DOCSLIB.ORG

On the Dissociation Between Vision and Perception

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

On the neuronal activity in the human brain during visual recognition, imagery and binocular rivalry Thesis by Gabriel Kreiman In partial fulfillment of the requirements for the degree of Doctor of Philosophy California Institute of Technology Pasadena, California 2002 (Defended August 29, 2001) ii © 2002 Gabriel Kreiman All Rights Reserved iii To all those teachers who taught me to enjoy learning iv v Acknowledgments Haec ego non multis scribo, sed tibi: satis enim magnum alter alteri theatrum sumus1. All of the work described in the following chapters would not have been possible without the enthusiastic help of a large and nice group of colleagues and friends. First of all, I would like to thank all the patients who participated in these experiments. We have not paid them and they have cooperated for the advancement of science. Candi Maechtlen and Irene Wainwright have provided valuable and prompt help throughout these years in several of the fundamental details that keep things going. Irene has also provided excellent editorial assistance in several of our publications. I have been fortunate to be able to interact and learn from a large number of teachers, colleagues and friends throughout my entire life. While a number of them have not contributed directly to this thesis work, it seems evident that they have enormously influenced my education and my preparation. Among them, I would like to especially mention my chess teacher Cesar Corte who was perhaps among the first who showed me the way to indulge in the wonderful task of solving new problems. The long hours of scientific exploration clearly have a root in me in the uncountable hours that we spent in front of a chessboard trying to figure out the solution to a problem or the best move. I would also like to express my gratitude to Rebeca Muller, Daniel Goldstein, Alberto Kornblihtt, Ernersto Timmermann, Rodolfo Ugalde and the math Olympiad team in Buenos Aires. I would like to also mention the continuous support from my family Raul, Lidia, Lauri, Elias, Haydee, Dora, Mariela and friends Damian Scherlis, Dan Rozenfarb, Diego Tisman and Dario Winter. When I arrived to Caltech, I learnt the first steps in Neuroscience during my rotation in the lab of Mark Konishi to whom I am greatly indebted. Fabrizio Gabbiani immersed me in the wonderful world of quantitative spike train analysis. I would like to 1 I write this not to the many, but to you only, for you and I are surely enough of an audience for each other. vi also thank Erin Schuman who introduced me to the hippocampus and taught me the first steps in electrophysiology. A number of people from UCLA and Caltech have helped me with the recordings including Anatol Bragin, Charles Wilson, Rick Staba, Erick Behnke, Jack Morrow and Eve Isham. Laurent Itti built the push buttons used in all our experiments. The data obtained during sleep (Chapter 5) were recorded by the skilful and laborious endeavor of Charles Wilson and Rick Staba. Jonathan Lin, a Surf student from Caltech, provided fundamental help for the analysis and study of the correlations during sleep. Most of the experiments to try to understand the psychophysics of flash suppression (briefly mentioned in Appendix 2) were carried out by SURF student Nick Knouf and by the enthusiastic collaboration of Pasadena High School student Shaun Lee. Michael Herzog was extremely kind in his discussions and suggestions about flash suppression, particularly in facilitating his programs to measure orientation discrimination. He was also key in the genesis of the idea to objectively measure suppression (see Appendix 2). The comparison of different methods of spike sorting (Appendix 1) was carried out by Angela Yu and Jason Davis. Maneesh Sahani and John Pezaris provided their algorithm (spikesort) for comparison purposes. Part of the spiker software developed by Angela Yu and myself was written by Christophe Pouzat. The experiment using repetitive transcranial magnetic stimulation during binocular rivalry (Appendix 3) was carried out in Harvard Medical School in collaboration with Julian Keenan and Alvaro Pascual Leone. Geraint Rees and Nikos Logothetis have been very kind in providing advice for the binocular rivalry and flash suppression experiments (Chapter 6). I would also like to thank a number of people for scientific discussions and for insightful comments to our writings: Mariela Zirlinger, Dan Rozenfarb, Terry Sejnowski and Francis Crick. My thesis committee, conformed by Mark Konishi, Richard Andersen, Shim Shimojo and John Allman (in addition to Itzhak Fried and Christof Koch) has provided valuable feedback. vii The support of my wife Mariela Zirlinger was also key to the completion of all this work. Itzhak Fried is the neurosurgeon at UCLA who