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A block-based gradient descent search algorithm for block motion estimation in video coding

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 1996年第4期6卷 419-422页

作者： Liu, LK Feig, E IBM IBM Thomas J. Watson Research Center Yorktown Heights NY USA

A block-based gradient descent search (BBGDS) algorithm is proposed in this paper to perform block motion estimation in video coding. The BBGDS evaluates the values of a given objective function starting from a small centralized checking block, The minimum within the checking block is found, and the gradient descent direction where the minimum is expected to lie is used to determine the search direction and the position of new checking block. The BBGDS is compared with full search (FS), three-step search (TSS), one-at-a-time search (OTS), and new three-step search (NTSS). Experimental results show that the proposed technique provides competitive performance with reduced computational complexity.

关键词： Motion estimation Video coding Computational complexity predictive coding Video compression Transform coding Degradation Video sequences Videoconference

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MOTION COMPENSATED INTERFRAME IMAGE PREDICTION

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IEEE TRANSACTIONS ON COMMUNICATIONS 1985年第9期33卷 1011-1015页

作者： KAPPAGANTULA, S RAO, KR UNIV TEXAS DEPT ELECT ENGNARLINGTONTX 76019

Interframe motion estimation of subblocks based on improved search techniques is developed. These techniques are based on minimizing the mean difference between the subblock in question in the present frame and the displaced subblock in the previous frame. The performance of the motion compensated prediction developed here is investigated for various block sizes and is compared to other techniques.

关键词： Motion estimation Image coding Motion detection predictive coding Signal Processing Society Communications Society Mobile communication Business communication Companies Bandwidth

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A pyramidal image coder using generalized rank-ordered prediction filter

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 1999年第4期9卷 540-544页

作者： Peng, ZS Huang, YF Costello, DJ Stevenson, RL Univ Notre Dame Dept Elect Engn Lab Image & Signal Anal Notre Dame IN 46556 USA

This paper presents a lossy image compression scheme that employs a generalized rank-ordered prediction filter for pyramidal image coding. The proposed prediction method renders significantly reduced variance of the quantizer input. Consequently, the quality of the decompressed image is much enhanced due to the greatly reduced quantization distortion. Both analytical and simulation results show that the proposed scheme yields high-quality performance.

关键词： image compression prediction filtering predictive coding pyramidal coding rank-ordered filter source coding

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Autism and psychosis as diametrical disorders of embodiment

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EVOLUTION MEDICINE AND PUBLIC HEALTH 2019年第1期2019卷 121-138页

作者： Crespi, Bernard Dinsdale, Natalie Simon Fraser Univ Dept Biol Sci 8888 Univ Dr Burnaby BC V5A 1S6 Canada Univ Saskatchewan Dept Psychol Saskatoon SK S7N 5A5 Canada

Humans have evolved an elaborate system of self-consciousness, self-identity, self-agency, and self-embodiment that is grounded in specific neurological structures including an expanded insula. Instantiation of the bodily self has been most-extensively studied via the 'rubber hand illusion', whereby parallel stimulation of a hidden true hand, and a viewed false hand, leads to the felt belief that the false hand is one's own. Autism and schizophrenia have both long been regarded as conditions centrally involving altered development of the self, but they have yet to be compared directly with regard to the self and embodiment. Here, we synthesize the embodied cognition literature for these and related conditions, and describe evidence that these two sets of disorders exhibit opposite susceptibilities from typical individuals to the rubber hand illusion: reduced on the autism spectrum and increased in schizophrenia and other psychotic-affective conditions. Moreover, the opposite illusion effects are mediated by a consilient set of associated phenomena, including empathy, interoception, anorexia risk and phenotypes, and patterns of genetic correlation. Taken together, these findings: (i) support the diametric model of autism and psychotic-affective disorders, (ii) implicate the adaptive human system of self-embodiment, and its neural bases, in neurodevelopmental disorders, and suggest new therapies and (iii) experimentally ground Bayesian predictive coding models with regard to autism compared with psychosis. Lay summary: Humans have evolved a highly developed sense of self and perception of one's own body. The 'rubber hand illusion' can be used to test individual variation in sense of self, relative to connection with others. We show that this illusion is reduced in autism spectrum disorders, and increased in psychotic and mood disorders. These findings have important implications for understanding and treatment of mental disorders.

