1
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Tootell RBH, Nasr S. Scotopic Vision Is Selectively Processed in Thick-Type Columns in Human Extrastriate Cortex. Cereb Cortex 2021; 31:1163-1181. [PMID: 33073288 PMCID: PMC7786355 DOI: 10.1093/cercor/bhaa284] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 07/25/2020] [Accepted: 08/17/2020] [Indexed: 11/26/2022] Open
Abstract
In humans, visual stimuli can be perceived across an enormous range of light levels. Evidence suggests that different neural mechanisms process different subdivisions of this range. For instance, in the retina, stimuli presented at very low (scotopic) light levels activate rod photoreceptors, whereas cone photoreceptors are activated relatively more at higher (photopic) light levels. Similarly, different retinal ganglion cells are activated by scotopic versus photopic stimuli. However, in the brain, it remains unknown whether scotopic versus photopic information is: 1) processed in distinct channels, or 2) neurally merged. Using high-resolution functional magnetic resonance imaging at 7 T, we confirmed the first hypothesis. We first localized thick versus thin-type columns within areas V2, V3, and V4, based on photopic selectivity to motion versus color, respectively. Next, we found that scotopic stimuli selectively activated thick- (compared to thin-) type columns in V2 and V3 (in measurements of both overlap and amplitude) and V4 (based on overlap). Finally, we found stronger resting-state functional connections between scotopically dominated area MT with thick- (compared to thin-) type columns in areas V2, V3, and V4. We conclude that scotopic stimuli are processed in partially segregated parallel streams, emphasizing magnocellular influence, from retina through middle stages of visual cortex.
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Affiliation(s)
- Roger B H Tootell
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
| | - Shahin Nasr
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA 02114, USA.,Department of Radiology, Harvard Medical School, Boston, MA 02115, USA
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2
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Krause F, Benjamins C, Eck J, Lührs M, van Hoof R, Goebel R. Active head motion reduction in magnetic resonance imaging using tactile feedback. Hum Brain Mapp 2019; 40:4026-4037. [PMID: 31179609 PMCID: PMC6772179 DOI: 10.1002/hbm.24683] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/16/2019] [Accepted: 05/21/2019] [Indexed: 01/19/2023] Open
Abstract
Head motion is a common problem in clinical as well as empirical (functional) magnetic resonance imaging applications, as it can lead to severe artefacts that reduce image quality. The scanned individuals themselves, however, are often not aware of their head motion. The current study explored whether providing subjects with this information using tactile feedback would reduce their head motion and consequently improve image quality. In a single session that included six runs, 24 participants performed three different cognitive tasks: (a) passive viewing, (b) mental imagery, and (c) speeded responses. These tasks occurred in two different conditions: (a) with a strip of medical tape applied from one side of the magnetic resonance head coil, via the participant's forehead, to the other side, and (b) without the medical tape being applied. Results revealed that application of medical tape to the forehead of subjects to provide tactile feedback significantly reduced both translational as well as rotational head motion. While this effect did not differ between the three cognitive tasks, there was a negative quadratic relationship between head motion with and without feedback. That is, the more head motion a subject produced without feedback, the stronger the motion reduction given the feedback. In conclusion, the here tested method provides a simple and cost-efficient way to reduce subjects' head motion, and might be especially beneficial when extensive head motion is expected a priori.
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Affiliation(s)
- Florian Krause
- Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Development and Research, Brain Innovation B.V., Maastricht, The Netherlands
| | - Caroline Benjamins
- Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Development and Research, Brain Innovation B.V., Maastricht, The Netherlands
| | - Judith Eck
- Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Development and Research, Brain Innovation B.V., Maastricht, The Netherlands
| | - Michael Lührs
- Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Development and Research, Brain Innovation B.V., Maastricht, The Netherlands
| | - Rick van Hoof
- Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Development and Research, Brain Innovation B.V., Maastricht, The Netherlands
| | - Rainer Goebel
- Department of Cognitive Neuroscience, Maastricht University, Maastricht, The Netherlands.,Department of Development and Research, Brain Innovation B.V., Maastricht, The Netherlands.,Department of Neuroimaging and Neuromodeling, Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, The Netherlands
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3
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Schultz J, Bülthoff HH. Perceiving animacy purely from visual motion cues involves intraparietal sulcus. Neuroimage 2019; 197:120-132. [PMID: 31028922 DOI: 10.1016/j.neuroimage.2019.04.058] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 04/23/2019] [Indexed: 11/17/2022] Open
Abstract
Distinguishing animate from inanimate objects is fundamental for social perception in humans and animals. Visual motion cues indicative of self-propelled object motion are useful for animacy perception: they can be detected over a wide expanse of visual field, at distance and in low visibility conditions, can attract attention and provide clues about object behaviour. However, the neural correlates of animacy perception evoked exclusively by visual motion cues, i.e. not relying on form, background or visual context, are unclear. We aimed to address this question in four psychophysical experiments in humans, two of which performed during neuroimaging. The stimulus was a single dot with constant form that moved on a blank background and evoked controlled degrees of perceived animacy through parametric variations of self-propelled motion cues. BOLD signals reflecting perceived animacy in a graded manner irrespective of eye movements were found in one intraparietal region. Additional whole-brain and region-of-interest analyses revealed no comparable effects in brain regions associated with social processing or other areas. Our study shows that animacy perception evoked solely by visual motion cues, a basic perceptual process in social cognition, engages brain regions not primarily associated with social cognition.
