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Experimental evidence for involvement of monocular channels in mental rotation. Psychon Bull Rev 2022; 30:575-584. [PMID: 36279047 DOI: 10.3758/s13423-022-02195-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2022] [Indexed: 11/08/2022]
Abstract
According to the prevailing view, cognitive processes of mental rotation are carried out by visuospatial perceptual circuits located primarily in high cortical areas. Here, we examined the functional involvement of (mostly subcortical) monocular channels in mental rotation tasks. Images of two rotated objects (0°, 50°, 100°, or 150°; identical or mirrored) were presented either to one eye (monocular) or segregated between the eyes (interocular). The results indicated a causal role for low monocular visual channels in mental rotation: Response times for identical ("same") objects at high angular disparities (100°, 150°) were shorter when both objects were presented to a single eye than when each object was presented to a different eye. We suggest that mental rotation processes rely on cortico-subcortical loops that support visuospatial perception. More generally, the findings highlight the potential contribution of lower-level mechanisms to what are typically considered to be high-level cognitive functions, such as mental representation.
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Khateeb K, Bloch J, Zhou J, Rahimi M, Griggs DJ, Kharazia VN, Le MN, Wang RK, Yazdan-Shahmorad A. A versatile toolbox for studying cortical physiology in primates. CELL REPORTS METHODS 2022; 2:100183. [PMID: 35445205 PMCID: PMC9017216 DOI: 10.1016/j.crmeth.2022.100183] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/06/2022] [Accepted: 02/23/2022] [Indexed: 12/02/2022]
Abstract
Lesioning and neurophysiological studies have facilitated the elucidation of cortical functions and mechanisms of functional recovery following injury. Clinical translation of such studies is contingent on their employment in non-human primates (NHPs), yet tools for monitoring and modulating cortical physiology are incompatible with conventional lesioning techniques. To address these challenges, we developed a toolbox validated in seven macaques. We introduce the photothrombotic method for inducing focal cortical lesions, a quantitative model for designing experiment-specific lesion profiles and optical coherence tomography angiography (OCTA) for large-scale (~5 cm2) monitoring of vascular dynamics. We integrate these tools with our electrocorticographic array for large-scale monitoring of neural dynamics and testing stimulation-based interventions. Advantageously, this versatile toolbox can be incorporated into established chronic cranial windows. By combining optical and electrophysiological techniques in the NHP cortex, we can enhance our understanding of cortical functions, investigate functional recovery mechanisms, integrate physiological and behavioral findings, and develop neurorehabilitative treatments. MOTIVATION The primate neocortex encodes for complex functions and behaviors, the physiologies of which are yet to be fully understood. Such an understanding in both healthy and diseased states can be crucial for the development of effective neurorehabilitative strategies. However, there is a lack of a comprehensive and adaptable set of tools that enables the study of multiple physiological phenomena in healthy and injured brains. Therefore, we developed a toolbox with the capability to induce targeted cortical lesions, monitor dynamics of underlying cortical microvasculature, and record and stimulate neural activity. With this toolbox, we can enhance our understanding of cortical functions, investigate functional recovery mechanisms, test stimulation-based interventions, and integrate physiological and behavioral findings.
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Affiliation(s)
- Karam Khateeb
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Washington National Primate Research Center, Seattle, WA 98195, USA
| | - Julien Bloch
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Washington National Primate Research Center, Seattle, WA 98195, USA
| | - Jasmine Zhou
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Washington National Primate Research Center, Seattle, WA 98195, USA
| | - Mona Rahimi
- Washington National Primate Research Center, Seattle, WA 98195, USA
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA 98195, USA
| | - Devon J. Griggs
- Washington National Primate Research Center, Seattle, WA 98195, USA
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA 98195, USA
| | - Viktor N. Kharazia
- Department of Physiology and Center for Integrative Neuroscience, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Minh N. Le
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Department of Ophthalmology, University of Washington Medicine, Seattle, WA 98195, USA
| | - Azadeh Yazdan-Shahmorad
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Washington National Primate Research Center, Seattle, WA 98195, USA
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA 98195, USA
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3
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Derrien D, Garric C, Sergent C, Chokron S. The nature of blindsight: implications for current theories of consciousness. Neurosci Conscious 2022; 2022:niab043. [PMID: 35237447 PMCID: PMC8884361 DOI: 10.1093/nc/niab043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 11/08/2021] [Accepted: 01/13/2022] [Indexed: 11/16/2022] Open
Abstract
Blindsight regroups the different manifestations of preserved discriminatory visual capacities following the damage to the primary visual cortex. Blindsight types differentially impact objective and subjective perception, patients can report having no visual awareness whilst their behaviour suggests visual processing still occurs at some cortical level. This phenomenon hence presents a unique opportunity to study consciousness and perceptual consciousness, and for this reason, it has had an historical importance for the development of this field of research. From these studies, two main opposing models of the underlying mechanisms have been established: (a) blindsight is perception without consciousness or (b) blindsight is in fact degraded vision, two views that mirror more general theoretical options about whether unconscious cognition truly exists or whether it is only a degraded form of conscious processing. In this article, we want to re-examine this debate in the light of recent advances in the characterization of blindsight and associated phenomena. We first provide an in-depth definition of blindsight and its subtypes, mainly blindsight type I, blindsight type II and the more recently described blindsense. We emphasize the necessity of sensitive and robust methodology to uncover the dissociations between perception and awareness that can be observed in brain-damaged patients with visual field defects at different cognitive levels. We discuss these different profiles of dissociation in the light of both contending models. We propose that the different types of dissociations reveal a pattern of relationship between perception, awareness and metacognition that is actually richer than what is proposed by either of the existing models. Finally, we consider this in the framework of current theories of consciousness and touch on the implications the findings of blindsight have on these.
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Affiliation(s)
- Diane Derrien
- Integrative Neuroscience and Cognition Center, UMR 8002, CNRS & Université de Paris, Paris 75006, France
- Institut de Neuropsychologie, Neurovision, NeuroCognition, Fondation Ophtalmologique Rothschild, Paris 75019, France
| | - Clémentine Garric
- Inserm, CHU Lille, U1172—LilNCog (JPARC)—Lille Neuroscience & Cognition, University of Lille, Lille 59000, France
| | - Claire Sergent
- Integrative Neuroscience and Cognition Center, UMR 8002, CNRS & Université de Paris, Paris 75006, France
| | - Sylvie Chokron
- Integrative Neuroscience and Cognition Center, UMR 8002, CNRS & Université de Paris, Paris 75006, France
- Institut de Neuropsychologie, Neurovision, NeuroCognition, Fondation Ophtalmologique Rothschild, Paris 75019, France
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Keliris GA, Shao Y, Schmid MC, Augath M, Logothetis NK, Smirnakis SM. Macaque Area V2/V3 Reorganization Following Homonymous Retinal Lesions. Front Neurosci 2022; 16:757091. [PMID: 35153666 PMCID: PMC8832035 DOI: 10.3389/fnins.2022.757091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 01/07/2022] [Indexed: 01/24/2023] Open
Abstract
In the adult visual system, topographic reorganization of the primary visual cortex (V1) after retinal lesions has been extensively investigated. In contrast, the plasticity of higher order extrastriate areas following retinal lesions is less well studied. Here, we used fMRI to study reorganization of visual areas V2/V3 following the induction of permanent, binocular, homonymous retinal lesions in 4 adult macaque monkeys. We found that the great majority of voxels that did not show visual modulation on the day of the lesion in the V2/V3 lesion projection zone (LPZ) demonstrated significant visual modulations 2 weeks later, and the mean modulation strength remained approximately stable thereafter for the duration of our observations (4-5 months). The distribution of eccentricities of visually modulated voxels inside the V2/V3 LPZ spanned a wider range post-lesion than pre-lesion, suggesting that neurons inside the LPZ reorganize by receiving input either from the foveal or the peripheral border of the LPZ, depending on proximity. Overall, we conclude that area V2/V3 of adult rhesus macaques displays a significant capacity for topographic reorganization following retinal lesions markedly exceeding the corresponding capacity of area V1.
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Affiliation(s)
- Georgios A. Keliris
- Physiology of Cognitive Processes, Max-Planck Institute for Biological Cybernetics, Tübingen, Germany,Bio-Imaging Lab, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium,*Correspondence: Georgios A. Keliris,
| | - Yibin Shao
- Physiology of Cognitive Processes, Max-Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Michael C. Schmid
- Physiology of Cognitive Processes, Max-Planck Institute for Biological Cybernetics, Tübingen, Germany,Schmid Research Group, Medicine Section, University of Fribourg, Fribourg, Switzerland
| | - Mark Augath
- Physiology of Cognitive Processes, Max-Planck Institute for Biological Cybernetics, Tübingen, Germany,Institute of Biomedical Engineering, ETH Zurich, Zurich, Switzerland
| | - Nikos K. Logothetis
- Physiology of Cognitive Processes, Max-Planck Institute for Biological Cybernetics, Tübingen, Germany,International Center for Primate Brain Research, Shanghai, China,Division of Imaging Science and Biomedical Engineering, University of Manchester, Manchester, United Kingdom
| | - Stelios M. Smirnakis
- Department of Neurology, Brigham and Women’s Hospital and Jamaica Plain Veterans Administration Hospital, Harvard Medical School, Boston, MA, United States,Stelios M. Smirnakis,
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5
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Fahrenthold BK, Cavanaugh MR, Jang S, Murphy AJ, Ajina S, Bridge H, Huxlin KR. Optic Tract Shrinkage Limits Visual Restoration After Occipital Stroke. Stroke 2021; 52:3642-3650. [PMID: 34266305 PMCID: PMC8545836 DOI: 10.1161/strokeaha.121.034738] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Supplemental Digital Content is available in the text. Background and Purpose: Damage to the adult primary visual cortex (V1) causes vision loss in the contralateral visual hemifield, initiating a process of trans-synaptic retrograde degeneration. The present study examined functional implications of this process, asking if degeneration impacted the amount of visual recovery attainable from visual restoration training in chronic patients, and if restoration training impacted optic tract (OT) shrinkage. Methods: Magnetic resonance imaging was used to measure OT volumes bilaterally in 36 patients with unilateral occipital stroke. From OT volumes, we computed laterality indices (LI), estimating the stroke-induced OT shrinkage in each case. A subset of these chronic patients (n=14, 13±6 months poststroke) underwent an average of nearly 1 year of daily visual restoration training, which repeatedly stimulated vision in their blind field. The amount of visual field recovery was quantified using Humphrey perimetry, and post training magnetic resonance imaging was used to assess the impact of training on OT shrinkage. Results: OT LI was correlated with time since stroke: it was close to 0 (no measurable OT shrinkage) in subacute participants (<6 months poststroke) while chronic participants (>6 months poststroke) exhibited LI >0, but with significant variability. Visual training did not systematically alter LI, but chronic patients with baseline LI≈0 (no OT shrinkage) exhibited greater visual field recovery than those with LI>0. Conclusions: Unilateral OT shrinkage becomes detectable with magnetic resonance imaging by ≈7 months poststroke, albeit with significant interindividual variability. Although visual restoration training did not alter the amount of degeneration already sustained, OT shrinkage appeared to serve as a biomarker of the potential for training-induced visual recovery in chronic cortically blind patients.
