PLOS ONE: FMRI Reveals a Dissociation between Grasping and Perceiving the Size of Real 3D Objects du gaideliai
Submit Your Manuscript du gaideliai Fair, rigorous peer review Broad scope and wide reach get started Why Publish with PLOS ONE Publication Criteria Editorial Policies Preparing A Manuscript Figure and Table Guidelines Supporting Information Guidelines Submitting a Manuscript About Us Journal Information Editorial Board Reviewer Guidelines Article-Level Metrics Open-Access du gaideliai License Media Downloads Guidelines for Comments Corrections Help Using This Site Contact Us Search Search advanced search
Affiliation: Department of Psychology, University or Western Ontario, London, Ontario, Canada ⨯ Melvyn A. Goodale,
Almost 15 years after its formulation, evidence for the neuro-functional dissociation between a dorsal action stream and a ventral perception stream in the human cerebral cortex is still based largely on neuropsychological case studies. To date, there is no unequivocal evidence for separate visual computations of object features for performance of goal-directed actions versus perceptual tasks in the neurologically intact human brain. We used functional magnetic resonance imaging to test explicitly whether or not brain areas mediating size computation for grasping are distinct from those mediating size computation for perception. Methodology/Principal Findings
Subjects were presented with the same real graspable 3D objects and were required to perform a number of different tasks: grasping, reaching, size discrimination, pattern discrimination du gaideliai or passive viewing. As in prior studies, the anterior intraparietal area (AIP) in the dorsal stream was more active during grasping, when object size was relevant for planning the grasp, than during reaching, when object properties were irrelevant for movement du gaideliai planning (grasping>reaching). du gaideliai Activity in AIP showed no modulation, however, when size was computed in the context of a purely perceptual task (size = pattern discrimination). Conversely, the lateral occipital (LO) cortex in the ventral stream was modulated when size was computed for perception (size>pattern discrimination) but not for action (grasping = reaching). Conclusions/Significance
While areas in both the dorsal and ventral streams responded to the simple presentation of 3D objects (passive viewing), these areas were differentially activated depending on whether du gaideliai the task was grasping or perceptual discrimination, respectively. The demonstration of dual coding of an object for the purposes of action on the one hand and perception on the other in the same healthy brains offers du gaideliai a substantial contribution to the current debate about the nature of the neural coding that takes place in the dorsal and ventral streams.
Competing interests: The authors have declared that no competing interests exist.
The visual processing of objects serves two major functions: object recognition and the control of object-directed actions. For example, we can distinguish between an orange and a small tangerine in a bowl of fruit, perhaps based on cues such as size. When grasping the orange however, the hand would open wider on approach than when grasping the tangerine. In both cases, we need to process visual features, du gaideliai and size is one of the critical features (along with shape, orientation, and slant). Goodale and Milner [1] proposed that the visual system does not construct a single representation of the world for these two different visual functions. They suggested instead that the perception of objects and the visual du gaideliai control of object-directed actions depend on separate streams in the cerebral cortex. According to their model, the ventral stream, in occipitotemporal cortex, transforms visual information into perceptual representations, enabling du gaideliai us, for example, to use relative size to distinguish the orange from the tangerine. du gaideliai In contrast, the dorsal stream, in occipitoparietal cortex, deals with the moment-to-moment information about the location and disposition of objects, enabling us, for example, to compute the real size of the orange to scale our grasp appropriately in flight. Here we used functional magnetic resonance imaging (fMRI) to test whether or not size-computation for action and size-computation for perception are separated in the brain.
