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adaptive coding of reward in schizophrenia, its change over time and relationship to apathy

BRAIN 2024年第7期147卷 2459-2470页

作者： Kaliuzhna, Mariia Carruzzo, Fabien Kuenzi, Noemie Tobler, Philippe N. Kirschner, Matthias Geffen, Tal Katthagen, Teresa Boege, Kerem Zierhut, Marco M. Schlagenhauf, Florian Kaiser, Stefan Univ Geneva Dept Psychiat Clin & Expt Psychopathol Lab CH-1205 Geneva Switzerland Geneva Univ Hosp Dept Psychiat CH-1205 Geneva Switzerland Univ Zurich Dept Econ Lab Social & Neural Syst Res CH-8006 Zurich Switzerland Charite Univ Med Berlin Dept Psychiat & Psychotherapy D-10117 Berlin Germany Batiment Voirons Chemin Petit Bel Air 2 CH-1226 Thonex Switzerland

adaptive coding of reward is the process by which neurons adapt their response to the context of available compensations. Higher rewards lead to a stronger brain response, but the increase of the response depends on the range of available rewards. A steeper increase is observed in a narrow range and a more gradual slope in a wider range. In schizophrenia, adaptive coding appears to be affected in different domains, especially in the reward domain. Here, we tested adaptive coding of reward in a large group of patients with schizophrenia (n = 86) and control subjects (n = 66). We assessed: (i) the association between adaptive coding deficits and symptoms;(ii) the longitudinal stability of deficits (the same task was performed 3 months apart);and (iii) the stability of results between two experimental *** used functional MRI and the monetary incentive delay task to assess adaptation of participants to two different reward ranges: a narrow range and a wide range. We used a region-of-interest analysis to evaluate adaptation within striatal and visual regions. Patients and control subjects underwent a full demographic and clinical *** found reduced adaptive coding in patients, with a decreased slope in the narrow reward range with respect to that of control participants, in striatal but not visual regions. This pattern was observed at both research sites. Upon retesting, patients increased their narrow-range slopes, showing improved adaptive coding, whereas control subjects slightly reduced them. At retesting, patients with overly steep slopes in the narrow range also showed higher levels of negative *** data confirm deficits in reward adaptation in schizophrenia and reveal an effect of practice in patients, leading to improvement, with steeper slopes upon retesting. However, in some patients, an excessively steep slope may result in poor discriminability of larger rewards, owing to early saturation of the brain response. Together, the loss of prec

关键词： adaptive coding schizophrenia reward functional MRI monetary incentive delay task negative symptoms

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adaptive coding For Data Exchange Between Quadrotors In The Formation

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IFAC-PapersOnLine 2016年第13期49卷 275-280页

作者： Fradkov, Alexander L. Tomashevich, Stanislav Andrievsky, Boris Amelin, Konstantin Kaliteevskiy, Ilya N. Institute for Problems of Mechanical Engineering the Russian Academy of Sciences 61 Bolshoy prospekt V.O. Saint Petersburg199178 Russia Saint-Petersburg State University 28 Universitetsky prospekt Peterhof Saint Petersburg198504 Russia ITMO University Saint Petersburg Russia

In the paper, the procedure of adaptive coding for data transmission between quadrotors, moving in formation, is presented and numerically studied. Quadrotor parameters identification is fulfilled based on processing the experimental data. The results are compared with the theoretical statements. Efficacy of the adaptive coding procedure is shown. © 2016

关键词： Codes (symbols) Data communication systems Data transfer Electronic data interchange Estimation adaptive coding Co operative control Control over networks Parameters identification Quad rotors

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adaptive coding FOR SELF-CLOCKING RECORDING

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IEEE TRANSACTIONS ON ELECTRONIC COMPUTERS 1967年第6期EC16卷 866-&页

作者： GABOR, A 30 Burlington Road Bedford Mass. 01730.

