61 results on '"Vossel, Simone"'
Search Results
52. Dynamic Coding of Events within the Inferior Frontal Gyrus in a Probabilistic Selective Attention Task
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Vossel, Simone, primary, Weidner, Ralph, additional, and Fink, Gereon R., additional
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- 2011
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53. Activities of Daily Living Neglect Test Battery
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Eschenbeck, Philipp, primary, Vossel, Simone, additional, Weiss, Peter H., additional, Saliger, Jochen, additional, Karbe, Hans, additional, and Fink, Gereon R., additional
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- 2010
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54. Cognitive subtypes of dyslexia
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Heim*, Stefan, primary, Tschierse, Julia, additional, Amunts, Katrin, additional, Wilms, Marcus, additional, Vossel, Simone, additional, Willmes, Klaus, additional, Grabowska, Anna, additional, and Huber, Walter, additional
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- 2008
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55. Behavioral and Neural Effects of Nicotine on Visuospatial Attentional Reorienting in Non-Smoking Subjects
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Vossel, Simone, primary, Thiel, Christiane M, additional, and Fink, Gereon R, additional
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- 2007
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56. Dorsal and Ventral Attention Systems: Distinct Neural Circuits but Collaborative Roles.
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Vossel, Simone, Geng, Joy J., and Fink, Gereon R.
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NEURAL circuitry , *ELECTROPHYSIOLOGY , *NERVOUS system , *BRAIN , *CENTRAL nervous system - Abstract
The idea of two separate attention networks in the human brain for the voluntary deployment of attention and the reorientation to unexpected events, respectively, has inspired an enormous amount of research over the past years. In this review, we will reconcile these theoretical ideas on the dorsal and ventral attentional system with recent empirical findings from human neuroimaging experiments and studies in stroke patients. We will highlight how novel methods—such as the analysis of effective connectivity or the combination of neurostimulation with functional magnetic resonance imaging—have contributed to our understanding of the functionality and interaction of the two systems. We conclude that neither of the two networks controls attentional processes in isolation and that the flexible interaction between both systems enables the dynamic control of attention in relation to top-down goals and bottom-up sensory stimulation. We discuss which brain regions potentially govern this interaction according to current task demands. [ABSTRACT FROM PUBLISHER]
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- 2014
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57. Neural Mechanisms of Attentional Reorienting in Three-Dimensional Space.
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Qi Chen, Weidner, Ralph, Vossel, Simone, Weiss, Peter H., and Fink, Gereon R.
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ATTENTION ,VISUAL perception ,RETINA ,NEUROLOGY ,MAGNETIC resonance imaging of the brain ,BIOLOGICAL neural networks - Abstract
How the human brain reconstructs the three-dimensional (3D) world from two-dimensional (2D) retinal images has received a great deal of interest as has how we shift attention in 2D space. In contrast, it remains poorly understood how visuospatial attention is shifted in depth. In this fMRI study, by constructing a virtual 3D environment in the MR scanner and by presenting targets either close to or far from the participants in an adapted version of the Posner spatial-cueing paradigm, we investigated the behavioral and neural mechanisms underlying visuospatial orienting/reorienting in depth. At the behavioral level, although covering the same spatial distance, attentional reorienting to objects unexpectedly appearing closer to the observer and in the unattended hemispace was faster than reorienting to unexpected objects farther away. At the neural level, we found that in addition to the classical attentional reorienting system in the right temporoparietal junction, two additional brain networks were differentially involved in aspects of attentional reorienting in depth. First, bilateral premotor cortex reoriented visuospatial attention specifically along the third dimension of visual space (i.e., from close to far or vice versa), compared with attentional reorienting within the same depth plane. Second, a network of areas reminiscent of the human "default-mode network," including posterior cingulate cortex, orbital prefrontal cortex, and left angular gyrus, was involved in the neural interaction between depth and attentional orienting, by boosting attentional reorienting to unexpected objects appearing both closer to the observer and in the unattended hemispace. [ABSTRACT FROM AUTHOR]
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- 2012
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58. Deconstructing the Architecture of Dorsal and Ventral Attention Systems with Dynamic Causal Modeling.
