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Conference on Optics and Photonics for Information Processing II

作者： Nitta, Kouichi Minami, Tomoyuki Matoba, Osamu Kobe Univ Grad Sch Engn Dept Comp Sci & Syst Engn Kobe Hyogo 6578501 Japan

ISBN: (纸本)9780819472922

We improve a method for single instruction, multiple data (SIMD) operations for two-dimensional patterns by use of image compression. In the method, image data is compressed with the novel encoding rule. The encoded data consists of a set of the pixel position where the pixel value is changed and the period of the pattern. The feature of the improved method is to consider the period of the patterns. And, desired processing is executed by specific operations equivalent to logical operations for the original data. We estimate effectiveness of the improved method. The method is implemented on a personal computer and compared with the simulator based on the conventional scheme. As results of estimation, it is verified that the computational costs of the method are about ten times as small as that with the conventional compressed scheme.

关键词： spatial coding SIMD pattern operation large scale information processing image compression prime factorization

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Motion and position coding

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VISION RESEARCH 2007年第18期47卷 2403-2410页

作者： Arnold, Derek H. Thompson, Michael Johnston, Alan UCL Dept Psychol London WC1E 6BT England UCL CoPLEX London WC1E 6BT England Univ Queensland Sch Psychol St Lucia Qld 4067 Australia

Motion contained within a static object can cause illusory position shifts toward the direction of internal motion. Here we present data suggesting this illusion is driven by modulations of apparent contrast. We observe position shifts at blurred stimulus regions without corresponding changes to internal structure, and find that low-contrast targets are more difficult to detect at the trailing, as opposed to leading, edges of movement. Motion induced position shifts are also shown to occur without conscious appreciation of motion direction. Our data suggests that motion can influence spatial coding via interactions that modulate apparent contrast, thereby changing the regions of the stimulus that are visible. (C) 2007 Elsevier Ltd. All rights reserved.

关键词： motion spatial coding position shift retinotopy

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A method for factorization by means of digital optical computing and image compression

A method for factorization by means of digital optical compu...

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Conference on Optics and Photonics for Information Processing

作者： Nitta, Kouichi Tado, Ysunori Matoba, Osamu Yoshimura, Takeaki Kobe Univ Fac Engn Dept Comp & Syst Engn Nada Ku Rokkodai 1-1 Kobe Hyogo 6578501 Japan

ISBN: (纸本)9780819468437

A method to reduce computational costs of a factorization algorithm based on two dimensional pattern processing is presented. We develop logical operations to implement a factorization in the data compressed domain. In the method, firstly, two dimensional discrete images for data processing is compressed in accordance with the presented coding. Secondly, sequences of logical operations are executed in compression domain. Finally, desired results are obtained by extraction of the compressed data after the operations. An advantaged feature of the presented method is that computational costs can be decreased by the data compression rate.

关键词： spatial coding pattern processing large scale information processing

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Building spike representation in tetrodes

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JOURNAL OF NEUROSCIENCE METHODS 2006年第2期157卷 364-373页

作者： Aur, Dorian Jog, Mandar S. Dept Clin Neurol Sci Movement Disorders Program London ON Canada

This paper presents anew technique for analyzing the recorded information from tetrodes in freely behaving rats, based on independent component analysis (ICA). The ion-specific pumps and channels allow fast transfer of charges such as Na+, K+, Cl- and eventually Ca2+ during each action potential (AP). These groups of charges under an electrical field have distinct spatial trajectories. Therefore, the generated signals within a tetrode are considered to be composed mainly by statistically independent signal sources that can be obtained by performing ICA. In order to compute the position of independent sources during AP generation, the triangulation method uses an iterative Newton-Raphson algorithm. The representation of the independent signal sources in three-dimensional tetrode space is then obtained. Since the charge movements are extensively spread on the neuron's surface, the representation in tetrode space reveals electrical spatial patterns of activation during each AP. The analysis of several spikes coming from the same neuron reveals small changes from spike to spike in the 3D shape. Since information within spikes is highly transferred by ionic fluxes these electrical patterns of activation reflect neuronal computation occurring during each AP. (c) 2006 Elsevier B.V. All rights reserved.

