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Aldo Junqueira Rodrigues - One of the best experts on this subject based on the ideXlab platform.
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Surgical anatomy of microneurosurgical sulcal key points.
Neurosurgery, 2006Co-Authors: Guilherme Carvalhal Ribas, Alexandre Yasuda, Eduardo Santamaria Carvalhal Ribas, Koshiro Nishikuni, Aldo Junqueira RodriguesAbstract:OBJECTIVE: The brain sulci constitute the main microanatomic delimiting landmarks and surgical corridors of modern microneurosurgery. Because of the frequent difficulty in intraoperatively localizing and visually identifying the brain sulci with assurance, the main purpose of this study was to establish cortical/sulcal key points of primary microneurosurgical importance to provide a sulcal anatomic framework for the placement of craniotomies and to facilitate the main sulci intraoperative identification. METHODS: The study was performed through the evaluation of 32 formalin-fixed cerebral hemispheres of 16 adult cadavers, which had been removed from the skulls after the introduction of plastic catheters through properly positioned burr holes necessary for the evaluation of cranial-cerebral relationships. Three-dimensional anatomic and surgical images are displayed to illustrate the use of sulcal key points. RESULTS: The points studied were the anterior sylvian point, the inferior rolandic point, the intersection of the inferior frontal Sulcus with the precentral Sulcus, the intersection of the superior frontal Sulcus with the precentral Sulcus, the superior rolandic point, the intersection of the intraparietal Sulcus with the Postcentral Sulcus, the superior point of the parieto-occipital Sulcus, the euryon (the craniometric point that corresponds to the center of the parietal tuberosity), the posterior point of the superior temporal Sulcus, and the opisthocranion, which corresponds to the most prominent point of the occipital bossa. These points presented regular neural and cranial-cerebral relationships and can be considered consistent microsurgical cortical key points. CONCLUSION: These sulcal and gyral key points can be particularly useful for initial intraoperative sulci identification and dissection. Together, they compose a framework that can help in the understanding of hemispheric lesion localization, in the placement of supratentorial craniotomies, as landmarks for the transsulcal approaches to periventricular and intraventricular lesions, and in orienting the anatomic removal of gyral sectors that contain infiltrative tumors.
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Surgical anatomy of microneurosurgical sulcal key points.
Neurosurgery, 2006Co-Authors: Guilherme Carvalhal Ribas, Alexandre Yasuda, Koshiro Nishikuni, Eduardo C Ribas, Aldo Junqueira RodriguesAbstract:The brain sulci constitute the main microanatomic delimiting landmarks and surgical corridors of modern microneurosurgery. Because of the frequent difficulty in intraoperatively localizing and visually identifying the brain sulci with assurance, the main purpose of this study was to establish cortical/sulcal key points of primary microneurosurgical importance to provide a sulcal anatomic framework for the placement of craniotomies and to facilitate the main sulci intraoperative identification. The study was performed through the evaluation of 32 formalin-fixed cerebral hemispheres of 16 adult cadavers, which had been removed from the skulls after the introduction of plastic catheters through properly positioned burr holes necessary for the evaluation of cranial-cerebral relationships. Three-dimensional anatomic and surgical images are displayed to illustrate the use of sulcal key points. The points studied were the anterior sylvian point, the inferior rolandic point, the intersection of the inferior frontal Sulcus with the precentral Sulcus, the intersection of the superior frontal Sulcus with the precentral Sulcus, the superior rolandic point, the intersection of the intraparietal Sulcus with the Postcentral Sulcus, the superior point of the parieto-occipital Sulcus, the euryon (the craniometric point that corresponds to the center of the parietal tuberosity), the posterior point of the superior temporal Sulcus, and the opisthocranion, which corresponds to the most prominent point of the occipital bossa. These points presented regular neural and cranial-cerebral relationships and can be considered consistent microsurgical cortical key points. These sulcal and gyral key points can be particularly useful for initial intraoperative sulci identification and dissection. Together, they compose a framework that can help in the understanding of hemispheric lesion localization, in the placement of supratentorial craniotomies, as landmarks for the transsulcal approaches to periventricular and intraventricular lesions, and in orienting the anatomic removal of gyral sectors that contain infiltrative tumors.
