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M. Denis - One of the best experts on this subject based on the ideXlab platform.
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Neural Correlates of Topographic Mental Exploration: The Impact of Route versus Survey Perspective Learning
NeuroImage, 2000Co-Authors: Emmanuel Mellet, Laurent Petit, S. Bricogne, Nathalie Tzourio-mazoyer, O. Ghaëm, Laure Zago, Olivier Etard, A. Berthoz, Bernard Mazoyer, M. DenisAbstract:There are two major sources of information to build a topographic representation of an environment, namely actual navigation within the environment (route perspective) and map learning (survey perspective). The aim of the present work was to use positron emission tomography (PET) to compare the neural substrate of the topographic representation built from these two modes. One group of subjects performed a mental exploration task in an environment learned from actual navigation (mental navigation task). Another group of subjects performed exploration in the same environment learned from a map (mental map task). A right hippocampal activation common to both mental navigation and mental map tasks was evidenced and may correspond the neural substrate of a "dual-perspective" representation. The parahippocampal gyrus was additionally activated bilaterally during mental navigation only. These results suggest that the right hippocampus involvement would be sufficient when the representation incorporates essentially survey information while the bilateral parahippocampal gyrus would be involved when the environment incorporates route information and includes "object" landmarks. The activation of a parietoFrontal network composed of the intraparietal Sulcus, the Superior Frontal Sulcus, the middle Frontal gyrus, and the pre-SMA was observed in common for both mental navigation and mental map and is likely to reflect the spatial mental imagery components of the tasks.
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RAPID COMMUNICATION Neural Correlates of Topographic Mental Exploration: The Impact of Route versus Survey Perspective Learning
2000Co-Authors: Emmanuel Mellet, S. Bricogne, Nathalie Tzourio-mazoyer, Laure Zago, Olivier Etard, A. Berthoz, Bernard Mazoyer, L. Petit, M. DenisAbstract:There are two major sources of information to builda topographic representation of an environment,namely actual navigation within the environment(route perspective) and map learning (survey perspec-tive). The aim of the present work was to use positronemission tomography (PET) to compare the neuralsubstrate of the topographic representation built fromthese two modes. One group of subjects performed amental exploration task in an environment learnedfrom actual navigation (mental navigation task). An-other group of subjects performed exploration in thesame environment learned from a map (mental maptask). A right hippocampal activation common to bothmental navigation and mental map tasks was evi-denced and may correspond the neural substrateof a “dual-perspective” representation. The parahip-pocampal gyrus was additionally activated bilaterallyduring mental navigation only. These results suggestthat the right hippocampus involvement would be suf-ficient when the representation incorporates essen-tially survey information while the bilateral parahip-pocampal gyrus would be involved when theenvironment incorporates route information and in-cludes “object” landmarks. The activation of a pariet-oFrontal network composed of the intraparietal sul-cus, the Superior Frontal Sulcus, the middle Frontalgyrus, and the pre-SMA was observed in common forboth mental navigation and mental map and is likelyto reflect the spatial mental imagery components ofthe tasks.
A. Berthoz - One of the best experts on this subject based on the ideXlab platform.
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Localization of human Frontal eye fields: anatomical and functional findings of functional magnetic resonance imaging and intracerebral electrical stimulation.
Journal of Neurosurgery, 2001Co-Authors: E. Lobel, P. Kahane, U. Leonards, M. Grosbras, Stéphane Lehéricy, D. Le Bihan, A. BerthozAbstract:OBJECT: The goal of this study was to investigate the anatomical localization and functional role of human Frontal eye fields (FEFs) by comparing findings from two independently conducted studies. METHODS: In the first study, 3-tesla functional magnetic resonance (fMR) imaging was performed in 14 healthy volunteers divided into two groups: the first group executed self-paced voluntary saccades in complete darkness and the second group repeated newly learned or familiar sequences of saccades. In the second study, intracerebral electrical stimulation (IES) was performed in 38 patients with epilepsy prior to surgery, and Frontal regions where stimulation induced versive eye movements were identified. These studies showed that two distinct oculomotor areas (OMAs) could be individualized in the region classically corresponding to the FEFs. One OMA was consistently located at the intersection of the Superior Frontal Sulcus with the fundus of the Superior portion of the precentral Sulcus, and was the OMA in which saccadic eye movements could be the most easily elicited by electrical stimulation. The second OMA was located more laterally, close to the surface of the precentral gyrus. The fMR imaging study and the IES study demonstrated anatomical and stereotactic agreement in the identification of these cortical areas. CONCLUSIONS: These findings indicate that infracentimetric localization of cortical areas can be achieved by measuring the vascular signal with the aid of 3-tesla fMR imaging and that neuroimaging and electrophysiological recording can be used together to obtain a better understanding of the human cortical functional anatomy.
