Pub Date : 2022-02-01Epub Date: 2022-05-27DOI: 10.1080/02643294.2022.2073808
Maryam Vaziri-Pashkam, Bevil R Conway
{"title":"How The visual system turns things the right way up.","authors":"Maryam Vaziri-Pashkam, Bevil R Conway","doi":"10.1080/02643294.2022.2073808","DOIUrl":"10.1080/02643294.2022.2073808","url":null,"abstract":"","PeriodicalId":50670,"journal":{"name":"Cognitive Neuropsychology","volume":"39 1","pages":"54-57"},"PeriodicalIF":2.6,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10759311/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47177981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-01DOI: 10.1080/02643294.2022.2040973
JohnMark Taylor, Yaoda Xu
Vannuscorps et al. (2021) present a comprehensive set of carefully designed behavioural experiments to characterize a young woman’s (“Davida’s”) unique neuropsychological deficit in object orientation perception. Specifically, when presented with 2D shapes defined by sharp edges with medium to high contrast, Davida reports seeing 90° and 180° rotated, and mirror-reversed, versions of the same shapes. By contrast, when shown 3D shapes or 2D shapes defined by blurred edges with low contrast, Davida’s performance is intact compared to agematched control participants. Vannuscorps et al. theorize that Davida’s deficit arises from a failure to map intermediate shape-centered representations (ISCRs) derived from cues preferentially processed in the parvocellular visual pathway from retinotopic coordinates to the higher-level spatiotopic or bodycentered coordinates that undergird conscious perception and action. They further propose that midlevel ventral stream regions such as LO1/2 (V4d in monkeys) may encode these ISCRs in retinotopic coordinates before they are transformed into spatiotopic or body-centered coordinates in downstream ventral and dorsal stream regions. Representations of multiple spatial reference frames have been most prominently associated with the primate posterior parietal cortex (PPC). In neuropsychological studies, damage to the human PPC has been linked to spatial neglect, which can occur with respect to retinotopic, body-centered, or spatiotopic reference frames (Halligan et al., 2003). In macaques, representations of different spatial reference frames have been linked to neurones in different subregions within the intraparietal sulcus (Colby & Goldberg, 1999). The re-representation of visual information from retinotopic coordinates in early visual areas to other reference frames is consistent with the idea that PPC plays an important role in the adaptive and dynamic aspect of visual information processing, whereby input from the ventral visual cortex is transformed to facilitate task performance and efficient interaction with the external world (Xu, 2018a & 2018b; see also Vaziri-Pashkam & Xu, 2017). Whereas previous studies have linked the representation of multiple spatial reference frames to PPC, Vannuscorps et al. (2021) suggest that it could occur earlier in regions immediately downstream from LO in the human brain, such as in V3A/V3B and IPS0. These brain regions have previously been linked to the representation of 3D space (e.g., Georgieva et al., 2009), the tracking of up to four object locations, and visual grouping (Bettencourt & Xu, 2016a; Xu & Chun, 2006, 2007 & 2009). The possibility of linking Davida’s behavioural deficit and the transformation of spatial reference frames to this general brain region presents an exciting opportunity that could help us better understand the precise function this region may play in visual perception. Vannuscorps et al. presume that Davida’s processing of the orientations of 2D shapes
{"title":"Identifying the neural loci mediating conscious object orientation perception using fMRI MVPA.","authors":"JohnMark Taylor, Yaoda Xu","doi":"10.1080/02643294.2022.2040973","DOIUrl":"https://doi.org/10.1080/02643294.2022.2040973","url":null,"abstract":"Vannuscorps et al. (2021) present a comprehensive set of carefully designed behavioural experiments to characterize a young woman’s (“Davida’s”) unique neuropsychological deficit in object orientation perception. Specifically, when presented with 2D shapes defined by sharp edges with medium to high contrast, Davida reports seeing 90° and 180° rotated, and mirror-reversed, versions of the same shapes. By contrast, when shown 3D shapes or 2D shapes defined by blurred edges with low contrast, Davida’s performance is intact compared to agematched control participants. Vannuscorps et al. theorize that Davida’s deficit arises from a failure to map intermediate shape-centered representations (ISCRs) derived from cues preferentially processed in the parvocellular visual pathway from retinotopic coordinates to the higher-level spatiotopic or bodycentered coordinates that undergird conscious perception and action. They further propose that midlevel ventral stream regions such as LO1/2 (V4d in monkeys) may encode these ISCRs in retinotopic coordinates before they are transformed into spatiotopic or body-centered coordinates in downstream ventral and dorsal stream regions. Representations of multiple spatial reference frames have been most prominently associated with the primate posterior parietal cortex (PPC). In neuropsychological studies, damage