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Affiliation(s)
- Berkeley K. Fahrenthold
- Flaum Eye Institute (B.K.F., M.R.C., S.J., K.R.H.), University of Rochester, NY. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. Department of Neurorehabilitation and Therapy Services, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
| | - Matthew R. Cavanaugh
- Flaum Eye Institute (B.K.F., M.R.C., S.J., K.R.H.), University of Rochester, NY. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. Department of Neurorehabilitation and Therapy Services, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
| | - Subin Jang
- Flaum Eye Institute (B.K.F., M.R.C., S.J., K.R.H.), University of Rochester, NY. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. Department of Neurorehabilitation and Therapy Services, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
| | - Allison J. Murphy
- Neuroscience Graduate Program (A.J.M.), University of Rochester, NY. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. Department of Neurorehabilitation and Therapy Services, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
| | | | | | - Krystel R. Huxlin
- Flaum Eye Institute (B.K.F., M.R.C., S.J., K.R.H.), University of Rochester, NY. Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, United Kingdom. Department of Neurorehabilitation and Therapy Services, The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
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6
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Klink PC, Aubry JF, Ferrera VP, Fox AS, Froudist-Walsh S, Jarraya B, Konofagou EE, Krauzlis RJ, Messinger A, Mitchell AS, Ortiz-Rios M, Oya H, Roberts AC, Roe AW, Rushworth MFS, Sallet J, Schmid MC, Schroeder CE, Tasserie J, Tsao DY, Uhrig L, Vanduffel W, Wilke M, Kagan I, Petkov CI. Combining brain perturbation and neuroimaging in non-human primates. Neuroimage 2021; 235:118017. [PMID: 33794355 PMCID: PMC11178240 DOI: 10.1016/j.neuroimage.2021.118017] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/07/2021] [Accepted: 03/22/2021] [Indexed: 12/11/2022] Open
Abstract
Brain perturbation studies allow detailed causal inferences of behavioral and neural processes. Because the combination of brain perturbation methods and neural measurement techniques is inherently challenging, research in humans has predominantly focused on non-invasive, indirect brain perturbations, or neurological lesion studies. Non-human primates have been indispensable as a neurobiological system that is highly similar to humans while simultaneously being more experimentally tractable, allowing visualization of the functional and structural impact of systematic brain perturbation. This review considers the state of the art in non-human primate brain perturbation with a focus on approaches that can be combined with neuroimaging. We consider both non-reversible (lesions) and reversible or temporary perturbations such as electrical, pharmacological, optical, optogenetic, chemogenetic, pathway-selective, and ultrasound based interference methods. Method-specific considerations from the research and development community are offered to facilitate research in this field and support further innovations. We conclude by identifying novel avenues for further research and innovation and by highlighting the clinical translational potential of the methods.
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Affiliation(s)
- P Christiaan Klink
- Department of Vision & Cognition, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
| | - Jean-François Aubry
- Physics for Medicine Paris, Inserm U1273, CNRS UMR 8063, ESPCI Paris, PSL University, Paris, France
| | - Vincent P Ferrera
- Department of Neuroscience & Department of Psychiatry, Columbia University Medical Center, New York, NY, USA; Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Andrew S Fox
- Department of Psychology & California National Primate Research Center, University of California, Davis, CA, USA
| | | | - Béchir Jarraya
- NeuroSpin, Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Institut National de la Santé et de la Recherche Médicale (INSERM), Cognitive Neuroimaging Unit, Université Paris-Saclay, France; Foch Hospital, UVSQ, Suresnes, France
| | - Elisa E Konofagou
- Ultrasound and Elasticity Imaging Laboratory, Department of Biomedical Engineering, Columbia University, New York, NY, USA; Department of Radiology, Columbia University, New York, NY, USA
| | - Richard J Krauzlis
- Laboratory of Sensorimotor Research, National Eye Institute, Bethesda, MD, USA
| | - Adam Messinger
- Laboratory of Brain and Cognition, National Institute of Mental Health, Bethesda, MD, USA
| | - Anna S Mitchell
- Department of Experimental Psychology, Oxford University, Oxford, United Kingdom
| | - Michael Ortiz-Rios
- Newcastle University Medical School, Newcastle upon Tyne NE1 7RU, United Kingdom; German Primate Center, Leibniz Institute for Primate Research, Kellnerweg 4, 37077 Göttingen, Germany
| | - Hiroyuki Oya
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA, USA; Department of Neurosurgery, University of Iowa, Iowa city, IA, USA
| | - Angela C Roberts
- Department of Physiology, Development and Neuroscience, Cambridge University, Cambridge, United Kingdom
| | - Anna Wang Roe
- Interdisciplinary Institute of Neuroscience and Technology, School of Medicine, Zhejiang University, Hangzhou 310029, China
| | | | - Jérôme Sallet
- Department of Experimental Psychology, Oxford University, Oxford, United Kingdom; Univ Lyon, Université Lyon 1, Inserm, Stem Cell and Brain Research Institute, U1208 Bron, France; Wellcome Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Michael Christoph Schmid
- Newcastle University Medical School, Newcastle upon Tyne NE1 7RU, United Kingdom; Faculty of Science and Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland
| | - Charles E Schroeder
- Nathan Kline Institute, Orangeburg, NY, USA; Columbia University, New York, NY, USA
| | - Jordy Tasserie
- NeuroSpin, Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Institut National de la Santé et de la Recherche Médicale (INSERM), Cognitive Neuroimaging Unit, Université Paris-Saclay, France
| | - Doris Y Tsao
- Division of Biology and Biological Engineering, Tianqiao and Chrissy Chen Institute for Neuroscience; Howard Hughes Medical Institute; Computation and Neural Systems, Caltech, Pasadena, CA, USA
| | - Lynn Uhrig
- NeuroSpin, Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), Institut National de la Santé et de la Recherche Médicale (INSERM), Cognitive Neuroimaging Unit, Université Paris-Saclay, France
| | - Wim Vanduffel
- Laboratory for Neuro- and Psychophysiology, Neurosciences Department, KU Leuven Medical School, Leuven, Belgium; Leuven Brain Institute, KU Leuven, Leuven Belgium; Harvard Medical School, Boston, MA, USA; Massachusetts General Hospital, Martinos Center for Biomedical Imaging, Charlestown, MA, USA
| | - Melanie Wilke
- German Primate Center, Leibniz Institute for Primate Research, Kellnerweg 4, 37077 Göttingen, Germany; Department of Cognitive Neurology, University Medicine Göttingen, Göttingen, Germany
| | - Igor Kagan
- German Primate Center, Leibniz Institute for Primate Research, Kellnerweg 4, 37077 Göttingen, Germany.
| | - Christopher I Petkov
- Newcastle University Medical School, Newcastle upon Tyne NE1 7RU, United Kingdom.
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8
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Abstract
This paper examines the applicability of predictive coding as an explanatory model for perception. This is carried out from two perspectives. First, the central assumptions of the model are re-examined in light of the neuroscientific evidence for the structure and functioning of key brain areas involved in perception. The inferential processes involved in predictive coding are then investigated in the context of ambiguous stimuli. This showed that while predictive coding may provide an accurate explanation for our perceptual experiences in some cases, there are also several instances where the picture is not as clear cut. Following on from this, particular emphasis is placed on ambiguous art in order to examine the psychological and cognitive implications of predictive coding in affective states. This not only sheds light on the impact of predictive coding for cognition and emotion, but also helps clarify the nature of ambiguous art.
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Affiliation(s)
- Jasper Wolf
- Arts and Sciences Department, UCL, Bloomsbury, London, United Kingdom.
