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Understanding smell-The olfactory stimulus problem

NEUROSCIENCE AND BIOBEHAVIORAL REVIEWS 2013年第8期37卷 1667-1679页

作者： Auffarth, Benjamin Fdn Res & Technol Inst Mol Biol & Biotechnol Iraklion Greece Free Univ Berlin Dept Neurobiol Berlin Germany BCCN Berlin Germany KTH Royal Inst Technol Sch Comp Sci & Commun Stockholm Sweden

The main problem with sensory processing is the difficulty in relating sensory input to physiological responses and perception. This is especially problematic at higher levels of processing, where complex cues elicit highly specific responses. In olfaction, this relationship is particularly obfuscated by the difficulty of characterizing stimulus statistics and perception. The core questions in olfaction are hence the so-called stimulus problem, which refers to the understanding of the stimulus, and the structure-activity and structure-odor relationships, which refer to the molecular basis of smell. It is widely accepted that the recognition of odorants by receptors is governed by the detection of physico-chemical properties and that the physical space is highly complex. Not surprisingly, ideas differ about how odor stimuli should be classified and about the very nature of information that the brain extracts from odors. Even though there are many measures for smell, there is none that accurately describes all aspects of it. Here, we summarize recent developments in the understanding of olfaction. We argue that an approach to olfactory function where information processing is emphasized could contribute to a high degree to our understanding of smell as a perceptual phenomenon emerging from neural computations. Further, we argue that combined analysis of the stimulus, biology, physiology, and behavior and perception can provide new insights into olfactory function. We hope that the reader can use this review as a competent guide and overview of research activities in olfactory physiology, psychophysics, computation, and psychology. We propose avenues for research, particularly in the systematic characterization of receptive fields and of perception. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Olfactory system Olfactory stimulus-problem Structure-activity relationship Structure-odor relationship Odor perception spatial coding Olfactory receptors Topography Hedonics Basic odors Vertebrate olfaction Insect olfaction

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Voting-Based Motion Estimation for Real-Time Video Transmission in Networked Mobile Camera Systems

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IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS 2013年第1期9卷 172-180页

作者： Lian, Feng-Li Lin, Yi-Chun Kuo, Chien-Ting Jean, Jong-Hann Natl Taiwan Univ Dept Elect Engn Taipei 10617 Taiwan St Johns Univ Dept Elect Engn Taipei Taiwan St Johns Univ Ctr Comp Taipei Taiwan

In a video-based surveillance system, a mobile camera can provide dynamical and wider monitoring range and the video data transmitted from cooperative mobile cameras can be used to actively detect the objects of interest. However, it is a difficult task to accurately detect the moving objects from the image frames captured by the mobile cameras and the data flow of surveillance video from multiple cameras could be huge. The camera motion usually causes the shifting of static background as well as the moving objects in the captured image frames. In order to correctly estimate the motion of moving objects, a voting-based motion estimation algorithm is proposed to process the image frames captured by the mobile camera. Based on the estimation, a content-based video transmission mechanism is then implemented to further effectively decrease encoding cost and bandwidth utilization. The overall approach consists of voting-based motion estimation, moving object edges detection and content-based sampling coding at temporal and spatial scales. Without knowing the prior knowledge of camera motion, the motion estimation algorithm only utilizes the shifting information of edges of static background to estimate the camera movement. The shifting information is determined based on the voting decision of several representative regions of interest and the estimated motion is then used to compensate for the visual content obtained from the captured image frames. The proposed algorithms have been experimentally tested on several practical scenarios and it is demonstrated that, under limited network bandwidth, the transmitted image quality can be progressively achieved and the transmission bandwidth utilization can be effectively decreased.

关键词： Motion detection spatial coding temporal sampling visual surveillance system

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Why you need to look where you step for precise foot placement: The effects of gaze eccentricity on stepping errors

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GAIT & POSTURE 2013年第2期38卷 242-246页

作者： Smid, K. A. den Otter, A. R. Univ Groningen Univ Med Ctr Groningen Ctr Human Movement Sci NL-9713 AV Groningen Netherlands

Previous research has shown that accurate stepping involves the fixation of gaze on the intended step location. One possible explanation for this visual strategy is that the fixation of locations that are eccentric relative to the step target, results in systematic localization errors, as has previously been demonstrated in pointing. To test this idea, we assessed the possible role of gaze stabilization in the spatial planning of accurate steps, and determined whether the direction of mediolateral stepping errors depended on the direction of gaze. Final foot position was recorded from ten healthy participants when making steps towards prints of their own foot, in light and in darkness, and fixating their gaze on (i) the stepping target or (ii) locations 30 cm to the left or right of the target. The results showed that accuracy and precision of foot placement were reduced when stepping in darkness or when fixating eccentric gaze targets, demonstrating that visual feedback on the target and/or foot facilitates spatial control of the foot, and that foveal information is superior to perifoveal information in this respect. Crucially, the direction of the mediolateral stepping errors depended on the direction of gaze: on average participants overstepped 12 mm contralateral to the direction of gaze when fixating eccentric locations, indicating that the fixation of locations eccentric to the stepping target results in inaccuracies in foot placement. These results provide new insights into the contributions of foveal vision to the spatial planning of precise steps, and explain why it is important to look where you step when accurate foot placement is required. (C) 2012 Elsevier B. V. All rights reserved.