to the human PPC has been linked to spatial neglect, which can occur with respect to retinotopic, body-centered, or spatiotopic reference frames (Halligan et al., 2003). In macaques, representations of different spatial reference frames have been linked to neurones in different subregions within the intraparietal sulcus (Colby & Goldberg, 1999). The re-representation of visual information from retinotopic coordinates in early visual areas to other reference frames is consistent with the idea that PPC plays an important role in the adaptive and dynamic aspect of visual information processing, whereby input from the ventral visual cortex is transformed to facilitate task performance and efficient interaction with the external world (Xu, 2018a & 2018b; see also Vaziri-Pashkam & Xu, 2017). Whereas previous studies have linked the representation of multiple spatial reference frames to PPC, Vannuscorps et al. (2021) suggest that it could occur earlier in regions immediately downstream from LO in the human brain, such as in V3A/V3B and IPS0. These brain regions have previously been linked to the representation of 3D space (e.g., Georgieva et al., 2009), the tracking of up to four object locations, and visual grouping (Bettencourt & Xu, 2016a; Xu & Chun, 2006, 2007 & 2009). The possibility of linking Davida’s behavioural deficit and the transformation of spatial reference frames to this general brain region presents an exciting opportunity that could help us better understand the precise function this region may play in visual perception. Vannuscorps et al. presume that Davida’s processing of the orientations of 2D shapes","PeriodicalId":50670,"journal":{"name":"Cognitive Neuropsychology","volume":"39 1-2","pages":"64-67"},"PeriodicalIF":3.4,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9994469/pdf/nihms-1874112.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9409621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-01Epub Date: 2021-08-24DOI: 10.1080/02643294.2021.1960495
Gilles Vannuscorps, Albert Galaburda, Alfonso Caramazza
We report the study of a woman who perceives 2D bounded regions of space ("shapes") defined by sharp edges of medium to high contrast as if they were rotated by 90, 180 degrees around their centre, mirrored across their own axes, or both. In contrast, her perception of 3D, strongly blurred or very low contrast shapes, and of stimuli emerging from a collection of shapes, is intact. This suggests that a stage in the process of constructing the conscious visual representation of a scene consists of representing mutually exclusive bounded regions extracted from the initial retinotopic space in "shape-centered" frames of reference. The selectivity of the disorder to shapes originally biased toward the parvocellular subcortical pathway, and the absence of any other type of error, additionally invite new hypotheses about the operations involved in computing these "intermediate shape-centered representations" and in mapping them onto higher frames for perception and action.
{"title":"Shape-centered representations of bounded regions of space mediate the perception of objects.","authors":"Gilles Vannuscorps, Albert Galaburda, Alfonso Caramazza","doi":"10.1080/02643294.2021.1960495","DOIUrl":"https://doi.org/10.1080/02643294.2021.1960495","url":null,"abstract":"<p><p>We report the study of a woman who perceives 2D bounded regions of space (\"shapes\") defined by sharp edges of medium to high contrast as if they were rotated by 90, 180 degrees around their centre, mirrored across their own axes, or both. In contrast, her perception of 3D, strongly blurred or very low contrast shapes, and of stimuli emerging from a collection of shapes, is intact. This suggests that a stage in the process of constructing the conscious visual representation of a scene consists of representing mutually exclusive bounded regions extracted from the initial retinotopic space in \"shape-centered\" frames of reference. The selectivity of the disorder to shapes originally biased toward the parvocellular subcortical pathway, and the absence of any other type of error, additionally invite new hypotheses about the operations involved in computing these \"intermediate shape-centered representations\" and in mapping them onto higher frames for perception and action.</p>","PeriodicalId":50670,"journal":{"name":"Cognitive Neuropsychology","volume":" ","pages":"1-50"},"PeriodicalIF":3.4,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39353021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-01Epub Date: 2022-02-22DOI: 10.1080/02643294.2022.2041588
Marcelo Armendariz, Will Xiao, Kasper Vinken, Gabriel Kreiman
Do computational models of vision need shape-based representations? Evidence from an individual with intriguing visual perceptions Marcelo Armendariz, Will Xiao, Kasper Vinken and Gabriel Kreiman Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA; Center for Brains, Minds, and Machines, Cambridge, MA, USA; Laboratory for Neuroand Psychophysiology, KU Leuven, Leuven, Belgium; Leuven Brain Institute, KU Leuven, Leuven, Belgium; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA; Department of Neurobiology, Harvard Medical School, Boston, MA, USA