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9
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Zeki S, Chén OY. The Bayesian‐Laplacian brain. Eur J Neurosci 2020; 51:1441-1462. [DOI: 10.1111/ejn.14540] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 07/22/2019] [Accepted: 07/29/2019] [Indexed: 01/29/2023]
Affiliation(s)
- Semir Zeki
- Laboratory of Neurobiology University College London London UK
| | - Oliver Y. Chén
- Laboratory of Neurobiology University College London London UK
- Department of Psychology Yale University New Haven CT USA
- Department of Engineering Science University of Oxford Oxford UK
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Schneider CL, Prentiss EK, Busza A, Matmati K, Matmati N, Williams ZR, Sahin B, Mahon BZ. Survival of retinal ganglion cells after damage to the occipital lobe in humans is activity dependent. Proc Biol Sci 2020; 286:20182733. [PMID: 30963844 PMCID: PMC6408898 DOI: 10.1098/rspb.2018.2733] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Damage to the optic radiations or primary visual cortex leads to blindness in all or part of the contralesional visual field. Such damage disconnects the retina from its downstream targets and, over time, leads to trans-synaptic retrograde degeneration of retinal ganglion cells. To date, visual ability is the only predictor of retinal ganglion cell degeneration that has been investigated after geniculostriate damage. Given prior findings that some patients have preserved visual cortex activity for stimuli presented in their blind field, we tested whether that activity explains variability in retinal ganglion cell degeneration over and above visual ability. We prospectively studied 15 patients (four females, mean age = 63.7 years) with homonymous visual field defects secondary to stroke, 10 of whom were tested within the first two months after stroke. Each patient completed automated Humphrey visual field testing, retinotopic mapping with functional magnetic resonance imaging, and spectral-domain optical coherence tomography of the macula. There was a positive relation between ganglion cell complex (GCC) thickness in the blind field and early visual cortex activity for stimuli presented in the blind field. Furthermore, residual visual cortex activity for stimuli presented in the blind field soon after the stroke predicted the degree of retinal GCC thinning six months later. These findings indicate that retinal ganglion cell survival after ischaemic damage to the geniculostriate pathway is activity dependent.
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Affiliation(s)
- Colleen L Schneider
- 1 Department of Brain and Cognitive Sciences, University of Rochester , Rochester, NY 14627 , USA.,2 Medical Scientist Training Program, University of Rochester School of Medicine and Dentistry , Rochester, NY 14642 , USA.,3 Department of Psychology, Carnegie Mellon University , Pittsburgh, PA 15206 , USA
| | - Emily K Prentiss
- 4 Department of Neurology, University of Rochester Medical Center , Rochester, NY 14642 , USA
| | - Ania Busza
- 4 Department of Neurology, University of Rochester Medical Center , Rochester, NY 14642 , USA
| | - Kelly Matmati
- 7 Department of Neurology, Rochester Regional Health , Rochester, NY 14621 , USA
| | - Nabil Matmati
- 7 Department of Neurology, Rochester Regional Health , Rochester, NY 14621 , USA
| | - Zoë R Williams
- 4 Department of Neurology, University of Rochester Medical Center , Rochester, NY 14642 , USA.,5 Department of Ophthalmology, University of Rochester Medical Center , Rochester, NY 14642 , USA.,6 Department of Neurosurgery, University of Rochester Medical Center , Rochester, NY 14642 , USA
| | - Bogachan Sahin
- 4 Department of Neurology, University of Rochester Medical Center , Rochester, NY 14642 , USA
| | - Bradford Z Mahon
- 3 Department of Psychology, Carnegie Mellon University , Pittsburgh, PA 15206 , USA.,4 Department of Neurology, University of Rochester Medical Center , Rochester, NY 14642 , USA.,6 Department of Neurosurgery, University of Rochester Medical Center , Rochester, NY 14642 , USA.,8 Center for Visual Science, University of Rochester , Rochester, NY 14642 , USA
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11
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Constans C, Ahnine H, Santin M, Lehericy S, Tanter M, Pouget P, Aubry JF. Non-invasive ultrasonic modulation of visual evoked response by GABA delivery through the blood brain barrier. J Control Release 2020; 318:223-231. [DOI: 10.1016/j.jconrel.2019.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 10/25/2019] [Accepted: 12/05/2019] [Indexed: 11/25/2022]
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12
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Neuronavigated TMS of early visual cortex eliminates unconscious processing of chromatic stimuli. Neuropsychologia 2020; 136:107266. [DOI: 10.1016/j.neuropsychologia.2019.107266] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 11/22/2022]
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13
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Vaidya AR, Pujara MS, Petrides M, Murray EA, Fellows LK. Lesion Studies in Contemporary Neuroscience. Trends Cogn Sci 2019; 23:653-671. [PMID: 31279672 PMCID: PMC6712987 DOI: 10.1016/j.tics.2019.05.009] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 05/22/2019] [Accepted: 05/23/2019] [Indexed: 02/06/2023]
Abstract
Studies of humans with focal brain damage and non-human animals with experimentally induced brain lesions have provided pivotal insights into the neural basis of behavior. As the repertoire of neural manipulation and recording techniques expands, the utility of studying permanent brain lesions bears re-examination. Studies on the effects of permanent lesions provide vital data about brain function that are distinct from those of reversible manipulations. Focusing on work carried out in humans and nonhuman primates, we address the inferential strengths and limitations of lesion studies, recent methodological developments, the integration of this approach with other methods, and the clinical and ecological relevance of this research. We argue that lesion studies are essential to the rigorous assessment of neuroscience theories.
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Affiliation(s)
- Avinash R Vaidya
- Department of Cognitive, Linguistic, and Psychological Sciences, Carney Institute for Brain Sciences, Brown University, Providence, RI, USA.
| | - Maia S Pujara
- Section on the Neurobiology of Learning and Memory, Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA.
| | - Michael Petrides
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Elisabeth A Murray
- Section on the Neurobiology of Learning and Memory, Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Lesley K Fellows
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
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14
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Garcea FE, Almeida J, Sims MH, Nunno A, Meyers SP, Li YM, Walter K, Pilcher WH, Mahon BZ. Domain-Specific Diaschisis: Lesions to Parietal Action Areas Modulate Neural Responses to Tools in the Ventral Stream. Cereb Cortex 2019; 29:3168-3181. [PMID: 30169596 PMCID: PMC6933536 DOI: 10.1093/cercor/bhy183] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 07/04/2018] [Indexed: 12/31/2022] Open
Abstract
Neural responses to small manipulable objects ("tools") in high-level visual areas in ventral temporal cortex (VTC) provide an opportunity to test how anatomically remote regions modulate ventral stream processing in a domain-specific manner. Prior patient studies indicate that grasp-relevant information can be computed about objects by dorsal stream structures independently of processing in VTC. Prior functional neuroimaging studies indicate privileged functional connectivity between regions of VTC exhibiting tool preferences and regions of parietal cortex supporting object-directed action. Here we test whether lesions to parietal cortex modulate tool preferences within ventral and lateral temporal cortex. We found that lesions to the left anterior intraparietal sulcus, a region that supports hand-shaping during object grasping and manipulation, modulate tool preferences in left VTC and in the left posterior middle temporal gyrus. Control analyses demonstrated that neural responses to "place" stimuli in left VTC were unaffected by lesions to parietal cortex, indicating domain-specific consequences for ventral stream neural responses in the setting of parietal lesions. These findings provide causal evidence that neural specificity for "tools" in ventral and lateral temporal lobe areas may arise, in part, from online inputs to VTC from parietal areas that receive inputs via the dorsal visual pathway.
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Affiliation(s)
- Frank E Garcea
- University of Rochester, Department of Brain & Cognitive Sciences, 358 Meliora Hall, Rochester, NY, USA
- University of Rochester, Center for Language Sciences, 358 Meliora Hall, Rochester, NY, USA
- University of Rochester, Center for Visual Science, 274 Meliora Hall, Rochester, NY, USA
- Moss Rehabilitation Research Institute, 50 Township Line Road, Elkins Park, PA, USA
| | - Jorge Almeida
- University of Coimbra, Faculty of Psychology and Educational Sciences, Rua do Colégio Novo, Coimbra, Portugal
- University of Coimbra, Proaction Laboratory, Faculty of Psychology and Educational Sciences, Rua do Colégio Novo, Coimbra, Portugal
| | - Maxwell H Sims
- University of Rochester, Department of Brain & Cognitive Sciences, 358 Meliora Hall, Rochester, NY, USA
| | - Andrew Nunno
- University of Rochester, Department of Brain & Cognitive Sciences, 358 Meliora Hall, Rochester, NY, USA
| | - Steven P Meyers
- University of Rochester Medical Center, Department of Imaging Sciences, 601 Elmwood Avenue, Rochester, NY, USA
- University of Rochester Medical Center, Department of Neurosurgery, 601 Elmwood Avenue, Rochester, NY, USA
| | - Yan Michael Li
- University of Rochester Medical Center, Department of Neurosurgery, 601 Elmwood Avenue, Rochester, NY, USA
| | - Kevin Walter
- University of Rochester Medical Center, Department of Neurosurgery, 601 Elmwood Avenue, Rochester, NY, USA
| | - Webster H Pilcher
- University of Rochester Medical Center, Department of Neurosurgery, 601 Elmwood Avenue, Rochester, NY, USA
| | - Bradford Z Mahon
- University of Rochester, Department of Brain & Cognitive Sciences, 358 Meliora Hall, Rochester, NY, USA
- University of Rochester, Center for Language Sciences, 358 Meliora Hall, Rochester, NY, USA
- University of Rochester, Center for Visual Science, 274 Meliora Hall, Rochester, NY, USA
- University of Rochester Medical Center, Department of Neurosurgery, 601 Elmwood Avenue, Rochester, NY, USA
- Department of Neurology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY, USA
- Department of Psychology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA, USA
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15
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Mazzi C, Savazzi S, Silvanto J. On the “blindness” of blindsight: What is the evidence for phenomenal awareness in the absence of primary visual cortex (V1)? Neuropsychologia 2019; 128:103-108. [DOI: 10.1016/j.neuropsychologia.2017.10.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/17/2017] [Accepted: 10/23/2017] [Indexed: 10/18/2022]
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16
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Koenig L, Ro T. Dissociations of conscious and unconscious perception in TMS-induced blindsight. Neuropsychologia 2019; 128:215-222. [DOI: 10.1016/j.neuropsychologia.2018.03.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 03/18/2018] [Accepted: 03/22/2018] [Indexed: 01/26/2023]
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17
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Abstract
The noninvasive estimation of neuronal receptive field (RF) properties in vivo allows a detailed understanding of brain organization as well as its plasticity by longitudinal following of potential changes. Visual RFs measured invasively by electrophysiology in animal models have traditionally provided a great extent of our current knowledge about the visual brain and its disorders. Voxel-based estimates of population RF (pRF) by functional magnetic resonance imaging (fMRI) in humans revolutionized the field and have been used extensively in numerous studies. However, current methods cannot estimate single-neuron RF sizes as they reflect large populations of neurons with individual RF scatter. Here, we introduce an approach to estimate RF size using spatial frequency selectivity to checkerboard patterns. This method allowed us to obtain noninvasive, average single-neuron RF estimates over a large portion of human early visual cortex. These estimates were significantly smaller compared with prior pRF methods. Furthermore, fMRI and electrophysiology experiments in nonhuman primates demonstrated an exceptionally good match, validating the approach.
