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Effects of Prior Information on Decoding Degraded Speech: An fMRI Study

HUMAN BRAIN MAPPING 2014年第1期35卷 61-74页

作者： Clos, Mareike Langner, Robert Meyer, Martin Oechslin, Mathias S. Zilles, Karl Eickhoff, Simon B. Res Ctr Julich Inst Neurosci & Med INM 1 INM 2 Julich Germany Univ Dusseldorf Inst Clin Neurosci & Med Psychol Dusseldorf Germany Univ Zurich Neuroplast & Learning Normal Aging Brain HAB LAB CH-8006 Zurich Switzerland Univ Geneva Geneva Neurosci Ctr Fac Psychol & Educ Sci CH-1211 Geneva 4 Switzerland Univ Dusseldorf C & O Vogt Brain Res Inst Dusseldorf Germany

Expectations and prior knowledge are thought to support the perceptual analysis of incoming sensory stimuli, as proposed by the predictive-coding framework. The current fMRI study investigated the effect of prior information on brain activity during the decoding of degraded speech stimuli. When prior information enabled the comprehension of the degraded sentences, the left middle temporal gyrus and the left angular gyrus were activated, highlighting a role of these areas in meaning extraction. In contrast, the activation of the left inferior frontal gyrus (area 44/45) appeared to reflect the search for meaningful information in degraded speech material that could not be decoded because of mismatches with the prior information. Our results show that degraded sentences evoke instantaneously different percepts and activation patterns depending on the type of prior information, in line with prediction-based accounts of perception. Hum Brain Mapp 35:61-74, 2014. (c) 2012 Wiley Periodicals, Inc.

关键词： auditory expectations Broca's region middle temporal gyrus predictive coding speech perception

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Dissociation of prediction from conscious perception

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PERCEPTION 2014年第10期43卷 1107-1113页

作者： Vetter, Petra Sanders, Lia L. O. Muckli, Lars Univ Glasgow Coll Med Vet & Life Sci Inst Neurosci & Psychol Ctr Cognit Neuroimaging Glasgow G12 8QB Lanark Scotland Univ Geneva Sch Med Dept Neurosci Lab Behav Neurol & Imaging Cognit CH-1211 Geneva Switzerland Univ Geneva Swiss Ctr Affect Sci CH-1211 Geneva Switzerland Humboldt Univ Berlin Sch Mind & Brain D-10117 Berlin Germany

The framework of predictive coding offers a parsimonious explanation for many perceptual phenomena. According to this framework, perception of the outer world is created by the comparison of incoming sensory information with an internal predictive model based on previous experience and context. However, it is unclear whether the predicted percept needs to enter conscious awareness for the internal predictive model to be effective. Here we used an apparent motion paradigm to show that while prediction and conscious awareness of a predicted percept may coincide, a dissociation can be observed. When sensory information provides reliable input for the internal predictive model, the predicted percept does not have to be consciously perceived for successful prediction. However, when sensory input is ambiguous, conscious awareness helps the prediction to take effect.

关键词： visual predictions conscious perception predictive coding apparent motion vision awareness

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Development of spatial integration depends on top-down and interhemispheric connections that can be perturbed in migraine: a DCM analysis

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NEUROLOGICAL SCIENCES 2014年第1-Sup期35卷 S215-S224页

作者： Fornari, Eleonora Rytsar, Romana Knyazeva, Maria G. CHU Vaudois CHUV Unit CIBM Ctr Imagerie Biomed CH-1011 Lausanne Switzerland Univ Lausanne CH-1011 Lausanne Switzerland CHU Vaudois Dept Radiol CH-1011 Lausanne Switzerland CHU Vaudois Dept Clin Neurosci CH-1011 Lausanne Switzerland

In humans, spatial integration develops slowly, continuing through childhood into adolescence. On the assumption that this protracted course depends on the formation of networks with slowly developing top-down connections, we compared effective connectivity in the visual cortex between 13 children (age 7-13) and 14 adults (age 21-42) using a passive perceptual task. The subjects were scanned while viewing bilateral gratings, which either obeyed Gestalt grouping rules [colinear gratings (CG)] or violated them [non-colinear gratings (NG)]. The regions of interest for dynamic causal modeling were determined from activations in functional MRI contrasts stimuli > background and CG > NG. They were symmetrically located in V1 and V3v areas of both hemispheres. We studied a common model, which contained reciprocal intrinsic and modulatory connections between these regions. An analysis of effective connectivity showed that top-down modulatory effects generated at an extrastriate level and interhemispheric modulatory effects between primary visual areas (all inhibitory) are significantly weaker in children than in adults, suggesting that the formation of feedback and interhemispheric effective connections continues into adolescence. These results are consistent with a model in which spatial integration at an extrastriate level results in top-down messages to the primary visual areas, where they are supplemented by lateral (interhemispheric) messages, making perceptual encoding more efficient and less redundant. Abnormal formation of top-down inhibitory connections can lead to the reduction of habituation observed in migraine patients.