has made all of these experiments recording the activity of single neurons possible. He has been a pioneer in the technique of chronic single unit recordings in epileptic patients. His scientific enthusiasm has been highly motivating and encouraging at the same time of helping the patients with their clinical problems. This is remarkable in itself but, in addition to that, Itzhak has proved to be extremely helpful in the design, analysis and discussion of our experiments. Finally, the inspiring driving force behind all the work here described is my advisor Christof Koch. His enthusiasm for research is contagious, imparting the basement in Beckman Institute a strong scientific momentum. Together with Francis Crick, he has had the insight that we can and we should rigorously study the neuronal correlates of consciousness. His curiosity and motivation has pushed the field of consciousness research (among other fields) into the mainstream of neuroscience exploration. He has created an excellent environment to learn and explore new questions. He has made the already interesting adventures of scientific exploration during my doctorate work even more fascinating, enlightening them with new views, new questions, new solutions and new challenges every time. I am immensely grateful to him for allowing me the opportunity to work throughout these years in the lab and for his continuous motivation and encouragement. viii ix Abstract How does the neuronal activity in our brains give rise to our perceptions? We recorded the electrophysiological activity of over one thousand individual neurons in the human brain during object recognition, binocular rivalry, visual imagery and sleep. Subjects were patients with intractable epilepsy implanted with depth electrodes in targets including the amygdala, entorhinal cortex and hippocampus to localize the seizure focus for potential surgical resection. This has allowed us to explore the neuronal responses during visual processing in humans at an unprecedented level of spatial and temporal resolution. We observed a high degree of selectivity in the responses to complex visual stimuli. Some units were selective to categories of pictures including faces, houses, objects, famous people and animals while others responded only to one or a few stimuli, suggesting a sparse representation of visual information in the medial temporal lobe. Most of the selective neurons modulated their responses depending on the subject's percept during flash suppression. To further explore the correlation between perception and neuronal activity we investigated the vivid images that can be voluntarily generated in our minds in the absence of concomitant visual input. Our study revealed neuronal correlates of visual imagery and supports a common substrate for the processing of visual input and recall. Since visual memory is also prominent during dreams, we investigated the neuronal responses during different stages of the sleep-wake cycle. We observed an increase in synchrony during slow wave sleep compared to the wake and rapid-eye- movement sleep states. Our results suggest that neuronal activity in the human medial temporal lobe correlates with perception, shows a strong degree of invariance to changes in the input and could be involved in processing, storing and recalling visual information. x xi Table of Contents Acknowledgments .............................................................................................................. v Abstract.............................................................................................................................. ix Table of Contents...............................................................................................................xi List of Figures.................................................................................................................. xix List of Tables ................................................................................................................. xxiv List of abbreviations ....................................................................................................... xxv 1 Introduction...................................................................................................................... 1 1.1. Informal definitions: statement of the questions ..........................................................................1 1.2. Brief history of theoretical ideas regarding perception ................................................................3 1.3. Why an experimental approach is necessary................................................................................6 1.4. Brief comments about epilepsy ....................................................................................................7
Recommended publications
  • Forschungsgruppen Ausland Research Groups Abroad

