The Experts below are selected from a list of 382347 Experts worldwide ranked by ideXlab platform
Ivan Bieche - One of the best experts on this subject based on the ideXlab platform.
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characterization of a germ line deletion including the entire ink4 arf locus in a melanoma Neural System tumor family identification of anril an antisense noncoding rna whose expression coclusters with arf
Cancer Research, 2007Co-Authors: Eric Pasmant, Ingrid Laurendeau, Delphine Heron, Michel Vidaud, Dominique Vidaud, Ivan BiecheAbstract:We have previously detected a large germ-line deletion, which included the entire p15/CDKN2B-p16/CDKN2A-p14/ARF gene cluster, in the largest melanoma-Neural System tumor (NST) syndrome family known to date by means of heterozygosity mapping based on microsatellite markers. Here, we used gene dose mapping with sequence-tagged site real-time PCR to locate the deletion end points, which were then precisely characterized by means of long-range PCR and nucleotide sequencing. The deletion was exactly 403,231 bp long and included the entire p15/CDKN2B, p16/CDKN2A , and p14/ARF genes. We then developed a simple and rapid assay to detect the junction fragment and to serve as a direct predictive DNA test for this large French family. We identified a new large antisense noncoding RNA (named ANRIL ) within the 403-kb germ-line deletion, with a first exon located in the promoter of the p14/ARF gene and overlapping the two exons of p15/CDKN2B . Expression of ANRIL mainly coclustered with p14/ARF both in physiologic (various normal human tissues) and in pathologic conditions (human breast tumors). This study points to the existence of a new gene within the p15/CDKN2B-p16/CDKN2A-p14/ARF locus putatively involved in melanoma-NST syndrome families and in melanoma-prone families with no identified p16/CDKN2A mutations as well as in somatic tumors. [Cancer Res 2007;67(8):3963–9]
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characterization of a germ line deletion including the entire ink4 arf locus in a melanoma Neural System tumor family identification of anril an antisense noncoding rna whose expression coclusters with arf
Cancer Research, 2007Co-Authors: Eric Pasmant, Ingrid Laurendeau, Delphine Heron, Michel Vidaud, Dominique Vidaud, Ivan BiecheAbstract:We have previously detected a large germ-line deletion, which included the entire p15/CDKN2B-p16/CDKN2A-p14/ARF gene cluster, in the largest melanoma-Neural System tumor (NST) syndrome family known to date by means of heterozygosity mapping based on microsatellite markers. Here, we used gene dose mapping with sequence-tagged site real-time PCR to locate the deletion end points, which were then precisely characterized by means of long-range PCR and nucleotide sequencing. The deletion was exactly 403,231 bp long and included the entire p15/CDKN2B, p16/CDKN2A, and p14/ARF genes. We then developed a simple and rapid assay to detect the junction fragment and to serve as a direct predictive DNA test for this large French family. We identified a new large antisense noncoding RNA (named ANRIL) within the 403-kb germ-line deletion, with a first exon located in the promoter of the p14/ARF gene and overlapping the two exons of p15/CDKN2B. Expression of ANRIL mainly coclustered with p14/ARF both in physiologic (various normal human tissues) and in pathologic conditions (human breast tumors). This study points to the existence of a new gene within the p15/CDKN2B-p16/CDKN2A-p14/ARF locus putatively involved in melanoma-NST syndrome families and in melanoma-prone families with no identified p16/CDKN2A mutations as well as in somatic tumors.
Susan M Courtney - One of the best experts on this subject based on the ideXlab platform.
