| Crick, F., Koch, C. A framework for consciousness Nature Neuroscience 2003 (6)2:119-126 [pdf] |
| Here we summarize our present approach to the problem of consciousness. After an introduction outlining our general strategy, we describe what is meant by the term 'framework' and set it out under ten headings. This framework offers a coherent scheme for explaining the neural correlates of (visual) consciousness in terms of competing cellular assemblies. Most of the ideas we favor have been suggested before, but their combination is original. We also outline some general experimental approaches to the problem and, finally, acknowledge some relevant aspects of the brain that have been left out of the proposed framework. |
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| Gold, I., Stoljar, D. A neuron doctrine in the philosophy of neuroscience Behavioral and Brain Sciences 1999 (22)5:585-642 [html] |
| Many neuroscientists and philosophers endorse a view about the explanatory reach of neuroscience which we will call the neuron doctrine to the effect that the framework for understanding the mind will be developed by neuroscience; or, as we will put it, that a successful theory of the mind will be solely neuroscientific. It is a consequence of this view that the sciences of the mind that cannot be expressed by means of neuroscientific concepts alone count as indirect sciences that will be discarded as neuroscience matures. This consequence is what makes the doctrine substantive, indeed, radical. We ask, first, what the neuron doctrine means and, second, whether it is true. In answer to the first question, we distinguish two versions of the doctrine. One version, the trivial neuron doctrine, turns out to be uncontroversial but unsubstantive because it fails to have the consequence that the non-neuroscientific sciences of the mind will eventually be discarded. A second version, the radical neuron doctrine, does have this consequence, but, unlike the first doctrine, is highly controversial. We argue that the neuron doctrine appears to be both substantive and uncontroversial only as a result of a conflation of these two versions. We then consider whether the radical doctrine is true. We present and evaluate three arguments for it, based either on general scientific and philosophical considerations or on the details of neuroscience itself; arguing that all three fail. We conclude that the evidence fails to support the radical neuron doctrine. |
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| O'Regan, J.K., Noë, A. A sensorimotor account of vision and visual consciousness Behavioral and Brain Sciences 2001 (24)5 [html] |
| Many current neurophysiological, psychophysical and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is assumed to give rise to the experience of seeing. The problem with this kind of approach is that it leaves unexplained how the existence of such a detailed internal representation might produce visual consciousness. An alternative proposal is made here. We propose that seeing is a way of acting. It is a particular way of exploring the environment. Activity in internal representations does not generate the experience of seeing. The outside world serves as its own, external, representation. The experience of seeing occurs when the organism masters what we call the governing laws of sensorimotor contingency. The advantage of this approach is that it provides a natural and principled way of accounting for visual consciousness, and for the differences in the perceived quality of sensory experience in the different sensory modalities. Several lines of empirical evidence are brought forward in support of the theory, in particular: evidence from experiments in sensorimotor adaptation, visual "filling in", visual stability despite eye movements, change blindness, sensory substitution, and color perception. |
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| Oren, M., Nayar, S.K. A theory of specular surface geometry International Journal of Computer Vision 1996 (24):105-124 [pdf] |
| Atheoretical framework is introduced for the perception of specular surface geometry.Whenan observer moves in three-dimensional space, real scene features such as surface markings remain stationary with respect to the surfaces they belong to. In contrast, a virtual feature which is the specular reflection of a real feature, travels on the surface. Based on the notion of caustics, a feature classification algorithm is developed that distinguishes real and virtual features from their image trajectories that result from observer motion. Next, using support functions of curves, a closed-form relation is derived between the image trajectory of a virtual feature and the geometry of the specular surface it travels on. It is shown that, in the 2D case, where camera motion and the surface profile are coplanar, the profile is uniquely recovered by tracking just two unknown virtual features. Finally, these results are generalized to the case of arbitrary 3D surface profiles that are traveled by virtual features when camera motion is not confined to a plane. This generalization includes a number of mathematical results that substantially enhance the present understanding of specular surface geometry. An algorithm is developed that uniquely recovers 3D surface profiles using a single virtual feature tracked from the occluding boundary of the object. All theoretical derivations and proposed algorithms are substantiated by experiments. |
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| Masson, T. Algèbres associatives et de Hopf, homologies et cohomologies usuelles 2000 [pdf] |
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| Clark, A. An embodied cognitive science? Trends in Cognitive Sciences 1999 (3)9:345-351 [html] |
| The last ten years have seen an increasing interest, within cognitive science, in issues concerning the physical body, the local environment, and the complex interplay between neural systems and the wider world in which they function. Yet many unanswered questions remain, and the shape of a genuinely physically embodied, environmentally embedded science of the mind is still unclear. In this article I will raise a number of critical questions concerning the nature and scope of this approach, drawing a distinction between two kinds of appeal to embodiment: (1) 'Simple' cases, in which bodily and environmental properties merely constrain accounts that retain the focus on inner organization and processing; and (2) More radical appeals, in which attention to bodily and environmental features is meant to transform both the subject matter and the theoretical framework of cognitive science. |
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| Bell, A.J., Sejnowski, T.J. An information maximisation approach to blind separation and blind deconvolution Neural Computation 1995 (7)6:1129-1159 [pdf] |
| We derive a new self-organising learning algorithm which maximises the information transferred in a network of non-linear units. The algo- rithm does not assume any knowledge of the input distributions, and is de ned here for the zero-noise limit. Under these conditions, infor- mation maximisation has extra properties not found in the linear case (Linsker 1989). The non-linearities in the transfer function are able to pick up higher-order moments of the input distributions and perform something akin to true redundancy reduction between units in the out- put representation. This enables the network to separate statistically independent components in the inputs: a higher-order generalisation of Principal Components Analysis. We apply the network to the source separation (or cocktail party) problem, successfully separating unknown mixtures of up to ten speak- ers. We also show that a variant on the network architecture is able to perform blind deconvolution (cancellation of unknown echoes and reverberation in a speech signal). Finally, we derive dependencies of information transfer on time delays. We suggest that information max- imisation provides a unifying framework for problems in `blind' signal processing. |
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| Saunders, B., van Brakel, J. Are there non-trivial constraints on colour categorization Behavioral and Brain Sciences 1997 (20)2 [html] |
| In this target article the following hypotheses are discussed: (1) colour is autonomous: a perceptuo-linguistic and behavioural universal; (2) it is completely described by three independent attributes: hue, brightness and saturation; (3) phenomenologically and psychophysically there are four unique hues: red, green, blue, yellow; (4) the unique hues are underpinned by two opponent psychophysical and/or neuronal channels: red/green, blue/yellow. The relevant literature is reviewed. We conclude: [i] psychophysics and neurophysiology fail to set nontrivial constraints on colour categorization; [ii] linguistic evidence provides no grounds for the universality of basic colour categories; [iii] neither the opponent hues red/green, blue/yellow nor hue, brightness and saturation are intrinsic to a universal concept of colour; (iv) colour is not autonomous. |