Self-clocking of binary information involves a coding constraint whereby the maximum length of zero strings is limited to a predetermined number. For reasons of operational stability it is desirable to keep this number low. The price of such constraint is a degradation in code density. The class of serial recording which includes the well-known frequency modulation and phase encoding represents one extreme where every other symbol is mandatory, making the code density one bit for every two symbols. This paper describes a coding method which improves code efficiency while maintaining the constraint on the length of zero strings. It will be shown that adaptive coding, which is an extension of the block code concept known from information theory, offers a significant improvement. The concept is illustrated by describing a practical application in which the code density is improved from two symbols per bit to three symbols per bit pair, while keeping the maximum length of zero strings to one. It is shown that while this technique represents an improvement by one third over phase encoding, it approaches the theoretical limit for this class of codes to within 4 percent.

关键词： adaptive coding Magnetic recording Encoding Transmitters Timing Tellurium Stability Frequency modulation Constraint theory Block codes

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adaptive coding in the human brain: Distinct object features are encoded by overlapping voxels in frontoparietal cortex

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CORTEX 2018年 108卷 25-34页

作者： Jackson, Jade B. Woolgar, Alexandra Kings Coll London Inst Psychiat Psychol & Neurosci Dept Neuroimaging Box 89De Crespigny Pk London SE5 8AF England Macquarie Univ Percept Act Res Ctr Sydney NSW Australia Macquarie Univ Dept Cognit Sci Sydney NSW Australia Macquarie Univ ARC Ctr Excellence Cognit & Its Disorders Sydney NSW Australia Univ Cambridge MRC Cognit & Brain Sci Unit Cambridge England

Our ability to flexibly switch between different tasks is a key component of cognitive control. Non-human primate (NHP) studies (e.g., Freedman, Riesenhuber, Poggio, & Miller, 2001) have shown that prefrontal neurons are re-used across tasks, re-configuring their responses to code currently relevant information. In a similar vein, in the human brain, the "multiple demand" (MD) system is suggested to exert control by adjusting its responses, selectively processing information in line with our current goals (Duncan, 2010). However, whether the same or different resources (underlying neural populations) in the human brain are recruited to solve different tasks remains elusive. In the present study, we aimed to bridge the gap between the NHP and human literature by examining human functional imaging data at an intermediate level of resolution: quantifying the extent to which single voxels contributed to multiple neural codes. Participants alternated between two tasks requiring the selection of feature information from two distinct sets of objects. We examined whether neural codes for the relevant stimulus features in the two different tasks depended on the same or different voxels. In line with the electrophysiological literature, MD voxels were more likely to contribute to multiple neural codes than we predicted based on permutation tests. Comparatively, in the visual system the neural codes depended on distinct sets of voxels. Our data emphasise the flexibility of the MD regions to re-configure their responses and adaptively code relevant information across different tasks. (C) 2018 The Authors. Published by Elsevier Ltd.

关键词： MVPA fMRI adaptive coding Voxel re-use

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adaptive coding OF MONOCHROME AND COLOR IMAGES

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IEEE TRANSACTIONS ON COMMUNICATIONS 1977年第11期25卷 1285-1292页

作者： CHEN, WH SMITH, CH FORD AEROSP & COMMUN CORP DIV WESTERN DEV LABSPALO ALTOCA 94303

An efficient adaptive encoding technique using a new implementation of the Fast Discrete Cosine Transform (FDCT) for bandwidth compression of monochrome and color images is described. Practical system application is attained by maintaining a balance between complexity of implementation and performance. FDCT sub-blocks are sorted into four classes according to level of image activity, measured by the total ac energy within each sub-block. Adaptivity is provided by distributing bits between classes, favoring higher levels of activity over lower levels. Excellent performance is demonstrated in terms of mean square error and direct comparison of original and reconstructed images. Results are presented for both noiseless and noisy transmission at a total rate of 1 bit and 0.5 bit per pixel for a monochrome image and for a total rate of 2 bits and 1 bit per pixel for a color image. In every case the total bit rate includes all overhead required for image reconstruction and bit protection.