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Neural System for updating object working memory from different sources sensory stimuli or long term memory
NeuroImage, 2007Co-Authors: Jennifer K Roth, Susan M CourtneyAbstract:Working memory (WM) is the active maintenance of currently relevant information so that it is available for use. A crucial component of WM is the ability to update the contents when new information becomes more relevant than previously maintained information. New information can come from different sources, including from sensory stimuli (SS) or from long-term memory (LTM). Updating WM may involve a single Neural System regardless of source, distinct Systems for each source, or a common network with additional regions involved specifically in sensory or LTM processes. The current series of experiments indicates that a single fronto-parietal network (including supplementary motor area, parietal, left inferior frontal junction, middle frontal gyrus) is active in updating WM regardless of the source of information. Bilateral cuneus was more active during updating WM from LTM than updating from SS, but the activity in this region was attributable to recalling information from LTM regardless of whether that information was to be entered into WM for future use or not. No regions were found to be more active during updating from SS than updating from LTM. Functional connectivity analysis revealed that different regions within this common update network were differentially more correlated with visual processing regions when participants updated from SS, and more correlated with LTM processing regions when participants updated from the contents of LTM. These results suggest that a single Neural mechanism is responsible for controlling the contents of WM regardless of whether that information originates from a sensory stimulus or from LTM. This network of regions involved in updating WM interacts with the rest of the brain differently depending on the source of newly relevant information.
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functional topography of a distributed Neural System for spatial and nonspatial information maintenance in working memory
Neuropsychologia, 2003Co-Authors: Joseph B Sala, Susan M Courtney, Pia RamaAbstract:We investigated the degree to which the distributed and overlapping patterns of activity for working memory (WM) maintenance of objects and spatial locations are functionally dissociable. Previous studies of the Neural System responsible for maintenance of different types of information in WM have reported seemingly contradictory results concerning the degree to which spatial and nonspatial information maintenance leads to distinct patterns of activation in prefrontal cortex. These inconsistent results may be partly attributable to the fact that different types of objects were used for the "object WM task" across studies. In the current study, we directly compared the patterns of response during WM tasks for face identity, house identity, and spatial location using functional magnetic resonance imaging (fMRI). Furthermore, independence of the Neural resources available for spatial and object WM was tested behaviorally using a dual-task paradigm. Together, these results suggest that the mechanisms for the maintenance of house identity information are distributed and overlapping with those that maintain spatial location information, while the mechanisms for maintenance of face identity information are relatively more independent. There is, however, a consistent functional topography that results in superior prefrontal cortex producing the greatest response during spatial WM tasks, and middle and inferior prefrontal cortices producing their greatest responses during object WM tasks, independent of the object type. These results argue for a dorsal-ventral functional organization for spatial and nonspatial information. However, objects may contain both spatial and nonspatial information and, thus, have a distributed but not equipotent representation across both dorsal and ventral prefrontal cortex.
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a Neural System for human visual working memory
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Leslie G Ungerleider, Susan M Courtney, James V HaxbyAbstract:Working memory is the process of actively maintaining a representation of information for a brief period of time so that it is available for use. In monkeys, visual working memory involves the concerted activity of a distributed Neural System, including posterior areas in visual cortex and anterior areas in prefrontal cortex. Within visual cortex, ventral stream areas are selectively involved in object vision, whereas dorsal stream areas are selectively involved in spatial vision. This domain specificity appears to extend forward into prefrontal cortex, with ventrolateral areas involved mainly in working memory for objects and dorsolateral areas involved mainly in working memory for spatial locations. The organization of this distributed Neural System for working memory in monkeys appears to be conserved in humans, though some differences between the two species exist. In humans, as compared with monkeys, areas specialized for object vision in the ventral stream have a more inferior location in temporal cortex, whereas areas specialized for spatial vision in the dorsal stream have a more superior location in parietal cortex. Displacement of both sets of visual areas away from the posterior perisylvian cortex may be related to the emergence of language over the course of brain evolution. Whereas areas specialized for object working memory in humans and monkeys are similarly located in ventrolateral prefrontal cortex, those specialized for spatial working memory occupy a more superior and posterior location within dorsal prefrontal cortex in humans than in monkeys. As in posterior cortex, this displacement in frontal cortex also may be related to the emergence of new areas to serve distinctively human cognitive abilities.