关键词： Children Effective connectivity Inhibition predictive coding Visual cortex Functional magnetic resonance imaging

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Compressive mapping of number to space reflects dynamic encoding mechanisms, not static logarithmic transform

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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2014年第21期111卷 7867-7872页

作者： Cicchini, Guido Marco Anobile, Giovanni Burr, David C. CNR Inst Neurosci I-56124 Pisa Italy Univ Florence Dept Neurosci Psychol Pharmacol & Child Hlth I-50135 Florence Italy

The mapping of number onto space is fundamental to measurement and mathematics. However, the mapping of young children, unschooled adults, and adults under attentional load shows strong compressive nonlinearities, thought to reflect intrinsic logarithmic encoding mechanisms, which are later "linearized" by education. Here we advance and test an alternative explanation: that the nonlinearity results from adaptive mechanisms incorporating the statistics of recent stimuli. This theory predicts that the response to the current trial should depend on the magnitude of the previous trial, whereas a static logarithmic nonlinearity predicts trialwise independence. We found a strong and highly significant relationship between numberline mapping of the current trial and the magnitude of the previous trial, in both adults and school children, with the current response influenced by up to 15% of the previous trial value. The dependency is sufficient to account for the shape of the numberline, without requiring logarithmic transform. We show that this dynamic strategy results in a reduction of reproduction error, and hence improvement in accuracy.

关键词： numerical cognition predictive coding approximate number system Weber-Fechner law serial dependency

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Did I Do That? Abnormal predictive Processes in Schizophrenia When Button Pressing to Deliver a Tone

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SCHIZOPHRENIA BULLETIN 2014年第4期40卷 804-812页

作者： Ford, Judith M. Palzes, Vanessa A. Roach, Brian J. Mathalon, Daniel H. San Francisco VA Med Ctr Mental Hlth Serv San Francisco CA USA Univ Calif San Francisco Dept Psychiat San Francisco CA USA

Motor actions are preceded by an efference copy of the motor command, resulting in a corollary discharge of the expected sensation in sensory cortex. These mechanisms allow animals to predict sensations, suppress responses to self-generated sensations, and thereby process sensations efficiently and economically. During talking, patients with schizophrenia show less evidence of pretalking activity and less suppression of the speech sound, consistent with dysfunction of efference copy and corollary discharge, respectively. We asked if patterns seen in talking would generalize to pressing a button to hear a tone, a paradigm translatable to less vocal animals. In 26 patients [23 schizophrenia, 3 schizoaffective (SZ)] and 22 healthy controls (HC), suppression of the N1 component of the auditory event-related potential was estimated by comparing N1 to tones delivered by button presses and N1 to those tones played back. The lateralized readiness potential (LRP) associated with the motor plan preceding presses to deliver tones was estimated by comparing right and left hemispheres' neural activity. The relationship between N1 suppression and LRP amplitude was assessed. LRP preceding button presses to deliver tones was larger in HC than SZ, as was N1 suppression. LRP amplitude and N1 suppression were correlated in both groups, suggesting stronger efference copies are associated with stronger corollary discharges. SZ have reduced N1 suppression, reflecting corollary discharge action, and smaller LRPs preceding button presses to deliver tones, reflecting the efference copy of the motor plan. Effects seen during vocalization largely extend to other motor acts more translatable to lab animals.

关键词： predictive coding efference copy corollary discharge ERPs

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A predictive processing theory of sensorimotor contingencies: Explaining the puzzle of perceptual presence and its absence in synesthesia

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COGNITIVE NEUROSCIENCE 2014年第2期5卷 97-118页

作者： Seth, Anil K. Univ Sussex Sch Engn & Informat Sackler Ctr Consciousness Sci Brighton BN1 9QJ E Sussex England

Normal perception involves experiencing objects within perceptual scenes as real, as existing in the world. This property of "perceptual presence" has motivated "sensorimotor theories" which understand perception to involve the mastery of sensorimotor contingencies. However, the mechanistic basis of sensorimotor contingencies and their mastery has remained unclear. Sensorimotor theory also struggles to explain instances of perception, such as synesthesia, that appear to lack perceptual presence and for which relevant sensorimotor contingencies are difficult to identify. On alternative "predictive processing" theories, perceptual content emerges from probabilistic inference on the external causes of sensory signals, however, this view has addressed neither the problem of perceptual presence nor synesthesia. Here, I describe a theory of predictive perception of sensorimotor contingencies which (1) accounts for perceptual presence in normal perception, as well as its absence in synesthesia, and (2) operationalizes the notion of sensorimotor contingencies and their mastery. The core idea is that generative models underlying perception incorporate explicitly counterfactual elements related to how sensory inputs would change on the basis of a broad repertoire of possible actions, even if those actions are not performed. These "counterfactually-rich" generative models encode sensorimotor contingencies related to repertoires of sensorimotor dependencies, with counterfactual richness determining the degree of perceptual presence associated with a stimulus. While the generative models underlying normal perception are typically counterfactually rich (reflecting a large repertoire of possible sensorimotor dependencies), those underlying synesthetic concurrents are hypothesized to be counterfactually poor. In addition to accounting for the phenomenology of synesthesia, the theory naturally accommodates phenomenological differences between a range of experiential states including