{"title":"Do computational models of vision need shape-based representations? Evidence from an individual with intriguing visual perceptions.","authors":"Marcelo Armendariz, Will Xiao, Kasper Vinken, Gabriel Kreiman","doi":"10.1080/02643294.2022.2041588","DOIUrl":"https://doi.org/10.1080/02643294.2022.2041588","url":null,"abstract":"Do computational models of vision need shape-based representations? Evidence from an individual with intriguing visual perceptions Marcelo Armendariz, Will Xiao, Kasper Vinken and Gabriel Kreiman Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA; Center for Brains, Minds, and Machines, Cambridge, MA, USA; Laboratory for Neuroand Psychophysiology, KU Leuven, Leuven, Belgium; Leuven Brain Institute, KU Leuven, Leuven, Belgium; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA; Department of Neurobiology, Harvard Medical School, Boston, MA, USA","PeriodicalId":50670,"journal":{"name":"Cognitive Neuropsychology","volume":" ","pages":"75-77"},"PeriodicalIF":3.4,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39944133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-01DOI: 10.1080/02643294.2022.2083947
Dina V Popovkina, Anitha Pasupathy
Vannuscorps and colleagues present the fascinating case of Davida, a young person who makes systematic errors in judgments related to orientations of sharp or high-contrast visual stimuli. In this commentary, we discuss the findings in the context of observations from mid-level ventral visual stream physiology. We propose two additional interpretations for the specificity of the behavioural deficits: the observed impairments in orientation judgments may be consistent with a system that is not able to unambiguously represent certain impoverished stimuli, or with a system that is not able to translate visual input into head- or body-centered coordinates. Davida's case offers a unique glimpse into the complex cascade of transformations that enable accurate orientation judgments, and sparks curiosity about which mechanistic disruptions can produce such specific unstable percepts.
{"title":"Davida's deficits: weak encoding of impoverished stimuli or faulty egocentric representation?","authors":"Dina V Popovkina, Anitha Pasupathy","doi":"10.1080/02643294.2022.2083947","DOIUrl":"https://doi.org/10.1080/02643294.2022.2083947","url":null,"abstract":"<p><p>Vannuscorps and colleagues present the fascinating case of Davida, a young person who makes systematic errors in judgments related to orientations of sharp or high-contrast visual stimuli. In this commentary, we discuss the findings in the context of observations from mid-level ventral visual stream physiology. We propose two additional interpretations for the specificity of the behavioural deficits: the observed impairments in orientation judgments may be consistent with a system that is not able to unambiguously represent certain impoverished stimuli, or with a system that is not able to translate visual input into head- or body-centered coordinates. Davida's case offers a unique glimpse into the complex cascade of transformations that enable accurate orientation judgments, and sparks curiosity about which mechanistic disruptions can produce such specific unstable percepts.</p>","PeriodicalId":50670,"journal":{"name":"Cognitive Neuropsychology","volume":"39 1-2","pages":"99-102"},"PeriodicalIF":3.4,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9484035/pdf/nihms-1812388.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9597423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-01Epub Date: 2022-03-25DOI: 10.1080/02643294.2022.2052715
Elisa Castaldi, Guido Marco Cicchini, Francesca Tinelli, Maria Concetta Morrone
Does more imply better vision? Elisa Castaldi , Guido Marco Cicchini, Francesca Tinelli and Maria Concetta Morrone Department of Neuroscience, Psychology, Pharmacology and Child Health, University of Florence, Florence, Italy; Institute of Neuroscience, National Research Council (CNR), Pisa, Italy; Scientific Institute Stella Maris (IRCSS), Pisa, Italy; Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
{"title":"Does more imply better vision?","authors":"Elisa Castaldi, Guido Marco Cicchini, Francesca Tinelli, Maria Concetta Morrone","doi":"10.1080/02643294.2022.2052715","DOIUrl":"https://doi.org/10.1080/02643294.2022.2052715","url":null,"abstract":"Does more imply better vision? Elisa Castaldi , Guido Marco Cicchini, Francesca Tinelli and Maria Concetta Morrone Department of Neuroscience, Psychology, Pharmacology and Child Health, University of Florence, Florence, Italy; Institute of Neuroscience, National Research Council (CNR), Pisa, Italy; Scientific Institute Stella Maris (IRCSS), Pisa, Italy; Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy","PeriodicalId":50670,"journal":{"name":"Cognitive Neuropsychology","volume":" ","pages":"78-80"},"PeriodicalIF":3.4,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40330835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-01Epub Date: 2022-02-19DOI: 10.1080/02643294.2022.2040975
Robert L Whitwell, Melvyn A Goodale