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| Tong, F., Nakayama, K., Vaughan, J.T., Kanwisher, N. Binocular rivalry and visual awareness in human extrastriate cortex Neuron 1998 (21):753-759 [pdf] |
| We used functional magnetic resonance imaging (fMRI) to monitor stimulus-selective responses of the human fusiform face area (FFA) and parahippocampal place area (PPA) during binocular rivalry in which a face and a house stimulus were presented to different eyes. Though retinal stimulation remained constant, subjects perceived changes from house to face that were accompanied by increasing FFA and decreasing PPA activity; perceived changes from face to house led to the opposite pattern of responses. These responses during rivalry were equal in magnitude to those evoked by nonrivalrous stimulus alternation, suggesting that activity in the FFA and PPA reflects the perceived rather than the retinal stimulus, and that neural competition during binocular rivalry has been resolved by these stages of visual processing. |
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| O'Regan, J.K., Rensink, R.A., Clark, J.J. Blindness to scene changes caused by mudsplashes Nature 1999 (34):398 [html] |
| Change-blindness, occurs when large changes are missed under natural viewing conditions because they occur simultaneously with a brief visual disruption, perhaps caused by an eye movement,, a flicker, a blink, or a camera cut in a film sequence. We have found that this can occur even when the disruption does not cover or obscure the changes. When a few small, high-contrast shapes are briefly spattered over a picture, like mudsplashes on a car windscreen, large changes can be made simultaneously in the scene without being noticed. This phenomenon is potentially important in driving, surveillance or navigation, as dangerous events occurring in full view can go unnoticed if they coincide with even very small, apparently innocuous, disturbances. It is also important for understanding how the brain represents the world. |
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| Brooks, R., L.A. Stein, Building Brains for Bodies Autonomous Robots 1994 (1)1:pp. 7-25 [pdf] |
| We describe a project to capitalize on newly available levels of computational resources in order to understand human cognition. We are building an integrated physical system including vision, sound input and output, and dextrous manipulation, all controlled by a continuously operating large scale parallel MIMD computer. The resulting system will learn to "think" by building on its bodily experiences to accomplish progressively more abstract tasks. Past experience suggests that in attempting to build such an integrated system we will have to fundamentally change the way artificial intelligence, cognitive science, linguistics, and philosophy think about the organization of intelligence. We expect to be able to better reconcile the theories that will be developed with current work in neuroscience. |
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| Faugeras, O.D., Luong, Q.-T. , Maybank, S.J. Camera Self-Calibration: Theory and Experiments 1992 :321-334 [html] |
| The problem of finding the internal orientation of a camera (camera calibration) is extremely important for practical applications. In this paper a complete method for calibrating a camera is presented. In contrast with existing methods it does not require a calibration object with a known 3D shape. The new method requires only point matches from image sequences. It is shown, using experiments with noisy data, that it is possible to calibrate a camera just by pointing it at the environment... |
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| Byrne, A., Hilbert, D.R. Color Realism and Color Science Behavioral and Brain Sciences 2003 26 [html] |
| he target article is an attempt to make some progress on the problem of color realism. Are objects colored? And what is the nature of the color properties? We defend the view that physical objects (for instance, tomatoes, radishes, and rubies) are colored, and that colors are physical properties, specifically types of reflectance. This is probably a minority opinion, at least among color scientists. Textbooks frequently claim that physical objects are not colored, and that the colors are "subjective" or "in the mind." The article has two other purposes: first, to introduce an interdisciplinary audience to some distinctively philosophical tools that are useful in tackling the problem of color realism and, second, to clarify the various positions and central arguments in the debate. The first part explains the problem of color realism and makes some useful distinctions. These distinctions are then used to expose various confusions that often prevent people from seeing that the issues are genuine and difficult, and that the problem of color realism ought to be of interest to anyone working in the field of color science. The second part explains the various leading answers to the problem of color realism, and (briefly) argues that all views other than our own have serious difficulties or are unmotivated. The third part explains and motivates our own view, that colors are types of reflectances, and defends it against objections made in the recent literature that are often taken as fatal. |
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| Maloney, L.T. Color Vision: From Genes to Perception 1999 [pdf] |
| Surface Color Perception. The study of surface color perception is a proper subset of the study of color perception, and one way to highlight the difference between them is to consider the effective stimulus appropriate to each. The effective stimulus for the study of color perception, broadly construed, is the spectral power distribution of light arriving at each point of the left and right retinas. There is no assumption that the patterns of light correspond to any possible arrangement of surfaces, objects and illuminants in a three-dimensional scene. In contrast, the study of surface color perception presupposes that the light reaching the retinas has a history. The effective stimulus is the result of the interaction of certain light sources (the illuminant) with the surfaces of objects in an environment. It is clear that any stimulus appropriate for the study of surface color perception is also appropriate for the study of color perception but not vice versa. |
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| Maloney, L.T., Wandell, B.A. Color constancy: a method for recovering surface spectral reflectance Journal of the Optical Society of America A 1985 [html] |
| Human and machine visual sensing is enhanced when surface properties of objects in scenes, including color, can be reliably estimated despite changes in the ambient lighting conditions. We describe a computational method for estimating surface spectral reflectance when the spectral power distribution of the ambient light is not known. |
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| Palmer, S.E. Color, Counsciousness, and the Isomorphism Constraint Behavioral and Brain Sciences 1999 (22)6 [html] |
| The relations among consciousness, brain, behavior, and scientific explanation are explored within the domain of color perception. Current scientific knowledge about color similarity, color composition, dimensional structure, unique colors, and color categories is used to assess Locke's "inverted spectrum argument" about the undetectability of color transformations. A symmetry analysis of color space shows that the literal interpretation of this argument -- reversing the experience of a rainbow -- would not work. Three other color-to-color transformations might, however, depending on the relevance of certain color categories. The approach is then generalized to examine behavioral detection of arbitrary differences in color experiences, leading to the formulation of a principled distinction, called the isomorphism constraint, between what can and cannot be determined about the nature of color experience by objective behavioral means. Finally, the prospects for achieving a biologically based explanation of color experience below the level of isomorphism are considered in light of the limitations of behavioral methods. Within-subject designs using biological interventions hold the greatest promise for scientific progress on consciousness, but objective knowledge of another person's experience appears impossible. The implications of these arguments for functionalism are discussed. |
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| Chalmers, D.J. Conscious Experience 1995 [html] |