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Affiliation(s)
- Johannes Schultz
- Institute of Experimental Epileptology and Cognition Research, University of Bonn, Germany; Department of Human Perception, Cognition and Action, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
| | - Heinrich H Bülthoff
- Department of Human Perception, Cognition and Action, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
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4
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Erlikhman G, Caplovitz GP, Gurariy G, Medina J, Snow JC. Towards a unified perspective of object shape and motion processing in human dorsal cortex. Conscious Cogn 2018; 64:106-120. [PMID: 29779844 DOI: 10.1016/j.concog.2018.04.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/20/2018] [Accepted: 04/26/2018] [Indexed: 01/06/2023]
Abstract
Although object-related areas were discovered in human parietal cortex a decade ago, surprisingly little is known about the nature and purpose of these representations, and how they differ from those in the ventral processing stream. In this article, we review evidence for the unique contribution of object areas of dorsal cortex to three-dimensional (3-D) shape representation, the localization of objects in space, and in guiding reaching and grasping actions. We also highlight the role of dorsal cortex in form-motion interaction and spatiotemporal integration, possible functional relationships between 3-D shape and motion processing, and how these processes operate together in the service of supporting goal-directed actions with objects. Fundamental differences between the nature of object representations in the dorsal versus ventral processing streams are considered, with an emphasis on how and why dorsal cortex supports veridical (rather than invariant) representations of objects to guide goal-directed hand actions in dynamic visual environments.
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Affiliation(s)
| | | | - Gennadiy Gurariy
- Department of Psychology, University of Nevada, Reno, USA; Department of Psychology, University of Wisconsin, Milwaukee, USA
| | - Jared Medina
- Department of Psychological and Brain Sciences, University of Delaware, USA
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5
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Bacha-Trams M, Glerean E, Dunbar R, Lahnakoski JM, Ryyppö E, Sams M, Jääskeläinen IP. Differential inter-subject correlation of brain activity when kinship is a variable in moral dilemma. Sci Rep 2017; 7:14244. [PMID: 29079809 PMCID: PMC5660240 DOI: 10.1038/s41598-017-14323-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 10/09/2017] [Indexed: 11/18/2022] Open
Abstract
Previous behavioural studies have shown that humans act more altruistically towards kin. Whether and how knowledge of genetic relatedness translates into differential neurocognitive evaluation of observed social interactions has remained an open question. Here, we investigated how the human brain is engaged when viewing a moral dilemma between genetic vs. non-genetic sisters. During functional magnetic resonance imaging, a movie was shown, depicting refusal of organ donation between two sisters, with subjects guided to believe the sisters were related either genetically or by adoption. Although 90% of the subjects self-reported that genetic relationship was not relevant, their brain activity told a different story. Comparing correlations of brain activity across all subject pairs between the two viewing conditions, we found significantly stronger inter-subject correlations in insula, cingulate, medial and lateral prefrontal, superior temporal, and superior parietal cortices, when the subjects believed that the sisters were genetically related. Cognitive functions previously associated with these areas include moral and emotional conflict regulation, decision making, and mentalizing, suggesting more similar engagement of such functions when observing refusal of altruism from a genetic sister. Our results show that mere knowledge of a genetic relationship between interacting persons robustly modulates social cognition of the perceiver.
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Affiliation(s)
- Mareike Bacha-Trams
- Brain and Mind Laboratory, Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland.
| | - Enrico Glerean
- Brain and Mind Laboratory, Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland
- Turku Pet Centre, University of Turku, Turku, Finland
| | - Robin Dunbar
- Social and Evolutionary Neuroscience Research Group, University of Oxford, Oxford, United Kingdom
- Department of Computer Science, Aalto University, Espoo, Finland
| | - Juha M Lahnakoski
- Brain and Mind Laboratory, Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland
- Independent Max Planck Research Group for Social Neuroscience, Max Planck Institute of Psychiatry, Munich, Germany
| | - Elisa Ryyppö
- Brain and Mind Laboratory, Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland
| | - Mikko Sams
- Brain and Mind Laboratory, Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland
| | - Iiro P Jääskeläinen
- Brain and Mind Laboratory, Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland.
- Advanced Magnetic Imaging (AMI) Centre, Aalto NeuroImaging, Aalto University, Espoo, Finland.
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6
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Takemura H, Rokem A, Winawer J, Yeatman JD, Wandell BA, Pestilli F. A Major Human White Matter Pathway Between Dorsal and Ventral Visual Cortex. Cereb Cortex 2016; 26:2205-2214. [PMID: 25828567 PMCID: PMC4830295 DOI: 10.1093/cercor/bhv064] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Human visual cortex comprises many visual field maps organized into clusters. A standard organization separates visual maps into 2 distinct clusters within ventral and dorsal cortex. We combined fMRI, diffusion MRI, and fiber tractography to identify a major white matter pathway, the vertical occipital fasciculus (VOF), connecting maps within the dorsal and ventral visual cortex. We use a model-based method to assess the statistical evidence supporting several aspects of the VOF wiring pattern. There is strong evidence supporting the hypothesis that dorsal and ventral visual maps communicate through the VOF. The cortical projection zones of the VOF suggest that human ventral (hV4/VO-1) and dorsal (V3A/B) maps exchange substantial information. The VOF appears to be crucial for transmitting signals between regions that encode object properties including form, identity, and color and regions that map spatial information.
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Affiliation(s)
| | - Ariel Rokem
- Department of Psychology, Stanford University, Stanford, CA, USA
| | - Jonathan Winawer
- Department of Psychology, New York University, New York, NY, USA
| | - Jason D. Yeatman
- Department of Psychology, Stanford University, Stanford, CA, USA
- Institute for Learning and Brain Science (ILABS), University of Washington, Seattle, WA, USA
| | - Brian A. Wandell
- Department of Psychology, Stanford University, Stanford, CA, USA
| | - Franco Pestilli
- Department of Psychology, Stanford University, Stanford, CA, USA
- Department of Psychological and Brain Sciences, Programs in Neuroscience and Cognitive Science, Indiana University, Bloomington, IN, USA
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7
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Erlikhman G, Gurariy G, Mruczek REB, Caplovitz GP. The neural representation of objects formed through the spatiotemporal integration of visual transients. Neuroimage 2016; 142:67-78. [PMID: 27033688 DOI: 10.1016/j.neuroimage.2016.03.044] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 03/15/2016] [Accepted: 03/17/2016] [Indexed: 11/18/2022] Open
Abstract
Oftentimes, objects are only partially and transiently visible as parts of them become occluded during observer or object motion. The visual system can integrate such object fragments across space and time into perceptual wholes or spatiotemporal objects. This integrative and dynamic process may involve both ventral and dorsal visual processing pathways, along which shape and spatial representations are thought to arise. We measured fMRI BOLD response to spatiotemporal objects and used multi-voxel pattern analysis (MVPA) to decode shape information across 20 topographic regions of visual cortex. Object identity could be decoded throughout visual cortex, including intermediate (V3A, V3B, hV4, LO1-2,) and dorsal (TO1-2, and IPS0-1) visual areas. Shape-specific information, therefore, may not be limited to early and ventral visual areas, particularly when it is dynamic and must be integrated. Contrary to the classic view that the representation of objects is the purview of the ventral stream, intermediate and dorsal areas may play a distinct and critical role in the construction of object representations across space and time.