关键词： rubber hand illusion embodied cognition autism schizophrenia anorexia interoception predictive coding

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The neural oscillations of speech processing and language comprehension: state of the art and emerging mechanisms

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EUROPEAN JOURNAL OF NEUROSCIENCE 2018年第7期48卷 2609-2621页

作者： Meyer, Lars Max Planck Inst Human Cognit & Brain Sci Dept Neuropsychol Stephanstr 1A D-04103 Leipzig Germany

Neural oscillations subserve a broad range of functions in speech processing and language comprehension. On the one hand, speech containssomewhatrepetitive trains of air pressure bursts that occur at three dominant amplitude modulation frequencies, physically marking the linguistically meaningful progressions of phonemes, syllables and intonational phrase boundaries. To these acoustic events, neural oscillations of isomorphous operating frequencies are thought to synchronise, presumably resulting in an implicit temporal alignment of periods of neural excitability to linguistically meaningful spectral information on the three low-level linguistic description levels. On the other hand, speech is a carrier signal that codes for high-level linguistic meaning, such as syntactic structure and semantic informationwhich cannot be read from stimulus acoustics, but must be acquired during language acquisition and decoded for language comprehension. Neural oscillations subserve the processing of both syntactic structure and semantic information. Here, I synthesise a mapping from each linguistic processing domain to a unique set of subserving oscillatory mechanismsthe mapping is plausible given the role ascribed to different oscillatory mechanisms in different subfunctions of cortical information processing and faithful to the underlying electrophysiology. In sum, the present article provides an accessible and extensive review of the functional mechanisms that neural oscillations subserve in speech processing and language comprehension.

关键词： chunking entrainment memory predictive coding

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Layer and rhythm specificity for predictive routing

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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2020年第49期117卷 31459-31469页

作者： Bastos, Andre M. Lundqvist, Mikael Waite, Ayan S. Kopell, Nancy Miller, Earl K. MIT Picower Inst Learning & Memory 77 Massachusetts Ave Cambridge MA 02139 USA MIT Dept Brain & Cognit Sci E25-618 Cambridge MA 02139 USA Stockholm Univ Dept Psychol Div Biol Psychol SE-10691 Stockholm Sweden Boston Univ Dept Math & Stat Boston MA 02215 USA Vanderbilt Univ Dept Psychol Nashville TN 37240 USA Vanderbilt Univ Vanderbilt Brain Inst Nashville TN 37240 USA

In predictive coding, experience generates predictions that attenuate the feeding forward of predicted stimuli while passing forward unpredicted "errors." Different models have suggested distinct cortical layers, and rhythms implement predictive coding. We recorded spikes and local field potentials from laminar electrodes in five cortical areas (visual area 4 [V4], lateral intraparietal [LIP], posterior parietal area 7A, frontal eye field [FEF], and prefrontal cortex [PFC]) while monkeys performed a task that modulated visual stimulus predictability. During predictable blocks, there was enhanced alpha (8 to 14 Hz) or beta (15 to 30 Hz) power in all areas during stimulus processing and prestimulus beta (15 to 30 Hz) functional connectivity in deep layers of PFC to the other areas. Unpredictable stimuli were associated with increases in spiking and in gamma-band (40 to 90 Hz) power/connectivity that fed forward up the cortical hierarchy via superficial-layer cortex. Power and spiking modulation by predictability was stimulus specific. Alpha/beta power in LIP, FEF, and PFC inhibited spiking in deep layers of V4. Area 7A uniquely showed increases in high-beta (similar to 22 to 28 Hz) power/connectivity to unpredictable stimuli. These results motivate a conceptual model, predictive routing. It suggests that predictive coding may be implemented via lower-frequency alpha/ beta rhythms that "prepare" pathways processing-predicted inputs by inhibiting feedforward gamma rhythms and associated spiking.

关键词： predictive coding cortical layers gamma oscillations beta oscillations neural synchronization

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Brain Prediction of Auditory Emphasis by Facial Expressions During Audiovisual Continuous Speech

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BRAIN TOPOGRAPHY 2015年第3期28卷 494-505页

作者： Strelnikov, Kuzma Foxton, Jessica Marx, Mathieu Barone, Pascal Univ Toulouse Univ Toulouse 3 CerCo Toulouse France CHU Purpan Fac Med Purpan CNRS CERCOUMR 5549 F-31052 Toulouse France Hop Purpan Serv Otorhinolaryngol Toulouse France

The visual cues involved in auditory speech processing are not restricted to information from lip movements but also include head or chin gestures and facial expressions such as eyebrow movements. The fact that visual gestures precede the auditory signal implicates that visual information may influence the auditory activity. As visual stimuli are very close in time to the auditory information for audiovisual syllables, the cortical response to them usually overlaps with that for the auditory stimulation;the neural dynamics underlying the visual facilitation for continuous speech therefore remain unclear. In this study, we used a three-word phrase to study continuous speech processing. We presented video clips with even (without emphasis) phrases as the frequent stimuli and with one word visually emphasized by the speaker as the non-frequent stimuli. Negativity in the resulting ERPs was detected after the start of the emphasizing articulatory movements but before the auditory stimulus, a finding that was confirmed by the statistical comparisons of the audiovisual and visual stimulation. No such negativity was present in the control visual-only condition. The propagation of this negativity was observed between the visual and fronto-temporal electrodes. Thus, in continuous speech, the visual modality evokes predictive coding for the auditory speech, which is analysed by the cerebral cortex in the context of the phrase even before the arrival of the corresponding auditory signal.

