The Experts below are selected from a list of 10404 Experts worldwide ranked by ideXlab platform
Liliane Borel - One of the best experts on this subject based on the ideXlab platform.
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Vestibular information is necessary for maintaining metric properties of Representational Space: Evidence from mental imagery
Neuropsychologia, 2011Co-Authors: Patrick Peruch, Christophe Lopez, Christine Redon-zouiteni, Guy Escoffier, Alain Zeitoun, Melanie Sanjuan, Arnaud Devèze, Jacques Magnan, Liliane BorelAbstract:The vestibular system contributes to a wide range of functions, from postural and oculomotor reflexes to spatial representation and cognition. Vestibular signals are important to maintain an internal, updated representation of the body position and movement in Space. However, it is not clear to what extent they are also necessary to mentally simulate movement in situations that do not involve displacements of the body, as in mental imagery. The present study assessed how vestibular loss can affect object-based mental transformations (OMTs), i.e., imagined rotations or translations of objects relative to the environment. Participants performed one task of mental rotation of 3D-objects and two mental scanning tasks dealing with the ability to build and manipulate mental images that have metric properties. Meniere's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (1 week and 1 month). They were compared to healthy participants tested at similar time intervals and to bilateral vestibular-defective patients tested after the recovery period. Vestibular loss impaired all mental imagery tasks. Performance varied according to the extent of vestibular loss (bilateral patients were frequently the most impaired) and according to the time elapsed after unilateral vestibular neurotomy (deficits were stronger at the early stage after neurotomy and then gradually compensated). These findings indicate that vestibular signals are necessary to perform OMTs and provide the first demonstration of the critical role of vestibular signals in processing metric properties of mental representations. They suggest that vestibular loss disorganizes brain structures commonly involved in mental imagery, and more generally in mental representation. (C) 2011 Elsevier Ltd. All rights reserved.
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Vestibular information is necessary for maintaining metric properties of Representational Space: Evidence from mental imagery
Neuropsychologia, 2011Co-Authors: Patrick Peruch, Christophe Lopez, Christine Redon-zouiteni, Guy Escoffier, Alain Zeitoun, Melanie Sanjuan, Arnaud Devèze, Jacques Magnan, Liliane BorelAbstract:The vestibular system contributes to a wide range of functions, from postural and oculomotor reflexes to spatial representation and cognition. Vestibular signals are important to maintain an internal, updated representation of the body position and movement in Space. However, it is not clear to what extent they are also necessary to mentally simulate movement in situations that do not involve displacements of the body, as in mental imagery. The present study assessed how vestibular loss can affect object-based mental transformations (OMTs), i.e., imagined rotations or translations of objects relative to the environment. Participants performed one task of mental rotation of 3D-objects and two mental scanning tasks dealing with the ability to build and manipulate mental images that have metric properties. Meniere's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (1 week and 1 month). They were compared to healthy participants tested at similar time intervals and to bilateral vestibular-defective patients tested after the recovery period. Vestibular loss impaired all mental imagery tasks. Performance varied according to the extent of vestibular loss (bilateral patients were frequently the most impaired) and according to the time elapsed after unilateral vestibular neurotomy (deficits were stronger at the early stage after neurotomy and then gradually compensated). These findings indicate that vestibular signals are necessary to perform OMTs and provide the first demonstration of the critical role of vestibular signals in processing metric properties of mental representations. They suggest that vestibular loss disorganizes brain structures commonly involved in mental imagery, and more generally in mental representation.
Patrick Peruch - One of the best experts on this subject based on the ideXlab platform.