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Neural Correlates of Topographic Mental Exploration: The Impact of Route versus Survey Perspective Learning
NeuroImage, 2000Co-Authors: Emmanuel Mellet, Laurent Petit, S. Bricogne, Nathalie Tzourio-mazoyer, O. Ghaëm, Laure Zago, Olivier Etard, A. Berthoz, Bernard Mazoyer, M. DenisAbstract:There are two major sources of information to build a topographic representation of an environment, namely actual navigation within the environment (route perspective) and map learning (survey perspective). The aim of the present work was to use positron emission tomography (PET) to compare the neural substrate of the topographic representation built from these two modes. One group of subjects performed a mental exploration task in an environment learned from actual navigation (mental navigation task). Another group of subjects performed exploration in the same environment learned from a map (mental map task). A right hippocampal activation common to both mental navigation and mental map tasks was evidenced and may correspond the neural substrate of a "dual-perspective" representation. The parahippocampal gyrus was additionally activated bilaterally during mental navigation only. These results suggest that the right hippocampus involvement would be sufficient when the representation incorporates essentially survey information while the bilateral parahippocampal gyrus would be involved when the environment incorporates route information and includes "object" landmarks. The activation of a parietoFrontal network composed of the intraparietal Sulcus, the Superior Frontal Sulcus, the middle Frontal gyrus, and the pre-SMA was observed in common for both mental navigation and mental map and is likely to reflect the spatial mental imagery components of the tasks.
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RAPID COMMUNICATION Neural Correlates of Topographic Mental Exploration: The Impact of Route versus Survey Perspective Learning
2000Co-Authors: Emmanuel Mellet, S. Bricogne, Nathalie Tzourio-mazoyer, Laure Zago, Olivier Etard, A. Berthoz, Bernard Mazoyer, L. Petit, M. DenisAbstract:There are two major sources of information to builda topographic representation of an environment,namely actual navigation within the environment(route perspective) and map learning (survey perspec-tive). The aim of the present work was to use positronemission tomography (PET) to compare the neuralsubstrate of the topographic representation built fromthese two modes. One group of subjects performed amental exploration task in an environment learnedfrom actual navigation (mental navigation task). An-other group of subjects performed exploration in thesame environment learned from a map (mental maptask). A right hippocampal activation common to bothmental navigation and mental map tasks was evi-denced and may correspond the neural substrateof a “dual-perspective” representation. The parahip-pocampal gyrus was additionally activated bilaterallyduring mental navigation only. These results suggestthat the right hippocampus involvement would be suf-ficient when the representation incorporates essen-tially survey information while the bilateral parahip-pocampal gyrus would be involved when theenvironment incorporates route information and in-cludes “object” landmarks. The activation of a pariet-oFrontal network composed of the intraparietal sul-cus, the Superior Frontal Sulcus, the middle Frontalgyrus, and the pre-SMA was observed in common forboth mental navigation and mental map and is likelyto reflect the spatial mental imagery components ofthe tasks.
Laurent Petit - One of the best experts on this subject based on the ideXlab platform.
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Neural Correlates of Topographic Mental Exploration: The Impact of Route versus Survey Perspective Learning
NeuroImage, 2000Co-Authors: Emmanuel Mellet, Laurent Petit, S. Bricogne, Nathalie Tzourio-mazoyer, O. Ghaëm, Laure Zago, Olivier Etard, A. Berthoz, Bernard Mazoyer, M. DenisAbstract:There are two major sources of information to build a topographic representation of an environment, namely actual navigation within the environment (route perspective) and map learning (survey perspective). The aim of the present work was to use positron emission tomography (PET) to compare the neural substrate of the topographic representation built from these two modes. One group of subjects performed a mental exploration task in an environment learned from actual navigation (mental navigation task). Another group of subjects performed exploration in the same environment learned from a map (mental map task). A right hippocampal activation common to both mental navigation and mental map tasks was evidenced and may correspond the neural substrate of a "dual-perspective" representation. The parahippocampal gyrus was additionally activated bilaterally during mental navigation only. These results suggest that the right hippocampus involvement would be sufficient when the representation incorporates essentially survey information while the bilateral parahippocampal gyrus would be involved when the environment incorporates route information and includes "object" landmarks. The activation of a parietoFrontal network composed of the intraparietal Sulcus, the Superior Frontal Sulcus, the middle Frontal gyrus, and the pre-SMA was observed in common for both mental navigation and mental map and is likely to reflect the spatial mental imagery components of the tasks.