关键词： Audio-visual speech Prosody Mismatch predictive coding

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Hierarchical modulation of auditory prediction error signaling is independent of attention

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COGNITIVE NEUROSCIENCE 2020年第3期11卷 132-142页

作者： Kompus, Kristiina Volehaugen, Vegard Todd, Juanita Westerhausen, Rene Univ Bergen Dept Biol & Med Psychol Jonas Lies Vei 91 N-5009 Bergen Norway Univ Tartu Inst Psychol Tartu Estonia Univ Newcastle Sch Psychol Newcastle NSW Australia Univ Oslo Dept Psychol Oslo Norway

The auditory system is tuned to detect rhythmic regularities in the environment which can occur on different timescales. Event-related potentials such as mismatch negativity (MMN) and P3b are thought to index local and global deviance, respectively. However, it is not clear how these hierarchical levels interact and to what extent attention modulates this interaction. In this EEG study with 17 healthy young adults, we used a hierarchical oddball paradigm with local (sequence-level) and global (block-level) violations in attended and unattended conditions. Amplitude of N2 and P3b were analyzed in a 2*2*2 factorial model (local status, global status, attention condition). We found a significant interaction between the local and global status on the N2 amplitude, while there was no significant three-way interaction with attention, together demonstrating that lower-level prediction error is modulated by detection of higher-order regularity but expressed independently of attention. By contrast, higher-level prediction error, indexed by P3b, was sensitive to global regularity violations if the auditory stream was attended. The results demonstrate the capacity of our auditory perception to preattentively resolve conflicts between different levels of predictive hierarchy even across longer time intervals as indexed by MMN modulation, while P3b represents a different, attention-dependent system.

关键词： predictive coding hierarchical processing mismatch negativity

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The predictive mind: An introduction to Bayesian Brain Theory

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ENCEPHALE-REVUE DE PSYCHIATRIE CLINIQUE BIOLOGIQUE ET THERAPEUTIQUE 2022年第4期48卷 436-444页

作者： Bottemanne, H. Longuet, Y. Gauld, C. Sorbonne Univ Paris Brain Inst Inst Cerveau ICM CNRSInserm Paris France Sorbonne Univ Dept Philosophy SND Res Unit UMR 8011CNRS Paris France Sorbonne Univ Pitie Salpetriere Hosp Assistance Publ Hop Paris AP HP Dept PsychiatDMU Neurosci Paris France Claude Bernard Lyon 1 Univ Dept Psychiat F-69000 Lyon France Univ Grenoble Dept Psychiat F-38000 Grenoble France Sorbonne Univ IHPST UMR 8590 F-1 Paris France

The question of how the mind works is at the heart of cognitive science. It aims to understand and explain the complex processes underlying perception, decision-making and learning, three fundamental areas of cognition. Bayesian Brain Theory, a computational approach derived from the principles of predictive Processing (PP), offers a mechanistic and mathematical formulation of these cognitive processes. This theory assumes that the brain encodes beliefs (probabilistic states) to generate predictions about sensory input, then uses prediction errors to update its beliefs. In this paper, we present an introduction to the fundamentals of Bayesian Brain Theory. We show how this innovative theory hybridizes concepts inherited from the philosophy of mind and experimental data from neuroscience, and how it translates complex cognitive processes such as perception, action, emotion, or belief, or even the psychiatric symptomatology. (c) 2021 L'Encephale, Paris.

关键词： predictive processing predictive coding Bayesian brain Belief Bayesianism Computational neuroscience Computational psychiatry Belief updating Interoception

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Perceptual grouping and the interactions between visual cortical areas

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NEURAL NETWORKS 2004年第5-6期17卷 695-705页

作者： Murray, SO Schrater, P Kersten, D Univ Minnesota Dept Psychol Minneapolis MN 55455 USA

Visual perception involves the grouping of individual elements into coherent patterns, such as object representations, that reduce the descriptive complexity of a visual scene. The computational and physiological bases of this perceptual remain poorly understood. We discuss recent fMRI evidence from our laboratory where we measured activity in a higher object processing area (LOC), and in primary visual cortex (V1) in response to visual elements that were either grouped into objects or randomly arranged. We observed significant activity increases in the LOC and concurrent reductions of activity in V1 when elements formed coherent shapes, suggesting that activity in early visual areas is reduced as a result of grouping processes performed in higher areas. In light of these results we review related empirical findings of context-dependent changes in activity, recent neurophysiology research related to cortical feedback, and computational models that incorporate feedback operations. We suggest that feedback from high-level visual areas reduces activity in lower areas in order to simplify the description of a visual image-consistent with both predictive coding models of perception and probabilistic notions of 'explaining away.' (C) 2004 Elsevier Ltd. All rights reserved.

关键词： feedback grouping predictive coding probabilistic models bayesian

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