    Forschungsgruppen Ausland Research Groups Abroad

    STRUKTUREN 04 STRUCTURES Forschungsgruppen Ausland Research Groups abroad Seite 136 Page 136 Partnergruppen Partner Groups Seite 141 Page 141 Max-Planck-Forschungsgruppen im Ausland Max Planck Research Groups abroad Seite 143 Page 143 Unabhängige Tandemforschungsgruppen von Independent Tandem Research Groups of Max-Planck-Instituten Max Planck Institutes Partnergruppen Partner Groups Partnergruppen sind ein Instrument zur gemeinsamen Förderung von Nachwuchs wissenschaftlern mit Ländern, die an einer Stär- kung ihrer Forschung durch internationale Kooperationen interessiert sind. Sie können mit einem Institut im Ausland eingerichtet werden, wenn ein exzellenter Nachwuchswissenschaftler oder eine exzellente Nachwuchswissenschaftlerin (Postdoc) im An- schluss an einen Forschungsaufenthalt an einem Max-Planck-Institut wieder an ein leistungsfähiges und angemessen ausgestat- tetes Labor seines/ihres Herkunftslandes zurückkehrt und an einem Forschungsthema weiter forscht, welches auch im Interesse des vorher gastgebenden Max-Planck-Instituts steht. Stand: 31. Dezember 2017 Partner Groups can be established in cooperation with an institute abroad. Following a research visit to a Max Planck Institute, an outstanding junior scientist (postdoc) returns to a well-equipped high-capacity laboratory in his home country and continues his research on a research topic that is also of interest to the previous host Max Planck Institute. As of 31st December 2017 INSTITUT | INSTITUTE PARTNERGRUPPE | PARTNERGROUP ARGENTINIEN | ARGENTINA MPI für Entwicklungsbiologie Instituto de Agrobiotecnología del Litoral, Santa Fe Prof. Dr. Detlef Weigel Dr. Pablo A. Manavella MPI für molekulare Pflanzenphysiologie Instituto de Agrobiotecnología del Litoral, Santa Fe Prof. Dr. Mark Stitt Dr. Carlos María Figueroa MPI für Pflanzenzüchtungsforschung Fundación Instituto Leloir, Buenos Aires Prof. Dr. George Coupland Dr. Julieta Mateos MPI für molekulare Physiologie Universidad de Buenos Aires Prof Dr.
  • Longitudinal Investigation of Disparity Vergence in Young Adult Convergence Insufficiency Patients

    Longitudinal Investigation of Disparity Vergence in Young Adult Convergence Insufficiency Patients

    New Jersey Institute of Technology Digital Commons @ NJIT Theses Electronic Theses and Dissertations Summer 2019 Longitudinal investigation of disparity vergence in young adult convergence insufficiency patients Patrick C. Crincoli New Jersey Institute of Technology Follow this and additional works at: https://digitalcommons.njit.edu/theses Part of the Biomedical Engineering and Bioengineering Commons Recommended Citation Crincoli, Patrick C., "Longitudinal investigation of disparity vergence in young adult convergence insufficiency patients" (2019). Theses. 1683. https://digitalcommons.njit.edu/theses/1683 This Thesis is brought to you for free and open access by the Electronic Theses and Dissertations at Digital Commons @ NJIT. It has been accepted for inclusion in Theses by an authorized administrator of Digital Commons @ NJIT. For more information, please contact [email protected]. Copyright Warning & Restrictions The copyright law of the United States (Title 17, United States Code) governs the making of photocopies or other reproductions of copyrighted material. Under certain conditions specified in the law, libraries and archives are authorized to furnish a photocopy or other reproduction. One of these specified conditions is that the photocopy or reproduction is not to be “used for any purpose other than private study, scholarship, or research.” If a, user makes a request for, or later uses, a photocopy or reproduction for purposes in excess of “fair use” that user may be liable for copyright infringement, This institution
  • Monocular Rivalry Exhibits Three Hallmarks of Binocular Rivalry