| It is widely accepted that conscious experience has a physical basis. That is, the properties of experience (phenomenal properties, or qualia) systematically depend on physical properties according to some lawful relation. There are two key questions about this relation. The first concerns the strength of the laws: are they logically or metaphysically necessary, so that consciousness is nothing "over and above" the underlying physical process, or are they merely contingent laws like the law of gravity? This question about the strength of the psychophysical link is the basis for debates over physicalism and property dualism. The second question concerns the shape of the laws: precisely how do phenomenal properties depend on physical properties? What sort of physical properties enter into the laws' antecedents, for instance; consequently, what sort of physical systems can give rise to conscious experience? It is this second question that I address in this paper. |
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| Bloch, A., Leonard, N.E., Marsden, J.E. Controlled Lagrangians and the stabilization of Mechanical Systems I: The First Matching Theorem IEEE Trans. on Systems and Control 2001 (45):2253-2270 [html] |
| We develop a method for the stabilization of mechanical systems with symmetry based on the technique of controlled Lagrangians. The procedure involves making structured modifications to the Lagrangian for the uncontrolled system, thereby constructing the controlled Lagrangian. The Euler-Lagrange equations derived from the controlled Lagrangian describe the closed-loop system, where new terms in these equations are identified with control forces. Since the controlled system is Lagrangian by construction, energy methods can be used to find control gains that yield closed-loop stability. In this paper we use kinetic shaping to preserve symmetry and only stabilize systems modulo the symmetry group. In the sequel to this paper (Part II), we extend the technique to include potential shaping and we achieve stabilization in the full phase space. The procedure is demonstrated for several underactuated balance problems, including the stabilization of an inverted planar pendulum on a cart moving on a line and an inverted spherical pendulum on a cart moving in the plane. |
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| Gegenfurtner, K.R. Cortical mechanisms of colour vision Nature reviews 2003 (4):563-572 [pdf] |
| The perception of colour is a central component of primate vision. Colour facilitates object perception and recognition, and has an important role in scene segmentation and visual memory. Moreover, it provides an aesthetic component to visual experiences that is fundamental to our perception of the world. Despite the long history of colour vision studies, much has still to be learned about the physiological basis of colour perception. Recent advances in our understanding of the early processing in the retina and thalamus have enabled us to take a fresh look at cortical processing of colour. These studies are beginning to indicate that colour is processed not in isolation, but together with information about luminance and visual form, by the same neural circuits, to achieve a unitary and robust representation of the visual world. |
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| Meredith, M.A., Nemitz, J.W., Stein, B. Determinants of multisensory integration in superior colliculus neurons. I. Temporal factors Journal of Neuroscience 1987 (10):3215-3229 [html] |
| One of the most impressive features of the central nervous system is its ability to process information from a variety of stimuli to produce an integrated, comprehensive representation of the external world. In the present study, the temporal disparity among combinations of different sensory stimuli was shown to be a critical factor influencing the integration of multisensory stimuli by superior colliculus neurons. Several temporal principles that govern multisensory integration were revealed: (1) maximal levels of response enhancement were generated by overlapping the peak discharge periods evoked by each modality; (2) the magnitude of this enhancement decayed monotonically to zero as the peak discharge periods became progressively more temporally disparate; (3) with further increases in temporal disparity, the same stimulus combinations that previously produced enhancement could often produce depression; and (4) these kinds of interactions could frequently be predicted from the discharge trains initiated by each stimulus alone. Since multisensory superior colliculus neurons project to premotor areas of the brain stem and spinal cord that control the orientation of the receptor organs (eyes, pinnae, head), they are believed to influence attentive and orientation behaviors. Therefore, it is likely that the temporal relationships of different environmental stimuli that control the activity of these neurons are also a powerful determinant of superior colliculus-mediated attentive and orientation behaviors. |
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| Lewicki, M. Efficient coding of natural sounds Nature Neuroscience 2002 (5)4:356-363 [pdf] |
| The auditory system encodes sound by decomposing the amplitude signal arriving at the ear into multiple frequency bands whose center frequencies and bandwidths are approximately exponential functions of the distance from the stapes. This organization is thought to result from the adaptation of cochlear mechanisms to the animal's auditory environment. Here we report that several basic auditory nerve fiber tuning properties can be accounted for by adapting a population of filter shapes to encode natural sounds efficiently. The form of the code depends on sound class, resembling a Fourier transformation when optimized for animal vocalizations and a wavelet transformation when optimized for non-biological environmental sounds. Only for the combined set does the optimal code follow scaling characteristics of physiological data. These results suggest that auditory nerve fibers encode a broad set of natural sounds in a manner consistent with information theoretic principles. |
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| Olshausen, B., Field, D. Emergence of simple-cell receptive field properties by learning a sparse code for natural images Nature 1996 (381):607-609 [html] |
| The receptive fields of simple cells in mammalian primary visual cortex can be characterized as being spatially localized, oriented and bandpass (selective to structure at different spatial scales), comparable to the basis functions of wavelet transforms. One approach to understanding such response properties of visual neurons has been to consider their relationship to the statistical structure of natural images in terms of efficient coding. Along these lines, a number of studies have attempted to train unsupervised learning algorithms on natural images in the hope of developing receptive fields with similar properties, but none has succeeded in producing a full set that spans the image space and contains all three of the above properties. Here we investigate the proposal that a coding strategy that maximizes sparseness is sufficient to account for these properties. We show that a learning algorithm that attempts to find sparse linear codes for natural scenes will develop a complete family of localized, oriented, bandpass receptive fields, similar to those found in the primary visual cortex. The resulting sparse image code provides a more efficient representation for later stages of processing because it possesses a higher degree of statistical independence among its outputs. |
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| Illman, S. Every proper smooth action of a Lie group is equivalent to a real analytic action: a contribution to Hilbert's fifth problem Prospects in topology 1994 (138):189-220 |
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| Ahissar, E., Arieli, A. Figuring space by time Neuron 2001 (32):185-201 [html] |
| Sensory information is encoded both in space and in time. Spatial encoding is based on the identity of activated receptors, while temporal encoding is based on the timing of activation. In order to generate accurate internal representations of the external world, the brain must decode both types of encoded information, even when processing stationary stimuli. We review here evidence in support of a parallel processing scheme for spatially and temporally encoded information in the tactile system and discuss the advantages and limitations of sensory-derived temporal coding in both the tactile and visual systems. Based on a large body of data, we propose a dynamic theory for vision, which avoids the impediments of previous dynamic theories. |
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| Masson, T. Géométrie différentielle, groupes et algèbres de Lie, fibrés et connexions 2001 [pdf] |
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| De Valois, R.L., De Valois, K.K., Switkes, E., Mahon, L. Hue scaling of isoluminant and cone-specific lights Vision Research 1997 (37)7:885-97 [html] |