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Affiliation(s)
| | | | - Ryan E B Mruczek
- Department of Psychology, University of Nevada, Reno, USA; Department of Psychology, Worcester State University, USA
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8
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Jiang X, Jiang Y, Parasuraman R. The Visual Priming of Motion-Defined 3D Objects. PLoS One 2015; 10:e0144730. [PMID: 26658496 PMCID: PMC4684376 DOI: 10.1371/journal.pone.0144730] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 11/23/2015] [Indexed: 11/21/2022] Open
Abstract
The perception of a stimulus can be influenced by previous perceptual experience, a phenomenon known as perceptual priming. However, there has been limited investigation on perceptual priming of shape perception of three-dimensional object structures defined by moving dots. Here we examined the perceptual priming of a 3D object shape defined purely by motion-in-depth cues (i.e., Shape-From-Motion, SFM) using a classic prime-target paradigm. The results from the first two experiments revealed a significant increase in accuracy when a “cloudy” SFM stimulus (whose object structure was difficult to recognize due to the presence of strong noise) was preceded by an unambiguous SFM that clearly defined the same transparent 3D shape. In contrast, results from Experiment 3 revealed no change in accuracy when a “cloudy” SFM stimulus was preceded by a static shape or a semantic word that defined the same object shape. Instead, there was a significant decrease in accuracy when preceded by a static shape or a semantic word that defined a different object shape. These results suggested that the perception of a noisy SFM stimulus can be facilitated by a preceding unambiguous SFM stimulus—but not a static image or a semantic stimulus—that defined the same shape. The potential neural and computational mechanisms underlying the difference in priming are discussed.
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Affiliation(s)
- Xiong Jiang
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, 20007, United States of America
- * E-mail:
| | - Yang Jiang
- Department of Behavioral Science, University of Kentucky College of Medicine, Lexington, KY, 40506, United States of America
| | - Raja Parasuraman
- Department of Psychology, George Mason University, Fairfax, VA, 22030, United States of America
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9
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Feng B, Yu ZL, Gu Z, Li Y. Analysis of fMRI data based on sparsity of source components in signal dictionary. Neurocomputing 2015. [DOI: 10.1016/j.neucom.2014.12.082] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Main KL, Pestilli F, Mezer A, Yeatman J, Martin R, Phipps S, Wandell B. Speed discrimination predicts word but not pseudo-word reading rate in adults and children. BRAIN AND LANGUAGE 2014; 138:27-37. [PMID: 25278418 PMCID: PMC4300234 DOI: 10.1016/j.bandl.2014.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 04/30/2014] [Accepted: 09/02/2014] [Indexed: 06/03/2023]
Abstract
Visual processing in the magnocellular pathway is a reputed influence on word recognition and reading performance. However, the mechanisms behind this relationship are still unclear. To explore this concept, we measured reading rate, speed-discrimination, and contrast detection thresholds in adults and children with a wide range of reading abilities. We found that speed discrimination thresholds are higher in children than in adults and are correlated with age. Speed discrimination thresholds are also correlated with reading rates but only for real words, not pseudo-words. Conversely, we found no correlations between contrast detection thresholds and the reading rates. We also found no correlations between speed discrimination or contrast detection and WASI subtest scores. These findings indicate that familiarity is a factor in magnocellular operations that may influence reading rate. We suggest this effect supports the idea that the magnocellular pathway contributes to word reading through an analysis of letter position.
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Affiliation(s)
- Keith L Main
- Department of Psychology, Stanford University, Stanford, CA, United States; War Related Illness and Injury Study Center, Veterans Affairs, Palo Alto Health Care System (VAPAHCS), Palo Alto, CA, United States; Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, CA, United States
| | - Franco Pestilli
- Department of Psychology, Stanford University, Stanford, CA, United States.
| | - Aviv Mezer
- Department of Psychology, Stanford University, Stanford, CA, United States
| | - Jason Yeatman
- Department of Psychology, Stanford University, Stanford, CA, United States
| | - Ryan Martin
- Department of Psychology, Loyola Marymount University, Los Angeles, CA, United States
| | - Stephanie Phipps
- Department of Psychology, Stanford University, Stanford, CA, United States
| | - Brian Wandell
- Department of Psychology, Stanford University, Stanford, CA, United States
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11
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Pestilli F, Yeatman JD, Rokem A, Kay KN, Wandell BA. Evaluation and statistical inference for human connectomes. Nat Methods 2014; 11:1058-63. [PMID: 25194848 PMCID: PMC4180802 DOI: 10.1038/nmeth.3098] [Citation(s) in RCA: 167] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 08/08/2014] [Indexed: 11/09/2022]
Abstract
Diffusion-weighted imaging coupled with tractography is the only method for in vivo mapping of human white-matter fascicles. Tractography takes diffusion measurements as input and produces a large collection of white-matter fascicles as output; the connectome. We introduce a method to evaluate the evidence supporting connectomes. Linear Fascicle Evaluation (LiFE) takes any connectome as input and predicts diffusion measurements as output, using the difference between the measured and predicted diffusion signals to measure prediction error. Finally, we introduce two metrics that use the prediction error to evaluate the evidence supporting properties of the connectome. One metric compares the mean prediction error between alternative hypotheses, and the second metric compares full distributions of prediction error. We use these metrics to (1) compare tractography algorithms, and (2) test hypotheses about tracts and connections.