    Monocular Rivalry Exhibits Three Hallmarks of Binocular Rivalry

    This article may not exactly replicate the final version published. It is not the copy of record. 1 Monocular rivalry exhibits three hallmarks of binocular rivalry Robert P. O’Shea 1* , David Alais 2, Amanda L. Parker 2 and David J. La Rooy 1 1Department of Psychology, University of Otago, PO Box 56, Dunedin, New Zealand 2 School of Psychology, The University of Sydney, Australia * Corresponding author: e-mail: [email protected] Acknowledgements: We are grateful to Frank Tong for allowing us to use his stimuli for Experiment 2, and to Janine Mendola for helpful discussion. O'Shea, R. P., Parker, A. L., La Rooy, D. J. & Alais, D. (2009).Monocular rivalry exhibits three hallmarks of binocular rivalry: Evidence for common processes. Vision Research, 49, 671–681. http://www.elsevier.com/wps/find/journaldescription.cws_home/263/descri ption#description This article may not exactly replicate the final version published. It is not the copy of record. 2 Abstract Binocular rivalry occurs when different images are presented one to each eye: the images are visible only alternately. Monocular rivalry occurs when different images are presented both to the same eye: the clarity of the images fluctuates alternately. Could both sorts of rivalry reflect the operation of a general visual mechanism for dealing with perceptual ambiguity? We report four experiments showing similarities between the two phenomena. First, we show that monocular rivalry can occur with complex images, as with binocular rivalry, and that the two phenomena are affected similarly by the size and colour of the images. Second, we show that the distribution of dominance periods during monocular rivalry has a gamma shape and is stochastic.
  • What Is Wrong with the No-Report Paradigm and How to Fix It Ned Block New York University Correspondence: Ned.Block@Nyu.Edu

    What Is Wrong with the No-Report Paradigm and How to Fix It Ned Block New York University Correspondence: [email protected]

    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by PhilPapers Forthcoming in Trends in Cognitive Sciences What is wrong with the no-report paradigm and how to fix it Ned Block New York University Correspondence: [email protected] Key words: consciousness, perception, rivalry, frontal, global workspace, higher order Abstract Is consciousness based in prefrontal circuits involved in cognitive processes like thought, reasoning, and memory or, alternatively, is it based in sensory areas in the back of the neocortex? The no-report paradigm has been crucial to this debate because it aims to separate the neural basis of the cognitive processes underlying post-perceptual decision and report from the neural basis of conscious perception itself. However, the no-report paradigm is problematic because, even in the absence of report, subjects might engage in post-perceptual cognitive processing. Therefore, to isolate the neural basis of consciousness, a no-cognition paradigm is needed. Here, I describe a no-cognition approach to binocular rivalry and outline how this approach can help resolve debates about the neural basis of consciousness. Acknowledgement: Thanks to Jan Brascamp, Susan Carey, Thomas Carlson, David Carmel, David Chalmers, Christof Koch, Hakwan Lau, Matthias Michel, Michael Pitts, Dawid Potgieter and Giulio Tononi for comments on an earlier version. What is the Neural Basis of Consciousness? In recent years the scientific study of consciousness (see Glossary) has focused on finding the neural basis of consciousness in the brain. There are many theories of the neural basis of consciousness, but in broad strokes theories tend to divide on whether consciousness is rooted in the ‘front’ or the ‘back’ of the brain.
  • On May 8Th, 2008 Human Brain Mapping (HBM) Published a Paper by A

    On May 8Th, 2008 Human Brain Mapping (HBM) Published a Paper by A

    Date: 16 June 2008 Dear Editors and Colleagues: On May 8th, 2008 Human Brain Mapping (HBM) published a paper by A. Shmuel and D. Leopold entitled “Neuronal correlates of spontaneous fluctuations in fMRI signals in monkey visual cortex: Implications for functional connectivity at rest” (DOI: 10.1002/hbm.20580). The authors are former postdoctoral fellows of mine and the data were collected in my laboratory, so it is with some unhappiness that I write to you to disavow the paper’s contents and conclusions, and to let you know that my colleagues and I are preparing a rebuttal for publication. My objections to the paper are both technical and ethical. The technical problem is that most of the measurements reported in the paper to be “at rest” were taken from the prestimulus interval of long observation periods with multiple trials during which visual stimuli were presented. The data came from another study of my laboratory (Shmuel, Augath, Oeltermann and Logothetis, 2006). In fact, a grey screen with a significant flicker at 30 and 60 Hz evoked electrical cortical activity, making it wrong to suppose that the comparison of neural with hemodynamic signals was within a rest period during which spontaneous activity alone prevailed (details in the rebuttal). This renders the conclusion in the paper, and thus the paper itself, invalid. These points were pointed out to the authors and to the editors as well, but the editors chose to accept it even in spite of the questionable ethical conduct of the authors, which the editors were also aware of, or should have been aware of (see below).
  • The Photographerls Guide to The