The most compelling evidence for the two-visual-systems model comes from double du gaideliai dissociation studies in neurological patients [1] . Patients with lesions in the superior parietal lobe, including the intraparietal sulcus, are unable to use visual information to correctly pre-shape the hand in order to pick up objects, even though they can discriminate between objects quite normally [2] . Conversely, patient DF, who has selective bilateral damage in the ventrolateral occipital region, has no difficulty using visual information to pre-shape her hand appropriately during grasping, even though she is unable to discriminate visually amongst such obje
Submit Your Manuscript du gaideliai Fair, rigorous peer review Broad scope and wide reach get started Why Publish with PLOS ONE Publication Criteria Editorial Policies Preparing A Manuscript Figure and Table Guidelines Supporting Information Guidelines Submitting a Manuscript About Us Journal Information Editorial Board Reviewer Guidelines Article-Level Metrics Open-Access du gaideliai License Media Downloads Guidelines for Comments Corrections Help Using This Site Contact Us Search Search advanced search
Affiliation: Department of Psychology, University or Western Ontario, London, Ontario, Canada ⨯ Melvyn A. Goodale,
Almost 15 years after its formulation, evidence for the neuro-functional dissociation between a dorsal action stream and a ventral perception stream in the human cerebral cortex is still based largely on neuropsychological case studies. To date, there is no unequivocal evidence for separate visual computations of object features for performance of goal-directed actions versus perceptual tasks in the neurologically intact human brain. We used functional magnetic resonance imaging to test explicitly whether or not brain areas mediating size computation for grasping are distinct from those mediating size computation for perception. Methodology/Principal Findings
Subjects were presented with the same real graspable 3D objects and were required to perform a number of different tasks: grasping, reaching, size discrimination, pattern discrimination du gaideliai or passive viewing. As in prior studies, the anterior intraparietal area (AIP) in the dorsal stream was more active during grasping, when object size was relevant for planning the grasp, than during reaching, when object properties were irrelevant for movement du gaideliai planning (grasping>reaching). du gaideliai Activity in AIP showed no modulation, however, when size was computed in the context of a purely perceptual task (size = pattern discrimination). Conversely, the lateral occipital (LO) cortex in the ventral stream was modulated when size was computed for perception (size>pattern discrimination) but not for action (grasping = reaching). Conclusions/Significance
While areas in both the dorsal and ventral streams responded to the simple presentation of 3D objects (passive viewing), these areas were differentially activated depending on whether du gaideliai the task was grasping or perceptual discrimination, respectively. The demonstration of dual coding of an object for the purposes of action on the one hand and perception on the other in the same healthy brains offers du gaideliai a substantial contribution to the current debate about the nature of the neural coding that takes place in the dorsal and ventral streams.
Competing interests: The authors have declared that no competing interests exist.
The visual processing of objects serves two major functions: object recognition and the control of object-directed actions. For example, we can distinguish between an orange and a small tangerine in a bowl of fruit, perhaps based on cues such as size. When grasping the orange however, the hand would open wider on approach than when grasping the tangerine. In both cases, we need to process visual features, du gaideliai and size is one of the critical features (along with shape, orientation, and slant). Goodale and Milner [1] proposed that the visual system does not construct a single representation of the world for these two different visual functions. They suggested instead that the perception of objects and the visual du gaideliai control of object-directed actions depend on separate streams in the cerebral cortex. According to their model, the ventral stream, in occipitotemporal cortex, transforms visual information into perceptual representations, enabling du gaideliai us, for example, to use relative size to distinguish the orange from the tangerine. du gaideliai In contrast, the dorsal stream, in occipitoparietal cortex, deals with the moment-to-moment information about the location and disposition of objects, enabling us, for example, to compute the real size of the orange to scale our grasp appropriately in flight. Here we used functional magnetic resonance imaging (fMRI) to test whether or not size-computation for action and size-computation for perception are separated in the brain.
The most compelling evidence for the two-visual-systems model comes from double du gaideliai dissociation studies in neurological patients [1] . Patients with lesions in the superior parietal lobe, including the intraparietal sulcus, are unable to use visual information to correctly pre-shape the hand in order to pick up objects, even though they can discriminate between objects quite normally [2] . Conversely, patient DF, who has selective bilateral damage in the ventrolateral occipital region, has no difficulty using visual information to pre-shape her hand appropriately during grasping, even though she is unable to discriminate visually amongst such obje
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