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Vestibular information is necessary for maintaining metric properties of Representational Space: Evidence from mental imagery
Neuropsychologia, 2011Co-Authors: Patrick Peruch, Christophe Lopez, Christine Redon-zouiteni, Guy Escoffier, Alain Zeitoun, Melanie Sanjuan, Arnaud Devèze, Jacques Magnan, Liliane BorelAbstract:The vestibular system contributes to a wide range of functions, from postural and oculomotor reflexes to spatial representation and cognition. Vestibular signals are important to maintain an internal, updated representation of the body position and movement in Space. However, it is not clear to what extent they are also necessary to mentally simulate movement in situations that do not involve displacements of the body, as in mental imagery. The present study assessed how vestibular loss can affect object-based mental transformations (OMTs), i.e., imagined rotations or translations of objects relative to the environment. Participants performed one task of mental rotation of 3D-objects and two mental scanning tasks dealing with the ability to build and manipulate mental images that have metric properties. Meniere's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (1 week and 1 month). They were compared to healthy participants tested at similar time intervals and to bilateral vestibular-defective patients tested after the recovery period. Vestibular loss impaired all mental imagery tasks. Performance varied according to the extent of vestibular loss (bilateral patients were frequently the most impaired) and according to the time elapsed after unilateral vestibular neurotomy (deficits were stronger at the early stage after neurotomy and then gradually compensated). These findings indicate that vestibular signals are necessary to perform OMTs and provide the first demonstration of the critical role of vestibular signals in processing metric properties of mental representations. They suggest that vestibular loss disorganizes brain structures commonly involved in mental imagery, and more generally in mental representation. (C) 2011 Elsevier Ltd. All rights reserved.
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Vestibular information is necessary for maintaining metric properties of Representational Space: Evidence from mental imagery
Neuropsychologia, 2011Co-Authors: Patrick Peruch, Christophe Lopez, Christine Redon-zouiteni, Guy Escoffier, Alain Zeitoun, Melanie Sanjuan, Arnaud Devèze, Jacques Magnan, Liliane BorelAbstract:The vestibular system contributes to a wide range of functions, from postural and oculomotor reflexes to spatial representation and cognition. Vestibular signals are important to maintain an internal, updated representation of the body position and movement in Space. However, it is not clear to what extent they are also necessary to mentally simulate movement in situations that do not involve displacements of the body, as in mental imagery. The present study assessed how vestibular loss can affect object-based mental transformations (OMTs), i.e., imagined rotations or translations of objects relative to the environment. Participants performed one task of mental rotation of 3D-objects and two mental scanning tasks dealing with the ability to build and manipulate mental images that have metric properties. Meniere's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (1 week and 1 month). They were compared to healthy participants tested at similar time intervals and to bilateral vestibular-defective patients tested after the recovery period. Vestibular loss impaired all mental imagery tasks. Performance varied according to the extent of vestibular loss (bilateral patients were frequently the most impaired) and according to the time elapsed after unilateral vestibular neurotomy (deficits were stronger at the early stage after neurotomy and then gradually compensated). These findings indicate that vestibular signals are necessary to perform OMTs and provide the first demonstration of the critical role of vestibular signals in processing metric properties of mental representations. They suggest that vestibular loss disorganizes brain structures commonly involved in mental imagery, and more generally in mental representation.
Carlo Umiltà - One of the best experts on this subject based on the ideXlab platform.
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lost in number Space after right brain damage a neural signature of Representational neglect
Cortex, 2008Co-Authors: Konstantinos Priftis, Francesca Meneghello, Carlo Umiltà, Francesco Piccione, F Giorgi, Marco ZorziAbstract:Abstract The human brain represents numbers along a mental number line, whose spatial nature was confirmed by studies of patients with visuospatial neglect. Here we describe a neural signature of neglect for the left “number Space” by using a task that does not require manipulation of numbers. Patients were asked to discriminate an infrequent (“one” or “nine”) from a frequent spoken number word (“five”). P3b brain waves, elicited by infrequent stimuli and indexing cognitive processing, were delayed to targets on the left of the number line (“one”) compared to targets on the right (“nine”). The delay of P3b is thus a neural signature of the disorder of Representational Space.
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Explicit versus Implicit Processing of Representational Space in Neglect: Dissociations in Accessing the Mental Number Line
Journal of cognitive neuroscience, 2006Co-Authors: Konstantinos Priftis, Francesca Meneghello, Marco Zorzi, Roberto Marenzi, Carlo UmiltàAbstract:The present study investigated the effects of left hemispatial neglect on two tasks activating the mental number line (MNL). Six patients with left neglect performed a mental number bisection task and a modified version of the Spatial Numerical Association of Response Codes (SNARC) task. Effects of left neglect were observed in the number bisection task, but not in the SNARC task. We argue that the dissociation between number bisection and SNARC resembles, in the Representational Space of the MNL, previously reported dissociations on neglect between explicit knowledge (assessed by direct tasks) and implicit knowledge (assessed by indirect tasks).