| ing a hue scaling technique, we have examined the appearance of colored spots produced by shifts from white to isoluminant stimuli along various color vectors in order to examine color appearance without the complications of the combined luminance and chromatic stimulation involved in most previous hue scaling studies, which have used flashes of monochromatic light. We also used spots lying along cone-isolating vectors in order to determine what hues would be reported with a change in activation of only single cone types or of only single geniculate opponent-cell types, an issue of direct relevance to any model of color vision. We find that: 1. Unique hues do not correspond either to the change in activation of single cone types or of single geniculate opponent-cell types. This is well known to be the case for yellow and blue, but we find it to be true for red and green as well. 2. These conclusions are not limited to the particular white (Illuminant C) used as an adapting background in most of the experiments. Shifts along the same cone-contrast vectors relative to different backgrounds lead to much the same hue percepts, independent of the starting white used. 3. The shifts of the perceptual colors from the geniculate axes are in the directions, and close to the absolute amounts, predicted by our [De Valois & De Valois (1993). Vision Research, 33, 1053-1065] multi-stage color model in which we postulate that the S-opponent cells are added to or subtracted from the M- and L-opponent cells to form the four perceptual color systems. 4. There are distinct asymmetries with respect to the extent to which various hues within each perceptual opponent system deviate from the geniculate opponent-cell axes. Blue is shifted more from the S-LM axis than is yellow; green is shifted more from the L-M axis than is red. There are also asymmetries in the angular extent of opponent color regions. Blue is seen over a larger range of color vectors than is yellow, and red over a slightly larger range than green. 5. Such asymmetries are not accounted for by any model that treats red-green and yellow-blue each as unitary, mirror-image opponent-color systems. Although red and green are perceptually opponent, the red and green perceptual systems do not appear to be constructed in a mirror-image fashion with respect to input from different cone types or from different geniculate opponent-cell types. The same is true for yellow and blue. |
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| Sharma, J., Angelucci, A., Sur, M. Induction of visual orientation modules in auditory cortex Nature 2000 (404):841-847 [pdf] |
| Modules of neurons sharing a common property are a basic organizational feature of mammalian sensory cortex. Primary visual cortex (V1) is characterized by orientation modules groups of cells that share a preferred stimulus orientation which are organized into a highly ordered orientation map. Here we show that in ferrets in which retinal projections are routed into the auditory pathway, visually responsive neurons in `rewired' primary auditory cortex are also organized into orientation modules. The orientation tuning of neurons within these modules is comparable to the tuning of cells in V1 but the orientation map is less orderly. Horizontal connections in rewired cortex are more patchy and periodic than connections in normal auditory cortex, but less so than connections in V1. These data show that afferent activity has a profound inØuence on diverse components of cortical circuitry, including thalamocortical and local intracortical connections, which are involved in the generation of orientation tuning, and long-range horizontal connections, which are important in creating an orientation map. |
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| Cardoso, J.-F. Infomax and maximum likelihood for source separation IEEE Letters on Signal Processing 1997 (4)4:112-114 [html] |
| Algorithms for the blind separation of sources can be derived from several different principles. This letter shows that the recently proposed infomax principle is equivalent to maximum likelihood. Introduction. Source separation consists in recovering a set of unobservable signals (sources) from a set of observed mixtures. |
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| Pylyshyn, Z. Is Vision Continuous With Cognition? The Case for Cognitive Impenetrability of Visual Perception Behavioral and Brain Sciences 1999 (22)3 [html] |
| Although the study of visual perception has made more progress in the past 40 years than any other area of cognitive science, there remain major disagreements as to how closely vision is tied to cognition. This target article sets out some of the arguments for both sides (arguments from computer vision, neuroscience, psychophysics, perceptual learning and other areas of vision science) and defends the position that an important part of visual perception, corresponding to what some people have called early vision, is prohibited from accessing relevant expectations, knowledge and utilities in determining the function it computes - in other words, it is cognitively impenetrable. That part of vision is complex and involves top-down interactions that are internal to the early vision system. Its function is to provide a structured representation of the 3-D surfaces of objects sufficient to serve as an index into memory, with somewhat different outputs being made available to other systems such as those dealing with motor control. The paper also addresses certain conceptual and methodological issues raised by this claim, such as whether signal detection theory and event-related potentials can be used to assess cognitive penetration of vision. A distinction is made among several stages in visual processing, including, in addition to the inflexible early-vision stage, a pre-perceptual attention-allocation stage and a post-perceptual evaluation, selection, and inference stage which accesses long-term memory. These two stages provide the primary ways in which cognition can affect the outcome of visual perception. The paper discusses arguments from computer vision and psychology showing that vision is "intelligent" and involves elements of "problem solving". The cases of apparently intelligent interpretation sometimes cited in support of this claim do not show cognitive penetration; rather, they show that certain natural constraints on interpretation, concerned primarily with optical and geometrical properties of the world, have been compiled into the visual system. The paper also examines a number of examples where instructions and "hints" are alleged to affect what is seen. In each case it is concluded that the evidence is more readily assimilated to the view that when cognitive effects are found, they have a locus outside early vision, in such processes as the allocation of focal attention and the identification of the stimulus. |
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| Lee, D.D., Seung, H.S. Learning the Parts of Objects by Non-negative Matrix Factorization Nature 1999 (401):788 [pdf] |
| Is perception of the whole based on perception of its parts? There is psychological and physiological evidence for parts-based representations in the brain, and certain computational theories of object recognition rely on such representations. But little is known about how brains or computers might learn the parts of objects. Here we demonstrate an algorithm for non-negative matrix factorization that is able to learn parts of faces and semantic features of text. This is in contrast to other methods, such as principal components analysis and vector quantization, that learn holistic, not parts-based, representations. Non-negative matrix factorization is distinguished from the other methods by its use of non-negativity constraints. These constraints lead to a parts-based representation because they allow only additive, not subtractive, combinations. When non-negative matrix factorization is implemented as a neural network, parts-based representations emerge by virtue of two properties: the firing rates of neurons are never negative and synaptic strengths do not change sign. |
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| Tenenbaum, J.B. Mapping a Manifold of Perceptual Observations 1998 (NIPS-10) [pdf] |
| Nonlinear dimensionality reduction is formulated here as the problem of trying to find a Euclidean feature-space embedding of a set of observations that preserves as closely as possible their intrinsic metric structure the distances between points on the observation manifold as measured along geodesic paths. Our isometric feature mapping procedure, or isomap, is able to reliably recover low-dimensional nonlinear structure in realistic perceptual data sets, such as a manifold of face images, where conventional global mapping methods find only local minima. The recovered map provides a canonical set of globally meaningful features, which allows perceptual transformations such as interpolation, extrapolation, and analogy highly nonlinear transformations in the original observation space to be computed with simple linear operations in feature space. |
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| Searle, J. Minds, Brains and programs Behavioral and Brain Sciences 1980 (3)7:585-642 [html] |