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Affiliation(s)
- Franco Pestilli
- Department of Psychology, Stanford University, Stanford, California, USA
| | - Jason D Yeatman
- Department of Psychology, Stanford University, Stanford, California, USA
| | - Ariel Rokem
- Department of Psychology, Stanford University, Stanford, California, USA
| | - Kendrick N Kay
- 1] Department of Psychology, Stanford University, Stanford, California, USA. [2] Department of Psychology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Brian A Wandell
- Department of Psychology, Stanford University, Stanford, California, USA
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12
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Fesi JD, Thomas AL, Gilmore RO. Cortical responses to optic flow and motion contrast across patterns and speeds. Vision Res 2014; 100:56-71. [PMID: 24751405 DOI: 10.1016/j.visres.2014.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 03/05/2014] [Accepted: 04/09/2014] [Indexed: 11/26/2022]
Abstract
Motion provides animals with fast and robust cues for navigation and object detection. In the first case, stereotyped patterns of optic flow inform a moving observer about the direction and speed of its own movement. In the case of object detection, regional differences in motion allow for the segmentation of figures from their background, even in the absence of color or shading cues. Previous research has investigated human electrophysiological responses to global motion across speeds, but only focused upon one type of optic flow pattern. Here, we compared steady-state visual evoked potential (SSVEP) responses across patterns and speeds, both for optic flow and for motion-defined figure patterns, to assess the extent to which the processes are pattern-general or pattern-specific. For optic flow, pattern and speed effects on response amplitudes varied substantially across channels, suggesting pattern-specific processing at slow speeds and pattern-general activity at fast speeds. Responses for coherence- and direction-defined figures were comparatively more uniform, with similar response profiles and spatial distributions. Self- and object-motion patterns activate some of the same circuits, but these data suggest differential sensitivity: not only across the two classes of motion, but also across the patterns within each class, and across speeds. Thus, the results demonstrate that cortical processing of global motion is complex and activates a distributed network.
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Affiliation(s)
- Jeremy D Fesi
- Department of Ophthalmology, McGill University, 687 Pine Avenue West, Montreal, QC H3A 1A1, Canada.
| | - Amanda L Thomas
- Department of Psychology, The Pennsylvania State University, 114 Moore Building, University Park, PA 16802, United States
| | - Rick O Gilmore
- Department of Psychology, The Pennsylvania State University, 114 Moore Building, University Park, PA 16802, United States; Social, Life, & Engineering Sciences Imaging Center, The Pennsylvania State University, University Park, PA 16802, United States
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13
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Gilaie-Dotan S, Saygin AP, Lorenzi LJ, Egan R, Rees G, Behrmann M. The role of human ventral visual cortex in motion perception. ACTA ACUST UNITED AC 2013; 136:2784-98. [PMID: 23983030 PMCID: PMC4017874 DOI: 10.1093/brain/awt214] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Visual motion perception is fundamental to many aspects of visual perception. Visual motion perception has long been associated with the dorsal (parietal) pathway and the involvement of the ventral 'form' (temporal) visual pathway has not been considered critical for normal motion perception. Here, we evaluated this view by examining whether circumscribed damage to ventral visual cortex impaired motion perception. The perception of motion in basic, non-form tasks (motion coherence and motion detection) and complex structure-from-motion, for a wide range of motion speeds, all centrally displayed, was assessed in five patients with a circumscribed lesion to either the right or left ventral visual pathway. Patients with a right, but not with a left, ventral visual lesion displayed widespread impairments in central motion perception even for non-form motion, for both slow and for fast speeds, and this held true independent of the integrity of areas MT/V5, V3A or parietal regions. In contrast with the traditional view in which only the dorsal visual stream is critical for motion perception, these novel findings implicate a more distributed circuit in which the integrity of the right ventral visual pathway is also necessary even for the perception of non-form motion.
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14
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Bernardino I, Castelhano J, Farivar R, Silva ED, Castelo-Branco M. Neural correlates of visual integration in Williams syndrome: gamma oscillation patterns in a model of impaired coherence. Neuropsychologia 2013; 51:1287-95. [PMID: 23587664 DOI: 10.1016/j.neuropsychologia.2013.03.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 03/04/2013] [Accepted: 03/27/2013] [Indexed: 10/27/2022]
Abstract
Williams syndrome (WS) is a clinical model of dorsal stream vulnerability and impaired visual integration. However, little is still known about the neurophysiological correlates of perceptual integration in this condition. We have used a 3D structure-from-motion (SFM) integrative task to characterize the neuronal underpinnings of 3D perception in WS and to probe whether gamma oscillatory patterns reflect changed holistic perception. Coherent faces were parametrically modulated in 3D depth (three different depth levels) to vary levels of stimulus ambiguity. We have found that the electrophysiological (EEG/ERP) correlates of such holistic percepts were distinct across groups. Independent component analysis demonstrated the presence of a novel component with a late positivity around 200 ms that was absent in controls. Source localization analysis of ERP signals showed a posterior occipital shift in WS and reduced parietal dorsal stream sources. Interestingly, low gamma-band oscillations (20-40 Hz) induced by this 3D perceptual integration task were significantly stronger and sustained during the stimulus presentation in WS whereas high gamma-band oscillations (60-90 Hz) were reduced in this clinical model of impaired visual coherence, as compared to controls. These observations suggest that dorsal stream processing of 3D SFM stimuli has distinct neural correlates in WS and different cognitive strategies are employed by these patients to reach visual coherence. Importantly, we found evidence for the presence of different sub-bands (20-40 Hz/60-90 Hz) within the gamma range which can be dissociated concerning the respective role on the coherent percept formation, both in typical and atypical development.