Peter Brugger - One of the best experts on this subject based on the ideXlab platform.
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Subjective time in near and far Representational Space.
Cognitive and behavioral neurology : official journal of the Society for Behavioral and Cognitive Neurology, 2008Co-Authors: Peter Zäch, Peter BruggerAbstract:OBJECTIVE: We set out to measure healthy subjects' estimates of temporal duration during the imagination of left and right sides of an object located in either near or far Representational Space. BACKGROUND: Duration estimates during the observation of small-scale scenes are shorter than those during the observation of the same scenes presented in a larger scale. It is not known whether a similar Space-time relationship also exists for objects merely imagined and whether subjective time varies with a forced focus on either the left or the right side of a mental image. METHODS: Eyes closed, 40 healthy, right-handed subjects (20 women) had to imagine a standard Swiss railway clock either at a distance of 30 cm or 6 m. They were required to focus on the imagined movement of the second hand and provide estimates of elapsed durations of 15 and 30 seconds. Separate estimates for the left and right side of the clockface were obtained. The magnitude of implicit line bisection error was assessed in a separate task. RESULTS: Irrespective of side of the clockface, duration estimates were shorter for the clockface imagined in far Space than for the one imagined immediately in front of the inner eye. For men, but not women, duration judgments (left relative to right side of the clockface) correlated with relative lengths of left and right line segments in the bisection task. CONCLUSIONS: Subjective time seems to run faster during the inspection of a small-size compared with a larger-size mental image. This finding underlines the equivalence of the laws that guide both exploration and representation of Space. Together with the observed correlation between spatial and temporal measures of lateral asymmetries, the result also illustrates the conceptual similarities in the processing of Space and time. The normative data presented here may be useful for clinical applications of the paradigm in patients with hemispatial neglect or a distorted perception of time.
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PSEUDONEGLECT IN Representational Space: EFFECTS OF MAGICAL IDEATION
2007Co-Authors: Peter Brugger, Werner Surbeck, Tobias LoetscherAbstract:SUMMARY Background. Magical thinking, a sign of schizotypy, is accompanied by a decrease in the strength of left hemisphere language dominance and by an inattention towards the right side of Space ("pseudoneglect"). We set out to explore whether it is also associated with a pseudoneglect in imagined Space. Material and methods. Forty healthy right-handed adults were asked to imagine the contours of the European continent, viewed from a point in outer Space directly over Switzerland. After having contemplated this mental map for one minute, they were asked to name as many European countries as they could. All subjects filled in the Magical Ideation (MI) scale, and we split the population at the median scale score into low and high MI groups. Results. The twenty subjects of the high MI group named less countries than those of the low MI group overall, but the difference was only significant for eastern ("right-sided") countries. Conclusions. This study presents preliminary support for an association between magical thinking and right-sided inattention in the evocation of a mental map. We suggest that future studies should make use of tasks that allow a better quantification of left and right in imagined Space. The neuropsychiatric significance of lateralized abnormalities in the mental representation of Space is emphasized.
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A disengagement deficit in Representational Space.
Neuropsychologia, 2006Co-Authors: Tobias Loetscher, Peter BruggerAbstract:Some patients with hemispatial neglect show a deficit of "disengagement", i.e., their left-sided inattention is largely a consequence of an inability to move the spotlight of attention away from right-sided stimuli. We report a neglect patient with a failure of disengagement in imagined Space, a feature not previously described. The patient was repeatedly moved along a hallway and had to memorize 20 objects placed alongside the walls (alternating starting points). Each learning run was followed by a recall run, in which objects had to be named in their correct sequence from one imaginary starting point. Initially, when performance was still poor, only right-sided items were named, a response pattern mimicking a neglect of Representational Space. However, as recall improved over successive runs, left-sided objects were as well memorized as right-sided, but the latter were named before the former. By contrast, if photographs of single objects were presented in the center of a screen for laterality decisions, neither accuracy nor latency of the patient's decisions differentiated between left-sided and right-sided items. We interpret the sticking to the right side during initial periods of free recall, in the absence of side-differences during cued recognition, as a failure to disengage from the right side of a mental image. In view of the extensive cortical and subcortical lesions in our patient the current debate about the functional neuroanatomy of this deficit cannot be resolved. However, the present report adds to our understanding of the heterogeneous nature of deficiencies in the representation of Space.