Krishnankutty Sathian - One of the best experts on this subject based on the ideXlab platform.
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effective connectivity during haptic perception a study using granger causality analysis of functional magnetic resonance imaging data
NeuroImage, 2008Co-Authors: Gopikrishna Deshpande, Randall Stilla, Krishnankutty SathianAbstract:Although it is accepted that visual cortical areas are recruited during touch, it remains uncertain whether this depends on top-down inputs mediating visual imagery or engagement of modality-independent representations by bottom-up somatosensory inputs. Here we addressed this by examining effective connectivity in humans during haptic perception of shape and texture with the right hand. Multivariate Granger causality analysis of functional magnetic resonance imaging (fMRI) data was conducted on a network of regions that were shape- or texture-selective. A novel network reduction procedure was employed to eliminate connections that did not contribute significantly to overall connectivity. Effective connectivity during haptic perception was found to involve a variety of interactions between areas generally regarded as somatosensory, multisensory, visual and motor, emphasizing flexible cooperation between different brain regions rather than rigid functional separation. The left Postcentral Sulcus (PCS), left precentral gyrus and right posterior insula were important sources of connections in the network. Bottom-up somatosensory inputs from the left PCS and right posterior insula fed into visual cortical areas, both the shape-selective right lateral occipital complex (LOC) and the texture-selective right medial occipital cortex (probable V2). In addition, top-down inputs from left postero-supero-medial parietal cortex influenced the right LOC. Thus, there is strong evidence for the bottom-up somatosensory inputs predicted by models of visual cortical areas as multisensory processors and suggestive evidence for top-down parietal (but not prefrontal) inputs that could mediate visual imagery. This is consistent with modality-independent representations accessible through both bottom-up sensory inputs and top-down processes such as visual imagery.
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Selective visuo-haptic processing of shape and texture
Human brain mapping, 2008Co-Authors: Randall Stilla, Krishnankutty SathianAbstract:Previous functional neuroimaging studies have described shape-selectivity for haptic stimuli in many cerebral cortical regions, of which some are also visually shape-selective. However, the literature is equivocal on the existence of haptic or visuo-haptic texture-selectivity. We report here on a human functional magnetic resonance imaging (fMRI) study in which shape and texture perception were contrasted using haptic stimuli presented to the right hand, and visual stimuli presented centrally. Bilateral selectivity for shape, with overlap between modalities, was found in a dorsal set of parietal areas: the Postcentral Sulcus and anterior, posterior and ventral parts of the intraparietal Sulcus (IPS); as well as ventrally in the lateral occipital complex. The magnitude of visually- and haptically-evoked activity was significantly correlated across subjects in the left posterior IPS and right lateral occipital complex, suggesting that these areas specifically house representations of object shape. Haptic shape-selectivity was also found in the left Postcentral gyrus, the left lingual gyrus, and a number of frontal cortical sites. Haptic texture-selectivity was found in ventral somatosensory areas: the parietal operculum and posterior insula bilaterally, as well as in the right medial occipital cortex, overlapping with a medial occipital cortical region, which was texture-selective for visual stimuli. The present report corroborates and elaborates previous suggestions of specialized visuo-haptic processing of texture and shape.