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An Area Specialized for Spatial Working Memory in Human Frontal Cortex
Science (New York N.Y.), 1998Co-Authors: Susan M. Courtney, Laurent Petit, José M. Maisog, Leslie G. Ungerleider, James V. HaxbyAbstract:Working memory is the process of maintaining an active representation of information so that it is available for use. In monkeys, a preFrontal cortical region important for spatial working memory lies in and around the principal Sulcus, but in humans the location, and even the existence, of a region for spatial working memory is in dispute. By using functional magnetic resonance imaging in humans, an area in the Superior Frontal Sulcus was identified that is specialized for spatial working memory. This area is located more Superiorly and posteriorly in the human than in the monkey brain, which may explain why it was not recognized previously.
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Dissociation of Saccade-Related and Pursuit-Related Activation in Human Frontal Eye Fields as Revealed by fMRI
Journal of neurophysiology, 1997Co-Authors: Laurent Petit, Vincent P. Clark, John E. Ingeholm, J. V. HaxbyAbstract:The location of the human Frontal eye fields (FEFs) underlying horizontal visually guided saccadic and pursuit eye movements was investigated with the use of functional magnetic resonance imaging in five healthy humans. Execution of both saccadic and pursuit eye movements induced bilateral FEF activation located medially at the junction of the precentral Sulcus and the Superior Frontal Sulcus and extending laterally to the precentral gyrus. These findings extend previous functional imaging studies by providing the first functional imaging evidence of a specific activation in the FEF during smooth pursuit eye movements in healthy humans. FEF activation during smooth pursuit performance was smaller than during saccades. This finding, which may reflect the presence of a smaller pursuit-related region area in human FEF than the saccade-related region, is consistent with their relative size observed in the monkey. The mean location of the pursuit-related FEF was more inferior and lateral than the location of the saccade-related FEF. These results provide the first evidence that there are different subregions in the human FEF that are involved in the execution of two different types of eye movements, namely saccadic and pursuit eye movements. Moreover, this study provides additional evidence that the human FEF is located in Brodmann's area 6, unlike the monkey FEF which is located in the posterior part of Brodmann's area 8.
Guy Orban - One of the best experts on this subject based on the ideXlab platform.
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Orientation discrimination of objects and gratings compared: an fMRI study
The European journal of neuroscience, 2001Co-Authors: Isabelle Faillenot, Stefan Sunaert, Paul Van Hecke, Guy OrbanAbstract:We used functional magnetic resonance imaging to compare the human brain regions involved in orientation discrimination of two-dimensional (2D) objects and gratings. The orientation discrimination tasks, identification and successive discrimination, were contrasted to a dimming detection control condition with identical retinal input. Regions involved in orientation discrimination were very similar for the two types of tasks and for the two types of stimuli and both belonged to the dorsal and ventral visual pathways. They included posterior occipital, lingual, posterior fusiform, inferior temporal, dorsal intraparietal and medial parietal regions. The main difference between the two types of stimuli was a larger activation of precuneus when 2D objects were used compared to gratings. The main difference between discrimination tasks was an enhanced activity, at the group level, in Superior Frontal Sulcus in identification compared to successive discrimination, and at least at the single subject level, a larger activity in right fusiform cortex in successive discriminations compared to identification. Thus, in contradiction to generally accepted views, orientation discrimination of gratings and objects involve largely similar networks including both ventral and dorsal visual regions.
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The Neural Substrate of Orientation Working Memory
Journal of cognitive neuroscience, 2001Co-Authors: Luc Cornette, Patrick Dupont, Eric Salmon, Guy OrbanAbstract:We have used positron emission tomography (PET) to identify the neural substrate of two major cognitive components of working memory (WM), maintenance and manipulation of a single elementary visual attribute, i.e., the orientation of a grating presented in central vision. This approach allowed us to equate difficulty across tasks and prevented subjects from using verbal strategies or vestibular cues. Maintenance of orientations involved a distributed fronto-parietal network, that is, left and right lateral Superior Frontal Sulcus (SFSl), bilateral ventrolateral preFrontal cortex (VLPFC), bilateral precuneus, and right Superior parietal lobe (SPL). A more medial Superior Frontal Sulcus region (SFSm) was identified as being instrumental in the manipulative operation of updating orientations retained in the WM. Functional connectivity analysis revealed that orientation WM relies on a coordinated interaction between Frontal and parietal regions. In general, the current findings confirm the distinction between maintenance and manipulative processes, highlight the functional heterogeneity in the preFrontal cortex (PFC), and suggest a more dynamic view of WM as a process requiring the coordinated interaction of anatomically distinct brain areas.