Davida’s striking pattern of visual deficits and spared visual abilities presents us with a real challenge of interpretation (Vannuscorps et al., 2021). How is it that her perception of the orientation of high-contrast 2D objects with sharp edges is so wildly (but consistently) disturbed, while her everyday behaviour in the 3D visual world appears to be essentially normal? Indeed, if it were not for the fact that she shows disturbances in reading for which the perception of the orientation of letters is critical, her deficits may never have come to light. According to her case history, Davida is skilled at soccer and basketball, two activities that are not only visually demanding but require rapid computation of the orientation of objects in both world-centred and egocentric coordinates. In short, in a pre-literate world, Davida would have functioned just fine. Vannuscorps et al. (2021) interpret Davida’s deficits as evidence for a disturbance in an intermediate stage in the construction of conscious visual representations in shape-centred frames of reference – with a selectivity in the deficit biased toward the parvocellular pathway. If this is the case, then one can understand why reading would be particularly susceptible to such a disturbance in representation. Not only does the parvocellular pathway play a key role in the processing of print, but the correct perception of an individual letter critically depends on computing the orientation of the letter. For most people, reading is easiest with high-contrast sharply defined letters. For Davida, it is quite the opposite. She does better under dim lighting and with blurred letters, situations where the magnocellular projections to the ventral stream are providing the required input to decode the letters. Presumably, unlike people with normal vision, she would not show the transient improvement in the ability to read small print that occurs after adaptation to flicker, which reduces sensitivity to coarse-scaled visual signals from the magno pathway (Arnold et al., 2016). In fact, she might get worse. Davida’s deficit in the perception of the orientation of objects raises many interesting questions. We will focus on only one: does her deficit affect the selection of wrist orientation and hand posture when she reaches to grasp objects? The fact that Davida does so well interacting with objects in the real world suggests that the visuomotor mechanisms in her dorsal stream are functioning properly. This is perhaps not surprising since because dorsal stream processing relies heavily on visual input from the magnocellular pathway, and Davida’s magnocellular pathway seems intact. Nevertheless, Vannuscorps et al. (2021) tested her visuomotor abilities by having her reach out and place her right thumb and index finger on the ends of a 2D line or on two unconnected dots that were the same distance apart as the ends of the line – “as if she were grasping it/them”. Not surprisingly, Davida had no problem pl
{"title":"Coming to grips with a fundamental deficit in visual perception.","authors":"Robert L Whitwell, Melvyn A Goodale","doi":"10.1080/02643294.2022.2040975","DOIUrl":"https://doi.org/10.1080/02643294.2022.2040975","url":null,"abstract":"Davida’s striking pattern of visual deficits and spared visual abilities presents us with a real challenge of interpretation (Vannuscorps et al., 2021). How is it that her perception of the orientation of high-contrast 2D objects with sharp edges is so wildly (but consistently) disturbed, while her everyday behaviour in the 3D visual world appears to be essentially normal? Indeed, if it were not for the fact that she shows disturbances in reading for which the perception of the orientation of letters is critical, her deficits may never have come to light. According to her case history, Davida is skilled at soccer and basketball, two activities that are not only visually demanding but require rapid computation of the orientation of objects in both world-centred and egocentric coordinates. In short, in a pre-literate world, Davida would have functioned just fine. Vannuscorps et al. (2021) interpret Davida’s deficits as evidence for a disturbance in an intermediate stage in the construction of conscious visual representations in shape-centred frames of reference – with a selectivity in the deficit biased toward the parvocellular pathway. If this is the case, then one can understand why reading would be particularly susceptible to such a disturbance in representation. Not only does the parvocellular pathway play a key role in the processing of print, but the correct perception of an individual letter critically depends on computing the orientation of the letter. For most people, reading is easiest with high-contrast sharply defined letters. For Davida, it is quite the opposite. She does better under dim lighting and with blurred letters, situations where the magnocellular projections to the ventral stream are providing the required input to decode the letters. Presumably, unlike people with normal vision, she would not show the transient improvement in the ability to read small print that occurs after adaptation to flicker, which reduces sensitivity to coarse-scaled visual signals from the magno pathway (Arnold et al., 2016). In fact, she might get worse. Davida’s deficit in the perception of the orientation of objects raises many interesting questions. We will focus on only one: does her deficit affect the selection of wrist orientation and hand posture when she reaches to grasp objects? The fact that