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Posteromedial Parietal Cortical Activity and Inputs Predict Tactile Spatial Acuity
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2007Co-Authors: Randall Stilla, Stephen M. Laconte, Gopikrishna Deshpande, Krishnankutty SathianAbstract:We used functional magnetic resonance imaging (fMRI) to investigate the neural circuitry underlying tactile spatial acuity at the human finger pad. Stimuli were linear, three-dot arrays, applied to the immobilized right index finger pad using a computer-controlled, MRI-compatible, pneumatic stimulator. Activity specific for spatial processing was isolated by contrasting discrimination of left-right offsets of the central dot in the array with discrimination of the duration of stimulation by an array without a spatial offset. This contrast revealed activity in a distributed frontoparietal cortical network, within which the levels of activity in right posteromedial parietal cortical foci [right posterior intraparietal Sulcus (pIPS) and right precuneus] significantly predicted individual acuity thresholds. Connectivity patterns were assessed using both bivariate analysis of Granger causality with the right pIPS as a reference region and multivariate analysis of Granger causality for a selected set of regions. The strength of inputs into the right pIPS was significantly greater in subjects with better acuity than those with poorer acuity. In the better group, the paths predicting acuity converged from the left Postcentral Sulcus and right frontal eye field onto the right pIPS and were selective for the spatial task, and their weights predicted the level of right pIPS activity. We propose that the optimal strategy for fine tactile spatial discrimination involves interaction in the pIPS of a top-down control signal, possibly attentional, with somatosensory cortical inputs, reflecting either visualization of the spatial configurations of tactile stimuli or engagement of modality-independent circuits specialized for fine spatial processing.
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Activity and effective connectivity of parietal and occipital cortical regions during haptic shape perception.
Neuropsychologia, 2006Co-Authors: Scott Peltier, Randall Stilla, Erica Mariola, Stephen M. Laconte, Krishnankutty SathianAbstract:It is now widely accepted that visual cortical areas are active during normal tactile perception, but the underlying mechanisms are still not clear. The goal of the present study was to use functional magnetic resonance imaging (fMRI) to investigate the activity and effective connectivity of parietal and occipital cortical areas during haptic shape perception, with a view to potentially clarifying the role of top-down and bottom-up inputs into visual areas. Subjects underwent fMRI scanning while engaging in discrimination of haptic shape or texture, and in separate runs, visual shape or texture. Accuracy did not differ significantly between tasks. Haptic shape-selective regions, identified on a contrast between the haptic shape and texture conditions in individual subjects, were found bilaterally in the Postcentral Sulcus (PCS), multiple parts of the intraparietal Sulcus (IPS) and the lateral occipital complex (LOC). The IPS and LOC foci tended to be shape-selective in the visual modality as well. Structural equation modelling was used to study the effective connectivity among the haptic shape-selective regions in the left hemisphere, contralateral to the stimulated hand. All possible models were tested for their fit to the correlations among the observed time-courses of activity. Two equivalent models emerged as the winners. These models, which were quite similar, were characterized by both bottom-up paths from the PCS to parts of the IPS, and top-down paths from the LOC and parts of the IPS to the PCS. We conclude that interactions between unisensory and multisensory cortical areas involve bidirectional information flow.
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tactile discrimination of grating orientation fmri activation patterns
Human Brain Mapping, 2005Co-Authors: Randall Stilla, Erica Mariola, Minming Zhang, Mark Stoesz, Xiaoping Hu, Krishnankutty SathianAbstract:Grating orientation discrimination is employed widely to test tactile spatial acuity. We used functional magnetic resonance imaging (fMRI) to investigate the neural circuitry underlying performance of this task. Two studies were carried out. In the first study, an extensive set of parietal and frontal cortical areas was activated during covert task performance, relative to a rest baseline. The active regions included the Postcentral Sulcus bilaterally and foci in the left parietal operculum, left anterior intraparietal Sulcus, and bilateral premotor and prefrontal cortex. The second study examined selective recruitment of cortical areas during discrimination of grating orientation (a task with a macrospatial component) compared to discrimination of grating spacing (a purely microspatial task). The foci activated on this contrast were in the left anterior intraparietal Sulcus, right Postcentral Sulcus and gyrus, left parieto-occipital cortex, bilateral frontal eye fields, and bilateral ventral premotor cortex. These findings not only confirm and extend previous studies of the neural processing underlying grating orientation discrimination, but also demonstrate that a distributed network of putatively multisensory areas is involved. Hum Brain Mapp, 2005. © 2005 Wiley-Liss, Inc.
Guilherme Carvalhal Ribas - One of the best experts on this subject based on the ideXlab platform.