关键词： tetrode independent component analysis Newton-Raphson spatial coding neuronal computation

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Long lasting aftereffect of a single prism adaptation: directionally biased shift in proprioception and late onset shift of internal egocentric reference frame

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EXPERIMENTAL BRAIN RESEARCH 2006年第1期174卷 189-198页

作者： Hatada, Yohko Miall, R. Chris Rossetti, Yves UCL Inst Cognit Neurosci London WC1N 3AR England Inst Federatif Neurosci Lyon INSERM U534 Bron France Univ Birmingham Sch Psychol Behav Brain Sci Ctr Birmingham B15 2TT W Midlands England Univ Lyon 1 Hosp Civils Lyon Hop Henry Gabrielle St Genis Laval France

We aimed to dissociate components in prism adaptation and its aftereffect by using prism adaptation training in healthy humans. Arm proprioceptive aftereffects are usually measured by indicating the subjective straight ahead direction with eyes closed (S). This measure however could be affected by other components besides proprioception, such as an efferent motor component and internal egocentric reference frame. Here we report a very long lasting proprioceptive shift, detected by two measuring methods, that is a component of the adaptation aftereffects to left wedge prism glasses. In order to minimize possible active motor components, arm passive proprioceptive midsagittal judgment was measured (P). The subject's arm was passively brought from the right or left lateral position, and stopped by subjects' verbal order. The results from these different measurements of midsagittal judgment were compared for 7 days after prism adaptation. Surprisingly, we found two distinctly separate aftereffects of proprioceptive shift depending on the directions of the passive arm movement. The shift of the midsagittal plane appeared only when tested from the left (Pl). This indicates that our strong prism adaptation procedure affected proprioception in a directionally biased way and not a spatially ubiquitous way. Further, the early aftereffect seen in active straight ahead pointing (S) was mostly similar to this biased shift in proprioception (Pl). However the long lasting aftereffect in straight ahead pointing was independently maintained up to day 7, when the passive proprioception had returned to pretest level. These results indicate that active straight ahead pointing (S) involves other components in addition to the passively measurable proprioceptive component. We suggest a late onset shift in the internal egocentric reference frame is involved in S. Possible neural mechanisms for these phenomena are discussed.

关键词： visuo-motor sensory-motor plasticity spatial coding perception

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The future for SNARC could be stark...

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CORTEX 2006年第8期42卷 1066-1068页

作者： Fischer, Martin H. Univ Dundee Dept Psychol Dundee DD1 4HN Scotland

The present report by Wood et al. (2006, this issue) invites us to reconsider what we should believe about the cognitive representation of numbers. Researchers interested in numerical cognition have quickly embraced the idea that systematic spatial performance biases in number-related tasks must reflect an inherent spatial attribute of the underlying cognitive representation of numbers. The association between numbers and space (SNARC - spatial numerical association of response codes - effect) has effectively been used to augment the "mental number line" metaphor. Here I discuss the possibility that the SNARC effect is merely an instance of strategic problem solving.

关键词： mental number line SNARC effect spatial coding spatial strategy

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Orthogonal spatial coding in indoor wireless optical link reducing power and bandwidth requirements

Orthogonal spatial coding in indoor wireless optical link re...

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4th International Conference on Optical Networking and Communications

作者： Alqudah, YA Kavehrad, M Penn State Univ CICTR University Pk PA 16802 USA

ISBN: (纸本)0819451800

Although uniform distribution of optical power is one of the main requirements for multi-access support in a wireless optical link, Multi Spot Diffusing Configuration (MSDC) provides uniformity along with spatial independence that allows spatial diversity techniques over the link. Independent spatial channels are generated by a multibeam transmitter producing spatially confined diffusing spots, and a multibranch receiver with narrow field-of-view branches. In this paper, we propose an orthogonal spatial coding technique that utilizes the independence of channels to reduce power and bandwidth requirements. The technique is based on treating the in channels between a transmitter and a receiver as an m-dimensional space. Thus, enabling data transmission through varying signal level and its location in space. Our study shows that using 8 channels, the proposed technique enables transmission at rates 10 and 12 times higher than combining when power per channel and user are constrained, respectively.

