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Schwartz R, Rozier C, Seidel Malkinson T, Lehongre K, Adam C, Lambrecq V, Navarro V, Naccache L, Axelrod V. Comparing stimulus-evoked and spontaneous response of the face-selective multi-units in the human posterior fusiform gyrus. Neurosci Conscious 2021; 2021:niab033. [PMID: 34667640 PMCID: PMC8520048 DOI: 10.1093/nc/niab033] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 08/03/2021] [Accepted: 09/02/2021] [Indexed: 11/23/2022] Open
Abstract
The stimulus-evoked neural response is a widely explored phenomenon. Conscious awareness is associated in many cases with the corresponding selective stimulus-evoked response. For example, conscious awareness of a face stimulus is associated with or accompanied by stimulus-evoked activity in the fusiform face area (FFA). In addition to the stimulus-evoked response, spontaneous (i.e. task-unrelated) activity in the brain is also abundant. Notably, spontaneous activity is considered unconscious. For example, spontaneous activity in the FFA is not associated with conscious awareness of a face. The question is: what is the difference at the neural level between stimulus-evoked activity in a case that this activity is associated with conscious awareness of some content (e.g. activity in the FFA in response to fully visible face stimuli) and spontaneous activity in that same region of the brain? To answer this question, in the present study, we had a rare opportunity to record two face-selective multi-units in the vicinity of the FFA in a human patient. We compared multi-unit face-selective task-evoked activity with spontaneous prestimulus and a resting-state activity. We found that when activity was examined over relatively long temporal windows (e.g. 100–200 ms), face-selective stimulus-evoked firing in the recorded multi-units was much higher than the spontaneous activity. In contrast, when activity was examined over relatively short windows, we found many cases of high firing rates within the spontaneous activity that were comparable to stimulus-evoked activity. Our results thus indicate that the sustained activity is what might differentiate between stimulus-evoked activity that is associated with conscious awareness and spontaneous activity.
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Affiliation(s)
- Rina Schwartz
- The Gonda Multidisciplinary Brain Research Center, Bar Ilan University, Ramat Gan 52900, Israel
| | - Camille Rozier
- Institut National de la Santé et de la Recherche Médicale Unité 1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche (UMR) 7225, Université Pierre-et-Marie-Curie Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière ICM, Paris 75013, France
| | - Tal Seidel Malkinson
- Institut National de la Santé et de la Recherche Médicale Unité 1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche (UMR) 7225, Université Pierre-et-Marie-Curie Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière ICM, Paris 75013, France
| | - Katia Lehongre
- Institut National de la Santé et de la Recherche Médicale Unité 1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche (UMR) 7225, Université Pierre-et-Marie-Curie Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière ICM, Paris 75013, France
| | - Claude Adam
- Neurology Department, AP-HP, GH Pitie-Salpêtrière-Charles Foix, Epilepsy Unit, 47-83 boulevard de l'Hôpital, Paris 75013, France
| | - Virginie Lambrecq
- Institut National de la Santé et de la Recherche Médicale Unité 1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche (UMR) 7225, Université Pierre-et-Marie-Curie Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière ICM, Paris 75013, France
| | - Vincent Navarro
- Institut National de la Santé et de la Recherche Médicale Unité 1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche (UMR) 7225, Université Pierre-et-Marie-Curie Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière ICM, Paris 75013, France
| | - Lionel Naccache
- Institut National de la Santé et de la Recherche Médicale Unité 1127, Centre National de la Recherche Scientifique Unité Mixte de Recherche (UMR) 7225, Université Pierre-et-Marie-Curie Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle Épinière ICM, Paris 75013, France
| | - Vadim Axelrod
- The Gonda Multidisciplinary Brain Research Center, Bar Ilan University, Ramat Gan 52900, Israel
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Stein T, Kaiser D, Fahrenfort JJ, van Gaal S. The human visual system differentially represents subjectively and objectively invisible stimuli. PLoS Biol 2021; 19:e3001241. [PMID: 33951043 PMCID: PMC8128378 DOI: 10.1371/journal.pbio.3001241] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 05/17/2021] [Accepted: 04/20/2021] [Indexed: 11/18/2022] Open
Abstract
The study of unconscious processing requires a measure of conscious awareness. Awareness measures can be either subjective (based on participant's report) or objective (based on perceptual performance). The preferred awareness measure depends on the theoretical position about consciousness and may influence conclusions about the extent of unconscious processing and about the neural correlates of consciousness. We obtained functional magnetic resonance imaging (fMRI) measurements from 43 subjects while they viewed masked faces and houses that were either subjectively or objectively invisible. Even for objectively invisible (perceptually indiscriminable) stimuli, we found significant category information in both early, lower-level visual areas and in higher-level visual cortex, although representations in anterior, category-selective ventrotemporal areas were less robust. For subjectively invisible stimuli, similar to visible stimuli, there was a clear posterior-to-anterior gradient in visual cortex, with stronger category information in ventrotemporal cortex than in early visual cortex. For objectively invisible stimuli, however, category information remained virtually unchanged from early visual cortex to object- and category-selective visual areas. These results demonstrate that although both objectively and subjectively invisible stimuli are represented in visual cortex, the extent of unconscious information processing is influenced by the measurement approach. Furthermore, our data show that subjective and objective approaches are associated with different neural correlates of consciousness and thus have implications for neural theories of consciousness.
