradiography and was named the middle longitudinal Fasciculus (MdLF). Recently, the use of diffusion tensor tractography has allowed it to be depicted in human volunteers. In the present study, a technique of fiber dissection was used in 18 cadaveric human brains to investigate the presence of this Fasciculus and to detail its anatomical relationships. On the basis of our findings, fiber dissection provides evidence for a long horizontal bundle medial to the arcuate Fasciculus and extending to the superior temporal gyrus. Its fibers occupy the lateral-most layer of the upper portion of the stratum sagittale and partially cover the inferior fronto-occipital Fasciculus, which is situated deeper and slightly inferiorly. Whereas MdLF fibers continue on a relatively superficial level to reach the superior temporal gyrus, the inferior fronto-occipital Fasciculus penetrates the deep temporal white matter and crosses the insular lobe. Although diffusion tensor imaging suggests that the MdLF terminates in the angular gyrus, this was not confirmed by the present study. These long association fibers continue onward posteriorly into upper portions of the occipital lobe. Further studies are needed to understand the role of the MdLF in brain function.
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cortex sparing fiber dissection an improved method for the study of white matter anatomy in the human brain
Journal of Anatomy, 2011Co-Authors: Juan Martino, Francesco Vergani, Philip C De Witt Hamer, Christian Brogna, Enrique Marco De Lucas, Alfonso Vazquezbarquero, Juan A Garciaporrero, Hugues DuffauAbstract:Classical fiber dissection of post mortem human brains enables us to isolate a fiber tract by removing the cortex and overlying white matter. In the current work, a modification of the dissection methodology is presented that preserves the cortex and the relationships within the brain during all stages of dissection, i.e. ‘cortex-sparing fiber dissection’. Thirty post mortem human hemispheres (15 right side and 15 left side) were dissected using cortex-sparing fiber dissection. Magnetic resonance imaging study of a healthy brain was analyzed using diffusion tensor imaging (DTI)-based tractography software. DTI fiber tract reconstructions were compared with cortex-sparing fiber dissection results. The fibers of the superior longitudinal Fasciculus (SLF), inferior fronto-occipital Fasciculus (IFOF), inferior longitudinal Fasciculus (ILF) and uncinate Fasciculus (UF) were isolated so as to enable identification of their cortical terminations. Two segments of the SLF were identified: first, an indirect and superficial component composed of a horizontal and vertical segment; and second, a direct and deep component or arcuate Fasciculus. The IFOF runs within the insula, temporal stem and sagittal stratum, and connects the frontal operculum with the occipital, parietal and temporo-basal cortex. The UF crosses the limen insulae and connects the orbito-frontal gyri with the anterior temporal lobe. Finally, a portion of the ILF was isolated connecting the fusiform gyrus with the occipital gyri. These results indicate that cortex-sparing fiber dissection facilitates study of the 3D anatomy of human brain tracts, enabling the tracing of fibers to their terminations in the cortex. Consequently, it is an important tool for neurosurgical training and neuroanatomical research.
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intraoperative subcortical stimulation mapping of language pathways in a consecutive series of 115 patients with grade ii glioma in the left dominant hemisphere
Journal of Neurosurgery, 2008Co-Authors: Hugues Duffau, Emmanuel Mandonnet, Laurent Capelle, S Peggy T Gatignol, Luc TaillandierAbstract:Object Despite better knowledge of cortical language organization, its subcortical anatomofunctional connectivity remains poorly understood. The authors used intraoperative subcortical stimulation in awake patients undergoing operation for a glioma in the left dominant hemisphere to map the language pathways and to determine the contribution of such a method to surgical results. Methods One hundred fifteen patients harboring a World Health Organization Grade II glioma within language areas underwent operation after induction of local anesthesia, using direct electrical stimulation to perform online cortical and subcortical language mapping throughout the resection. Results After detection of cortical language sites, the authors identified 1 or several of the following subcortical language pathways in all patients: 1) arcuate Fasciculus, eliciting phonemic paraphasia when stimulated; 2) inferior frontooccipital Fasciculus, generating semantic paraphasia when stimulated; 3) subcallosal Fasciculus, inducing ...