关键词： adaptive coding Color Image coding Image reconstruction Colored noise Pixel Discrete cosine transforms Bandwidth Energy measurement Mean square error methods

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adaptive coding of Orofacial and Speech Actions in Motor and Somatosensory Spaces with and without Overt Motor Behavior

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JOURNAL OF COGNITIVE NEUROSCIENCE 2015年第2期27卷 334-351页

作者： Sato, Marc Vilain, Coriandre Lamalle, Laurent Grabski, Krystyna CNRS F-13100 Aix En Provence France Aix Marseille Univ F-13100 Aix En Provence France Grenoble Univ Grenoble France Univ Grenoble Alpes INSERM IRMaGE UMSUS1 7 Grenoble France CHU Grenoble CNRS UMS 3552 Unite IRM Rech 3T Grenoble France McGill Univ Montreal PQ Canada

Studies of speech motor control suggest that articulatory and phonemic goals are defined in multidimensional motor, somatosensory, and auditory spaces. To test whether motor simulation might rely on sensory-motor coding common with those for motor execution, we used a repetition suppression (RS) paradigm while measuring neural activity with sparse sampling fMRI during repeated overt and covert orofacial and speech actions. RS refers to the phenomenon that repeated stimuli or motor acts lead to decreased activity in specific neural populations and are associated with enhanced adaptive learning related to the repeated stimulus attributes. Common suppressed neural responses were observed in motor and posterior parietal regions in the achievement of both repeated overt and covert orofacial and speech actions, including the left premotor cortex and inferior frontal gyrus, the superior parietal cortex and adjacent intraprietal sulcus, and the left IC and the SMA. Interestingly, reduced activity of the auditory cortex was observed during overt but not covert speech production, a finding likely reflecting a motor rather an auditory imagery strategy by the participants. By providing evidence for adaptive changes in premotor and associative somatosensory brain areas, the observed RS suggests online state coding of both orofacial and speech actions in somatosensory and motor spaces with and without motor behavior and sensory feedback.

关键词： Motor Activity Premotor Cortex Sensory Feedback adaptive coding Primary Auditory Cortex Speech Compressed sensing Motor

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adaptive coding IN WIRELESS ACOUSTIC SENSOR NETWORKS FOR DISTRIBUTED BLIND SYSTEM IDENTIFICATION 57

ADAPTIVE CODING IN WIRELESS ACOUSTIC SENSOR NETWORKS FOR DIS...

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57th Asilomar Conference on Signals, Systems and Computers

作者： Blochberger, M. Ostergaard, J. Ali, R. Moonen, M. Elvander, F. Jensen, J. van Waterschoot, T. Katholieke Univ Leuven Dept Elect Engn ESAT STADIUS Leuven Belgium Aalborg Univ Dept Elect Syst Aalborg Denmark Univ Surrey Dept Mus & Media Guildford Surrey England Aalto Univ Dept Informat & Commun Engn Espoo Finland

ISBN: (纸本)9798350325744

With distributed signal processing gaining traction in the audio and speech processing landscape through the utilization of interconnected devices constituting wireless acoustic sensor networks, additional challenges arise, including optimal data transmission between devices. In this paper, we extend an adaptive distributed blind system identification algorithm by introducing a residual-based adaptive coding scheme to minimize communication costs within the network. We introduce a coding scheme that takes advantage of the convergence of estimates, i.e., vanishing residuals, to minimize information being sent. The scheme is adaptive, i.e., tracks changes in the estimated system and utilizes entropy coding and adaptive gain to fit the time-varying residual variance to pre-trained codebooks. We use a low-complexity approach for gain adaptation, based on a recursive variance estimate. We demonstrate the approach's effectiveness with numerical simulations and its performance in various scenarios.

关键词： adaptive coding blind system identification alternating direction method of multipliers

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adaptive coding Tree for Complexity Control of High Efficiency Video Encoders

Adaptive Coding Tree for Complexity Control of High Efficien...