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transient and sustained activity in a distributed Neural System for human working memory
Nature, 1997Co-Authors: Susan M Courtney, Leslie G Ungerleider, Katrina Keil, James V HaxbyAbstract:Working memory involves the short-term maintenance of an active representation of information so that it is available for further processing. Visual working memory tasks, in which subjects retain the memory of a stimulus over brief delays, require both the perceptual encoding of the stimulus and the subsequent maintenance of its representation after the stimulus is removed from view. Such tasks activate multiple areas in visual and prefrontal cortices1–9. To delineate the roles these areas play in perception and working memory maintenance, we used functional magnetic resonance imaging (fMRI) to obtain dynamic measures of Neural activity related to different components of a face working memory task—non-selective transient responses to visual stimuli, selective transient responses to faces, and sustained responses over memory delays. Three occipitotemporal areas in the ventral object vision pathway had mostly transient responses to stimuli, indicating their predominant role in perceptual processing, whereas three prefrontal areas demonstrated sustained activity over memory delays, indicating their predominant role in working memory. This distinction, however, was not absolute. Additionally, the visual areas demonstrated different degrees of selectivity, and the prefrontal areas demonstrated different strengths of sustained activity, revealing a continuum of functional specialization, from occipital through multiple prefrontal areas, regarding each area's relative contribution to perceptual and mnemonic processing.
Eric Pasmant - One of the best experts on this subject based on the ideXlab platform.
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characterization of a germ line deletion including the entire ink4 arf locus in a melanoma Neural System tumor family identification of anril an antisense noncoding rna whose expression coclusters with arf
Cancer Research, 2007Co-Authors: Eric Pasmant, Ingrid Laurendeau, Delphine Heron, Michel Vidaud, Dominique Vidaud, Ivan BiecheAbstract:We have previously detected a large germ-line deletion, which included the entire p15/CDKN2B-p16/CDKN2A-p14/ARF gene cluster, in the largest melanoma-Neural System tumor (NST) syndrome family known to date by means of heterozygosity mapping based on microsatellite markers. Here, we used gene dose mapping with sequence-tagged site real-time PCR to locate the deletion end points, which were then precisely characterized by means of long-range PCR and nucleotide sequencing. The deletion was exactly 403,231 bp long and included the entire p15/CDKN2B, p16/CDKN2A , and p14/ARF genes. We then developed a simple and rapid assay to detect the junction fragment and to serve as a direct predictive DNA test for this large French family. We identified a new large antisense noncoding RNA (named ANRIL ) within the 403-kb germ-line deletion, with a first exon located in the promoter of the p14/ARF gene and overlapping the two exons of p15/CDKN2B . Expression of ANRIL mainly coclustered with p14/ARF both in physiologic (various normal human tissues) and in pathologic conditions (human breast tumors). This study points to the existence of a new gene within the p15/CDKN2B-p16/CDKN2A-p14/ARF locus putatively involved in melanoma-NST syndrome families and in melanoma-prone families with no identified p16/CDKN2A mutations as well as in somatic tumors. [Cancer Res 2007;67(8):3963–9]
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characterization of a germ line deletion including the entire ink4 arf locus in a melanoma Neural System tumor family identification of anril an antisense noncoding rna whose expression coclusters with arf
Cancer Research, 2007Co-Authors: Eric Pasmant, Ingrid Laurendeau, Delphine Heron, Michel Vidaud, Dominique Vidaud, Ivan BiecheAbstract:We have previously detected a large germ-line deletion, which included the entire p15/CDKN2B-p16/CDKN2A-p14/ARF gene cluster, in the largest melanoma-Neural System tumor (NST) syndrome family known to date by means of heterozygosity mapping based on microsatellite markers. Here, we used gene dose mapping with sequence-tagged site real-time PCR to locate the deletion end points, which were then precisely characterized by means of long-range PCR and nucleotide sequencing. The deletion was exactly 403,231 bp long and included the entire p15/CDKN2B, p16/CDKN2A, and p14/ARF genes. We then developed a simple and rapid assay to detect the junction fragment and to serve as a direct predictive DNA test for this large French family. We identified a new large antisense noncoding RNA (named ANRIL) within the 403-kb germ-line deletion, with a first exon located in the promoter of the p14/ARF gene and overlapping the two exons of p15/CDKN2B. Expression of ANRIL mainly coclustered with p14/ARF both in physiologic (various normal human tissues) and in pathologic conditions (human breast tumors). This study points to the existence of a new gene within the p15/CDKN2B-p16/CDKN2A-p14/ARF locus putatively involved in melanoma-NST syndrome families and in melanoma-prone families with no identified p16/CDKN2A mutations as well as in somatic tumors.