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Affiliation(s)
- Timo Stein
- Brain and Cognition, Department of Psychology, University of Amsterdam, the Netherlands
| | - Daniel Kaiser
- Department of Psychology, University of York, United Kingdom
| | - Johannes J. Fahrenfort
- Brain and Cognition, Department of Psychology, University of Amsterdam, the Netherlands
- Cognitive Psychology, Department of Experimental and Applied Psychology, Vrije Universiteit Amsterdam, the Netherlands
| | - Simon van Gaal
- Brain and Cognition, Department of Psychology, University of Amsterdam, the Netherlands
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3
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Herman WX, Smith RE, Kronemer SI, Watsky RE, Chen WC, Gober LM, Touloumes GJ, Khosla M, Raja A, Horien CL, Morse EC, Botta KL, Hirsch LJ, Alkawadri R, Gerrard JL, Spencer DD, Blumenfeld H. A Switch and Wave of Neuronal Activity in the Cerebral Cortex During the First Second of Conscious Perception. Cereb Cortex 2020; 29:461-474. [PMID: 29194517 DOI: 10.1093/cercor/bhx327] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Indexed: 12/17/2022] Open
Abstract
Conscious perception occurs within less than 1 s. To study events on this time scale we used direct electrical recordings from the human cerebral cortex during a conscious visual perception task. Faces were presented at individually titrated visual threshold for 9 subjects while measuring broadband 40-115 Hz gamma power in a total of 1621 intracranial electrodes widely distributed in both hemispheres. Surface maps and k-means clustering analysis showed initial activation of visual cortex for both perceived and non-perceived stimuli. However, only stimuli reported as perceived then elicited a forward-sweeping wave of activity throughout the cerebral cortex accompanied by large-scale network switching. Specifically, a monophasic wave of broadband gamma activation moves through bilateral association cortex at a rate of approximately 150 mm/s and eventually reenters visual cortex for perceived but not for non-perceived stimuli. Meanwhile, the default mode network and the initial visual cortex and higher association cortex networks are switched off for the duration of conscious stimulus processing. Based on these findings, we propose a new "switch-and-wave" model for the processing of consciously perceived stimuli. These findings are important for understanding normal conscious perception and may also shed light on its vulnerability to disruption by brain disorders.