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A disengagement deficit in Representational Space.
Neuropsychologia, 2006Co-Authors: Tobias Loetscher, Peter BruggerAbstract:Abstract Some patients with hemispatial neglect show a deficit of “disengagement”, i.e., their left-sided inattention is largely a consequence of an inability to move the spotlight of attention away from right-sided stimuli. We report a neglect patient with a failure of disengagement in imagined Space, a feature not previously described. The patient was repeatedly moved along a hallway and had to memorize 20 objects placed alongside the walls (alternating starting points). Each learning run was followed by a recall run, in which objects had to be named in their correct sequence from one imaginary starting point. Initially, when performance was still poor, only right-sided items were named, a response pattern mimicking a neglect of Representational Space. However, as recall improved over successive runs, left-sided objects were as well memorized as right-sided, but the latter were named before the former. By contrast, if photographs of single objects were presented in the center of a screen for laterality decisions, neither accuracy nor latency of the patient's decisions differentiated between left-sided and right-sided items. We interpret the sticking to the right side during initial periods of free recall, in the absence of side-differences during cued recognition, as a failure to disengage from the right side of a mental image. In view of the extensive cortical and subcortical lesions in our patient the current debate about the functional neuroanatomy of this deficit cannot be resolved. However, the present report adds to our understanding of the heterogeneous nature of deficiencies in the representation of Space.
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Stimulus-response compatibility in Representational Space.
Neuropsychologia, 1998Co-Authors: Daniel Bächtold, Martin Baumüller, Peter BruggerAbstract:Abstract Spatial stimulus—response (S-R) compatibility designates the observation that speeded reactions to unilateral stimuli are faster for the hand ipsilateral than for the hand contralateral to the sensory hemifield containing the stimulus. In two experiments involving presentation of the numbers 1 to 11 in the center of the visual field we show (1) a left-hand reaction time (RT) advantage for numerals 6 for subjects who conceive of the numbers as distances on a ruler, and (2) a reversal of this RT advantage for subjects who conceive of them as hours on a clock face. While the results in the first task (RULER) replicate a robust finding from the neuropsychology of number processing (the ‘‘SNARC effect’’) those in the second task (CLOCK) show that extension of the number scale from left to right in Representational Space cannot be the decisive factor for the observed interaction between hand and number size. Taken together, the findings in the two tasks are best accounted for in terms of an interaction between lateralized mental representations and lateralized motor outputs (i.e. an analog of traditional spatial S-R compatibility effects in Representational Space). We discuss potential clinical applications of the two tasks in patients with neglect of Representational Space.
Yaoda Xu - One of the best experts on this subject based on the ideXlab platform.
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an information driven 2 pathway characterization of occipitotemporal and posterior parietal visual object representations
Cerebral Cortex, 2019Co-Authors: Maryam Vaziripashkam, Yaoda XuAbstract:Recent studies have demonstrated the existence of rich visual representations in both occipitotemporal cortex (OTC) and posterior parietal cortex (PPC). Using fMRI decoding and a bottom-up data-driven approach, we showed that although robust object category representations exist in both OTC and PPC, there is an information-driven 2-pathway separation among these regions in the Representational Space, with occipitotemporal regions arranging hierarchically along 1 pathway and posterior parietal regions along another pathway. We obtained 10 independent replications of this 2-pathway distinction, accounting for 58-81% of the total variance of the region-wise differences in visual representation. The separation of the PPC regions from higher occipitotemporal regions was not driven by a difference in tolerance to changes in low-level visual features, did not rely on the presence of special object categories, and was present whether or not object category was task relevant. Our information-driven 2-pathway structure differs from the well-known ventral-what and dorsal-where/how characterization of posterior brain regions. Here both pathways contain rich nonspatial visual representations. The separation we see likely reflects a difference in neural coding scheme used by PPC to represent visual information compared with that of OTC.