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Affiliation(s)
- Inês Bernardino
- Visual Neuroscience Laboratory, IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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15
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Graewe B, Lemos R, Ferreira C, Santana I, Farivar R, De Weerd P, Castelo-Branco M. Impaired processing of 3D motion-defined faces in mild cognitive impairment and healthy aging: an fMRI study. Cereb Cortex 2012; 23:2489-99. [PMID: 22879351 DOI: 10.1093/cercor/bhs246] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mild cognitive impairment (MCI), which shows high risk for conversion to Alzheimer's disease (AD), is accompanied by progressive visual deteriorations that so far are poorly understood. Here, we compared dorsal and ventral visual stream functional magnetic resonance imaging (fMRI) activity among amnestic MCI, healthy elderly, and young participants during structure-from-motion (SFM) face categorization performance. Task performance varied with stimulus depth and duration levels and differences among groups were highly correlated with face-related fMRI activation patterns. Young participants showed larger activation to faces than scrambled faces (face sensitivity) in the right fusiform face area (FFA) and right occipital face area (OFA) whereas in elderly, this difference was reduced. Surprisingly, in MCI, scrambled faces elicited larger activation in right FFA/OFA than faces. The latter observation may be related to the additional finding of elevated depth sensitivity in left FFA/OFA of MCI, suggesting that an increased representation of low-level stimulus aspects may impair face perception in MCI. Discriminant function analysis using face and depth sensitivity indices in FFA/OFA classified MCI and healthy elderly with 88.2% accuracy, marking a fundamental distinction between groups. Potentially related findings include altered activation patterns in dorsal-ventral stream integration regions and attention-related networks of MCI patients. Our results highlight aberrant visual and additional potentially compensatory processes that identify dispositions of (preclinical) AD.
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Affiliation(s)
- Britta Graewe
- Department of Cognitive Neuroscience, Faculty of Psychology & Neuroscience, Maastricht University, PO Box 616, 6200 MD Maastricht, the Netherlands
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16
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Graewe B, De Weerd P, Farivar R, Castelo-Branco M. Stimulus dependency of object-evoked responses in human visual cortex: an inverse problem for category specificity. PLoS One 2012; 7:e30727. [PMID: 22363479 PMCID: PMC3281870 DOI: 10.1371/journal.pone.0030727] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 12/27/2011] [Indexed: 11/19/2022] Open
Abstract
Many studies have linked the processing of different object categories to specific event-related potentials (ERPs) such as the face-specific N170. Despite reports showing that object-related ERPs are influenced by visual stimulus features, there is consensus that these components primarily reflect categorical aspects of the stimuli. Here, we re-investigated this idea by systematically measuring the effects of visual feature manipulations on ERP responses elicited by both structure-from-motion (SFM)-defined and luminance-defined object stimuli. SFM objects elicited a novel component at 200-250 ms (N250) over parietal and posterior temporal sites. We found, however, that the N250 amplitude was unaffected by restructuring SFM stimuli into meaningless objects based on identical visual cues. This suggests that this N250 peak was not uniquely linked to categorical aspects of the objects, but is strongly determined by visual stimulus features. We provide strong support for this hypothesis by parametrically manipulating the depth range of both SFM- and luminance-defined object stimuli and showing that the N250 evoked by SFM stimuli as well as the well-known N170 to static faces were sensitive to this manipulation. Importantly, this effect could not be attributed to compromised object categorization in low depth stimuli, confirming a strong impact of visual stimulus features on object-related ERP signals. As ERP components linked with visual categorical object perception are likely determined by multiple stimulus features, this creates an interesting inverse problem when deriving specific perceptual processes from variations in ERP components.
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Affiliation(s)
- Britta Graewe
- Department of Cognitive Neuroscience, Faculty of Psychology & Neuroscience, Maastricht University, Maastricht, The Netherlands.
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17
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Abstract
Depth structure, the third dimension of object shape, is extracted from disparity, motion, texture, and shading in the optic array. Gradient-selective neurons play a key role in this process. Such neurons occur in CIP, AIP, TEs, and F5 (for first- or second-order disparity gradients), in MT/V5, in FST (for speed gradients), and in CIP and TEs (for texture gradients). Most of these regions are activated during magnetic resonance scanning in alert monkeys by comparing 3D conditions with the 2D controls for the different cues. Similarities in activation patterns of monkeys and humans tested with identical paradigms suggest that like gradient-selective neurons are found in corresponding human cortical areas. This view gains credence as the homologies between such areas become more evident. Furthermore, 3D shape-processing networks are similar in the two species, with the exception of the greater involvement of human posterior parietal cortex in the extraction of 3D shape from motion. Thus we can begin to understand how depth structure is extracted from motion, disparity, and texture in the primate brain, but the extraction of depth structure from shading and that of wire-like objects requires further scrutiny.
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Affiliation(s)
- Guy A Orban
- Laboratorium voor Neuro-en Psychofysiologie, KU Leuven Medical School, Leuven, Belgium.
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18
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Enzweiler M, Gavrila DM. A multilevel Mixture-of-Experts framework for pedestrian classification. IEEE TRANSACTIONS ON IMAGE PROCESSING : A PUBLICATION OF THE IEEE SIGNAL PROCESSING SOCIETY 2011; 20:2967-2979. [PMID: 21486715 DOI: 10.1109/tip.2011.2142006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Notwithstanding many years of progress, pedestrian recognition is still a difficult but important problem. We present a novel multilevel Mixture-of-Experts approach to combine information from multiple features and cues with the objective of improved pedestrian classification. On pose-level, shape cues based on Chamfer shape matching provide sample-dependent priors for a certain pedestrian view. On modality-level, we represent each data sample in terms of image intensity, (dense) depth, and (dense) flow. On feature-level, we consider histograms of oriented gradients (HOG) and local binary patterns (LBP). Multilayer perceptrons (MLP) and linear support vector machines (linSVM) are used as expert classifiers.
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Affiliation(s)
- Markus Enzweiler
- Environment Perception Department, Daimler AG Group Research & MCG Development, 89081 Ulm, Germany.