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Surgical anatomy of microneurosurgical sulcal key points.
Neurosurgery, 2006Co-Authors: Guilherme Carvalhal Ribas, Alexandre Yasuda, Eduardo Santamaria Carvalhal Ribas, Koshiro Nishikuni, Aldo Junqueira RodriguesAbstract:OBJECTIVE: The brain sulci constitute the main microanatomic delimiting landmarks and surgical corridors of modern microneurosurgery. Because of the frequent difficulty in intraoperatively localizing and visually identifying the brain sulci with assurance, the main purpose of this study was to establish cortical/sulcal key points of primary microneurosurgical importance to provide a sulcal anatomic framework for the placement of craniotomies and to facilitate the main sulci intraoperative identification. METHODS: The study was performed through the evaluation of 32 formalin-fixed cerebral hemispheres of 16 adult cadavers, which had been removed from the skulls after the introduction of plastic catheters through properly positioned burr holes necessary for the evaluation of cranial-cerebral relationships. Three-dimensional anatomic and surgical images are displayed to illustrate the use of sulcal key points. RESULTS: The points studied were the anterior sylvian point, the inferior rolandic point, the intersection of the inferior frontal Sulcus with the precentral Sulcus, the intersection of the superior frontal Sulcus with the precentral Sulcus, the superior rolandic point, the intersection of the intraparietal Sulcus with the Postcentral Sulcus, the superior point of the parieto-occipital Sulcus, the euryon (the craniometric point that corresponds to the center of the parietal tuberosity), the posterior point of the superior temporal Sulcus, and the opisthocranion, which corresponds to the most prominent point of the occipital bossa. These points presented regular neural and cranial-cerebral relationships and can be considered consistent microsurgical cortical key points. CONCLUSION: These sulcal and gyral key points can be particularly useful for initial intraoperative sulci identification and dissection. Together, they compose a framework that can help in the understanding of hemispheric lesion localization, in the placement of supratentorial craniotomies, as landmarks for the transsulcal approaches to periventricular and intraventricular lesions, and in orienting the anatomic removal of gyral sectors that contain infiltrative tumors.
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Surgical anatomy of microneurosurgical sulcal key points.
Neurosurgery, 2006Co-Authors: Guilherme Carvalhal Ribas, Alexandre Yasuda, Koshiro Nishikuni, Eduardo C Ribas, Aldo Junqueira RodriguesAbstract:The brain sulci constitute the main microanatomic delimiting landmarks and surgical corridors of modern microneurosurgery. Because of the frequent difficulty in intraoperatively localizing and visually identifying the brain sulci with assurance, the main purpose of this study was to establish cortical/sulcal key points of primary microneurosurgical importance to provide a sulcal anatomic framework for the placement of craniotomies and to facilitate the main sulci intraoperative identification. The study was performed through the evaluation of 32 formalin-fixed cerebral hemispheres of 16 adult cadavers, which had been removed from the skulls after the introduction of plastic catheters through properly positioned burr holes necessary for the evaluation of cranial-cerebral relationships. Three-dimensional anatomic and surgical images are displayed to illustrate the use of sulcal key points. The points studied were the anterior sylvian point, the inferior rolandic point, the intersection of the inferior frontal Sulcus with the precentral Sulcus, the intersection of the superior frontal Sulcus with the precentral Sulcus, the superior rolandic point, the intersection of the intraparietal Sulcus with the Postcentral Sulcus, the superior point of the parieto-occipital Sulcus, the euryon (the craniometric point that corresponds to the center of the parietal tuberosity), the posterior point of the superior temporal Sulcus, and the opisthocranion, which corresponds to the most prominent point of the occipital bossa. These points presented regular neural and cranial-cerebral relationships and can be considered consistent microsurgical cortical key points. These sulcal and gyral key points can be particularly useful for initial intraoperative sulci identification and dissection. Together, they compose a framework that can help in the understanding of hemispheric lesion localization, in the placement of supratentorial craniotomies, as landmarks for the transsulcal approaches to periventricular and intraventricular lesions, and in orienting the anatomic removal of gyral sectors that contain infiltrative tumors.