| What psychological and philosophical significance should we attach to recent efforts at computer simulations of human cognitive capacities? In answering this question, I find it useful to distinguish what I will call "strong" AI from "weak" or "cautious" AI (artificial intelligence). According to weak AI, the principal value of the computer in the study of the mind is that it gives us a very powerful tool. For example, it enables us to formulate and test hypotheses in a more rigorous and precise fashion. But according to strong AI, the computer is not merely a tool in the study of the mind; rather, the appropriately programmed computer really is a mind, in the sense that computers given the right programs can be literally said to understand and have other cognitive states. In strong AI, because the programmed computer has cognitive states, the programs are not mere tools that enable us to test psychological explanations; rather, the programs are themselves the explanations. |
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| Gallese, V., Goldman, A. Mirror neurons and the simulation theory of mind-reading Trends in Cognitive Sciences 1998 (2)12 [pdf] |
| A new class of visuomotor neuron has been recently discovered in the monkey s premotor cortex: mirror neurons. These neurons respond both when a particular action is performed by the recorded monkey and when the same action, performed by another individual, is observed. Mirror neurons appear to form a cortical system matching observation and execution of goal-related motor actions. Experimental evidence suggests that a similar matching system also exists in humans. What might be the functional role of this matching system? One possible function is to enable an organism to detect certain mental states of observed conspecifics. This function might be part of, or a precursor to, a more general mind-reading ability. Two different accounts of mindreading have been suggested. According to theory theory , mental states are represented as inferred posits of a naive theory. According to simulation theory , other people s mental states are represented by adopting their perspective: by tracking or matching their states with resonant states of one s own. The activity of mirror neurons, and the fact that observers undergo motor facilitation in the same muscular groups as those utilized by target agents, are findings that accord well with simulation theory but would not be predicted by theory theory. |
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| Leopold, D.A., Logothetis, N.K. Multistable phenomena: changing views in perception Trends in Cognitive Sciences 1999 (3)7 [pdf] |
| Traditional explanations of multistable visual phenomena (e.g. ambiguous figures, perceptual rivalry) suggest that the basis for spontaneous reversals in perception lies in antagonistic connectivity within the visual system. In this review, we suggest an alternative, albeit speculative, explanation for visual multistability that spontaneous alternations reflect responses to active, programmed events initiated by brain areas that integrate sensory and non-sensory information to coordinate a diversity of behaviors. Much evidence suggests that perceptual reversals are themselves more closely related to the expression of a behavior than to passive sensory responses: (1) they are initiated spontaneously, often voluntarily, and are influenced by subjective variables such as attention and mood; (2) the alternation process is greatly facilitated with practice and compromised by lesions in non-visual cortical areas; (3) the alternation process has temporal dynamics similar to those of spontaneously initiated behaviors; (4) functional imaging reveals that brain areas associated with a variety of cognitive behaviors are specifically activated when vision becomes unstable. In this scheme, reorganizations of activity throughout the visual cortex, concurrent with perceptual reversals, are initiated by higher, largely non-sensory brain centers. Such direct intervention in the processing of the sensory input by brain structures associated with planning and motor programming might serve an important role in perceptual organization, particularly in aspects related to selective attention. |
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| Amari, S.-I. Natural Gradient Learning for Over- and Under-Complete Bases in ICA Neural Computation 1999 [pdf] |
| Independent component analysis or blind source separation is a new technique of extracting independent signals from mixtures. It is applicable even when the number of independent sources is unknown and is larger or smaller than the number of observed mixture signals. This article extends the natural gradient learning algorithm to be applicable to these overcomplete and undercomplete cases. Here, the observed signals are assumed to be whitened by preprocessing, so that we use the natural Riemannian gradient in Stiefel manifolds. |
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| Rees, G., Kreiman, G., Koch, C. Neural Correlates of Consciousness in Humans Nature reviews Neuroscience 2002 (3):261-270 [html] |
| The directness and vivid quality of conscious experience belies the complexity of the underlying neural mechanisms, which remain incompletely understood. Recent work has focused on identifying the brain structures and patterns of neural activity within the primate visual system that are correlated with the content of visual consciousness. Functional neuroimaging in humans and electrophysiology in awake mokeys indicate that there are important differences between striate and extrastriate visual cortex in how well neural activity correlates with consciousness. Moreover, recent neuroimaging studies indicate that, in addition to these ventral areas of visual cortex, dorsal prefrontal and parietal areas might contribute to conscious visual experience. |
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| Nadal, J.-P. , Parga, N. Non linear neurons in the low noise limit: a factorial code maximizes information transfer Network 1994 [html] |
| We investigate the consequences of maximizing information transfer in a simple neural network (one input layer, one output layer), focussing on the case of non linear transfer functions. We assume that both receptive fields (synaptic efficacies) and transfer functions can be adapted to the environment. The main result is that, for bounded and invertible transfer functions, in the case of a vanishing additive output noise, and no input noise, maximization of information (Linsker's infomax principle) leads to a factorial code - hence to the same solution as required by the redundancy reduction principle of Barlow, or, in the signal processing language, to Independent Component Analysis (ICA). We show also that this result is valid for linear, more generally unbounded, transfer functions, provided optimization is performed under an additive constraint, that is which can be written as a sum of terms, each one being specific to one output neuron. Finally we study the effect of a non zero input noise. We find that, at first order in the input noise, assumed to be small as compared to the - small - output noise, the above results are still valid, provided the output noise is uncorrelated from one neuron to the other. |
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| Tenenbaum, J.B., de Silva, V., Langford, J.C. Nonlinear Dimensionality Reduction by Locally Linear Embedding Science 2000 (290):2323-2326 [pdf] |
| Many areas of science depend on exploratory data analysis and visualization. The need to analyze large amounts of multivariate data raises the fundamental problem of dimensionality reduction: how to discover compact representations of high-dimensional data. Here, we introduce locally linear embedding (LLE), an unsupervised learning algorithm that computes low-dimensional, neighborhood- preserving embeddings of high-dimensional inputs. Unlike clustering methods for local dimensionality reduction, LLE maps its inputs into a single global coordinate system of lower dimensionality, and its optimizations do not involve local minima. By exploiting the local symmetries of linear reconstructions, LLE is able to learn the global structure of nonlinear manifolds, such as those generated by images of faces or documents of text. |
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| Mitchell, J.F., Stoner, G.R., Reynolds, J.H. Object-based attention determines dominance in binocular rivalry Nature 2004 (429):410-413 [pdf] |