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29th Picture coding Symposium (PCS)

作者： Correa, Guilherme Assuncao, Pedro da Silva Cruz, Luis A. Agostini, Luciano DEEC FCTUC Univ Coimbra Inst Telecomunicacoes Coimbra Portugal DEE ESTG Polytech Inst Leiria Leiria Portugal GACI CDTEC Fed Univ Pelotas Pelotas Brazil

ISBN: (纸本)9781457720482

The emerging HEVC standard introduces several techniques which increase compression efficiency in comparison to its predecessors. However, such advances are accompanied by increases in computational complexity, limiting the encoder use in computational or power-constrained devices. This paper proposes a novel complexity control method for the future HEVC encoders based on a dynamic adjustment of the newly proposed coding tree structures. The relationship between coding tree depths and the encoding complexity is explored to selectively constrain encoding possibilities in order to not exceed a predefined complexity target. Experimental results show that the encoder computational complexity can be downscaled to 60% with a bit rate increase under 3.5% and a PSNR decrease under 0.1 dB.

关键词： ENCODER COMPRESSION EFFICIENCY encoding complexity complexity classes adaptive coding Control Methods

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adaptive coding and Modulation for Return Satellite Links using Binary Turbo coding

Adaptive Coding and Modulation for Return Satellite Links us...

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5th Advanced Satellite Multimedia Systems Conference / 11th Signal Processing for Space Communications Workshop (ASMS/SPSC)

作者： Crozier, Stewart Kerr, Ron Lodge, John Commun Res Ctr Canada 3701 Carling AveBox 11490Stn H Ottawa ON K2H 8S2 Canada

ISBN: (纸本)9781424468331

A turbo code that is based on an 8-state binary constituent code is considered in this paper for use in an adaptive coding and modulation system for a return satellite link. The paper presents the results of finding good puncture-constrained dithered relative prime interleavers along with data puncture patterns to provide the required performance. A trade-off between waterfall and flare performance can be made by selecting the best puncture masks for the required error rate. The performance of the turbo code with a packet size of 1504 data bits is presented for the following modulations: BPSK, QPSK, 8 PSK and 16 APSK. A comparison with other coding strategies shows that this code is an attractive option for use in a return satellite link application using adaptive coding and modulation.

关键词： 16 APSK 8 PSK BPSK QPSK adaptive codes adaptive coding binary turbo coding modulation quadrature phase shift keying return satellite links satellite links turbo codes

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Capacity analysis and system optimization for the reverse link of multi-beam satellite broadband systems exploiting adaptive coding and modulation

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING 2004年第4期22卷 425-448页

作者： Rinaldo, R De Gaudenzi, R European Space Agcy ESTEC TEC ETC NL-2200 AG Noordwijk Netherlands

This paper deals with the system capacity analysis and assessment of the potential advantages provided by the introduction of adaptive coding and Modulation (ACM) in the reverse link of multi-beam broadband satellite systems. ACM is intended to increase the system throughput for a given terminal EIRP power by optimizing the individual links physical layer to the current channel conditions. The physical layer adaptation will be driven by the inbound demodulator signal over noise plus interference ratio (SNIR) estimation. A general methodology for ACM physical layer optimization based on the system capacity maximization is also illustrated. A theoretical analysis of ACM systems capacity is performed for both time division multiple access (TDMA) and code division multiple access (CDMA) schemes. As the exact analytical capacity computation results to be very complex while Monte Carlo approach leads to very time consuming simulations, a simplified semi-analytic approach is devised. Numerical results showing the huge improvement in terms of capacity by the ACM adoption are obtained for both the semi-analytic and the Monte Carlo approaches in a realistic study case corresponding to a Ka-band multibeam satellite system. A good match between the two approaches is also demonstrated. Copyright (C) 2004 John Wiley Sons, Ltd.

关键词： system optimization Satellite systems Physical layer Code division multiple access reverse link broadband system adaptive coding system capacity time division multiple access multi-beam

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