关键词： predictive coding Presence Sensorimotor contingencies Veridicality Counterfactuals Synesthesia Active inference Bayesian brain

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Toward an integrative view of human pain and suffering Reply to comments on "Facing the experience of pain: A neuropsychological perspective"

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PHYSICS OF LIFE REVIEWS 2014年第3期11卷 569-572页

作者： Fabbro, Franco Crescentini, Cristiano Univ Udine Dept Human Sci I-33100 Udine Italy Scuola Super Sant Anna Perceptual Robot PERCRO Lab Pisa Italy

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predictive coding of music - Brain responses to rhythmic incongruity

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CORTEX 2009年第1期45卷 80-92页

作者： Vuust, Peter Ostergaard, Leif Pallesen, Karen Johanne Bailey, Christopher Roepstorff, Andreas Univ Aarhus Ctr Functionally Integrat Neurosci DK-8000 Aarhus C Denmark Royal Acad Mus Aarhus Denmark Univ Helsinki Cent Hosp Helsinki Brain Res Ctr BioMag Lab FIN-00014 Helsinki Finland Aarhus Univ Hosp PET Ctr DK-8000 Aarhus C Denmark Univ Aarhus Inst Anthropol Linguist & Archaeol DK-8000 Aarhus C Denmark

During the last decades, models of music processing in the brain have mainly discussed the specificity of brain modules involved in processing different musical components. We argue that predictive coding offers an explanatory framework for functional integration in musical processing. Further, we provide empirical evidence for such a network in the analysis of event-related MEG-components to rhythmic incongruence in the context of strong metric anticipation. This is seen in a mismatch negativity (MMNm) and a subsequent P3am component, which have the proper-ties of an error term and a subsequent evaluation in a predictive coding framework. There were both quantitative and qualitative differences in the evoked responses in expert jazz musicians compared with rhythmically unskilled non-musicians. We propose that these differences trace a functional adaptation and/or a genetic pre-disposition in experts which allows for a more precise rhythmic prediction. (C) 2008 Elsevier Srl. All rights reserved.

关键词： Music MEG Meter predictive coding MMN

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On Optimal coding of Hidden Markov Sources

On Optimal Coding of Hidden Markov Sources

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Data Compression Conference (DCC)

作者： Salehifar, Mehdi Akyol, Emrah Viswanatha, Kumar Rose, Kenneth Univ Calif Santa Barbara Dept Elect & Comp Engn Santa Barbara CA 93106 USA

ISBN: (纸本)9781479938827

The hidden Markov model (HMM) is widely used to model processes in several real world applications, including speech processing and recognition, image understanding and sensor networks. A problem of concern is that of quantization of the sequence of observations generated by an HMM, which is referred as a hidden Markov source (HMS). Despite the importance of the problem, and the well-defined structure of the process, there has been very limited work addressing the optimal quantization of HMS, and conventional approaches focus on optimization of parameters of known quantization schemes. This paper proposes a method that directly tracks the state probability distribution of the underlying source and optimizes the encoder structure according to the estimated HMS status. Unlike existing approaches, no stationarity assumption is needed, and code parameters are updated on the fly: with each observation, both the encoder and the decoder refine the estimated probability distribution over the states. The main approach is then specialized to a practical variant involving switched quantizers, and an algorithm that iteratively optimizes the quantizer codebooks is derived. Numerical results show superiority of the proposed approach over prior methods.

关键词： Finite state quantizer Hidden Markov source predictive coding Quantization

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Varieties of cognitive penetration in visual perception

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CONSCIOUSNESS AND COGNITION 2014年第1期27卷 62-75页

作者： Vetter, Petra Newen, Albert Ruhr Univ Bochum Inst Philosophie 2 Ctr Mind Brain & Cognit Evolut D-44780 Bochum Germany Univ Geneva Lab Behav Neurol & Imaging Cognit Dept Neurosci CH-1211 Geneva Switzerland Univ Geneva Swiss Ctr Affect Sci CH-1211 Geneva Switzerland

Is our perceptual experience a veridical representation of the world or is it a product of our beliefs and past experiences? Cognitive penetration describes the influence of higher level cognitive factors on perceptual experience and has been a debated topic in philosophy of mind and cognitive science. Here, we focus on visual perception, particularly early vision, and how it is affected by contextual expectations and memorized cognitive contents. We argue for cognitive penetration based on recent empirical evidence demonstrating contextual and top-down influences on early visual processes. On the basis of a perceptual model, we propose different types of cognitive penetration depending on the processing level on which the penetration happens and depending on where the penetrating influence comes from. Our proposal has two consequences: (1) the traditional controversy on whether cognitive penetration occurs or not is ill posed, and (2) a clear-cut perception-cognition boundary cannot be maintained. (C) 2014 Elsevier Inc. All rights reserved.

关键词： Cognitive penetration Visual perception Early visual processes V1 Top-down modulation Contextual influences predictive coding Perception-cognition boundary Philosophy of mind

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