James V Haxby - One of the best experts on this subject based on the ideXlab platform.
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The distributed human Neural System for face perception
Trends in Cognitive Sciences, 2000Co-Authors: James V Haxby, Maria Ida Gobbini, Elizabeth A. HoffmanAbstract:Face perception, perhaps the most highly developed visual skill in humans, is mediated by a distributed Neural System in humans that is comprised of multiple, bilateral regions. We propose a model for the organization of this System that emphasizes a distinction between the representation of invariant and changeable aspects of faces. The representation of invariant aspects of faces underlies the recognition of individuals, whereas the representation of changeable aspects of faces, such as eye gaze, expression, and lip movement, underlies the perception of information that facilitates social communication. The model is also hierarchical insofar as it is divided into a core System and an extended System. The core System is comprised of occipitotemporal regions in extrastriate visual cortex that mediate the visual analysis of faces. In the core System, the representation of invariant aspects is mediated more by the face-responsive region in the fusiform gyrus, whereas the representation of changeable aspects is mediated more by the face-responsive region in the superior temporal sulcus. The extended System is comprised of regions from Neural Systems for other cognitive functions that can be recruited to act in concert with the regions in the core System to extract meaning from faces.
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a Neural System for human visual working memory
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Leslie G Ungerleider, Susan M Courtney, James V HaxbyAbstract:Working memory is the process of actively maintaining a representation of information for a brief period of time so that it is available for use. In monkeys, visual working memory involves the concerted activity of a distributed Neural System, including posterior areas in visual cortex and anterior areas in prefrontal cortex. Within visual cortex, ventral stream areas are selectively involved in object vision, whereas dorsal stream areas are selectively involved in spatial vision. This domain specificity appears to extend forward into prefrontal cortex, with ventrolateral areas involved mainly in working memory for objects and dorsolateral areas involved mainly in working memory for spatial locations. The organization of this distributed Neural System for working memory in monkeys appears to be conserved in humans, though some differences between the two species exist. In humans, as compared with monkeys, areas specialized for object vision in the ventral stream have a more inferior location in temporal cortex, whereas areas specialized for spatial vision in the dorsal stream have a more superior location in parietal cortex. Displacement of both sets of visual areas away from the posterior perisylvian cortex may be related to the emergence of language over the course of brain evolution. Whereas areas specialized for object working memory in humans and monkeys are similarly located in ventrolateral prefrontal cortex, those specialized for spatial working memory occupy a more superior and posterior location within dorsal prefrontal cortex in humans than in monkeys. As in posterior cortex, this displacement in frontal cortex also may be related to the emergence of new areas to serve distinctively human cognitive abilities.