关键词： Gaze spatial coding Stepping Visual guidance Sensorimotor control

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Visuospatial properties of caudal area 7b in Macaca fascicularis

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Zoological Research 2013年第2期34卷 50-61页

作者： Hui-Hui JIANG Ying-Zhou HU Jian-Hong WANG Yuan-Ye MA Xin-Tian HU Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences&Yunnan Province Kunming Institute of ZoologyChinese Academy of SciencesKunming 650223China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Brain and Cognitive Sciences Institute of BiophysicsChinese Academy of SciencesBeijing 100101China Kunming Primate Research Center Kunming Institute of ZoologyChinese Academy of SciencesKunming 650223China

To proceed from sensation to movement,integration and transformation of information from different senses and reference frames are *** brain areas are involved in this transformation process,but previous neuroanatomical and neurophysiological studies have implicated the caudal area 7b as one particular component of this transformation *** this study,we present the first quantitative report on the spatial coding properties of caudal area *** results showed that neurons in this area had intermediate component characteristics in the transformation system;the area contained bimodal neurons,and neurons in this area encode spatial information using a hybrid reference *** results provide evidence that caudal area 7b may belong to the reference frame transformation system,thus contributing to our general understanding of the transformation system.

关键词： Reference frame spatial coding Receptive field Area 7b

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Gaze-centered spatial updating in delayed reaching even in the presence of landmarks

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VISION RESEARCH 2013年 87卷 46-52页

作者： Schuetz, I. Henriques, D. Y. P. Fiehler, K. Univ Giessen Dept Psychol D-35390 Giessen Germany York Univ Sch Kinesiol & Hlth Sci Ctr Vis Res Toronto ON M3J 2R7 Canada

Previous results suggest that the brain predominantly relies on a constantly updated gaze-centered target representation to guide reach movements when no other visual information is available. In the present study, we investigated whether the addition of reliable visual landmarks influences the use of spatial reference frames for immediate and delayed reaching. Subjects reached immediately or after a delay of 8 or 12 s to remembered target locations, either with or without landmarks. After target presentation and before reaching they shifted gaze to one of five different fixation points and held their gaze at this location until the end of the reach. With landmarks present, gaze-dependent reaching errors were smaller and more precise than when reaching without landmarks. Delay influenced neither reaching errors nor variability. These findings suggest that when landmarks are available, the brain seems to still use gaze-dependent representations but combine them with gaze-independent allocentric information to guide immediate or delayed reach movements to visual targets. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： spatial updating spatial coding Reaching Landmarks Delayed reaching Reference frame

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Singing Numbers ... in Cognitive Space - A Dual-Task Study of the Link Between Pitch, Space, and Numbers

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TOPICS IN COGNITIVE SCIENCE 2013年第2期5卷 354-366页

作者： Fischer, Martin H. Riello, Marianna Giordano, Bruno L. Rusconi, Elena Univ Potsdam Div Cognit Sci D-14476 Potsdam Germany Univ Trento Ctr Mind Brain Sci Trento Italy McGill Univ Dept Mus Res Ctr Interdisciplinary Res Mus Media & Technol Montreal PQ H3A 2T5 Canada Univ Glasgow Inst Neurosci & Psychol Glasgow G12 8QQ Lanark Scotland Univ Parma Dept Neurosci I-43100 Parma Italy UCL Dept Secur & Crime Sci London WC1E 6BT England

We assessed the automaticity of spatial-numerical and spatial-musical associations by testing their intentionality and load sensitivity in a dual-task paradigm. In separate sessions, 16 healthy adults performed magnitude and pitch comparisons on sung numbers with variable pitch. Stimuli and response alternatives were identical, but the relevant stimulus attribute (pitch or number) differed between tasks. Concomitant tasks required retention of either color or location information. Results show that spatial associations of both magnitude and pitch are load sensitive and that the spatial association for pitch is more powerful than that for magnitude. These findings argue against the automaticity of spatial mappings in either stimulus dimension.

关键词： Auditory pitch Dual task Mental number line SMARC SNARC spatial coding

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Feature binding across different visual dimensions

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ATTENTION PERCEPTION & PSYCHOPHYSICS 2012年第7期74卷 1406-1415页

作者： Ward, Robert Arend, Isabel Bangor Univ Wolfson Ctr Clin & Cognit Neurosci Bangor LL57 2AS Gwynedd Wales Ben Gurion Univ Negev Dept Psychol IL-84105 Beer Sheva Israel

The human brain represents different kinds of visual feature dimensions in different ways. For example, surface features exhibit some properties that are very different from contour features, and some feature dimensions may be represented more extensively in either the dorsal or the ventral visual stream. Given such differences, we investigated feature binding across different feature dimensions and whether some feature dimensions might be more easily bound together than others. In Experiment 1, we looked at cross-dimension bindings for all combinations of color, orientation, and shape dimensions, while at the same time controlling for feature discriminability. Rates of correct binding, illusory conjunctions, and feature errors were equivalent in all cases. There was no bias so that some feature dimensions were easier to combine than others. In Experiment 2, we manipulated the difficulty of feature discrimination for the key, target-defining feature and the report feature. Rates of binding errors increased with difficulty of the key feature, but not with that of the report feature. The accuracy of feature discrimination could be dissociated from the accuracy of binding the feature to an object. Across both experiments, the accuracy of feature binding was independent of specific feature dimensions or perceptibility. These findings are discussed in relation to both feature integration and multiple-stage accounts of visual feature integration.