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19
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Reverberi C, Görgen K, Haynes JD. Compositionality of rule representations in human prefrontal cortex. ACTA ACUST UNITED AC 2011; 22:1237-46. [PMID: 21817092 DOI: 10.1093/cercor/bhr200] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Rules are widely used in everyday life to organize actions and thoughts in accordance with our internal goals. At the simplest level, single rules can be used to link individual sensory stimuli to their appropriate responses. However, most tasks are more complex and require the concurrent application of multiple rules. Experiments on humans and monkeys have shown the involvement of a frontoparietal network in rule representation. Yet, a fundamental issue still needs to be clarified: Is the neural representation of multiple rules compositional, that is, built on the neural representation of their simple constituent rules? Subjects were asked to remember and apply either simple or compound rules. Multivariate decoding analyses were applied to functional magnetic resonance imaging data. Both ventrolateral frontal and lateral parietal cortex were involved in compound representation. Most importantly, we were able to decode the compound rules by training classifiers only on the simple rules they were composed of. This shows that the code used to store rule information in prefrontal cortex is compositional. Compositional coding in rule representation suggests that it might be possible to decode other complex action plans by learning the neural patterns of the known composing elements.
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Affiliation(s)
- Carlo Reverberi
- Bernstein Centre for Computational Neuroscience, Charité-Universitätsmedizin Berlin, 10115 Berlin, Germany.
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20
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Seemüller A, Fiehler K, Rösler F. Unimodal and crossmodal working memory representations of visual and kinesthetic movement trajectories. Acta Psychol (Amst) 2011; 136:52-9. [PMID: 20970103 DOI: 10.1016/j.actpsy.2010.09.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 09/27/2010] [Accepted: 09/30/2010] [Indexed: 11/16/2022] Open
Abstract
The present study investigated whether visual and kinesthetic stimuli are stored as multisensory or modality-specific representations in unimodal and crossmodal working memory tasks. To this end, angle-shaped movement trajectories were presented to 16 subjects in delayed matching-to-sample tasks either visually or kinesthetically during encoding and recognition. During the retention interval, a secondary visual or kinesthetic interference task was inserted either immediately or with a delay after encoding. The modality of the interference task interacted significantly with the encoding modality. After visual encoding, memory was more impaired by a visual than by a kinesthetic secondary task, while after kinesthetic encoding the pattern was reversed. The time when the secondary task had to be performed interacted with the encoding modality as well. For visual encoding, memory was more impaired, when the secondary task had to be performed at the beginning of the retention interval. In contrast, memory after kinesthetic encoding was more affected, when the secondary task was introduced later in the retention interval. The findings suggest that working memory traces are maintained in a modality-specific format characterized by distinct consolidation processes that take longer after kinesthetic than after visual encoding.
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21
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Chan JS, Simões-Franklin C, Garavan H, Newell FN. Static images of novel, moveable objects learned through touch activate visual area hMT+. Neuroimage 2010; 49:1708-16. [DOI: 10.1016/j.neuroimage.2009.09.068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 09/28/2009] [Accepted: 09/29/2009] [Indexed: 11/16/2022] Open
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22
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Farivar R. Dorsal–ventral integration in object recognition. ACTA ACUST UNITED AC 2009; 61:144-53. [DOI: 10.1016/j.brainresrev.2009.05.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 04/29/2009] [Accepted: 05/23/2009] [Indexed: 10/20/2022]
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23
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The integration of higher order form and motion by the human brain. Neuroimage 2008; 42:1529-36. [DOI: 10.1016/j.neuroimage.2008.04.265] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2008] [Revised: 04/23/2008] [Accepted: 04/25/2008] [Indexed: 11/24/2022] Open
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24
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Paradis AL, Droulez J, Cornilleau-Pérès V, Poline JB. Processing 3D form and 3D motion: respective contributions of attention-based and stimulus-driven activity. Neuroimage 2008; 43:736-47. [PMID: 18805496 DOI: 10.1016/j.neuroimage.2008.08.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 07/31/2008] [Accepted: 08/19/2008] [Indexed: 11/30/2022] Open
Abstract
This study aims at segregating the neural substrate for the 3D-form and 3D-motion attributes in structure-from-motion perception, and at disentangling the stimulus-driven and endogenous-attention-driven processing of these attributes. Attention and stimulus were manipulated independently: participants had to detect the transitions of one attribute--form, 3D motion or colour--while the visual stimulus underwent successive transitions of all attributes. We compared the BOLD activity related to form and 3D motion in three conditions: stimulus-driven processing (unattended transitions), endogenous attentional selection (task) or both stimulus-driven processing and attentional selection (attended transitions). In all conditions, the form versus 3D-motion contrasts revealed a clear dorsal/ventral segregation. However, while the form-related activity is consistent with previously described shape-selective areas, the activity related to 3D motion does not encompass the usual "visual motion" areas, but rather corresponds to a high-level motion system, including IPL and STS areas. Second, we found a dissociation between the neural processing of unattended attributes and that involved in endogenous attentional selection. Areas selective for 3D-motion and form showed either increased activity at transitions of these respective attributes or decreased activity when subjects' attention was directed to a competing attribute. We propose that both facilitatory and suppressive mechanisms of attribute selection are involved depending on the conditions driving this selection. Therefore, attentional selection is not limited to an increased activity in areas processing stimulus properties, and may unveil different functional localization from stimulus modulation.
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Affiliation(s)
- A-L Paradis
- CNRS, UPR640, Laboratoire de Neurosciences Cognitives et Imagerie Cérébrale, 75013 Paris, France.
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25
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Zhuang J, Peltier S, He S, LaConte S, Hu X. Mapping the connectivity with structural equation modeling in an fMRI study of shape-from-motion task. Neuroimage 2008; 42:799-806. [PMID: 18599316 DOI: 10.1016/j.neuroimage.2008.05.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 05/08/2008] [Accepted: 05/20/2008] [Indexed: 11/29/2022] Open
Abstract
In this fMRI study, we explore the connectivity among brain regions in a shape-from-motion task using the causal mapping analysis of structural equation modeling (SEM). An important distinction of our approach is that we have adapted SEM from its traditional role in confirmatory analysis to provide utility as an exploratory mapping technique. Our current approaches include (I) detecting brain regions that fit well in a hypothesized neural network model, and (II) identifying the best connectivity model at each brain region. We demonstrate that SEM effectively detects the dorsal and ventral visual pathways from the covariance structure in fMRI data, confirming previous neuroscience results. Further, our SEM mapping methodology found that the two pathways interact through specific cortical areas such as the superior lateral occipital cortex in the perception of shape from motion.