Davida does so well interacting with objects in the real world suggests that the visuomotor mechanisms in her dorsal stream are functioning properly. This is perhaps not surprising since because dorsal stream processing relies heavily on visual input from the magnocellular pathway, and Davida’s magnocellular pathway seems intact. Nevertheless, Vannuscorps et al. (2021) tested her visuomotor abilities by having her reach out and place her right thumb and index finger on the ends of a 2D line or on two unconnected dots that were the same distance apart as the ends of the line – “as if she were grasping it/them”. Not surprisingly, Davida had no problem pl","PeriodicalId":50670,"journal":{"name":"Cognitive Neuropsychology","volume":" ","pages":"109-112"},"PeriodicalIF":3.4,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39941809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-01Epub Date: 2022-03-25DOI: 10.1080/02643294.2022.2052718
Edward H SIlson, Antony B Morland
If you were to ask someone in the street what they find most fascinating about the human brain the chances are they will tell you about a strange neuropsychological case study in which the patient presents with an odd and intriguingly specific deficit. Perhaps they lost the ability to recognize faces, tasted in colors or could no longer navigate familiar environments. Neuropsychological case studies, it turns out, are thus intrinsically fascinating to both scientists and the general public alike. Consistent with this general tenet, the case of ‘Davida’ reported by Vannuscorps et al. (Vannuscorps et al., 2021) is no exception. Davida, a right-handed young woman who is unremarkable in terms of her medical, neuropsychological, and neurological history nevertheless presents with a specific deficit in which she perceives 2D bounded shapes, defined by sharp edges of high contrast, as either inverted, mirror-reversed or plane-rotated by 90 or 180 degrees. Remarkably, her ability to judge the shape, size, location, distance, and tilt of 2D stimuli is no different from controls and her perception of 3D, strongly blurred or very low contrast shapes is intact—a curious case if ever there was one. When reading case-studies one can be left questioning the depth and breadth of the testing, wishing that further tests had been conducted to rule out all manner of possible explanations. Of course, time is tight when conducting these studies, but that sense of a missed opportunity can persist, nevertheless. That is not the case when reading Vannuscorps et al. Over the course of two years, Davida completed six experimental phases comprising over fifty individual experiments. Within these, many of the conceivable adaptations and modifications to the experimental set-up were tested including, but not limited to, visual, auditory, and somatosensory perception, visual illusions, object naming, object matching and drawing/tracing—a monumental achievement for both the researchers and Davida herself. Collectively, these data provide a benchmark for comprehensive behavioral profiling in such casestudies. The fact that Davida systematically mis-perceives 2D shapes defined by sharp and high contrast edges as either reversed or plane-rotated and yet perceives low contrast 2D shapes and 3D shapes correctly, suggests a dissociation between the visual information originating from the parvocellular and magnocellular pathways, pointing to a failure to integrate parvocellular information correctly. But, perhaps the most intriguing implication of Davida’s behavioral profile is that the implied cortical locus of her deficit lies at an intermediate stage of visual processing, somewhere between retinotopic based frames of representation in early visual cortex (e.g., V1-V3) (Wandell et al., 2007), and more abstract spatiotopic and bodycentered coordinate systems that are presumably computed more anterior in the brain (Groen et al., 2021). Vannuscorps et al. term this type of representati
{"title":"The search for shape-centered representations.","authors":"Edward H SIlson, Antony B Morland","doi":"10.1080/02643294.2022.2052718","DOIUrl":"https://doi.org/10.1080/02643294.2022.2052718","url":null,"abstract":"If you were to ask someone in the street what they find most fascinating about the human brain the chances are they will tell you about a strange neuropsychological case study in which the patient presents with an odd and intriguingly specific deficit. Perhaps they lost the ability to recognize faces, tasted in colors or could no longer navigate familiar environments. Neuropsychological case studies, it turns out, are thus intrinsically fascinating to both scientists and the general public alike. Consistent with this general tenet, the case of ‘Davida’ reported by Vannuscorps et al. (Vannuscorps et al., 2021) is no exception. Davida, a right-handed young woman who is unremarkable in terms of her medical, neuropsychological, and neurological history nevertheless presents with a specific deficit in which she perceives 2D bounded shapes, defined by sharp edges of high contrast, as either inverted, mirror-reversed or plane-rotated by 90 or 180 degrees. Remarkably, her ability to judge the shape, size, location, distance, and tilt of 2D stimuli is no different from controls and her perception