    The Photographerls Guide to The

    THE PHOTOGRAPHER’S GUIDE TO THE EYE EYES—NOSTRILS—LIPS—SHINY THINGS. My eyes scanned the photo of two women almost the way a monkey’s would, going first to the faces, specifically features that WHAT SCIENCE IS would indicate friend, foe, or possible mate, then to the brightest objects in the image: a blue bottle, a pendant. Surprisingly, it took LEARNING ABOUT HOW forever (almost three seconds) for me to look at the famous—and famously gorgeous—face in the photo, Angelina Jolie. WE SEE CAN HELP YOU In this impulsive type of seeing, called “bottom-up,” my eyes went first to the face of the other woman in the picture until I consciously ordered them to spend time on Jolie—“top-down TAKE MORE COMPELLING attentional deployment” in scientific lingo. That’s because, researchers have found, we recognize culture-defined beauty only PICTURES after taking the reflexive glances all primate eyes perform within the first few milliseconds. In other words, we see first with our BY NEAL MATTHEWS animal selves and then with our acculturated minds. We process visual information very quickly, as the brain electronically parcels parts of images to different cortical areas concerned with faces, colors, shapes, motion, and many other aspects of a scene, where they are broken down even further. Then the brain puts all that information back together into a coherent composite before directing the eyes to move. My eye tracks were being recorded by vision researcher Laurent Itti, an associate professor of computer science, psychology, and neuroscience at the University of Southern California’s iLab (ilab.usc.edu).
  • Visible Binocular Beats from Invisible Monocular Stimuli During Binocular Rivalry Thomas A

    Visible Binocular Beats from Invisible Monocular Stimuli During Binocular Rivalry Thomas A

    Brief Communication 1055 Visible binocular beats from invisible monocular stimuli during binocular rivalry Thomas A. Carlson and Sheng He When two qualitatively different stimuli are presented in rivalry [14–16]. Random dot stereograms can be seen at the same time, one to each eye, the stimuli can either superimposed on, but not interacting with two orthogonal integrate or compete with each other. When they gratings engaged in rivalry, a phenomenon that Wolfe compete, one of the two stimuli is alternately termed ‘trinocular vision’ [5]. Hastorf and Myro also suppressed, a phenomenon called binocular rivalry reported that form and color rivalry could be de-coupled [1,2]. When they integrate, observers see some form of from one another ([17]; and see [5,18] for a general review). the combined stimuli. Many different properties (for Nevertheless, there are also challenges to the coexistence example, shape or color) of the two stimuli can induce of stereopsis and rivalry, particularly for the claim that they binocular rivalry. Not all differences result in rivalry, can be perceived at the same spatial location [6,7]. however. Visual ‘beats’, for example, are the result of integration of high-frequency flicker between the two During the experiment, an observer’s left eye was pre- eyes [3,4], and are thus a binocular fusion phenomenon. sented with a red triangle facing left and the right eye a It remains in dispute whether binocular fusion and green triangle facing right (each side of the triangle rivalry can co-exist with one another [5–7]. Here, we extended 2.1° visual angle), and each was illuminated, report that rivalry and beats, two apparently opposing respectively, with red or green light-emitting diodes (LEDs) phenomena, can be perceived at the same time within from behind a plastic diffuser.
  • Spatio-Temporal Integration of an Object's Surface Information in Mid-Level Vision

    Spatio-Temporal Integration of an Object's Surface Information in Mid-Level Vision