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18
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Elorette C, Forcelli PA, Saunders RC, Malkova L. Colocalization of Tectal Inputs With Amygdala-Projecting Neurons in the Macaque Pulvinar. Front Neural Circuits 2018; 12:91. [PMID: 30405362 PMCID: PMC6207581 DOI: 10.3389/fncir.2018.00091] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 10/03/2018] [Indexed: 12/25/2022] Open
Abstract
Neuropsychological and neuroimaging studies have suggested the presence of a fast, subcortical route for the processing of emotionally-salient visual information in the primate brain. This putative pathway consists of the superior colliculus (SC), pulvinar and amygdala. While the presence of such a pathway has been confirmed in sub-primate species, it has yet to be documented in the primate brain using conventional anatomical methods. We injected retrograde tracers into the amygdala and anterograde tracers into the colliculus, and examined regions of colocalization of these signals within the pulvinar of the macaque. Anterograde tracers injected into the SC labeled axonal projections within the pulvinar, primarily within the oral, lateral and medial subdivisions. These axonal projections from the colliculus colocalized with cell bodies within the pulvinar that were labeled by retrograde tracer injected into the lateral amygdala. This zone of overlap was most notable in the medial portions of the medial (PM), oral (PO) and inferior pulvinar (PI), and was often densely concentrated in the vicinity of the brachium of the SC. These data provide an anatomical basis for the previously suggested pathway mediating fast processing of emotionally salient information.
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Affiliation(s)
- Catherine Elorette
- Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, DC, United States
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, Washington, DC, United States
| | - Patrick A. Forcelli
- Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, DC, United States
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, Washington, DC, United States
- Department of Neuroscience, Georgetown University School of Medicine, Washington, DC, United States
| | - Richard C. Saunders
- Laboratory of Neuropsychology, National Institute of Mental Health (NIMH), Bethesda, ML, United States
| | - Ludise Malkova
- Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, Washington, DC, United States
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, Washington, DC, United States
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19
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Casco C, Barollo M, Contemori G, Battaglini L. Neural Restoration Training improves visual functions and expands visual field of patients with homonymous visual field defects. Restor Neurol Neurosci 2018. [PMID: 29526854 DOI: 10.3233/rnn-170752] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND In recent years, the introduction of visual rehabilitation for patients with homonymous visual field defects has been met with both enthusiasm and caution. Despite the evidence that restitutive training results in expansion of the visual field, several concerns have been raised. OBJECTIVE We tested the effectiveness of a new rehabilitative protocol called "Neuro Restoration Training" (NRT) in reducing visual field defects and in restituting visual functions in the restored hemianopic area. METHODS Ten patients with homonymous visual field defects (lesion age >6 months) where trained in detecting low contrast Gabor patches randomly presented in the blind field, which refers to regions of 0 dB sensitivity, and along the hemianopic boundary between absolute (0 dB) and partial blindness (>0 dB). Training included static, drifting, and flickering Gabors in different blocks. Positions along the hemianopic boundary were systematically shifted toward the blind field according to the threshold reduction during the training. Before and after the training, we assessed visual field expansion and improvement in different high-level transfer tasks (i.e., letter identification and shape recognition) performed in the hemianopic boundary and in the blind field. RESULTS NRT led to significant visual field enlargement (≈5 deg), as indicated by the conventional Humphrey perimetry, and two custom made evaluations of visual field expansion with eye movement control (one static and one dynamic). The restored area acquired new visual functions such as small letter recognition and perception of moving shapes. Finally, for some patients, NRT also improved detection, either aware or not, of high contrast flickering grating and recognition of geometrical shapes entirely presented within the blind field. CONCLUSION These results suggest that NRT may lead to visual field enlargement and translate into untrained visual functions.
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Affiliation(s)
- Clara Casco
- Department of General Psychology, University of Padova, Padova, Italy.,Neuro.Vis.U.S. Laboratory, University of Padova, Padova, Italy
| | - Michele Barollo
- Department of General Psychology, University of Padova, Padova, Italy.,Neuro.Vis.U.S. Laboratory, University of Padova, Padova, Italy
| | - Giulio Contemori
- Department of General Psychology, University of Padova, Padova, Italy.,Neuro.Vis.U.S. Laboratory, University of Padova, Padova, Italy
| | - Luca Battaglini
- Department of General Psychology, University of Padova, Padova, Italy.,Neuro.Vis.U.S. Laboratory, University of Padova, Padova, Italy
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20
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Prentiss EK, Schneider CL, Williams ZR, Sahin B, Mahon BZ. Spontaneous in-flight accommodation of hand orientation to unseen grasp targets: A case of action blindsight. Cogn Neuropsychol 2018; 35:343-351. [PMID: 29544406 PMCID: PMC6193269 DOI: 10.1080/02643294.2018.1432584] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The division of labour between the dorsal and ventral visual pathways is well established. The ventral stream supports object identification, while the dorsal stream supports online processing of visual information in the service of visually guided actions. Here, we report a case of an individual with a right inferior quadrantanopia who exhibited accurate spontaneous rotation of his wrist when grasping a target object in his blind visual field. His accurate wrist orientation was observed despite the fact that he exhibited no sensitivity to the orientation of the handle in a perceptual matching task. These findings indicate that non-geniculostriate visual pathways process basic volumetric information relevant to grasping, and reinforce the observation that phenomenal awareness is not necessary for an object's volumetric properties to influence visuomotor performance.
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Affiliation(s)
- Emily K. Prentiss
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, NY, USA
| | - Colleen L. Schneider
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, NY, USA
- Medical Scientist Training Program, University of Rochester School of Medicine & Dentistry, Rochester, NY, USA
| | - Zoë R. Williams
- Department of Ophthalmology, University of Rochester Medical Center, Rochester, NY, USA
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
- Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY, USA
| | - Bogachan Sahin
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
| | - Bradford Z. Mahon
- Department of Brain & Cognitive Sciences, University of Rochester, Rochester, NY, USA
- Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA
- Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY, USA
- Center for Visual Science, University of Rochester, Rochester, NY, USA
- Center for Language Science, University of Rochester, Rochester, NY, USA
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21
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Ajina S, Bridge H. Blindsight relies on a functional connection between hMT+ and the lateral geniculate nucleus, not the pulvinar. PLoS Biol 2018; 16:e2005769. [PMID: 30044775 PMCID: PMC6078309 DOI: 10.1371/journal.pbio.2005769] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 08/06/2018] [Accepted: 07/09/2018] [Indexed: 12/23/2022] Open
Abstract
When the primary visual cortex (V1) is damaged, the principal visual pathway is lost, causing a loss of vision in the opposite visual field. While conscious vision is impaired, patients can still respond to certain images; this is known as 'blindsight'. Recently, a direct anatomical connection between the lateral geniculate nucleus (LGN) and human motion area hMT+ has been implicated in blindsight. However, a functional connection between these structures has not been demonstrated. We quantified functional MRI responses to motion in 14 patients with unilateral V1 damage (with and without blindsight). Patients with blindsight showed significant activity and a preserved sensitivity to speed in motion area hMT+, which was absent in patients without blindsight. We then compared functional connectivity between motion area hMT+ and a number of structures implicated in blindsight, including the ventral pulvinar. Only patients with blindsight showed an intact functional connection with the LGN but not the other structures, supporting a specific functional role for the LGN in blindsight.
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Affiliation(s)
- Sara Ajina
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Holly Bridge
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
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22
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Almeida J, Amaral L, Garcea FE, Aguiar de Sousa D, Xu S, Mahon BZ, Martins IP. Visual and visuomotor processing of hands and tools as a case study of cross talk between the dorsal and ventral streams. Cogn Neuropsychol 2018; 35:288-303. [PMID: 29792367 DOI: 10.1080/02643294.2018.1463980] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
A major principle of organization of the visual system is between a dorsal stream that processes visuomotor information and a ventral stream that supports object recognition. Most research has focused on dissociating processing across these two streams. Here we focus on how the two streams interact. We tested neurologically-intact and impaired participants in an object categorization task over two classes of objects that depend on processing within both streams-hands and tools. We measured how unconscious processing of images from one of these categories (e.g., tools) affects the recognition of images from the other category (i.e., hands). Our findings with neurologically-intact participants demonstrated that processing an image of a hand hampers the subsequent processing of an image of a tool, and vice versa. These results were not present in apraxic patients (N = 3). These findings suggest local and global inhibitory processes working in tandem to co-register information across the two streams.