of 3D, strongly blurred or very low contrast shapes is intact—a curious case if ever there was one. When reading case-studies one can be left questioning the depth and breadth of the testing, wishing that further tests had been conducted to rule out all manner of possible explanations. Of course, time is tight when conducting these studies, but that sense of a missed opportunity can persist, nevertheless. That is not the case when reading Vannuscorps et al. Over the course of two years, Davida completed six experimental phases comprising over fifty individual experiments. Within these, many of the conceivable adaptations and modifications to the experimental set-up were tested including, but not limited to, visual, auditory, and somatosensory perception, visual illusions, object naming, object matching and drawing/tracing—a monumental achievement for both the researchers and Davida herself. Collectively, these data provide a benchmark for comprehensive behavioral profiling in such casestudies. The fact that Davida systematically mis-perceives 2D shapes defined by sharp and high contrast edges as either reversed or plane-rotated and yet perceives low contrast 2D shapes and 3D shapes correctly, suggests a dissociation between the visual information originating from the parvocellular and magnocellular pathways, pointing to a failure to integrate parvocellular information correctly. But, perhaps the most intriguing implication of Davida’s behavioral profile is that the implied cortical locus of her deficit lies at an intermediate stage of visual processing, somewhere between retinotopic based frames of representation in early visual cortex (e.g., V1-V3) (Wandell et al., 2007), and more abstract spatiotopic and bodycentered coordinate systems that are presumably computed more anterior in the brain (Groen et al., 2021). Vannuscorps et al. term this type of representati","PeriodicalId":50670,"journal":{"name":"Cognitive Neuropsychology","volume":" ","pages":"85-87"},"PeriodicalIF":3.4,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40330839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"心理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-01Epub Date: 2022-02-07DOI: 10.1080/02643294.2022.2036113
Irina M Harris
In the target article, Vannuscorps, Galaburda and Caramazza describe a fascinating case, Davida, who most frequently misperceives the orientation of 2D shapes. Davida’s deficit is remarkable by its specificity: it only applies to shapes defined by high-contrast bounded regions of space, but not to 3D shapes, low spatial frequency stimuli, or shapes defined by unconnected colinear dots. On the other hand, it generalizes across perception and action tasks, with very similar patterns of errors. This prompted Vannuscorps and colleagues to propose that Davida has a deficit in mapping a shape-centred representation processed specifically in the parvocellular pathway onto higher-level spatial reference frames centred on the viewer and the environment that are responsible for delivering our conscious perception and guide our actions. They suggest that these representations, which they call intermediate shape-centred representations (ISCRs) occur at an early – and pre-conscious – stage of visual processing that is common to the ventral and dorsal visual streams. In this commentary I highlight some other evidence that would support the existence of such early shape-centred representations and speculate that Davida’s faulty perception of orientation is due to a difficulty in maintaining a stable binding between ISCRs and a spatial reference frame. Davida clearly has no problem recognizing shapes and identifying objects (with the exception of orientation-defined letters, such as b, d, p, q), even though her perception of their orientation is mostly incorrect. Thus, her performance strongly suggests that the shape and identity of an object is extracted before an orientation vector that describes how the object is positioned in space is assigned to the object. In this, she is similar to previously-described cases of orientation agnosia, who can recognize objects presented in a variety of orientations, but cannot interpret their orientations (Cooper & Humphreys, 2000; Fujinaga et al., 2005; Harris et al., 2001; Karnath et al., 2000; Turnbull et al., 1997; Turnbull et al., 1995). A similar dissociation was described in a number of studies conducted with neurotypical participants, which found that object identity is determined faster than object orientation (De Caro, 1998; De Caro & Reeves, 2000; Harris et al., 2020), as well as other studies that show implicit object recognition from brief displays, as indexed by priming and repetition blindness, is orientation-invariant and that any costs incurred by presenting an object in an unfamiliar orientation occur at a later stage of conscious report (Dux & Harris, 2007; Harris & Dux, 2005; Harris et al., 2008; Hayward et al., 2010). Collectively, these findings provide empirical support for an early theoretical position advocated by Corballis (1988) who argued that one must know an object’s identity before one can determine its orientation, because orientation can only be judged relative to an objectcentred reference f
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