关键词： equal gain combining spatial coding wireless optical

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Human sound localization at near-threshold levels

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HEARING RESEARCH 2005年第1-2期199卷 124-134页

作者： Sabin, AT Macpherson, EA Middlebrooks, JC Kresge Hearing Res Inst Cent Syst Lab Ann Arbor MI 48109 USA

Physiological studies of spatial hearing show that the spatial receptive fields of cortical neurons typically are narrow at near-threshold levels, broadening at moderate levels. The apparent loss of neuronal spatial selectivity at increasing sound levels conflicts with the accurate performance of human subjects localizing at moderate sound levels. In the present study, human sound localization was evaluated across a wide range of sensation levels, extending down to the detection threshold. Listeners reported whether they heard each target sound and, if the target was audible, turned their heads to face the apparent source direction. Head orientation was tracked electromagnetically. At near-threshold levels, the lateral (left/right) components of responses were highly variable and slightly biased towards the midline, and front vertical components consistently exhibited a strong bias towards the horizontal plane. Stimulus levels were specified relative to the detection threshold for a front-positioned source, so low-level rear targets often were inaudible. As the sound level increased, first lateral and then vertical localization neared asymptotic levels. The improvement of localization over a range of increasing levels, in which neural spatial receptive fields presumably are broadening, indicates that sound localization does not depend on narrow spatial receptive fields of cortical neurons. (C) 2004 Elsevier B.V. All rights reserved.

关键词： sound localization psychoacoustics spatial coding auditory cortex

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Processing of spatial visual information along the pathway between the suprageniculate nucleus and the anterior ectosylvian cortex

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BRAIN RESEARCH BULLETIN 2005年第4期67卷 281-289页

作者： Eördegh, G Nagy, A Berényi, AB Benedek, GB Univ Szeged Fac Med Dept Physiol Albert Szent Gyorgyi Med & Pharmaceut Ctr H-6720 Szeged Hungary

This study describes the visual information coding ability of single neurons in the suprageniculate nucleus (Sg), and provides new data concerning the visual information flow in the suprageniculate/anterior ectosylvian pathways of the feline brain. The visual receptive fields of the Sg neurons have an internal structure rather similar to that described earlier in the anterior ectosylvian visual area (AEV). The majority of the Sg units can provide information via their discharge rate at the site of the visual stimulus within their large receptive fields. This suggests that they may serve as panoramic localizers. The sites of maximum responsivity of the Sg neurons are distributed over the whole investigated part of the visual field. There is no significant difference between the distributions of spatial location of maximum sensitivity of the AEV and the Sg neurons. The mean visual response latency of the Sg units was found to be significantly shorter than the mean latency of the AEV neurons, but there was no difference between the shortest latency values of the thalamic and the cortical single-units. This suggests that the visual information flows predominantly from the Sg to the AEV, though the cortico-thalamic route is also active. The Sg seems to represent a thalamic nucleus rather similar in function to both the first-order relays and the higher-order thalamic nuclei. These results, together with the fact that the superior colliculus provides the common ascending source of information to the suprageniculate/anterior ectosylvian pathway, suggest a unique function of the AEV and the Sg in sensorimotor integration. (c) 2005 Elsevier Inc. All rights reserved.

关键词： suprageniculate nucleus AEV panoramic localizers spatial coding latency visual

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Odor coding in projection neurons of the honeybee brain

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CHEMICAL SENSES 2005年第SUPPL_1期30卷 I301-i302页

作者： Menzel, R Galizia, G Müller, D Szyszka, P Free Univ Berlin Inst Biol D-1000 Berlin Germany

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