| A question of long-standing interest to philosophers, psychologists and neuroscientists is how the brain selects which signals enter consciousness1,2. Binocular rivalry and attention both involve selection of visual stimuli, but affect perception quite differently. During binocular rivalry, awareness alternates between two different stimuli presented to the two eyes. In contrast, attending to one of two different stimuli impairs discrimination of the ignored stimulus, but without causing it to disappear from consciousness. Here we show that despite this difference, attention and rivalry rely on shared object-based selection mechanisms. We cued attention to one of two superimposed transparent surfaces and then deleted the image of one surface from each eye, resulting in rivalry. Observers usually reported seeing only the cued surface. They were also less accurate in judging unpredictable changes in the features of the uncued surface. Our design ensured that selection of the cued surface could not have resulted from spatial, ocular or feature-based mechanisms. Rather, attention was drawn to one surface, and this caused the other surface to be perceptually suppressed during rivalry. These results raise the question of how object representations compete during these two forms of perceptual selection, even as the features of those objects change unpredictably over time. |
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| Block, N. On a confusion about a function of cousciousness Behavioral and Brain Sciences 1995 (18)2:227-287 [html] |
| Consciousness is a mongrel concept: there are a number of very different "consciousnesses." Phenomenal consciousness is experience; the phenomenally conscious aspect of a state is what it is like to be in that state. The mark of access-consciousness, by contrast, is availability for use in reasoning and rationally guiding speech and action. These concepts are often partly or totally conflated, with bad results. This target article uses as an example a form of reasoning about a function of "consciousness" based on the phenomenon of blindsight. Some information about stimuli in the blind field is represented in the brains of blindsight patients, as shown by their correct "guesses," but they cannot harness this information in the service of action, and this is said to show that a function of phenomenal consciousness is somehow to enable information represented in the brain to guide action. But stimuli in the blind field are BOTH access-unconscious and phenomenally unconscious. The fallacy is: an obvious function of the machinery of access-consciousness is illicitly transferred to phenomenal consciousness. |
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| Chalmers, D.J. On the Search for the Neural Correlate of Consciousnes Toward a Science of Consciousness II 1998 [html] |
| I'm going to talk about one aspect of the role that neuroscience plays in the search for a theory of consciousness. Whether or not neuroscience can solve all the problems of consciousness singlehandedly, there is no question that it has a major role to play. We've seen at this conference that there's a vast amount of progress in neurobiological research, and that much of it is clearly bearing on the problems of consciousness. But the conceptual foundations of this sort of research are only beginning to be laid. So I will look at some of the things that are going on from a philosopher's perspective and will see if there's anything helpful to say about these foundations. |
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| Todorov, E., Jordan, M.I. Optimal feedback control as a theory of motor coordination Nature Neuroscience 2002 (5):11 [pdf] |
| Motor coordination the marshalling of redundant actuators in the service of a desired behavioral outcome is among the most important and least understood facets of motor function. Models that focus on mechanisms for achieving behavioral goals often fail to account for experimental data on movement variability and the exploitation of redundancy. Models that focus on variability and redundancy often fail to explain how goals are achieved in the first place. Here we show that not only are variability and goal achievement compatible, but indeed that allowing variability in redundant dimensions is the optimal strategy in the face of uncertainty. Our approach is based on stochastic optimal control theory, which provides, for a given task, the feedback control law that maximizes expected performance. This control law does not enforce a "desired trajectory" an approach that we show to be suboptimal but instead corrects only those deviations that interfere with the task goals. We find that the resulting behavior exhibits goal-directed adjustments, synergies, controlled parameters , simplifying rules , and discrete coordination modes none of which are built in a priori. Experimentally, we investigate a range of motor tasks and report patterns of variability in close agreement with the model. |
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| Barsalou, L.W. Perceptual symbols systems Behavioral and Brain Sciences 1999 (22):577-660 [html] |
| Prior to the twentieth century, theories of knowledge were inherently perceptual. Since then, developments in logic, statistics, and programming languages have inspired amodal theories that rest on principles fundamentally different from those underlying perception. In addition, perceptual approaches have become widely viewed as untenable, because they are assumed to implement recording systems, not conceptual systems. A perceptual theory of knowledge is developed here in the contexts of current cognitive science and neuroscience. During perceptual experience, association areas in the brain capture bottom-up patterns of activation in sensory-motor areas. Later, in a top-down manner, association areas partially reactivate sensory-motor areas to implement perceptual symbols. The storage and reactivation of perceptual symbols operates at the level of perceptual components--not at the level of holistic perceptual experiences. Through the use of selective attention, schematic representations of perceptual components are extracted from experience and stored in memory (e.g., individual memories of green, purr, hot). As memories of the same component become organized around a common frame, they implement a simulator that produces limitless simulations of the component (e.g., simulations of purr). Not only do such simulators develop for aspects of sensory experience, they also develop for aspects of proprioception (e.g., lift, run) and for introspection (e.g., compare, memory, happy, hungry). Once established, these simulators implement a basic conceptual system that represents types, supports categorization, and produces categorical inferences. These simulators further support productivity, propositions, and abstract concepts, thereby implementing a fully functional conceptual system. Productivity results from integrating simulators combinatorially and recursively to produce complex simulations. Propositions result from binding simulators to perceived individuals to represent type-token relations. Abstract concepts are grounded in complex simulations of combined physical and introspective events. Thus, a perceptual theory of knowledge can implement a fully functional conceptual system while avoiding what it is becoming increasingly apparent would be problems for amodal symbol systems. Implications for cognition, neuroscience, evolution, development, and artificial intelligence are explored. |
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| Paz, R. & al Preparatory activity in motor cortex reflects learning of local visuomotors skills Nature Neuroscience 2003 (6)8:882-890 [pdf] |
| In humans, learning to produce correct visually guided movements to adapt to new sensorimotor conditions requires the formation of an internal model that represents the new transformation between visual input and the required motor command. When the new environment requires adaptation to directional errors, learning generalizes poorly to untrained locations and directions, indicating that such learning is local. Here we replicated these behavioral findings in rhesus monkeys using a visuomotor rotation task and simultaneously recorded neuronal activity. Specific changes in activity were observed only in a subpopulation of cells in the motor cortex with directional properties corresponding to the locally learned rotation. These changes adhered to the dynamics of behavior during learning and persisted between learning and relearning of the same rotation. These findings suggest a neural mechanism for the locality of newly acquired sensorimotor tasks and provide electrophysiological evidence for their retention in working memory. |
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| Tye, M. Qualia 2003 [html] |
| Feelings and experiences vary widely. For example, I run my fingers over sandpaper, smell a skunk, feel a sharp pain in my finger, seem to see bright purple, become extremely angry. In each of these cases, I am the subject of a mental state with a very distinctive subjective character. There is something it is like for me to undergo each state, some phenomenology that it has. Philosophers often use the term "qualia" (singular "quale") to refer to the introspectively accessible, phenomenal aspects of our mental lives. In this standard, broad sense of the term, it is difficult to deny that there are qualia. Disagreement typically centers on which mental states have qualia, whether qualia are intrinsic qualities of their bearers, and how qualia relate to the physical world both inside and outside the head. The status of qualia is hotly debated in philosophy largely because it is central to a proper understanding of the nature of consciousness. Qualia are at the very heart of the mind-body problem. |