Bruno Weder - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Lesions in Patients With Unilateral Tactile Agnosia Using Cytoarchitectonic Probabilistic Maps
2015Co-Authors: Katrin Amunts, Karl Zilles, Christian Fretz, Bruno WederAbstract:Abstract: We propose a novel methodical approach to lesion analyses involving high-resolutionMR images in combination with probabilistic cytoarchitectonic maps. 3D-MR images of the whole brain and the man-ually segmented lesion mask are spatially normalized to the reference brain of a stereotaxic probabilistic cytoarchitectonic atlas using a multiscale registration algorithm based on an elastic model. The procedure is demonstrated in three patients suffering from aperceptive tactile agnosia of the right hand due to chronic in-farction of the left parietal cortex. Patient 1 presents a lesion in areas of the Postcentral Sulcus, Patient 3 in areas of the superior parietal lobule and adjacent intraparietal Sulcus, and Patient 2 lesions in both regions. On the basis of neurobehavioral data, we conjectureddegradation of sequential elementary sensory informa-tion processingwithin the Postcentral gyrus, impeding texture recognition in Patients 1 and 2, and disturbed kinaesthetic information processing in the posterior parietal lobe, causing degraded shape recognition in the patients 2 and 3. The involvement of Brodmann areas 4a, 4p, 3a, 3b, 1, 2, and areas IP1 and IP2 of the intrapar-ietal Sulcus was assessed in terms of the voxel overlap between the spatially transformed lesion masks and the 50%-isocontours of the cytoarchitectonic maps. The disruption of the critical cytoarchitectonic areas and the impaired subfunctions, texture and shape recognition, relate as conjectured above. We conclude that the proposed method represents a promising approach to hypothesis-driven lesion analyses, yielding lesion
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analysis of lesions in patients with unilateral tactile agnosia using cytoarchitectonic probabilistic maps
Human Brain Mapping, 2009Co-Authors: Lars Homke, Ferdinand Binkofski, Karl Zilles, Katrin Amunts, Christian Fretz, Bruno Weder, Lutz BonigAbstract:We propose a novel methodical approach to lesion analyses involving high-resolution MR images in combination with probabilistic cytoarchitectonic maps. 3D-MR images of the whole brain and the man- ually segmented lesion mask are spatially normalized to the reference brain of a stereotaxic probabilistic cytoarchitectonic atlas using a multiscale registration algorithm based on an elastic model. The procedure is demonstrated in three patients suffering from aperceptive tactile agnosia of the right hand due to chronic in- farction of the left parietal cortex. Patient 1 presents a lesion in areas of the Postcentral Sulcus, Patient 3 in areas of the superior parietal lobule and adjacent intraparietal Sulcus, and Patient 2 lesions in both regions. On the basis of neurobehavioral data, we conjectured degradation of sequential elementary sensory informa- tion processing within the Postcentral gyrus, impeding texture recognition in Patients 1 and 2, and disturbed kinaesthetic information processing in the posterior parietal lobe, causing degraded shape recognition in the patients 2 and 3. The involvement of Brodmann areas 4a, 4p, 3a, 3b, 1, 2, and areas IP1 and IP2 of the intrapar- ietal Sulcus was assessed in terms of the voxel overlap between the spatially transformed lesion masks and the 50%-isocontours of the cytoarchitectonic maps. The disruption of the critical cytoarchitectonic areas and the impaired subfunctions, texture and shape recognition, relate as conjectured above. We conclude that the proposed method represents a promising approach to hypothesis-driven lesion analyses, yielding lesion- function correlates based on a cytoarchitectonic model. Finally, the lesion-function correlates are validated by functional imaging reference data. Hum Brain Mapp 30:1444-1456, 2009. V C 2008 Wiley-Liss, Inc.
Koshiro Nishikuni - One of the best experts on this subject based on the ideXlab platform.
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Surgical anatomy of microneurosurgical sulcal key points.