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Affiliation(s)
- Jiancheng Zhuang
- Dornsife Neuroscience Imaging Center, University of Southern California, 3620 South McClintock Avenue, SGM 501, Los Angeles, CA 90089, USA.
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26
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Formisano E, De Martino F, Valente G. Multivariate analysis of fMRI time series: classification and regression of brain responses using machine learning. Magn Reson Imaging 2008; 26:921-34. [PMID: 18508219 DOI: 10.1016/j.mri.2008.01.052] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 01/14/2008] [Indexed: 10/22/2022]
Abstract
Machine learning and pattern recognition techniques are being increasingly employed in functional magnetic resonance imaging (fMRI) data analysis. By taking into account the full spatial pattern of brain activity measured simultaneously at many locations, these methods allow detecting subtle, non-strictly localized effects that may remain invisible to the conventional analysis with univariate statistical methods. In typical fMRI applications, pattern recognition algorithms "learn" a functional relationship between brain response patterns and a perceptual, cognitive or behavioral state of a subject expressed in terms of a label, which may assume discrete (classification) or continuous (regression) values. This learned functional relationship is then used to predict the unseen labels from a new data set ("brain reading"). In this article, we describe the mathematical foundations of machine learning applications in fMRI. We focus on two methods, support vector machines and relevance vector machines, which are respectively suited for the classification and regression of fMRI patterns. Furthermore, by means of several examples and applications, we illustrate and discuss the methodological challenges of using machine learning algorithms in the context of fMRI data analysis.
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Affiliation(s)
- Elia Formisano
- Faculty of Psychology, Department of Cognitive Neuroscience, University of Maastricht, Maastricht, The Netherlands.
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27
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Consciousness, accessibility, and the mesh between psychology and neuroscience. Behav Brain Sci 2008; 30:481-99; discussion 499-548. [PMID: 18366828 DOI: 10.1017/s0140525x07002786] [Citation(s) in RCA: 326] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
How can we disentangle the neural basis of phenomenal consciousness from the neural machinery of the cognitive access that underlies reports of phenomenal consciousness? We see the problem in stark form if we ask how we can tell whether representations inside a Fodorian module are phenomenally conscious. The methodology would seem straightforward: Find the neural natural kinds that are the basis of phenomenal consciousness in clear cases--when subjects are completely confident and we have no reason to doubt their authority--and look to see whether those neural natural kinds exist within Fodorian modules. But a puzzle arises: Do we include the machinery underlying reportability within the neural natural kinds of the clear cases? If the answer is "Yes," then there can be no phenomenally conscious representations in Fodorian modules. But how can we know if the answer is "Yes"? The suggested methodology requires an answer to the question it was supposed to answer! This target article argues for an abstract solution to the problem and exhibits a source of empirical data that is relevant, data that show that in a certain sense phenomenal consciousness overflows cognitive accessibility. I argue that we can find a neural realizer of this overflow if we assume that the neural basis of phenomenal consciousness does not include the neural basis of cognitive accessibility and that this assumption is justified (other things being equal) by the explanations it allows.
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28
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Schultz J, Chuang L, Vuong QC. A Dynamic Object-Processing Network: Metric Shape Discrimination of Dynamic Objects by Activation of Occipitotemporal, Parietal, and Frontal Cortices. Cereb Cortex 2007; 18:1302-13. [DOI: 10.1093/cercor/bhm162] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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29
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De Martino F, Gentile F, Esposito F, Balsi M, Di Salle F, Goebel R, Formisano E. Classification of fMRI independent components using IC-fingerprints and support vector machine classifiers. Neuroimage 2007; 34:177-94. [PMID: 17070708 DOI: 10.1016/j.neuroimage.2006.08.041] [Citation(s) in RCA: 188] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Revised: 08/23/2006] [Accepted: 08/29/2006] [Indexed: 10/24/2022] Open
Abstract
We present a general method for the classification of independent components (ICs) extracted from functional MRI (fMRI) data sets. The method consists of two steps. In the first step, each fMRI-IC is associated with an IC-fingerprint, i.e., a representation of the component in a multidimensional space of parameters. These parameters are post hoc estimates of global properties of the ICs and are largely independent of a specific experimental design and stimulus timing. In the second step a machine learning algorithm automatically separates the IC-fingerprints into six general classes after preliminary training performed on a small subset of expert-labeled components. We illustrate this approach in a multisubject fMRI study employing visual structure-from-motion stimuli encoding faces and control random shapes. We show that: (1) IC-fingerprints are a valuable tool for the inspection, characterization and selection of fMRI-ICs and (2) automatic classifications of fMRI-ICs in new subjects present a high correspondence with those obtained by expert visual inspection of the components. Importantly, our classification procedure highlights several neurophysiologically interesting processes. The most intriguing of which is reflected, with high intra- and inter-subject reproducibility, in one IC exhibiting a transiently task-related activation in the 'face' region of the primary sensorimotor cortex. This suggests that in addition to or as part of the mirror system, somatotopic regions of the sensorimotor cortex are involved in disambiguating the perception of a moving body part. Finally, we show that the same classification algorithm can be successfully applied, without re-training, to fMRI collected using acquisition parameters, stimulation modality and timing considerably different from those used for training.