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Affiliation(s)
- Jorge Almeida
- a Faculty of Psychology and Educational Sciences , University of Coimbra , Coimbra , Portugal.,b Faculty of Psychology and Educational Sciences , Proaction Laboratory, University of Coimbra , Coimbra , Portugal
| | - Lénia Amaral
- b Faculty of Psychology and Educational Sciences , Proaction Laboratory, University of Coimbra , Coimbra , Portugal
| | - Frank E Garcea
- c Department of Brain and Cognitive Sciences , University of Rochester , Rochester , NY , USA.,d Center for Visual Science, University of Rochester , Rochester , NY , USA
| | - Diana Aguiar de Sousa
- e Faculty of Medicine , Laboratório de Estudos da Linguagem, Centro de Estudos Egas Moniz, University of Lisbon, Hospital Santa Maria , Lisbon , Portugal
| | - Shan Xu
- f School of Psychology, Beijing Normal University , Beijing , People's Republic of China
| | - Bradford Z Mahon
- c Department of Brain and Cognitive Sciences , University of Rochester , Rochester , NY , USA.,d Center for Visual Science, University of Rochester , Rochester , NY , USA.,g Department of Neurosurgery , University of Rochester , Rochester , NY , USA
| | - Isabel Pavão Martins
- e Faculty of Medicine , Laboratório de Estudos da Linguagem, Centro de Estudos Egas Moniz, University of Lisbon, Hospital Santa Maria , Lisbon , Portugal
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23
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Organization of area hV5/MT+ in subjects with homonymous visual field defects. Neuroimage 2018; 190:254-268. [PMID: 29627591 DOI: 10.1016/j.neuroimage.2018.03.062] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 03/05/2018] [Accepted: 03/26/2018] [Indexed: 11/21/2022] Open
Abstract
Damage to the primary visual cortex (V1) leads to a visual field loss (scotoma) in the retinotopically corresponding part of the visual field. Nonetheless, a small amount of residual visual sensitivity persists within the blind field. This residual capacity has been linked to activity observed in the middle temporal area complex (V5/MT+). However, it remains unknown whether the organization of hV5/MT+ changes following early visual cortical lesions. We studied the organization of area hV5/MT+ of five patients with dense homonymous defects in a quadrant of the visual field as a result of partial V1+ or optic radiation lesions. To do so, we developed a new method, which models the boundaries of population receptive fields directly from the BOLD signal of each voxel in the visual cortex. We found responses in hV5/MT+ arising inside the scotoma for all patients and identified two possible sources of activation: 1) responses might originate from partially lesioned parts of area V1 corresponding to the scotoma, and 2) responses can also originate independent of area V1 input suggesting the existence of functional V1-bypassing pathways. Apparently, visually driven activity observed in hV5/MT+ is not sufficient to mediate conscious vision. More surprisingly, visually driven activity in corresponding regions of V1 and early extrastriate areas including hV5/MT+ did not guarantee visual perception in the group of patients with post-geniculate lesions that we examined. This suggests that the fine coordination of visual activity patterns across visual areas may be an important determinant of whether visual perception persists following visual cortical lesions.
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24
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Abstract
Much remains to be understood about visual system malfunction following injury. The resulting deficits range from dense, visual field scotomas to mild dysfunction of visual perception. Despite the predictive value of anatomical localization studies, much patient-to-patient variability remains regarding (a) perceptual abilities following injury and (b) the capacity of individual patients for visual rehabilitation. Visual field perimetry is used to characterize the visual field deficits that result from visual system injury. However, standard perimetry mapping does not always precisely correspond to underlying anatomical or functional deficits. Functional magnetic resonance imaging can be used to probe the function of surviving visual circuits, allowing us to classify better how the pattern of injury relates to residual visual perception. Identifying pathways that are potentially modifiable by training may guide the development of improved strategies for visual rehabilitation. This review discusses primary visual cortex lesions, which cause dense contralateral scotomas.
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Affiliation(s)
- Stelios M Smirnakis
- Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts 02115.,Department of Neurology, Jamaica Plain Campus, Veterans Administration Boston Healthcare System, Boston, Massachusetts 02130.,Harvard Medical School, Boston, Massachusetts 02115;
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25
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Wandell BA, Le RK. Diagnosing the Neural Circuitry of Reading. Neuron 2017; 96:298-311. [PMID: 29024656 DOI: 10.1016/j.neuron.2017.08.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 07/18/2017] [Accepted: 08/04/2017] [Indexed: 12/21/2022]
Abstract
We summarize the current state of knowledge of the brain's reading circuits, and then we describe opportunities to use quantitative and reproducible methods for diagnosing these circuits. Neural circuit diagnostics-by which we mean identifying the locations and responses in an individual that differ significantly from measurements in good readers-can help parents and educators select the best remediation strategy. A sustained effort to develop and share diagnostic methods can support the societal goal of improving literacy.
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Affiliation(s)
- Brian A Wandell
- Psychology Department, Stanford University, Stanford, CA 94305, USA.
| | - Rosemary K Le
- Psychology Department, Stanford University, Stanford, CA 94305, USA
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26
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Towards building a more complex view of the lateral geniculate nucleus: Recent advances in understanding its role. Prog Neurobiol 2017. [DOI: 10.1016/j.pneurobio.2017.06.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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27
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Rockland KS. What do we know about laminar connectivity? Neuroimage 2017; 197:772-784. [PMID: 28729159 DOI: 10.1016/j.neuroimage.2017.07.032] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 07/13/2017] [Accepted: 07/15/2017] [Indexed: 12/17/2022] Open
Abstract
In this brief review, I attempt an overview of the main components of anatomical laminar-level connectivity. These are: extrinsic outputs, excitatory and inhibitory intrinsic connectivity, and intrinsic inputs. Supporting data are biased from the visual system of nonhuman primates (NHPs), but I have drawn as much as possible from a broader span in order to treat the important issue of area-specific variability. In a second part, I briefly discuss laminar connectivity in the context of network organization (feedforward/feedback cortical connections, and the major types of corticothalamic connections). I also point out anatomical issues in need of clarification, including more systematic, whole brain coverage of tracer injections; more data on anterogradely labeled terminations; more complete, area-specific quantitative data about projection neurons, and quantitative data on terminal density and convergence. Postsynaptic targets are largely unknown, but their identification is essential for understanding the finer analysis and principles of laminar patterns. Laminar resolution MRI offers a promising new tool for exploring laminar connectivity: it is potentially fast and macro-scale, and allows for repeated investigation under different stimulus conditions. Conversely, anatomical resolution, although detailed beyond the current level of MRI visualization, offers a rich trove for experimental design and interpretation of fMRI activation patterns.
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Affiliation(s)
- Kathleen S Rockland
- Department of Anatomy&Neurobiology, Boston University School of Medicine, 72 East Concord St., Boston, MA 02118, USA.
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28
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McCloskey M, Chaisilprungraung T. The value of cognitive neuropsychology: The case of vision research. Cogn Neuropsychol 2017. [PMID: 28649924 DOI: 10.1080/02643294.2017.1342618] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Cognitive neuropsychological evidence is widely viewed as inherently flawed or weak, despite well-reasoned arguments to the contrary by many theorists. Rather than attempting yet another defence of cognitive neuropsychology on logical grounds, we point out through examples that in practice, cognitive neuropsychological evidence is widely accepted as valid and important, and has had a major impact on cognitive theory and research. Objections offered in the abstract rarely arise in the context of actual studies. We develop these points through examples from the domain of vision, discussing cerebral achromatopsia and akinetopsia, selective impairment and sparing of face recognition, perception-action dissociations, and blindsight.
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Affiliation(s)
- Michael McCloskey
- a Department of Cognitive Science , Johns Hopkins University , Baltimore , MD , USA
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29
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Cavanaugh MR, Huxlin KR. Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness. Neurology 2017; 88:1856-1864. [PMID: 28404802 PMCID: PMC5419988 DOI: 10.1212/wnl.0000000000003921] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 02/01/2017] [Indexed: 11/25/2022] Open
Abstract
Objective: To assess if visual discrimination training improves performance on visual perimetry tests in chronic stroke patients with visual cortex involvement. Methods: 24-2 and 10-2 Humphrey visual fields were analyzed for 17 chronic cortically blind stroke patients prior to and following visual discrimination training, as well as in 5 untrained, cortically blind controls. Trained patients practiced direction discrimination, orientation discrimination, or both, at nonoverlapping, blind field locations. All pretraining and posttraining discrimination performance and Humphrey fields were collected with online eye tracking, ensuring gaze-contingent stimulus presentation. Results: Trained patients recovered ∼108 degrees2 of vision on average, while untrained patients spontaneously improved over an area of ∼16 degrees2. Improvement was not affected by patient age, time since lesion, size of initial deficit, or training type, but was proportional to the amount of training performed. Untrained patients counterbalanced their improvements with worsening of sensitivity over ∼9 degrees2 of their visual field. Worsening was minimal in trained patients. Finally, although discrimination performance improved at all trained locations, changes in Humphrey sensitivity occurred both within trained regions and beyond, extending over a larger area along the blind field border. Conclusions: In adults with chronic cortical visual impairment, the blind field border appears to have enhanced plastic potential, which can be recruited by gaze-controlled visual discrimination training to expand the visible field. Our findings underscore a critical need for future studies to measure the effects of vision restoration approaches on perimetry in larger cohorts of patients.
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30
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Ajina S, Bridge H. Blindsight and Unconscious Vision: What They Teach Us about the Human Visual System. Neuroscientist 2016; 23:529-541. [PMID: 27777337 DOI: 10.1177/1073858416673817] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Damage to the primary visual cortex removes the major input from the eyes to the brain, causing significant visual loss as patients are unable to perceive the side of the world contralateral to the damage. Some patients, however, retain the ability to detect visual information within this blind region; this is known as blindsight. By studying the visual pathways that underlie this residual vision in patients, we can uncover additional aspects of the human visual system that likely contribute to normal visual function but cannot be revealed under physiological conditions. In this review, we discuss the residual abilities and neural activity that have been described in blindsight and the implications of these findings for understanding the intact system.