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Vossel, Simone, Weidner, Ralph, Driver, Jon, Friston, Karl J., and Fink, Gereon R.
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CAUSAL models , *CEREBRAL sulci , *VISUAL cortex , *BRAIN chemistry , *BAYESIAN analysis , *DENTATE gyrus , *STATISTICAL decision making - Abstract
Attentional orientation to a spatial cue and reorientation--after invalid cueing--are mediated by two distinct networks in the human brain. A bilateral dorsal frontoparietal network, comprising the intraparietal sulcus (IPS) and the frontal eye fields (FEF), controls the voluntary deployment of attention and may modulate visual cortex in preparation for upcoming stimulation. In contrast, reorienting attention to invalidly cued targets engages a right-lateralized ventral frontoparietal network comprising the temporoparietal junction (TPJ) and ventral frontal cortex. The present fMRI study investigated the functional architecture of these two attentional systems by characterizing effective connectivity during lateralized orienting and reorienting of attention, respectively. Subjects performed a modified version of Posner's location-cueing paradigm. Dynamic causal modeling (DCM) of regional responses in the dorsal and ventral network, identified in a conventional (SPM) whole-brain analysis, was used to compare different functional architectures. Bayesian model selection showed that top-down connections from left and right IPS to left and right visual cortex, respectively, were modulated by the direction of attention. Moreover, model evidence was highest for a model with directed influences from bilateral IPS to FEF, and reciprocal coupling between right and left FEF. Invalid cueing enhanced forward connections from visual areas to right TPJ, and directed influences from right TPJ to right IPS and IFG (inferior frontal gyrus). These findings shed further light on the functional organization of the dorsal and ventral attentional network and support a context-sensitive lateralization in the top-down (backward) mediation of attentional orienting and the bottom-up (forward) effects of invalid cueing. [ABSTRACT FROM AUTHOR]
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- 2012
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59. Behavioral and Neural Effects of Nicotine on Visuospatial Attentional Reorienting in Non-Smoking Subjects.
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Vossel, Simone, Thiel, Christiane M., and Fink, Gereon R.
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NICOTINE , *NEUROTRANSMITTERS , *TOBACCO use , *NEUROPSYCHOPHARMACOLOGY , *COGNITION , *PLACEBOS - Abstract
The cholinergic neurotransmitter system has been proposed to be involved in the processing of probabilistic top-down information provided by endogenous cues in location-cueing paradigms. It has been shown that the behavioral and neural effects of a nicotinic cholinergic stimulation resemble the effects obtained by manipulating the validity of the spatial cues: enhancing cortical nicotine levels and decreasing cue validity both reduce the reaction time difference between invalidly and validly cued targets (ie, the ‘validity effect’) as well as neural activity related to attentional reorienting in parietal brain regions. In the present study, we investigated whether the behavioral and neural effects of nicotine in location-cueing paradigms are dependent upon different a priori cue validities. Twenty-four subjects were investigated in a double-blind placebo-controlled between-subject design with functional magnetic resonance imaging. Nicotine was administered to non-smoking volunteers via polacrilex gums (Nicorette®, 2 mg) before performing a location-cueing paradigm with valid and invalid cues in the context of 90 and 60% cue validity in the MR scanner. Nicotine significantly reduced the validity effect in the 90% but not in the 60% cue validity condition. Fronto-parietal and cingulate regions showed stronger nicotinic reductions of reorienting-related neural activity in the high than in the low cue validity condition. Our data reveal an interaction effect between the pharmacological and cognitive modulation of attentional reorienting, which is evident at both a behavioral as well as the neuronal level.Neuropsychopharmacology (2008) 33, 731–738; doi:10.1038/sj.npp.1301469; published online 6 June 2007 [ABSTRACT FROM AUTHOR]
- Published
- 2008
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60. Cortical Coupling Reflects Bayesian Belief Updating in the Deployment of Spatial Attention
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Klaas E. Stephan, Simone Vossel, Karl J. Friston, Christian Mathys, University of Zurich, and Vossel, Simone