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Affiliation(s)
- Federico De Martino
- Department of Cognitive Neurosciences, Faculty of Psychology, University of Maastricht, Maastricht, The Netherlands
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30
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Pihlajamäki M, Tanila H, Könönen M, Hänninen T, Aronen HJ, Soininen H. Distinct and overlapping fMRI activation networks for processing of novel identities and locations of objects. Eur J Neurosci 2005; 22:2095-105. [PMID: 16262647 DOI: 10.1111/j.1460-9568.2005.04380.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The ventral visual stream processes information about the identity of objects ('what'), whereas the dorsal stream processes the spatial locations of objects ('where'). There is a corresponding, although disputed, distinction for the ventrolateral and dorsolateral prefrontal areas. Furthermore, there seems to be a distinction between the anterior and posterior medial temporal lobe (MTL) structures in the processing of novel items and new spatial arrangements, respectively. Functional differentiation of the intermediary mid-line cortical and temporal neocortical structures that communicate with the occipitotemporal, occipitoparietal, prefrontal, and MTL structures, however, is unclear. Therefore, in the present functional magnetic resonance imaging (fMRI) study, we examined whether the distinction among the MTL structures extends to these closely connected cortical areas. The most striking difference in the fMRI responses during visual presentation of changes in either items or their locations was the bilateral activation of the temporal lobe and ventrolateral prefrontal cortical areas for novel object identification in contrast to wide parietal and dorsolateral prefrontal activation for the novel locations of objects. An anterior-posterior distinction of fMRI responses similar to the MTL was observed in the cingulate/retrosplenial, and superior and middle temporal cortices. In addition to the distinct areas of activation, certain frontal, parietal, and temporo-occipital areas responded to both object and spatial novelty, suggesting a common attentional network for both types of changes in the visual environment. These findings offer new insights to the functional roles and intrinsic specialization of the cingulate/retrosplenial, and lateral temporal cortical areas in visuospatial cognition.
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Affiliation(s)
- Maija Pihlajamäki
- Department of Neurology, Kuopio University Hospital, PO Box 1777, 70211 Kuopio, Finland
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31
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Mendes M, Silva F, Simões L, Jorge M, Saraiva J, Castelo-Branco M. Visual magnocellular and structure from motion perceptual deficits in a neurodevelopmental model of dorsal stream function. ACTA ACUST UNITED AC 2005; 25:788-98. [PMID: 16256320 DOI: 10.1016/j.cogbrainres.2005.09.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Revised: 09/09/2005] [Accepted: 09/13/2005] [Indexed: 01/24/2023]
Abstract
Williams syndrome (WS) is a neurodevelopmental disorder of genetic origin that has been used as a model to understand visual cognition. We have investigated early deficits in the afferent magnocellular pathway and their relation to abnormal visual dorsal processing in WS. A spatiotemporal contrast sensitivity task that is known to selectively activate that pathway was used in six WS subjects. Additionally, we have compared visual performance in 2D and 3D motion integration tasks. A novel 3D motion coherence task (using spheres with unpredictable axis of rotation) was used in order to investigate possible impairment of occipitoparietal areas that are known to be involved in 3D structure from motion (SFM) perception. We have found a significant involvement of low-level magnocellular maps in WS as assessed by the contrast sensitivity task. On the contrary, no significant differences were observed between WS and the control groups in the 2D motion integration tasks. However, all WS subjects were significantly impaired in the 3D SFM task. Our findings suggest that magnocellular damage may occur in addition to dorsal stream deficits in these patients. They are also consistent with recently described genetic and neuroanatomic abnormalities in retinotopic visual areas. Finally, selective SFM coherence deficits support the proposal that there is a specific pathway in the dorsal stream that is involved in motion processing of 3D surfaces, which seems to be impaired in this disorder.
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Affiliation(s)
- Mafalda Mendes
- Centre for Ophthalmology, IBILI, Faculty of Medicine, Az. de Sta Comba, 3000-354 Coimbra, Portugal
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32
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Abstract
The discovery and analysis of cortical visual areas is a major accomplishment of visual neuroscience. In the past decade the use of noninvasive functional imaging, particularly functional magnetic resonance imaging (fMRI), has dramatically increased our detailed knowledge of the functional organization of the human visual cortex and its relation to visual perception. The fMRI method offers a major advantage over other techniques applied in neuroscience by providing a large-scale neuroanatomical perspective that stems from its ability to image the entire brain essentially at once. This bird's eye view has the potential to reveal large-scale principles within the very complex plethora of visual areas. Thus, it could arrange the entire constellation of human visual areas in a unified functional organizational framework. Here we review recent findings and methods employed to uncover the functional properties of the human visual cortex focusing on two themes: functional specialization and hierarchical processing.
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Affiliation(s)
- Kalanit Grill-Spector
- Department of Psychology and Neuroscience, Stanford University, Stanford, California 94305-2130, USA.
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33
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Peuskens H, Claeys KG, Todd JT, Norman JF, Van Hecke P, Orban GA. Attention to 3-D shape, 3-D motion, and texture in 3-D structure from motion displays. J Cogn Neurosci 2004; 16:665-82. [PMID: 15165355 DOI: 10.1162/089892904323057371] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
We used fMRI to directly compare the neural substrates of three-dimensional (3-D) shape and motion processing for realistic textured objects rotating in depth. Subjects made judgments about several different attributes of these objects, including 3-D shape, the 3-D motion, and the scale of surface texture. For all of these tasks, we equated visual input, motor output, and task difficulty, and we controlled for differences in spatial attention. Judgments about 3-D shape from motion involve both parietal and occipito-temporal regions. The processing of 3-D shape is associated with the analysis of 3-D motion in parietal regions and the analysis of surface texture in occipito-temporal regions, which is consistent with the different behavioral roles that are typically attributed to the dorsal and ventral processing streams.
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34
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Claeys KG, Lindsey DT, De Schutter E, Orban GA. A higher order motion region in human inferior parietal lobule: evidence from fMRI. Neuron 2004; 40:631-42. [PMID: 14642285 DOI: 10.1016/s0896-6273(03)00590-7] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The proposal that motion is processed by multiple mechanisms in the human brain has received little anatomical support so far. Here, we compared higher- and lower-level motion processing in the human brain using functional magnetic resonance imaging. We observed activation of an inferior parietal lobule (IPL) motion region by isoluminant red-green gratings when saliency of one color was increased and by long-range apparent motion at 7 Hz but not 2 Hz. This higher order motion region represents the entire visual field, while traditional motion regions predominantly process contralateral motion. Our results suggest that there are two motion-processing systems in the human brain: a contralateral lower-level luminance-based system, extending from hMT/V5+ into dorsal IPS and STS, and a bilateral higher-level saliency-based system in IPL.
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Affiliation(s)
- Kristl G Claeys
- Laboratorium voor Neuro- en Psychofysiologie, Katholieke Universiteit Leuven, Campus Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium
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