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Affiliation(s)
- Sara Ajina
- 1 Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Holly Bridge
- 1 Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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31
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Shapcott KA, Schmiedt JT, Saunders RC, Maier A, Leopold DA, Schmid MC. Correlated activity of cortical neurons survives extensive removal of feedforward sensory input. Sci Rep 2016; 6:34886. [PMID: 27721468 PMCID: PMC5056506 DOI: 10.1038/srep34886] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 09/19/2016] [Indexed: 11/09/2022] Open
Abstract
A fundamental property of brain function is that the spiking activity of cortical neurons is variable and that some of this variability is correlated between neurons. Correlated activity not due to the stimulus arises from shared input but the neuronal circuit mechanisms that result in these noise correlations are not fully understood. Here we tested in the visual system if correlated variability in mid-level area V4 of visual cortex is altered following extensive lesions of primary visual cortex (V1). To this end we recorded longitudinally the neuronal correlations in area V4 of two behaving macaque monkeys before and after a V1 lesion while the monkeys fixated a grey screen. We found that the correlations of neuronal activity survived the lesions in both monkeys. In one monkey, the correlation of multi-unit spiking signals was strongly increased in the first week post-lesion, while in the second monkey, correlated activity was slightly increased, but not greater than some week-by-week fluctuations observed. The typical drop-off of inter-neuronal correlations with cortical distance was preserved after the lesion. Therefore, as V4 noise correlations remain without feedforward input from V1, these results suggest instead that local and/or feedback input seem to be necessary for correlated activity.
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Affiliation(s)
- Katharine A Shapcott
- Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with Max Planck Society, 60528 Frankfurt, Germany
| | - Joscha T Schmiedt
- Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with Max Planck Society, 60528 Frankfurt, Germany
| | - Richard C Saunders
- Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland 20892, USA
| | - Alexander Maier
- Vanderbilt University, Department of Psychology, Nashville, Tennessee 37240, USA
| | - David A Leopold
- Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland 20892, USA.,Neurophysiology Imaging Facility, National Institute of Mental Health, National Institute of Neurological Disorders and Stroke, and National Eye Institute, Bethesda, Maryland 20892, USA
| | - Michael C Schmid
- Ernst Strüngmann Institute (ESI) for Neuroscience in cooperation with Max Planck Society, 60528 Frankfurt, Germany.,Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
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Ross AI, Schenk T, Billino J, Macleod MJ, Hesse C. Avoiding unseen obstacles: Subcortical vision is not sufficient to maintain normal obstacle avoidance behaviour during reaching. Cortex 2016; 98:177-193. [PMID: 27773358 DOI: 10.1016/j.cortex.2016.09.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 09/15/2016] [Accepted: 09/18/2016] [Indexed: 10/20/2022]
Abstract
Previous research found that a patient with cortical blindness (homonymous hemianopia) was able to successfully avoid an obstacle placed in his blind field, despite reporting no conscious awareness of it [Striemer, C. L., Chapman, C. S., & Goodale, M. A., 2009, PNAS, 106(37), 15996-16001]. This finding led to the suggestion that dorsal stream areas, that are assumed to mediate obstacle avoidance behaviour, may obtain their visual input primarily from subcortical pathways. Hence, it was suggested that normal obstacle avoidance behaviour can proceed without input from the primary visual cortex. Here we tried to replicate this finding in a group of patients (N = 6) that suffered from highly circumscribed lesions in the occipital lobe (including V1) that spared the subcortical structures that have been associated with action-blindsight. We also tested if obstacle avoidance behaviour differs depending on whether obstacles are placed only in the blind field or in both the blind and intact visual field of the patients simultaneously. As expected, all patients successfully avoided obstacles placed in their intact visual field. However, none of them showed reliable avoidance behaviour - as indicated by adjustments in the hand trajectory in response to obstacle position - for obstacles placed in their blind visual field. The effects were not dependent on whether one or two obstacles were present. These findings suggest that behaviour in complex visuomotor tasks relies on visual input from occipital areas.
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Affiliation(s)
- Alasdair I Ross
- School of Psychology, University of Aberdeen, Aberdeen, United Kingdom
| | - Thomas Schenk
- Clinical Neuropsychology, Ludwig-Maximilians-Universität München, Germany
| | - Jutta Billino
- Experimental Psychology, Justus-Liebig-Universität, Giessen, Germany
| | - Mary J Macleod
- School of Medicine & Dentistry, University of Aberdeen, Aberdeen, United Kingdom
| | - Constanze Hesse
- School of Psychology, University of Aberdeen, Aberdeen, United Kingdom.
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Zeki S. Multiple asynchronous stimulus- and task-dependent hierarchies (STDH) within the visual brain's parallel processing systems. Eur J Neurosci 2016; 44:2515-2527. [DOI: 10.1111/ejn.13270] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 04/25/2016] [Accepted: 05/03/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Semir Zeki
- Wellcome Laboratory of Neurobiology; University College London; London WC1E 6BT UK
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Abstract
Whether the visual brain uses a parallel or a serial, hierarchical, strategy to process visual signals, the end result appears to be that different attributes of the visual scene are perceived asynchronously--with colour leading form (orientation) by 40 ms and direction of motion by about 80 ms. Whatever the neural root of this asynchrony, it creates a problem that has not been properly addressed, namely how visual attributes that are perceived asynchronously over brief time windows after stimulus onset are bound together in the longer term to give us a unified experience of the visual world, in which all attributes are apparently seen in perfect registration. In this review, I suggest that there is no central neural clock in the (visual) brain that synchronizes the activity of different processing systems. More likely, activity in each of the parallel processing-perceptual systems of the visual brain is reset independently, making of the brain a massively asynchronous organ, just like the new generation of more efficient computers promise to be. Given the asynchronous operations of the brain, it is likely that the results of activities in the different processing-perceptual systems are not bound by physiological interactions between cells in the specialized visual areas, but post-perceptually, outside the visual brain.
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Affiliation(s)
- Semir Zeki
- Laboratory of Neurobiology, University College London, London WC1E 6BT, UK
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35
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Coordinated Neuronal Activity Enhances Corticocortical Communication. Neuron 2015; 87:827-39. [PMID: 26291164 DOI: 10.1016/j.neuron.2015.07.026] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 06/12/2015] [Accepted: 07/21/2015] [Indexed: 11/22/2022]
Abstract
Relaying neural signals between cortical areas is central to cognition and sensory processing. The temporal coordination of activity in a source population has been suggested to determine corticocortical signaling efficacy, but others have argued that coordination is functionally irrelevant. We reasoned that if coordination significantly influenced signaling, spiking in downstream networks should be preceded by transiently elevated coordination in a source population. We developed a metric to quantify network coordination in brief epochs, and applied it to simultaneous recordings of neuronal populations in cortical areas V1 and V2 of the macaque monkey. Spiking in the input layers of V2 was preceded by brief epochs of elevated V1 coordination, but this was not the case in other layers of V2. Our results indicate that V1 coordination influences its signaling to direct downstream targets, but that coordinated V1 epochs do not propagate through multiple downstream networks as in some corticocortical signaling schemes.
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Abstract
Area V5 of the visual brain, first identified anatomically in 1969 as a separate visual area, is critical for the perception of visual motion. As one of the most intensively studied parts of the visual brain, it has yielded many insights into how the visual brain operates. Among these are: the diversity of signals that determine the functional capacities of a visual area; the relationship between single cell activity in a specialized visual area and perception of, and preference for, attributes of a visual stimulus; the multiple asynchronous inputs into, and outputs from, an area as well as the multiple operations that it undertakes asynchronously; the relationship between activity at given, specialized, areas of the visual brain and conscious awareness; and the mechanisms used to “bind” signals from one area with those from another, with a different specialization, to give us our unitary perception of the visual world. Hence V5 is, in a sense, a microcosm of the visual world and its study gives important insights into how the whole visual brain is organized—anatomically, functionally and perceptually.
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Affiliation(s)
- Semir Zeki
- Wellcome Laboratory of Neurobiology, Cell and Developmental Biology, University College London London, UK
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37
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Schmid MC, Maier A. To see or not to see--thalamo-cortical networks during blindsight and perceptual suppression. Prog Neurobiol 2015; 126:36-48. [PMID: 25661166 DOI: 10.1016/j.pneurobio.2015.01.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 01/05/2015] [Accepted: 01/14/2015] [Indexed: 11/15/2022]
Abstract
Even during moments when we fail to be fully aware of our environment, our brains never go silent. Instead, it appears that the brain can also operate in an alternate, unconscious mode. Delineating unconscious from conscious neural processes is a promising first step toward investigating how awareness emerges from brain activity. Here we focus on recent insights into the neuronal processes that contribute to visual function in the absence of a conscious visual percept. Drawing on insights from findings on the phenomenon of blindsight that results from injury to primary visual cortex and the results of experimentally induced perceptual suppression, we describe what kind of visual information the visual system analyzes unconsciously and we discuss the neuronal routing and responses that accompany this process. We conclude that unconscious processing of certain visual stimulus attributes, such as the presence of visual motion or the emotional expression of a face can occur in a geniculo-cortical circuit that runs independent from and in parallel to the predominant route through primary visual cortex. We speculate that in contrast, bidirectional neuronal interactions between cortex and the thalamic pulvinar nucleus that support large-scale neuronal integration and visual awareness are impeded during blindsight and perceptual suppression.
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Affiliation(s)
- Michael C Schmid
- Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Deutschordenstraße 46, Frankfurt a. M. 60528, Germany.
| | - Alexander Maier
- Vanderbilt University, Department of Psychology, 111 21st Avenue South, 301 Wilson Hall, Nashville, TN 37240, USA.
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Abstract
In 1998 several groups reported the feasibility of fMRI experiments in monkeys, with the goal to bridge the gap between invasive nonhuman primate studies and human functional imaging. These studies yielded critical insights in the neuronal underpinnings of the BOLD signal. Furthermore, the technology has been successful in guiding electrophysiological recordings and identifying focal perturbation targets. Finally, invaluable information was obtained concerning human brain evolution. We here provide a comprehensive overview of awake monkey fMRI studies mainly confined to the visual system. We review the latest insights about the topographic organization of monkey visual cortex and discuss the spatial relationships between retinotopy and category- and feature-selective clusters. We briefly discuss the functional layout of parietal and frontal cortex and continue with a summary of some fascinating functional and effective connectivity studies. Finally, we review recent comparative fMRI experiments and speculate about the future of nonhuman primate imaging.