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Bayesian inference ,attentional networks ,fMRI ,saccades ,spatial cueing ,Adult ,Attention ,Bayes Theorem ,Computer Simulation ,Cues ,Female ,Humans ,Neuronal Plasticity ,Putamen ,Saccades ,Spatial Processing ,Visual Fields ,Young Adult ,Models, Neurological ,Temporoparietal junction ,610 Medicine & health ,Intraparietal sulcus ,050105 experimental psychology ,Developmental psychology ,170 Ethics ,03 medical and health sciences ,0302 clinical medicine ,ddc:590 ,Models ,medicine ,10237 Institute of Biomedical Engineering ,0501 psychology and cognitive sciences ,Attentional networks ,Spatial cueing ,Neural correlates of consciousness ,General Neuroscience ,05 social sciences ,Attentional control ,2800 General Neuroscience ,Cue validity ,Articles ,Frontal eye fields ,Saccadic masking ,Settore M-PSI/02 - Psicobiologia e Psicologia Fisiologica ,medicine.anatomical_structure ,Neurological ,Psychology ,030217 neurology & neurosurgery ,Cognitive psychology - Abstract
The deployment of visuospatial attention and the programming of saccades are governed by the inferred likelihood of events. In the present study, we combined computational modeling of psychophysical data with fMRI to characterize the computational and neural mechanisms underlying this flexible attentional control. Sixteen healthy human subjects performed a modified version of Posner's location-cueing paradigm in which the percentage of cue validity varied in time and the targets required saccadic responses. Trialwise estimates of the certainty (precision) of the prediction that the target would appear at the cued location were derived from a hierarchical Bayesian model fitted to individual trialwise saccadic response speeds. Trial-specific model parameters then entered analyses of fMRI data as parametric regressors. Moreover, dynamic causal modeling (DCM) was performed to identify the most likely functional architecture of the attentional reorienting network and its modulation by (Bayes-optimal) precision-dependent attention. While the frontal eye fields (FEFs), intraparietal sulcus, and temporoparietal junction (TPJ) of both hemispheres showed higher activity on invalid relative to valid trials, reorienting responses in right FEF, TPJ, and the putamen were significantly modulated by precision-dependent attention. Our DCM results suggested that the precision of predictability underlies the attentional modulation of the coupling of TPJ with FEF and the putamen. Our results shed new light on the computational architecture and neuronal network dynamics underlying the context-sensitive deployment of visuospatial attention., The Journal of Neuroscience, 35 (33), ISSN:0270-6474, ISSN:1529-2401
- Published
- 2015
61. Cholinergic stimulation enhances Bayesian belief updating in the deployment of spatial attention.
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Vossel S, Bauer M, Mathys C, Adams RA, Dolan RJ, Stephan KE, and Friston KJ
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- Adult, Bayes Theorem, Cues, Eye Movements drug effects, Female, Galantamine pharmacology, Humans, Learning drug effects, Male, Photic Stimulation, Young Adult, Attention drug effects, Cholinergic Agonists pharmacology, Space Perception drug effects
- Abstract
The exact mechanisms whereby the cholinergic neurotransmitter system contributes to attentional processing remain poorly understood. Here, we applied computational modeling to psychophysical data (obtained from a spatial attention task) under a psychopharmacological challenge with the cholinesterase inhibitor galantamine (Reminyl). This allowed us to characterize the cholinergic modulation of selective attention formally, in terms of hierarchical Bayesian inference. In a placebo-controlled, within-subject, crossover design, 16 healthy human subjects performed a modified version of Posner's location-cueing task in which the proportion of validly and invalidly cued targets (percentage of cue validity, % CV) changed over time. Saccadic response speeds were used to estimate the parameters of a hierarchical Bayesian model to test whether cholinergic stimulation affected the trial-wise updating of probabilistic beliefs that underlie the allocation of attention or whether galantamine changed the mapping from those beliefs to subsequent eye movements. Behaviorally, galantamine led to a greater influence of probabilistic context (% CV) on response speed than placebo. Crucially, computational modeling suggested this effect was due to an increase in the rate of belief updating about cue validity (as opposed to the increased sensitivity of behavioral responses to those beliefs). We discuss these findings with respect to cholinergic effects on hierarchical cortical processing and in relation to the encoding of expected uncertainty or precision., (Copyright © 2014 the authors 0270-6474/14/3415735-08$15.00/0.)
- Published
- 2014
- Full Text
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