    Spatio-temporal integration of an object's surface information in mid-level vision A DISSERTATION SUBMITTED TO THE FACULTY OF UNIVERSITY OF MINNESOTA BY Shin Ho Cho IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Professor Daniel J. Kersten and Sheng He June 2015 © Copyright by Shin Ho Cho 2015 All right Reserved Acknowledgements I would like to express the deepest appreciation to my two academic advisers, Professor Daniel J. Kersten, and Professor Sheng He. Both have the attitude and the substance of a genius: they continually and convincingly conveyed a spirit of adventure in regard to research and scholarship, and an excitement to explore the unknown intellectual world. Without their guidance and persistent help this dissertation would not have been possible. I would like to thank my committee members Professor Stephen Engel and Professor Bin He, whose comments and encouragement were very helpful in progressing my research and enabling me to finish this dissertation project. Also, I thank the University of Minnesota for financial support, especially the Doctoral Dissertation Fellowship Program. Shinho Cho (조신호) i To my parents and wife ii Abstract The human visual system can construct a 3D viewpoint of visual objects based on their 2D contours. This process is presumably an essential part of the visual system that enables interaction with an environment, e.g., grasping an object. Despite its importance, it is not clearly understood to what extent conscious awareness is involved in constructing 3D information from visual input. Here we investigated whether the 3D viewpoint of the object could be extracted and represented by the visual system when observers were not aware of the object’s image.
  • Chromostereo.Pdf

    Chromostereo.Pdf

    ChromoStereoscopic Rendering for Trichromatic Displays Le¨ıla Schemali1;2 Elmar Eisemann3 1Telecom ParisTech CNRS LTCI 2XtremViz 3Delft University of Technology Figure 1: ChromaDepth R glasses act like a prism that disperses incoming light and induces a differing depth perception for different light wavelengths. As most displays are limited to mixing three primaries (RGB), the depth effect can be significantly reduced, when using the usual mapping of depth to hue. Our red to white to blue mapping and shading cues achieve a significant improvement. Abstract The chromostereopsis phenomenom leads to a differing depth per- ception of different color hues, e.g., red is perceived slightly in front of blue. In chromostereoscopic rendering 2D images are produced that encode depth in color. While the natural chromostereopsis of our human visual system is rather low, it can be enhanced via ChromaDepth R glasses, which induce chromatic aberrations in one Figure 2: Chromostereopsis can be due to: (a) longitunal chro- eye by refracting light of different wavelengths differently, hereby matic aberration, focus of blue shifts forward with respect to red, offsetting the projected position slightly in one eye. Although, it or (b) transverse chromatic aberration, blue shifts further toward might seem natural to map depth linearly to hue, which was also the the nasal part of the retina than red. (c) Shift in position leads to a basis of previous solutions, we demonstrate that such a mapping re- depth impression. duces the stereoscopic effect when using standard trichromatic dis- plays or printing systems. We propose an algorithm, which enables an improved stereoscopic experience with reduced artifacts.
  • The Figure Is in the Brain of the Beholder: Neural Correlates of Individual Percepts in The

    The Figure Is in the Brain of the Beholder: Neural Correlates of Individual Percepts in The

    The Figure is in the Brain of the Beholder: Neural Correlates of Individual Percepts in the Bistable Face-Vase Image A Thesis Presented to The Division of Philosophy, Religion, Psychology, and Linguistics Reed College In Partial Fulfillment of the Requirements for the Degree Bachelor of Arts Phoebe Bauer May 2015 Approved for the Division (Psychology) Michael Pitts Acknowledgments I think some people experience a degree of unease when being taken care of, so they only let certain people do it, or they feel guilty when it happens. I don’t really have that. I love being taken care of. Here is a list of people who need to be explicitly thanked because they have done it so frequently and are so good at it: Chris: thank you for being my support system across so many contexts, for spinning with me, for constantly reminding me what I’m capable of both in and out of the lab. Thank you for validating and often mirroring my emotions, and for never leaving a conflict unresolved. Rennie: thank you for being totally different from me and yet somehow understanding the depths of my opinions and thought experiments. Thank you for being able to talk about magic. Thank you for being my biggest ego boost and accepting when I internalize it. Ben: thank you for taking the most important classes with me so that I could get even more out of them by sharing. Thank you for keeping track of priorities (quality dining: yes, emotional explanations: yes, fretting about appearances: nu-uh). #AshHatchtag & Stella & Master Tran: thank you for being a ceaseless source of cheer and laughter and color and love this year.
  • UC Merced Proceedings of the Annual Meeting of the Cognitive Science Society