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Affiliation(s)
- Wim Vanduffel
- Laboratory for Neuro- and Psychophysiology, KU Leuven Medical School, Campus Gasthuisberg, Leuven, 3000, Belgium; Department of Radiology, Harvard Medical School, Boston, MA 02129, USA; A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA.
| | - Qi Zhu
- Laboratory for Neuro- and Psychophysiology, KU Leuven Medical School, Campus Gasthuisberg, Leuven, 3000, Belgium
| | - Guy A Orban
- Laboratory for Neuro- and Psychophysiology, KU Leuven Medical School, Campus Gasthuisberg, Leuven, 3000, Belgium; Department of Neuroscience, University of Parma, Parma, 43125, Italy
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Abstract
Behavioral responses to visual stimuli exhibit visual field asymmetries, but cortical folding and the close proximity of visual cortical areas make electrophysiological comparisons between different stimulus locations problematic. Retinotopy-constrained source estimation (RCSE) uses distributed dipole models simultaneously constrained by multiple stimulus locations to provide separation between individual visual areas that is not possible with conventional source estimation methods. Magnetoencephalography and RCSE were used to estimate time courses of activity in V1, V2, V3, and V3A. Responses to left and right hemifield stimuli were not significantly different. Peak latencies for peripheral stimuli were significantly shorter than those for perifoveal stimuli in V1, V2, and V3A, likely related to the greater proportion of magnocellular input to V1 in the periphery. Consistent with previous results, sensor magnitudes for lower field stimuli were about twice as large as for upper field, which is only partially explained by the proximity to sensors for lower field cortical sources in V1, V2, and V3. V3A exhibited both latency and amplitude differences for upper and lower field responses. There were no differences for V3, consistent with previous suggestions that dorsal and ventral V3 are two halves of a single visual area, rather than distinct areas V3 and VP.
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Affiliation(s)
- Donald J Hagler
- Department of Radiology, University of California-San Diego, La Jolla, CA, USA
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40
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Shigihara Y, Zeki S. Parallel processing of face and house stimuli by V1 and specialized visual areas: a magnetoencephalographic (MEG) study. Front Hum Neurosci 2014; 8:901. [PMID: 25426050 PMCID: PMC4224090 DOI: 10.3389/fnhum.2014.00901] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 10/21/2014] [Indexed: 11/25/2022] Open
Abstract
We used easily distinguishable stimuli of faces and houses constituted from straight lines, with the aim of learning whether they activate V1 on the one hand, and the specialized areas that are critical for the processing of faces and houses on the other, with similar latencies. Eighteen subjects took part in the experiment, which used magnetoencephalography (MEG) coupled to analytical methods to detect the time course of the earliest responses which these stimuli provoke in these cortical areas. Both categories of stimuli activated V1 and areas of the visual cortex outside it at around 40 ms after stimulus onset, and the amplitude elicited by face stimuli was significantly larger than that elicited by house stimuli. These results suggest that “low-level” and “high-level” features of form stimuli are processed in parallel by V1 and visual areas outside it. Taken together with our previous results on the processing of simple geometric forms (Shgihara and Zeki, 2013; Shigihara and Zeki, 2014), the present ones reinforce the conclusion that parallel processing is an important component in the strategy used by the brain to process and construct forms.
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Affiliation(s)
| | - Semir Zeki
- Wellcome Laboratory of Neurobiology, University College London London, UK
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41
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Foley R. The case for characterising type-2 blindsight as a genuinely visual phenomenon. Conscious Cogn 2014; 32:56-67. [PMID: 25444645 DOI: 10.1016/j.concog.2014.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 09/08/2014] [Accepted: 09/12/2014] [Indexed: 11/25/2022]
Abstract
Type-2 blindsight is often characterised as involving a non-visual form of awareness that blindsight subjects experience under certain presentation conditions. This paper evaluates the claim that type-2 awareness is non-visual and the proposal that it is a cognitive form of awareness. It is argued that, contrary to the standard account, type-2 awareness is best characterised as visual both because it satisfies certain criteria for being visual and because it can accommodate facts about the phenomenon that the cognitive account cannot. The conclusion is made that type-2 blindsight is best characterised as involving a form of abnormal, degraded visual awareness.
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Affiliation(s)
- Robert Foley
- The Rotman Institute, Western University, Stevenson Hall 2150G, London, Ontario N6A 5B8, Canada.
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42
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Abstract
The local field potential (LFP) in visual cortex is typically characterized by the following spectral pattern: before the onset of a visual stimulus, low-frequency oscillations (beta, 12-20 Hz) dominate, whereas during the presentation of a stimulus these oscillations diminish and are replaced by fluctuations at higher frequencies (gamma, >30 Hz). The origin of beta oscillations in vivo remains unclear, as is the basis of their suppression during visual stimulation. Here we investigate the contribution of ascending input from primary visual cortex (V1) to beta oscillation dynamics in extrastriate visual area V4 of behaving monkeys. We recorded LFP activity in V4 before and after resecting a portion of V1. After the surgery, the visually induced gamma LFP activity in the lesion projection zone of V4 was markedly reduced, consistent with previously reported spiking responses (Schmid et al., 2013). In the beta LFP range, the lesion had minimal effect on the normal pattern of spontaneous oscillations. However, the lesion led to a surprising and permanent reversal of the normal beta suppression during visual stimulation, with visual stimuli eliciting beta magnitude increases up to 50%, particularly in response to moving stimuli. This reversed beta activity pattern was specific to stimulus locations affected by the V1 lesion. Our results shed light on the mechanisms of beta activity in extrastriate visual cortex: The preserved spontaneous oscillations point to a generation mechanism independent of the geniculostriate pathway, whereas the positive beta responses support the contribution of visual information to V4 via direct thalamo-extrastriate projections.
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43
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Silvanto J. Why is "blindsight" blind? A new perspective on primary visual cortex, recurrent activity and visual awareness. Conscious Cogn 2014; 32:15-32. [PMID: 25263935 DOI: 10.1016/j.concog.2014.08.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 07/30/2014] [Accepted: 08/04/2014] [Indexed: 01/19/2023]
Abstract
The neuropsychological phenomenon of blindsight has been taken to suggest that the primary visual cortex (V1) plays a unique role in visual awareness, and that extrastriate activation needs to be fed back to V1 in order for the content of that activation to be consciously perceived. The aim of this review is to evaluate this theoretical framework and to revisit its key tenets. Firstly, is blindsight truly a dissociation of awareness and visual detection? Secondly, is there sufficient evidence to rule out the possibility that the loss of awareness resulting from a V1 lesion simply reflects reduced extrastriate responsiveness, rather than a unique role of V1 in conscious experience? Evaluation of these arguments and the empirical evidence leads to the conclusion that the loss of phenomenal awareness in blindsight may not be due to feedback activity in V1 being the hallmark awareness. On the basis of existing literature, an alternative explanation of blindsight is proposed. In this view, visual awareness is a "global" cognitive function as its hallmark is the availability of information to a large number of perceptual and cognitive systems; this requires inter-areal long-range synchronous oscillatory activity. For these oscillations to arise, a specific temporal profile of neuronal activity is required, which is established through recurrent feedback activity involving V1 and the extrastriate cortex. When V1 is lesioned, the loss of recurrent activity prevents inter-areal networks on the basis of oscillatory activity. However, as limited amount of input can reach extrastriate cortex and some extrastriate neuronal selectivity is preserved, computations involving comparison of neural firing rates within a cortical area remain possible. This enables "local" read-out from specific brain regions, allowing for the detection and discrimination of basic visual attributes. Thus blindsight is blind due to lack of "global" long-range synchrony, and it functions via "local" neural readout from extrastriate areas.
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Affiliation(s)
- Juha Silvanto
- University of Westminster, Faculty of Science and Technology, Department of Psychology, 309 Regent Street, W1B 2HW London, UK; Brain Research Unit, O.V. Lounasmaa Laboratory, School of Science, Aalto University, PO BOX 15100, 00076 Aalto, Finland.
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44
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Markov NT, Vezoli J, Chameau P, Falchier A, Quilodran R, Huissoud C, Lamy C, Misery P, Giroud P, Ullman S, Barone P, Dehay C, Knoblauch K, Kennedy H. Anatomy of hierarchy: feedforward and feedback pathways in macaque visual cortex. J Comp Neurol 2014; 522:225-59. [PMID: 23983048 PMCID: PMC4255240 DOI: 10.1002/cne.23458] [Citation(s) in RCA: 417] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 04/10/2013] [Accepted: 08/14/2013] [Indexed: 12/18/2022]
Abstract
The laminar location of the cell bodies and terminals of interareal connections determines the hierarchical structural organization of the cortex and has been intensively studied. However, we still have only a rudimentary understanding of the connectional principles of feedforward (FF) and feedback (FB) pathways. Quantitative analysis of retrograde tracers was used to extend the notion that the laminar distribution of neurons interconnecting visual areas provides an index of hierarchical distance (percentage of supragranular labeled neurons [SLN]). We show that: 1) SLN values constrain models of cortical hierarchy, revealing previously unsuspected areal relations; 2) SLN reflects the operation of a combinatorial distance rule acting differentially on sets of connections between areas; 3) Supragranular layers contain highly segregated bottom-up and top-down streams, both of which exhibit point-to-point connectivity. This contrasts with the infragranular layers, which contain diffuse bottom-up and top-down streams; 4) Cell filling of the parent neurons of FF and FB pathways provides further evidence of compartmentalization; 5) FF pathways have higher weights, cross fewer hierarchical levels, and are less numerous than FB pathways. Taken together, the present results suggest that cortical hierarchies are built from supra- and infragranular counterstreams. This compartmentalized dual counterstream organization allows point-to-point connectivity in both bottom-up and top-down directions.