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Does the left inferior longitudinal Fasciculus play a role in language? A brain stimulation study.
Brain - A Journal of Neurology, 2007Co-Authors: Emmanuel Mandonnet, Aurélien Nouet, Peggy Gatignol, Laurent Capelle, Hugues DuffauAbstract:Although advances in diffusion tensor imaging have enabled us to better study the anatomy of the inferior longitudinal Fasciculus (ILF), its function remains poorly understood. Recently, it was suggested that the subcortical network subserving the language semantics could be constituted, in parallel with the inferior occipitofrontal Fasciculus, by the left ILF, joining the posterior occipitotemporal regions to the temporal pole, then relayed by the uncinate Fasciculus connecting the anterior temporal pole to the frontobasal areas. Nevertheless, this hypothesis was solely based on neurofunctional imaging, allowing a cortical mapping but with no anatomofunctional information regarding the white matter. Here, we report a series of 12 patients operated on under local anaesthesia for a cerebral low-grade glioma located within the left temporal lobe. Before and during resection, we used the method of intraoperative direct electrostimulation, enabling us to perform accurate and reliable anatomofunctional correlations both at cortical and subcortical levels. In order to map the ILF. Using postoperative MRI, we correlated these functional findings with the anatomical locations of the sites where language disturbances were elicited by stimulations, both at cortical and subcortical levels. Our goal was to study the potential existence of parallel and distributed language networks crossing the left dominant temporal lobe, subserved by distinct subcortical pathways--namely the inferior occipitofrontal Fasciculus and the ILF. Intraoperative stimulation of the anterior and middle temporal cortex elicited anomia in four patients. At the subcortical level, semantic paraphasia were induced in seven patients during stimulation of the inferior occipitofrontal Fasciculus, and phonological paraphasia was generated in seven patients by stimulating the arcuate Fasciculus. Interestingly, subcortical stimulation never elicited any language disturbances when performed at the level of the ILF. In addition, following a transient postoperative language deficit, all patients recovered, despite the resection of at least one part of the ILF, as confirmed by control MRI. On the basis of these results, we suggest that the "semantic ventral stream" could be constituted by at least two parallel pathways within the left dominant temporal lobe: (i) a direct pathway, the inferior occipitofrontal Fasciculus, that connects the posterior temporal areas and the orbitofrontal region, crucial for language semantic processing, since it elicits semantic paraphasia when stimulated; (ii) and also possibly an indirect pathway subserved by the ILF, not indispensable for language, since it can be compensated both during stimulation and after resection.
Marco Catani - One of the best experts on this subject based on the ideXlab platform.
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monkey to human comparative anatomy of the frontal lobe association tracts
Cortex, 2012Co-Authors: Flavio Dellacqua, Michel Thiebaut De Schotten, Romain Valabregue, Marco CataniAbstract:The greater expansion of the frontal lobes along the phylogeny scale has been interpreted as the signature of evolutionary changes underlying higher cognitive abilities in humans functions in humans. However, it is unknown how an increase in number of gyri, sulci and cortical areas in the frontal lobe have coincided with a parallel increase in connectivity. Here, using advanced tractography based on spherical deconvolution, we produced an atlas of human frontal association connections that we compared with axonal tracing studies of the monkey brain. We report several similarities between human and monkey in the cingulum, uncinate, superior longitudinal Fasciculus, frontal aslant tract and orbito-polar tract. These similarities suggest to preserved functions across anthropoids. In addition, we found major differences in the arcuate Fasciculus and the inferior fronto-occipital Fasciculus. These differences indicate possible evolutionary changes in the connectional anatomy of the frontal lobes underlying unique human abilities.