关键词： Illusory conjunctions Feature integration spatial coding Task difficulty

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Imitation components in the human brain: An fMRI study

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NEUROIMAGE 2012年第2期59卷 1622-1630页

作者： Mengotti, Paola Corradi-Dell'Acqua, Corrado Rumiati, Raffaella Ida SISSA Cognit Neurosci Sect I-34136 Trieste Italy Univ Geneva Swiss Ctr Affect Sci Geneva Switzerland

Human ability to imitate movements is instantiated in parietal, premotor and opercular structures, often referred to as the human homologue of the macaque mirror neuron system. As most studies employed imitation of specular models (participants imitated the seen movement as their mirror reflection), it is unclear whether the structures implicated code for the anatomical compatibility between the performer and the model or the spatial compatibility between the location at which both movements occur. We used fMRI to disentangle the neural mechanisms underlying anatomical and spatial components of imitation. Participants moved one finger which was either spatially or anatomically compatible with the finger moved in a video-display. In keeping with the existent behavioral literature, we found that during the spatial task, participants' responses were faster when the seen movement was also anatomically compatible, whereas in the anatomical task, responses were faster when the seen movement was also spatially compatible. Critically, the activity of the parietal opercula bilaterally was associated with the anatomical compatibility effect. Furthermore, increased activity of the left middle frontal gyms and right superior temporal sulcus (extending to the temporo-parietal junction) was found in those trials in which the spatial mapping between the seen and executed movements was detrimental for the anatomical task. Our findings extend current understanding of the role played by spatial and anatomical components in imitation and provide new insights about the parietal opercula. (C) 2011 Elsevier Inc. All rights reserved.

关键词： Parietal operculum Neuroimaging spatial coding Finger movement Superior temporal sulcus

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The development of the SNARC effect: Evidence for early verbal coding

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JOURNAL OF EXPERIMENTAL CHILD PSYCHOLOGY 2012年第4期111卷 671-680页

作者： Imbo, Ineke De Brauwer, Jolien Fias, Wim Gevers, Wim Univ Ghent Dept Expt Psychol B-9000 Ghent Belgium Lessius Univ Coll Expertise Ctr CODE B-2018 Antwerp Belgium Univ Libre Bruxelles Unite Rech & Neurosci Cognit B-1000 Brussels Belgium

In a recent study, Gevers and colleagues (2010, Journal of Experimental Psychology: General, Vol. 139, pp. 180-190) showed that the SNARC (spatial numerical association of response codes) effect in adults results not only from spatial coding of magnitude (e.g., mental number line hypothesis) but also from verbal coding. Because children are surrounded by rulers, number lines, and the like in the classroom, it is intuitively appealing to assume that they first use their mental number line to represent numbers and that only later in development a verbal recoding of magnitude information takes place. However, this hypothesis has never been tested. The goal of the current study was to define the developmental pattern of both accounts (spatial and verbal) in explaining the SNARC effect. To this end, 9- and 11-year-olds were tested in a magnitude comparison task. Surprisingly, clear and robust evidence for verbal coding of magnitude information was observed in both age groups. Our results imply that the ability to use verbal coding of magnitude information is robustly present early in formal schooling. (C) 2011 Elsevier Inc. All rights reserved.

关键词： SNARC effect Cognitive development Magnitude comparison Numerical cognition spatial coding Verbal coding

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Are there relationships among different spatial skills of individuals with blindness?

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RESEARCH IN DEVELOPMENTAL DISABILITIES 2012年第6期33卷 2164-2176页

作者： Koustriava, Eleni Papadopoulos, Konstantinos Univ Macedonia Dept Educ & Social Policy Thessaloniki 54006 Greece

The aim of this study was to detect the possible relationships between various spatial skills of individuals with blindness. Twenty-eight individuals with blindness participated in five experiments that examined the body knowledge, laterality, directionality, perspective-taking, spatial coding of the near space and spatial knowledge of the far space. According to the results a positive correlation between body knowledge and directionality has emerged. Moreover, body knowledge and spatial coding of near space are found to be predictors of perspective-taking, while directionality and perspective-taking are found to be predictors of spatial coding of near space, and directionality and perspective-taking predictors of spatial knowledge of far space. This finding suggest that future studies should seriously take into account the possibility that the development of a certain skill could in fact be the result of the development of another skill/s. Moreover, the findings support the notion that a delay in the development of a spatial skill may not necessarily be a result of the visual impairment itself but of the incomplete development of another spatial skill. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： Visual impairments Body knowledge Directionality Perspective-taking spatial coding spatial knowledge

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