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Affiliation(s)
- Nikola T Markov
- Stem Cell and Brain Research Institute, INSERM U846, 69500, Bron, France; Université de Lyon, Université Lyon I, 69003, Lyon, France; Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, 06520-8001, USA
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Shigihara Y, Zeki S. Parallel processing in the brain's visual form system: an fMRI study. Front Hum Neurosci 2014; 8:506. [PMID: 25126064 PMCID: PMC4115635 DOI: 10.3389/fnhum.2014.00506] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 06/23/2014] [Indexed: 11/17/2022] Open
Abstract
We here extend and complement our earlier time-based, magneto-encephalographic (MEG), study of the processing of forms by the visual brain (Shigihara and Zeki, 2013) with a functional magnetic resonance imaging (fMRI) study, in order to better localize the activity produced in early visual areas when subjects view simple geometric stimuli of increasing perceptual complexity (lines, angles, rhombuses) constituted from the same elements (lines). Our results show that all three categories of form activate all three visual areas with which we were principally concerned (V1–V3), with angles producing the strongest and rhombuses the weakest activity in all three. The difference between the activity produced by angles and rhombuses was significant, that between lines and rhombuses was trend significant while that between lines and angles was not. Taken together with our earlier MEG results, the present ones suggest that a parallel strategy is used in processing forms, in addition to the well-documented hierarchical strategy.
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Affiliation(s)
| | - Semir Zeki
- Wellcome Laboratory of Neurobiology, University College London London, UK
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46
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Population receptive field analysis of the primary visual cortex complements perimetry in patients with homonymous visual field defects. Proc Natl Acad Sci U S A 2014; 111:E1656-65. [PMID: 24706881 DOI: 10.1073/pnas.1317074111] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Injury to the primary visual cortex (V1) typically leads to loss of conscious vision in the corresponding, homonymous region of the contralateral visual hemifield (scotoma). Several studies suggest that V1 is highly plastic after injury to the visual pathways, whereas others have called this conclusion into question. We used functional magnetic resonance imaging (fMRI) to measure area V1 population receptive field (pRF) properties in five patients with partial or complete quadrantic visual field loss as a result of partial V1+ or optic radiation lesions. Comparisons were made with healthy controls deprived of visual stimulation in one quadrant ["artificial scotoma" (AS)]. We observed no large-scale changes in spared-V1 topography as the V1/V2 border remained stable, and pRF eccentricity versus cortical-distance plots were similar to those of controls. Interestingly, three observations suggest limited reorganization: (i) the distribution of pRF centers in spared-V1 was shifted slightly toward the scotoma border in 2 of 5 patients compared with AS controls; (ii) pRF size in spared-V1 was slightly increased in patients near the scotoma border; and (iii) pRF size in the contralesional hemisphere was slightly increased compared with AS controls. Importantly, pRF measurements yield information about the functional properties of spared-V1 cortex not provided by standard perimetry mapping. In three patients, spared-V1 pRF maps overlapped significantly with dense regions of the perimetric scotoma, suggesting that pRF analysis may help identify visual field locations amenable to rehabilitation. Conversely, in the remaining two patients, spared-V1 pRF maps failed to cover sighted locations in the perimetric map, indicating the existence of V1-bypassing pathways able to mediate useful vision.
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47
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Teo L, Bourne JA. A reproducible and translatable model of focal ischemia in the visual cortex of infant and adult marmoset monkeys. Brain Pathol 2014; 24:459-74. [PMID: 25469561 DOI: 10.1111/bpa.12129] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 01/21/2014] [Indexed: 12/12/2022] Open
Abstract
Models of ischemic brain injury in the nonhuman primate (NHP) are advantageous for investigating mechanisms of central nervous system (CNS) injuries and testing of new therapeutic strategies. However, issues of reproducibility and survivability persist in NHP models of CNS injuries. Furthermore, there are currently no pediatric NHP models of ischemic brain injury. Therefore, we have developed a NHP model of cortical focal ischemia that is highly reproducible throughout life to enable better understanding of downstream consequences of injury. Posterior cerebral arterial occlusion was induced through intracortical injections of endothelin-1 in adult (n = 5) and neonatal (n = 3) marmosets, followed by magnetic resonance imaging (MRI), histology and immunohistochemistry. MRI revealed tissue hyperintensity at the lesion site at 1-7 days followed by isointensity at 14-21 days. Peripheral macrophage and serum albumin infiltration was detected at 1 day, persisting at 21 days. The proportional loss of total V1 as a result of infarction was consistent in adults and neonates. Minor hemorrhagic transformation was detected at 21 days at the lesion core, while neovascularization was detected in neonates, but not in adults. We have developed a highly reproducible and survivable model of focal ischemia in the adult and neonatal marmoset primary visual cortex, demonstrating similar downstream anatomical and cellular pathology to those observed in post-ischemic humans.
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Affiliation(s)
- Leon Teo
- Australian Regenerative Medicine Institute, Monash University, Clayton, Vic., Australia
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48
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Tohmi M, Meguro R, Tsukano H, Hishida R, Shibuki K. The extrageniculate visual pathway generates distinct response properties in the higher visual areas of mice. Curr Biol 2014; 24:587-97. [PMID: 24583013 DOI: 10.1016/j.cub.2014.01.061] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 11/29/2013] [Accepted: 01/29/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Visual information conveyed through the extrageniculate visual pathway, which runs from the retina via the superior colliculus (SC) and the lateral posterior nucleus (LPN) of the thalamus to the higher visual cortex, plays a critical role in the visual capabilities of many mammalian species. However, its functional role in the higher visual cortex remains unclear. Here, we observed visual cortical area activity in anesthetized mice to evaluate the role of the extrageniculate pathway on their specialized visual properties. RESULTS The preferred stimulus velocities of neurons in the higher visual areas (lateromedial [LM], anterolateral [AL], anteromedial [AM], and rostrolateral [RL] areas) were measured using flavoprotein fluorescence imaging and two-photon calcium imaging and were higher than those in the primary visual cortex (V1). Further, the velocity-tuning properties of the higher visual areas were different from each other. The response activities in these areas decreased after V1 ablation; however, the visual properties' differences were preserved. After SC destruction, these preferences for high velocities disappeared, and their tuning profiles became similar to that of the V1, whereas the tuning profile of the V1 remained relatively normal. Neural tracer experiments revealed that each of these higher visual areas connected with specific subregions of the LPN. CONCLUSIONS The preservation of visual property differences among the higher visual areas following V1 lesions and their loss following SC lesions indicate that pathways from the SC through the thalamus to higher cortical areas are sufficient to support these differences.
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Affiliation(s)
- Manavu Tohmi
- Department of Neurophysiology, Brain Research Institute, Niigata University, 1-757 Asahi-machi, Chuo-ku, Niigata 951-8585, Japan.
| | - Reiko Meguro
- Department of Neurobiology and Anatomy, Niigata University School of Medicine, 1-757 Asahi-machi, Chuo-ku, Niigata 951-8510, Japan
| | - Hiroaki Tsukano
- Department of Neurophysiology, Brain Research Institute, Niigata University, 1-757 Asahi-machi, Chuo-ku, Niigata 951-8585, Japan
| | - Ryuichi Hishida
- Department of Neurophysiology, Brain Research Institute, Niigata University, 1-757 Asahi-machi, Chuo-ku, Niigata 951-8585, Japan
| | - Katsuei Shibuki
- Department of Neurophysiology, Brain Research Institute, Niigata University, 1-757 Asahi-machi, Chuo-ku, Niigata 951-8585, Japan
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49
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Kaneko T, Sakai T, Miyabe-Nishiwaki T, Tomonaga M. A case of naturally occurring visual field loss in a chimpanzee with an arachnoid cyst. Neuropsychologia 2013; 51:2856-62. [PMID: 24036355 DOI: 10.1016/j.neuropsychologia.2013.09.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Revised: 08/26/2013] [Accepted: 09/04/2013] [Indexed: 10/26/2022]
Abstract
Deficits in the occipital cortex have varying consequences among mammalian species. Such variations are indicative of evolutionary transitions in the striate cortical contribution to visually guided behavior. However, little is known about the role of the striate cortex in visually guided behavior in chimpanzees due to ethical concerns about invasive experiments and methodological limitations such as the inability to monitor gaze movements. We had the opportunity to study the behavioral consequences of a deficit in the occipital cortex in a chimpanzee with a naturally occurring arachnoid cyst in her right occipital lobe. We assessed the chimpanzee's ability to detect a small light probe (0.5 visual degree, Michelson contrast > 0.9) presented at several locations in the visual field while monitoring gaze direction using an infra-red remote eye-tracker recently introduced to studies of great apes. The results showed the chimpanzee was unable to detect the probe in the lower left quadrant of the visual field, suggesting severe loss of contrast sensitivity in a part of hemivisual field that is retinotopically corresponded to the hemisphere of the cyst. A chimpanzee with a naturally occurring deficit in the right striate cortex and the availability of remote eye-tracking technology presented a unique opportunity to compare the role of the occipital lobe in visually guided behavior among various primate species.
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Affiliation(s)
- Takaaki Kaneko
- Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan.
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Binda P, Thomas JM, Boynton GM, Fine I. Minimizing biases in estimating the reorganization of human visual areas with BOLD retinotopic mapping. J Vis 2013; 13:13. [PMID: 23788461 DOI: 10.1167/13.7.13] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
There is substantial interest in using functional magnetic resonance imaging (fMRI) retinotopic mapping techniques to examine reorganization of the occipital cortex after vision loss in humans and nonhuman primates. However, previous reports suggest that standard phase encoding and the more recent population Receptive Field (pRF) techniques give biased estimates of retinotopic maps near the boundaries of retinal or cortical scotomas. Here we examine the sources of this bias and show how it can be minimized with a simple modification of the pRF method. In normally sighted subjects, we measured fMRI responses to a stimulus simulating a foveal scotoma; we found that unbiased retinotopic map estimates can be obtained in early visual areas, as long as the pRF fitting algorithm takes the scotoma into account and a randomized "multifocal" stimulus sequence is used.
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Affiliation(s)
- Paola Binda
- Department of Psychology, University of Washington, Seattle, WA, USA.
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