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virtual in vivo interactive dissection of white matter fasciculi in the human brain
NeuroImage, 2002Co-Authors: Marco Catani, Robert Howard, Sinisa Pajevic, Derek K JonesAbstract:This work reports the use of diffusion tensor magnetic resonance tractography to visualize the three-dimensional (3D) structure of the major white matter fasciculi within living human brain. Specifically, we applied this technique to visualize in vivo (i) the superior longitudinal (arcuate) Fasciculus, (ii) the inferior longitudinal Fasciculus, (iii) the superior fronto-occipital (subcallosal) Fasciculus, (iv) the inferior fronto-occipital Fasciculus, (v) the uncinate Fasciculus, (vi) the cingulum, (vii) the anterior commissure, (viii) the corpus callosum, (ix) the internal capsule, and (x) the fornix. These fasciculi were first isolated and were then interactively displayed as a 3D-rendered object. The virtual tract maps obtained in vivo using this approach were faithful to the classical descriptions of white matter anatomy that have previously been documented in postmortem studies. Since we have been able to interactively delineate and visualize white matter fasciculi over their entire length in vivo, in a manner that has only previously been possible by histological means, virtual in vivo interactive dissection (VIVID) adds a new dimension to anatomical descriptions of the living human brain.
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doi:10.1006/nimg.2002.1136 Virtual in Vivo Interactive Dissection of White Matter Fasciculi
2001Co-Authors: In The Human Brain, Sinisa Pajevic, Marco Catani, Robert J. Howard, Derek K JonesAbstract:This work reports the use of diffusion tensor magnetic resonance tractography to visualize the threedimensional (3D) structure of the major white matter fasciculi within living human brain. Specifically, we applied this technique to visualize in vivo (i) the superior longitudinal (arcuate) Fasciculus, (ii) the inferior longitudinal Fasciculus, (iii) the superior fronto-occipital (subcallosal) Fasciculus, (iv) the inferior frontooccipital Fasciculus, (v) the uncinate Fasciculus, (vi) the cingulum, (vii) the anterior commissure, (viii) the corpus callosum, (ix) the internal capsule, and (x) the fornix. These fasciculi were first isolated and were then interactively displayed as a 3D-rendered object. The virtual tract maps obtained in vivo using this approach were faithful to the classical descriptions of white matter anatomy that have previously been documented in postmortem studies. Since we have been able to interactively delineate and visualize white matter fasciculi over their entire length in vivo, in a manner that has only previously been possible by histological means, “virtual in vivo interactive dissection” (VIVID) adds a new dimension to anatomical descriptions of the living human brain. © 2002 Elsevie
Erin D Bigler - One of the best experts on this subject based on the ideXlab platform.
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the temporal stem in traumatic brain injury preliminary findings
Brain Imaging and Behavior, 2010Co-Authors: Erin D Bigler, Stephen R Mccauley, Ragini Yallampalli, Sanjeev Shah, Marianne Macleod, Zili Chu, Jill V HunterAbstract:The temporal stem (TS) of the temporal lobe is a major white matter (WM) region containing several major pathways that connect the temporal lobe with the rest of the brain. Because of its location, it may be particularly vulnerable to shear-strain effects resulting from traumatic brain injury (TBI). A case vignette is presented in a patient with severe brain injury and focal TS pathology. Also, 12 severe TBI subjects unselected for TS pathology were compared to demographically matched, neurologically-intact controls using diffusion tensor imaging (DTI) to examine white matter tracts associated with the TS, including the inferior fronto-occipital Fasciculus (IFOF), inferior longitudinal Fasciculus (ILF), arcuate Fasciculus (AF), cingulum bundle (CB) and the uncinate Fasciculus (UF). For each tract, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were computed and compared between the two groups and also examined in relationship to memory performance in the TBI subjects. Significant FA and ADC differences were observed in all tracts in the TBI patients compared to controls, with several relationships with memory outcome noted in the IFOF, ILF and AF. Based on these preliminary findings, the potential role of TBI-induced WM disconnection involving the TS is discussed as well as the relationship of TS damage to neurobehavioral outcome. The need for future studies specifically examining the role of TS injury in TBI is emphasized.