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Affiliation(s)
- Wendy X Herman
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Rachel E Smith
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Sharif I Kronemer
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Rebecca E Watsky
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - William C Chen
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Leah M Gober
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - George J Touloumes
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Meenakshi Khosla
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Anusha Raja
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Corey L Horien
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Elliot C Morse
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Katherine L Botta
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Lawrence J Hirsch
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Rafeed Alkawadri
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Jason L Gerrard
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Dennis D Spencer
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
| | - Hal Blumenfeld
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
- Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
- Department of Neuroscience, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, USA
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4
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Unconscious processing of facial expression as revealed by affective priming under continuous flash suppression. Psychon Bull Rev 2018; 25:2215-2223. [DOI: 10.3758/s13423-018-1437-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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5
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Rothkirch M, Hesselmann G. What We Talk about When We Talk about Unconscious Processing - A Plea for Best Practices. Front Psychol 2017; 8:835. [PMID: 28588539 PMCID: PMC5440724 DOI: 10.3389/fpsyg.2017.00835] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 05/08/2017] [Indexed: 12/24/2022] Open
Abstract
In this perspective article, we first outline the large diversity of methods, measures, statistical analyses, and concepts in the field of the experimental study of unconscious processing. We then suggest that this diversity implies that comparisons between different studies on unconscious processing are fairly limited, especially when stimulus awareness has been assessed in different ways. Furthermore, we argue that flexible choices of methods and measures will inevitably lead to an overestimation of unconscious processes. In the concluding paragraph, we briefly present solutions and strategies for future research. We make a plea for the introduction of "best practices," similar to previous attempts to constitute practicing standards for functional magnetic resonance imaging (fMRI) and electroencephalography (EEG).
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Affiliation(s)
- Marcus Rothkirch
- Visual Perception Laboratory, Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlin, Germany
| | - Guido Hesselmann
- Visual Perception Laboratory, Department of Psychiatry and Psychotherapy, Campus Charité Mitte, Charité – Universitätsmedizin BerlinBerlin, Germany
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6
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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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Hesselmann G, Darcy N, Sterzer P, Knops A. Exploring the boundary conditions of unconscious numerical priming effects with continuous flash suppression. Conscious Cogn 2015; 31:60-72. [DOI: 10.1016/j.concog.2014.10.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 10/21/2014] [Accepted: 10/22/2014] [Indexed: 11/27/2022]
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8
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Ludwig K, Kathmann N, Sterzer P, Hesselmann G. Investigating category- and shape-selective neural processing in ventral and dorsal visual stream under interocular suppression. Hum Brain Mapp 2015; 36:137-49. [PMID: 25270984 PMCID: PMC6869721 DOI: 10.1002/hbm.22618] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/18/2014] [Accepted: 08/19/2014] [Indexed: 11/09/2022] Open
Abstract
Recent behavioral and neuroimaging studies using continuous flash suppression (CFS) have suggested that action-related processing in the dorsal visual stream might be independent of perceptual awareness, in line with the "vision-for-perception" versus "vision-for-action" distinction of the influential dual-stream theory. It remains controversial if evidence suggesting exclusive dorsal stream processing of tool stimuli under CFS can be explained by their elongated shape alone or by action-relevant category representations in dorsal visual cortex. To approach this question, we investigated category- and shape-selective functional magnetic resonance imaging-blood-oxygen level-dependent responses in both visual streams using images of faces and tools. Multivariate pattern analysis showed enhanced decoding of elongated relative to non-elongated tools, both in the ventral and dorsal visual stream. The second aim of our study was to investigate whether the depth of interocular suppression might differentially affect processing in dorsal and ventral areas. However, parametric modulation of suppression depth by varying the CFS mask contrast did not yield any evidence for differential modulation of category-selective activity. Together, our data provide evidence for shape-selective processing under CFS in both dorsal and ventral stream areas and, therefore, do not support the notion that dorsal "vision-for-action" processing is exclusively preserved under interocular suppression.