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| Dennett, D.C. Quining Qualia Readings in Philosophy and Cognitive Science 1993 [htm] |
| "Qualia" is an unfamiliar term for something that could not be more familiar to each of us: the ways things seem to us. As is so often the case with philosophical jargon, it is easier to give examples than to give a definition of the term. Look at a glass of milk at sunset; the way it looks to you--the particular, personal, subjective visual quality of the glass of milk is the quale of your visual experience at the moment. The way the milk tastes to you then is another, gustatory quale, and how it sounds to you as you swallow is an auditory quale; These various "properties of conscious experience" are prime examples of qualia. Nothing, it seems, could you know more intimately than your own qualia; let the entire universe be some vast illusion, some mere figment of Descartes' evil demon, and yet what the figment is made of (for you) will be the qualia of your hallucinatory experiences. Descartes claimed to doubt everything that could be doubted, but he never doubted that his conscious experiences had qualia, the properties by which he knew or apprehended them. |
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| Jameson, K.A., Highnote, S.M. Richer color experience in observers with multiple photopigment opsin genes Psychonomics Bulletin & Review 2001 (8)2:244-261 [pdf] |
| Traditional color vision theory posits that three types of retinal photopigrnents transduce light into a trivariate neural color code, thereby explaining color-matching behaviors. This principle of trichromacy is in need of reexamination in view of molecular genetics results suggesting that a substantial percentage of women possess more than three classes of retinal photopigrnents. At issue is the question of whether four-photopigrnent retinas necessarily yield trichromatic color perception. In the present paper, we review results and theory underlying the accepted photoreceptor-based model of trichromacy. A review of the psychological literature shows that gender-linked differences in color perception warrant further investigation of retinal photopigrnent classes and color perception relations. We use genetic analyses to examine an important position in the gene sequence, and we empirically assess and compare the color perception of individuals possessing more than three retinal photopigment genes with those possessing fewer retinal photopigrnent genes. Women with four-photopigment genotypes are found to perceive significantly more chromatic appearances in comparison with either male or female trichromat controls. We provide a rationale for this previously undetected finding and discuss implications for theories of color perception and gender differences in color behavior. |
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| Harris, C.M., Wolpert, D.M. Signal-dependent noise determines motor planning Nature 1998 (394):780-784 [pdf] |
| When we make saccadic eye movements or goal-directed arm movements, there is an infinite number of possible trajectories that the eye or arm could take to reach the target. However, humans show highly stereotyped trajectories in which velocity profiles of both the eye and hand are smooth and symmetric for brief movements. Here we present a unifying theory of eye and arm movements based on the single physiological assumption that the neural control signals are corrupted by noise whose variance increases with the size of the control signal. We propose that in the presence of such signal-dependent noise, the shape of a trajectory is selected to minimize the variance of the final eye or arm position. This minimum-variance theory accurately predicts the trajectories of both saccades and arm movements and the speed accuracy trade-off described by Fitt s law. These profiles are robust to changes in the dynamics of the eye or arm, as found empirically. Moreover, the relation between path curvature and hand velocity during drawing movements reproduces the empirical two-thirds power law. This theory provides a simple and powerful unifying perspective for both eye and arm movement control. |
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| Penrose, R. Techniques of Differential Topology in Relativity 1972 |
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| Churchland, P.S., Sejnowski, T.J. The Computational Brain 1992 [html] |
| This attractive and well-illustrated volume falls somewhere between a trade book and a textbook, with a style well suited for the Scientific American reader, as well as the active scientist, who may know something of either computer science or neuroscience but welcomes a crisp narrative that includes the necessary background from each discipline.... The reader will be well rewarded who seeks to understand, from well-chosen examples, how to merge the analysis of neuroscientific data with the developments of computational principles." -- Michael A. Arbib, Science The Computational Brain is the first unified and broadly accessible book to bring together computational concepts and behavioral data within a neurobiological framework. Churchland and Sejnowski address the foundational ideas of the emerging field of computational neuroscience, examine a diverse range of neural network models, and consider future directions of the field. |
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| Varela, F.J. The Embodied Mind: Cognitive science and human experience 1991 |
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| Csiszar, I. The Method of Types EEETIT: IEEE Transactions on Information Theory 1998 (44)6:2505-2523 [html] |
| The method of types is one of the key technical tools in Shannon Theory, and this tool is valuable also in other fields. In this paper, some key applications will be presented in sufficient detail enabling an interested nonspecialist to gain a working knowledge of the method, and a wide selection of further applications will be surveyed. These range from hypothesis testing and large deviations theory through error exponents for discrete memoryless channels and capacity of arbitrarily varying channels to multiuser problems. While the method of types is suitable primarily for discrete memoryless models, its extensions to certain models with memory will also be discussed. |
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| Lotto, B.R., Purves, D. The empirical basis of color perception Consciousness and Cognition 2002 (11):609-629 [html] |
| Rationalizing the perceptual effects of spectral stimuli has been a major challenge in vision science for at least the last 200 years. Here we review evidence that this otherwise puzzling body of phenomenology is generated by an empirical strategy of perception in which the color an observer sees is entirely determined by the probability distribution of the possible sources of the stimulus. The rationale for this strategy in color vision, as in other visual perceptual domains, is the inherent ambiguity of the real-world origins of any spectral stimulus. |
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| Wegner, D.M. The mind's best trick: how we experience conscious will Trends in Cognitive Sciences 2003 (7)2:65-69 [pdf] |
| We often experience consciously willing our actions. This experience is so profound that it tempts us to believe that our actions are caused by consciousness. It could also be a trick, however the mind s way of estimating its own apparent authorship by drawing causal inferences about relationships between thoughts and actions. Cognitive, social, and neuropsychological studies of apparent mental causation suggest that experiences of conscious will frequently depart from actual causal processes and so may not reflect direct perceptions of conscious thought causing action. |
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| Koch, C., Segev, I. The role of single neurons in information processing Nature Neuroscience 2000 (3):1171-1177 [pdf] |
| Neurons carry out the many operations that extract meaningful information from sensory receptor arrays at the organism s periphery and translate these into action, imagery and memory. Within today s dominant computational paradigm, these operations, involving synapses, membrane ionic channels and changes in membrane potential, are thought of as steps in an algorithm or as computations. The role of neurons in these computations has evolved conceptually from that of a simple integrator of synaptic inputs until a threshold is reached and an output pulse is initiated, to a much more sophisticated processor with mixed analog-digital logic and highly adaptive synaptic elements. |