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Separate Neural Correlates for the Mnemonic Components of Successive Discrimination and Working Memory Tasks
Cerebral cortex (New York N.Y. : 1991), 2001Co-Authors: Luc Cornette, Patrick Dupont, Guy Bormans, Luc Mortelmans, Guy OrbanAbstract:We have used positron emission tomography to map the mnemonic components of two tasks at the extremes of the visual short-term/ working memory spectrum. The successive discrimination task requires only storage of a single item for very short time (ultra-short- term memory), while the 2back task requires both maintenance (i.e. storage and rehearsal) and manipulation of several items (working memory). We tested whether or not the storage component, common to the two tasks, engaged the same cerebral regions. To remove unnecessary confounds, we reduced the cues available to the subjects to a single elementary attribute, the orientation of a grating presented in central vision. This prevented subjects from using verbal strategies or vestibular cues and allowed equating of difficulty among tasks. Ultra-short-term memory for orientation engaged a large expanse of occipito-temporal cortex with a rate-dependent antero-posterior gradient: a fast trial rate engaged posterior regions, a slow trial rate anterior regions. On the other hand, working memory for orientation involved the left inferior parietal cortex, left dorsolateral preFrontal cortex and a left Superior Frontal Sulcus region, and to a lesser degree the symmetrical right Superior Frontal region and a left Superior parietal region. Direct comparison of the two orientation memory networks confirmed their functional segregation. We conclude that at least the storage of orientation information engages distinct regions depending on whether or not short-term memory/working memory involves rehearsal and/or manipulative processes.
Emmanuel Mellet - One of the best experts on this subject based on the ideXlab platform.
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Neural Correlates of Topographic Mental Exploration: The Impact of Route versus Survey Perspective Learning
NeuroImage, 2000Co-Authors: Emmanuel Mellet, Laurent Petit, S. Bricogne, Nathalie Tzourio-mazoyer, O. Ghaëm, Laure Zago, Olivier Etard, A. Berthoz, Bernard Mazoyer, M. DenisAbstract:There are two major sources of information to build a topographic representation of an environment, namely actual navigation within the environment (route perspective) and map learning (survey perspective). The aim of the present work was to use positron emission tomography (PET) to compare the neural substrate of the topographic representation built from these two modes. One group of subjects performed a mental exploration task in an environment learned from actual navigation (mental navigation task). Another group of subjects performed exploration in the same environment learned from a map (mental map task). A right hippocampal activation common to both mental navigation and mental map tasks was evidenced and may correspond the neural substrate of a "dual-perspective" representation. The parahippocampal gyrus was additionally activated bilaterally during mental navigation only. These results suggest that the right hippocampus involvement would be sufficient when the representation incorporates essentially survey information while the bilateral parahippocampal gyrus would be involved when the environment incorporates route information and includes "object" landmarks. The activation of a parietoFrontal network composed of the intraparietal Sulcus, the Superior Frontal Sulcus, the middle Frontal gyrus, and the pre-SMA was observed in common for both mental navigation and mental map and is likely to reflect the spatial mental imagery components of the tasks.
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RAPID COMMUNICATION Neural Correlates of Topographic Mental Exploration: The Impact of Route versus Survey Perspective Learning
2000Co-Authors: Emmanuel Mellet, S. Bricogne, Nathalie Tzourio-mazoyer, Laure Zago, Olivier Etard, A. Berthoz, Bernard Mazoyer, L. Petit, M. DenisAbstract:There are two major sources of information to builda topographic representation of an environment,namely actual navigation within the environment(route perspective) and map learning (survey perspec-tive). The aim of the present work was to use positronemission tomography (PET) to compare the neuralsubstrate of the topographic representation built fromthese two modes. One group of subjects performed amental exploration task in an environment learnedfrom actual navigation (mental navigation task). An-other group of subjects performed exploration in thesame environment learned from a map (mental maptask). A right hippocampal activation common to bothmental navigation and mental map tasks was evi-denced and may correspond the neural substrateof a “dual-perspective” representation. The parahip-pocampal gyrus was additionally activated bilaterallyduring mental navigation only. These results suggestthat the right hippocampus involvement would be suf-ficient when the representation incorporates essen-tially survey information while the bilateral parahip-pocampal gyrus would be involved when theenvironment incorporates route information and in-cludes “object” landmarks. The activation of a pariet-oFrontal network composed of the intraparietal sul-cus, the Superior Frontal Sulcus, the middle Frontalgyrus, and the pre-SMA was observed in common forboth mental navigation and mental map and is likelyto reflect the spatial mental imagery components ofthe tasks.