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Affiliation(s)
- Karin Ludwig
- Visual Perception LaboratoryDepartment of Psychiatry and PsychotherapyCampus Charité MitteCharité – Universitätsmedizin BerlinBerlinGermany
- Department of PsychologyHumboldt‐Universität zu BerlinBerlinGermany
| | - Norbert Kathmann
- Department of PsychologyHumboldt‐Universität zu BerlinBerlinGermany
| | - Philipp Sterzer
- Visual Perception LaboratoryDepartment of Psychiatry and PsychotherapyCampus Charité MitteCharité – Universitätsmedizin BerlinBerlinGermany
| | - Guido Hesselmann
- Visual Perception LaboratoryDepartment of Psychiatry and PsychotherapyCampus Charité MitteCharité – Universitätsmedizin BerlinBerlinGermany
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9
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Yang E, Brascamp J, Kang MS, Blake R. On the use of continuous flash suppression for the study of visual processing outside of awareness. Front Psychol 2014; 5:724. [PMID: 25071685 PMCID: PMC4093749 DOI: 10.3389/fpsyg.2014.00724] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 06/23/2014] [Indexed: 11/25/2022] Open
Abstract
The interocular suppression technique termed continuous flash suppression (CFS) has become an immensely popular tool for investigating visual processing outside of awareness. The emerging picture from studies using CFS is that extensive processing of a visual stimulus, including its semantic and affective content, occurs despite suppression from awareness of that stimulus by CFS. However, the current implementation of CFS in many studies examining processing outside of awareness has several drawbacks that may be improved upon for future studies using CFS. In this paper, we address some of those shortcomings, particularly ones that affect the assessment of unawareness during CFS, and ones to do with the use of "visible" conditions that are often included as a comparison to a CFS condition. We also discuss potential biases in stimulus processing as a result of spatial attention and feature-selective suppression. We suggest practical guidelines that minimize the effects of those limitations in using CFS to study visual processing outside of awareness.
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Affiliation(s)
- Eunice Yang
- School of Optometry, University of California at BerkeleyBerkeley, CA, USA
| | - Jan Brascamp
- Helmholtz Institute and Division of Experimental Psychology, Department of Psychology, Utrecht UniversityUtrecht, Netherlands
| | - Min-Suk Kang
- Department of Psychology, Sungkyunkwan UniversitySeoul, Republic of Korea
- Center for Neuroscience Imaging Research, Institute for Basic ScienceDaejeon, Republic of Korea
| | - Randolph Blake
- Department of Psychology, Vanderbilt UniversityNashville, TN, USA
- Department of Brain and Cognitive Sciences, Seoul National UniversitySeoul, Republic of Korea
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10
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Cox MA, Lowe KA, Blake R, Maier A. Sustained perceptual invisibility of solid shapes following contour adaptation to partial outlines. Conscious Cogn 2014; 26:37-50. [PMID: 24657633 DOI: 10.1016/j.concog.2014.02.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 01/23/2014] [Accepted: 02/24/2014] [Indexed: 11/28/2022]
Abstract
Contour adaptation (CA) is a recently described paradigm that renders otherwise salient visual stimuli temporarily perceptually invisible. Here we investigate whether this illusion can be exploited to study visual awareness. We found that CA can induce seconds of sustained invisibility following similarly long periods of uninterrupted adaptation. Furthermore, even fragmented adaptors are capable of producing CA, with the strength of CA increasing monotonically as the adaptors encompass a greater fraction of the stimulus outline. However, different types of adaptor patterns, such as distinctive shapes or illusory contours, produce equivalent levels of CA suggesting that the main determinants of CA are low-level stimulus characteristics, with minimal modulation by higher-order visual processes. Taken together, our results indicate that CA has desirable properties for studying visual awareness, including the production of prolonged periods of perceptual dissociation from stimulation as well as parametric dependencies of that dissociation on a host of stimulus parameters.
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Affiliation(s)
- M A Cox
- Department of Psychological Sciences, College of Arts and Science, Vanderbilt University, WH 008, 111 21st Ave S, Nashville, TN 37240, United States
| | - K A Lowe
- Department of Psychological Sciences, College of Arts and Science, Vanderbilt University, WH 008, 111 21st Ave S, Nashville, TN 37240, United States
| | - R Blake
- Department of Psychological Sciences, College of Arts and Science, Vanderbilt University, WH 008, 111 21st Ave S, Nashville, TN 37240, United States
| | - A Maier
- Department of Psychological Sciences, College of Arts and Science, Vanderbilt University, WH 008, 111 21st Ave S, Nashville, TN 37240, United States.
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11
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Ludwig K, Sterzer P, Kathmann N, Franz V, Hesselmann G. Learning to detect but not to grasp suppressed visual stimuli. Neuropsychologia 2013; 51:2930-8. [DOI: 10.1016/j.neuropsychologia.2013.09.035] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/26/2013] [Accepted: 09/18/2013] [Indexed: 11/25/2022]
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