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| Stockman, A., Sharpe L.T., The spectral sensitivities of the middle- and long-wavelength-sensitive cones derived from measurements in observers of known genotype Vision Research 2000 (40)13:1711-37 |
| The spectral sensitivities of middle- (M-) and long- (L-) wavelength-sensitive cones have been measured in dichromats of known genotype: M-cone sensitivities in nine protanopes, and L-cone sensitivities in 20 deuteranopes. We have used these dichromat cone spectral sensitivities, along with new luminous efficiency determinations, and existing spectral sensitivity and color matching data from normal trichromats, to derive estimates of the human M- and L-cone spectral sensitivities for 2 and 10 degrees dia. central targets, and an estimate of the photopic luminosity function [V(lambda)] for 2 degrees dia. targets, which we refer to as V(2)*(lambda). These new estimates are consistent with dichromatic and trichromatic spectral sensitivities and color matches. |
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| Norman, J. Two visual systems and two theories of perception: An attempt to reconcile the constructivist and ecological approaches Behavioral and Brain Sciences 2002 (25)1:73-144 [html] |
| The two contrasting theoretical approaches to visual perception, the constructivist and the ecological, are briefly presented and illustrated through their analyses of space perception and size perception. Earlier calls for their reconciliation and unification are reviewed. Neurophysiological, neuropsychological, and psychophysical evidence for the existence of two quite distinct visual systems, the ventral and the dorsal, is presented. These two perceptual systems differ in their functions; the ventral system\u2019s central function is that of identification, while the dorsal system is mainly engaged in the visual control of motor behavior. The strong parallels between the ecological approach and the functioning of the dorsal system and between the constructivist approach and the functioning of the ventral system are noted. It is also shown that the experimental paradigms used by the proponents of these two approaches match the functions of the respective visual systems. A dual-process approach to visual perception emerges from this analysis, with the ecological-dorsal process transpiring mainly without conscious awareness, while the constructivist-ventral process is normally conscious. Some implications of this dual-process approach to visual-perceptual phenomena are presented, with emphasis on space perception. |
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| Bourbaki, N. Variétes différentielles et analytiques. Fascicule de résultats 1971-1997 |
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| Marr, D. Vision: a computational investigation into the human representation and processing of visual information 1982 |
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| von Melschner, L., Pallas, S.L., Sur, M. Visual behaviour mediated by retinal projections directed to the auditory pathway Nature 2000 (404):871-876 [html] |
| An unresolved issue in cortical development concerns the relative contributions of intrinsic and extrinsic factors to the functional specification of different cortical areas1-4. Ferrets in which retinal projections are redirected neonatally to the auditory thalamus5 have visually responsive cells in auditory thalamus and cortex, form a retinotopic map in auditory cortex and have visual receptive field properties in auditory cortex that are typical of cells in visual cortex5-8. Here we report that this cross-modal projection and its representation in auditory cortex can mediate visual behaviour. When light stimuli are presented in the portion of the visual field that is 'seen' only by this projection, 'rewired' ferrets respond as though they perceive the stimuli to be visual rather than auditory. Thus the perceptual modality of a neocortical region is instructed to a significant extent by its extrinsic inputs. In addition, gratings of different spatial frequencies can be discriminated by the rewired pathway, although the grating acuity is lower than that of the normal visual pathway. |
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| Nagel, T. What is it like to be a bat? The Philosophical Review 1974 (LXXXIII)4:435-50 [html] |
| Consciousness is what makes the mind-body problem really intractable. Perhaps that is why current discussions of the problem give it little attention or get it obviously wrong. The recent wave of reductionist euphoria has produced several analyses of mental phenomena and mental concepts designed to explain the possibility of some variety of materialism, psychophysical identification, or reduction.1 But the problems dealt with are those common to this type of reduction and other types, and what makes the mind-body problem unique, and unlike the water-H2O problem or the Turing machine-IBM machine problem or the lightning-electrical discharge problem or the gene-DNA problem or the oak tree-hydrocarbon problem, is ignored. |
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| Crick, F., Koch, C. A framework for consciousness Nature Neuroscience 2003 (6)2:119-126 |
| Gold, I., Stoljar, D. A neuron doctrine in the philosophy of neuroscience Behavioral and Brain Sciences 1999 (22)5:585-642 |
| O'Regan, J.K., Noë, A. A sensorimotor account of vision and visual consciousness Behavioral and Brain Sciences 2001 (24)5 |
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| Saunders, B., van Brakel, J. Are there non-trivial constraints on colour categorization Behavioral and Brain Sciences 1997 (20)2 |
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| Lewicki, M. Efficient coding of natural sounds Nature Neuroscience 2002 (5)4:356-363 |
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| Sharma, J., Angelucci, A., Sur, M. Induction of visual orientation modules in auditory cortex Nature 2000 (404):841-847 |
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| Lee, D.D., Seung, H.S. Learning the Parts of Objects by Non-negative Matrix Factorization Nature 1999 (401):788 |
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| Gallese, V., Goldman, A. Mirror neurons and the simulation theory of mind-reading Trends in Cognitive Sciences 1998 (2)12 |
| Leopold, D.A., Logothetis, N.K. Multistable phenomena: changing views in perception Trends in Cognitive Sciences 1999 (3)7 |
| Amari, S.-I. Natural Gradient Learning for Over- and Under-Complete Bases in ICA Neural Computation 1999 |
| Rees, G., Kreiman, G., Koch, C. Neural Correlates of Consciousness in Humans Nature reviews Neuroscience 2002 (3):261-270 |
| Bizzi, E., Tresch, M.C., Saltiel, P., d'Avella, A. New perspectives on spinal motor systems Nature Neuroscience 2000 (1):101-107 |
| Nadal, J.-P. , Parga, N. Non linear neurons in the low noise limit: a factorial code maximizes information transfer Network 1994 |
| Isidori, A. Nonlinear Control Systems 1995 |
| Tenenbaum, J.B., de Silva, V., Langford, J.C. Nonlinear Dimensionality Reduction by Locally Linear Embedding Science 2000 (290):2323-2326 |
| Mitchell, J.F., Stoner, G.R., Reynolds, J.H. Object-based attention determines dominance in binocular rivalry Nature 2004 (429):410-413 |
| Scheiner, C. Oculus, hoc est: fundamentum opticum 1619 |
| Block, N. On a confusion about a function of cousciousness Behavioral and Brain Sciences 1995 (18)2:227-287 |
| Chalmers, D.J. On the Search for the Neural Correlate of Consciousnes Toward a Science of Consciousness II 1998 |
| Todorov, E., Jordan, M.I. Optimal feedback control as a theory of motor coordination Nature Neuroscience 2002 (5):11 |
| Barsalou, L.W. Perceptual symbols systems Behavioral and Brain Sciences 1999 (22):577-660 |
| Paz, R. & al Preparatory activity in motor cortex reflects learning of local visuomotors skills Nature Neuroscience 2003 (6)8:882-890 |
| Kandel, E.R., Schwartz, J., Jessell, T.M. Principles of Neural Science 2000 |
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| Tye, M. Qualia 2003 |
| Dennett, D.C. Quining Qualia Readings in Philosophy and Cognitive Science 1993 |
| Amari, S.-I. , Cichocki, A., Yang, H.H. Recurrent Neural Networks for Blind Separation of Sources 1995 :37-42 |
| Jameson, K.A., Highnote, S.M. Richer color experience in observers with multiple photopigment opsin genes Psychonomics Bulletin & Review 2001 (8)2:244-261 |
| Linsker, R. Self-organization in a perceptual network IEEE Computer 1988 (21):105-117 |
| Harris, C.M., Wolpert, D.M. Signal-dependent noise determines motor planning Nature 1998 (394):780-784 |
| Barlow, H.B. Single units and sensation: A neuron doctrine for perceptual psychology? Perception 1972 (1)1:371-394 |
| Lawson, H.B., Michelsohn, M.-L. Spin Geometry 1989 |
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| Marsden, J.E., Ostrowski, J. Symmetries in Motion: Geometric Foundations of Motion Control Nonlinear Sci. Today 1998 |
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