    UC Merced Proceedings of the Annual Meeting of the Cognitive Science Society

    UC Merced Proceedings of the Annual Meeting of the Cognitive Science Society Title Voluntary versus Involuntary Perceptual Switching: Mechanistic Differences in Viewing an Ambiguous Figure Permalink https://escholarship.org/uc/item/333348w4 Journal Proceedings of the Annual Meeting of the Cognitive Science Society, 27(27) ISSN 1069-7977 Authors Rambusch, Jana Ziemke, Tom Publication Date 2005 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Voluntary versus Involuntary Perceptual Switching: Mechanistic Differences in Viewing an Ambiguous Figure Michelle Umali ([email protected]) Center for Neurobiology & Behavior, Columbia University 1051 Riverside Drive, New York, NY, 10032, USA Marc Pomplun ([email protected]) Department of Computer Science, University of Massachusetts at Boston 100 Morrissey Blvd., Boston, MA 02125, USA Abstract frequency, blink frequency, and pupil size, which have been robustly correlated with cognitive function (see Rayner, Here we demonstrate the mechanistic differences between 1998, for a review). Investigators utilizing this method have voluntary and involuntary switching of the perception of an examined the regions within ambiguous figures that receive ambiguous figure. In our experiment, participants viewed a attention during a specific interpretation, as well as changes 3D ambiguous figure, the Necker cube, and were asked to maintain one of two possible interpretations across four in eye movement parameters that may specify the time of different conditions of varying cognitive load. These switch. conditions differed in the instruction to freely view, make For example, Ellis and Stark (1978) reported that guided saccades, or fixate on a central cross. In the fourth prolonged fixation duration occurs at the time of perceptual condition, subjects were instructed to make guided saccades switching.
  • How Does Binocular Rivalry Emerge from Cortical

    How Does Binocular Rivalry Emerge from Cortical

    HOW DOES BINOCULAR RIVALRY EMERGE FROM CORTICAL MECHANISMS OF 3-D VISION? Stephen Grossberg, Arash Yazdanbakhsh, Yongqiang Cao, and Guru Swaminathan1 Department of Cognitive and Neural Systems and Center for Adaptive Systems Boston University 677 Beacon Street, Boston, MA 02215 Phone: 617-353-7858 Fax: 617-353-7755 Submitted: July, 2007 Technical Report CAS/CNS-2007-010 All correspondence should be addressed to Professor Stephen Grossberg Department of Cognitive and Neural Systems Boston University 677 Beacon Street Boston, MA 02215 Phone: 617-353-7858/7857 Fax: 617-353-7755 Email:[email protected] 1 SG was supported in part by the National Science Foundation (NSF SBE-0354378) and the office of Naval Research (ONR N00014-01-1-0624). AY was supported in part by the Air Force Office of Scientific Research (AFOSR F49620-01-1-0397) and the Office of Naval Research (ONR N00014-01-1-0624). YC was supported by the National Science Foundation (NSF SBE-0354378). GS was supported in part by the Air Force Office of Scientific Research (AFOSR F49620-98-1-0108 and F49620-01-1-0397), the National Science Foundation (NSF IIS-97-20333), the Office of Naval Research (ONR N00014-95-1-0657, N00014- 95-1-0409, and N00014-01-1-0624), and the Whitaker Foundation (RG-99-0186). Abstract Under natural viewing conditions, a single depthful percept of the world is consciously seen. When dissimilar images are presented to corresponding regions of the two eyes, binocular rivalry may occur, during which the brain consciously perceives alternating percepts through time. How do the same brain mechanisms that generate a single depthful percept of the world also cause perceptual bistability, notably binocular rivalry? What properties of brain representations correspond to consciously seen percepts? A laminar cortical model of how cortical areas V1, V2, and V4 generate depthful percepts is developed to explain and quantitatively simulate binocular rivalry data.