Neurosurgery, 2006Co-Authors: Guilherme Carvalhal Ribas, Alexandre Yasuda, Eduardo Santamaria Carvalhal Ribas, Koshiro Nishikuni, Aldo Junqueira RodriguesAbstract:OBJECTIVE: The brain sulci constitute the main microanatomic delimiting landmarks and surgical corridors of modern microneurosurgery. Because of the frequent difficulty in intraoperatively localizing and visually identifying the brain sulci with assurance, the main purpose of this study was to establish cortical/sulcal key points of primary microneurosurgical importance to provide a sulcal anatomic framework for the placement of craniotomies and to facilitate the main sulci intraoperative identification. METHODS: The study was performed through the evaluation of 32 formalin-fixed cerebral hemispheres of 16 adult cadavers, which had been removed from the skulls after the introduction of plastic catheters through properly positioned burr holes necessary for the evaluation of cranial-cerebral relationships. Three-dimensional anatomic and surgical images are displayed to illustrate the use of sulcal key points. RESULTS: The points studied were the anterior sylvian point, the inferior rolandic point, the intersection of the inferior frontal Sulcus with the precentral Sulcus, the intersection of the superior frontal Sulcus with the precentral Sulcus, the superior rolandic point, the intersection of the intraparietal Sulcus with the Postcentral Sulcus, the superior point of the parieto-occipital Sulcus, the euryon (the craniometric point that corresponds to the center of the parietal tuberosity), the posterior point of the superior temporal Sulcus, and the opisthocranion, which corresponds to the most prominent point of the occipital bossa. These points presented regular neural and cranial-cerebral relationships and can be considered consistent microsurgical cortical key points. CONCLUSION: These sulcal and gyral key points can be particularly useful for initial intraoperative sulci identification and dissection. Together, they compose a framework that can help in the understanding of hemispheric lesion localization, in the placement of supratentorial craniotomies, as landmarks for the transsulcal approaches to periventricular and intraventricular lesions, and in orienting the anatomic removal of gyral sectors that contain infiltrative tumors.
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Surgical anatomy of microneurosurgical sulcal key points.
Neurosurgery, 2006Co-Authors: Guilherme Carvalhal Ribas, Alexandre Yasuda, Koshiro Nishikuni, Eduardo C Ribas, Aldo Junqueira RodriguesAbstract:The brain sulci constitute the main microanatomic delimiting landmarks and surgical corridors of modern microneurosurgery. Because of the frequent difficulty in intraoperatively localizing and visually identifying the brain sulci with assurance, the main purpose of this study was to establish cortical/sulcal key points of primary microneurosurgical importance to provide a sulcal anatomic framework for the placement of craniotomies and to facilitate the main sulci intraoperative identification. The study was performed through the evaluation of 32 formalin-fixed cerebral hemispheres of 16 adult cadavers, which had been removed from the skulls after the introduction of plastic catheters through properly positioned burr holes necessary for the evaluation of cranial-cerebral relationships. Three-dimensional anatomic and surgical images are displayed to illustrate the use of sulcal key points. The points studied were the anterior sylvian point, the inferior rolandic point, the intersection of the inferior frontal Sulcus with the precentral Sulcus, the intersection of the superior frontal Sulcus with the precentral Sulcus, the superior rolandic point, the intersection of the intraparietal Sulcus with the Postcentral Sulcus, the superior point of the parieto-occipital Sulcus, the euryon (the craniometric point that corresponds to the center of the parietal tuberosity), the posterior point of the superior temporal Sulcus, and the opisthocranion, which corresponds to the most prominent point of the occipital bossa. These points presented regular neural and cranial-cerebral relationships and can be considered consistent microsurgical cortical key points. These sulcal and gyral key points can be particularly useful for initial intraoperative sulci identification and dissection. Together, they compose a framework that can help in the understanding of hemispheric lesion localization, in the placement of supratentorial craniotomies, as landmarks for the transsulcal approaches to periventricular and intraventricular lesions, and in orienting the anatomic removal of gyral sectors that contain infiltrative tumors.