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transient and sustained activity in a distributed Neural System for human working memory
Nature, 1997Co-Authors: Susan M Courtney, Leslie G Ungerleider, Katrina Keil, James V HaxbyAbstract:Working memory involves the short-term maintenance of an active representation of information so that it is available for further processing. Visual working memory tasks, in which subjects retain the memory of a stimulus over brief delays, require both the perceptual encoding of the stimulus and the subsequent maintenance of its representation after the stimulus is removed from view. Such tasks activate multiple areas in visual and prefrontal cortices1–9. To delineate the roles these areas play in perception and working memory maintenance, we used functional magnetic resonance imaging (fMRI) to obtain dynamic measures of Neural activity related to different components of a face working memory task—non-selective transient responses to visual stimuli, selective transient responses to faces, and sustained responses over memory delays. Three occipitotemporal areas in the ventral object vision pathway had mostly transient responses to stimuli, indicating their predominant role in perceptual processing, whereas three prefrontal areas demonstrated sustained activity over memory delays, indicating their predominant role in working memory. This distinction, however, was not absolute. Additionally, the visual areas demonstrated different degrees of selectivity, and the prefrontal areas demonstrated different strengths of sustained activity, revealing a continuum of functional specialization, from occipital through multiple prefrontal areas, regarding each area's relative contribution to perceptual and mnemonic processing.
Avis H. Cohen - One of the best experts on this subject based on the ideXlab platform.
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adaptive dynamic walking of a quadruped robot on natural ground based on biological concepts
The International Journal of Robotics Research, 2007Co-Authors: Hiroshi Kimura, Yasuhiro Fukuoka, Avis H. CohenAbstract:The paper reports on a project to make a quadruped robot walk with medium forward speed on irregular terrain in an outdoor environment using a Neural System model. The necessary conditions for stable dynamic walking on irregular terrain in general are proposed, and the Neural System is designed by comparing biological concepts with those necessary conditions described in physical terms. A PD-controller is used at joints to construct a virtual spring—damper System as the visco-elasticity model of a muscle. The Neural System model consists of a CPG (central pattern generator), responses and reflexes. A response directly and quickly modulates the CPG phase, and a reflex directly generates joint torque. The state of the virtual spring—damper System is switched, based on the CPG phase. In order to make a self-contained quadruped (called Tekken2) walk on natural ground, several new reflexes and responses are developed in addition to those developed in previous studies. A flexor reflex prevents a leg from stumbling on small bumps and pebbles. A sideways stepping reflex stabilizes rolling motion on a sideways inclined slope. A corrective stepping reflex/response prevents the robot from falling down in the case of loss of ground contact. A crossed flexor reflex helps a swinging leg keep enough clearance between the toe and the ground. The effectiveness of the proposed Neural System model control and especially the newly developed reflexes and responses are validated by indoor and outdoor experiments using Tekken2. A CPG receives sensory feedback as a result of motions induced by reflexes, and changes the period of its own active phase. Since a CPG has the ability of mutual entrainment with pitching motion of legs and rolling motion of the body in addition, the consistency between motion of a leg temporally modified by a reflex and motions of the other legs is maintained autonomously. It is shown that CPGs can be the center of sensorimotor coordination, and that the Neural System model simply defining the relationships between CPGs, sensory input, reflexes and mechanical System works very well even in complicated tasks such as adaptive dynamic walking on unstructured natural ground.
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adaptive dynamic walking of a quadruped robot on irregular terrain based on biological concepts
The International Journal of Robotics Research, 2003Co-Authors: Yasuhiro Fukuoka, Hiroshi Kimura, Avis H. CohenAbstract:We have been trying to induce a quadruped robot to walk with medium walking speed on irregular terrain based on biological concepts. We propose the necessary conditions for stable dynamic walking on irregular terrain in general, and we design the mechanical System and the Neural System by comparing biological concepts with those necessary conditions described in physical terms. A PD controller at the joints can construct the virtual spring-damper System as the visco-elasticity model of a muscle. The Neural System model consists of a central pattern generator (CPG) and reflexes. A CPG receives sensory input and changes the period of its own active phase. The desired angle and P-gain of each joint in the virtual spring-damper System is switched based on the phase signal of the CPG. CPGs, the motion of the virtual spring-damper System of each leg and the rolling motion of the body are mutually entrained through the rolling motion feedback to CPGs, and can generate adaptive walking. We report on our experimen...
