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Somatotopic organization of human somatosensory cortices for pain:: a single trial fMRI study

NEUROIMAGE 2004年第1期23卷 224-232页

作者： Bingel, U Lorenz, J Glauche, V Knab, R Gläscher, J Weiller, C Büchel, C Univ Hamburg Sch Med Dept Neurol Cognit Neurosci Lab Hamburg Germany Univ Hamburg Sch Med Dept Physiol Hamburg Germany

The ability to locate pain plays a pivotal role in immediate defense and withdrawal behavior. However, how the brain localizes nociceptive information without additional information from somatotopically organized mechano-receptive pathways is not well understood. To investigate the somatotopic organization of the nociceptive system, we applied Thulium-YAG-laser evoked pain stimuli, which have no concomitant tactile component, to the dorsum of the left hand and foot in randomized order. We used single-trial functional magnetic resonance imaging (fMRI) to assess differential hemodynamic responses to hand and foot stimulation for the group and in a single subject approach. The primary somatosensory cortex (SI) shows a clear somatotopic organization ipsi- and contralaterally to painful stimulation. Furthermore, a differential representation of hand and foot stimulation appeared within the contralateral opercular-insular region of the secondary somatosensory cortex (SII). This result provides evidence that both SI and SII encode spatial information of nociceptive stimuli without additional information from the tactile system and highlights the concept of a redundant representation of basic discriminative stimulus features in human somatosensory cortices, which seems adequate in view of the evolutionary importance of pain perception. (C) 2004 Elsevier Inc. All rights reserved.

关键词： pain nociception single trial fMRI laser neuroimaging somatotopy sensory coding SI SII

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Stochastic resonance and synchronization in the crayfish caudal photoreceptor

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MATHEMATICAL BIOSCIENCES 2004年第1-2期188卷 81-97页

作者： Bahar, S Moss, F New York Presbyterian Hosp Weill Cornell Med Coll Dept Neurol Surg New York NY 10021 USA Univ Missouri Ctr Neurodynam St Louis MO 63121 USA

Stochastic resonance is the process by which noise added to a weak external stimulus can enhance encoding efficiency in the sensory periphery and thence in the central nervous system. Stochastic synchronization is the process by which noisy phase synchronization of two periodic (or aperiodic) signals can occur. Together with a brief review of both concepts, we illustrate their applications to the encoding of weak external hydrodynamic signals in the mechanosensory system of the crayfish. (C) 2003 Elsevier Inc. All rights reserved.

关键词： stochastic synchronization stochastic resonance crayfish photoreceptor crayfish mechanoreceptor sensory coding

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Stochastic resonance and synchronization in the crayfish caudal photoreceptor

Stochastic resonance and synchronization in the crayfish cau...

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International Conference on Topics in Biomathematics and Related Computational Problems at the Beginning of the Third Millennium

作者： Bahar, S Moss, F New York Presbyterian Hosp Weill Cornell Med Coll Dept Neurol Surg New York NY 10021 USA Univ Missouri Ctr Neurodynam St Louis MO 63121 USA

关键词： stochastic synchronization stochastic resonance crayfish photoreceptor crayfish mechanoreceptor sensory coding

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How accurate need sensory coding be for behaviour? Experiments using a mobile robot

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NEUROCOMPUTING 2001年 38卷 1113-1119页

作者： Blanchard, M Rind, FC Verschure, PFMJ Univ Zurich ETH Zurich Inst Neuroinformat CH-8057 Zurich Switzerland Univ Newcastle Upon Tyne Sch Med Dept Neurosci Newcastle Upon Tyne NE2 4HH Tyne & Wear England

This paper argues that for those neuronal systems which control behaviour, reliable responses are more appropriate than precise responses. We illustrate this argument using a mobile robot controlled by the responses of a neuronal model of the locust LGMD system, a visual system which responds to looming objects. Our experiments show that although the responses of the model LGMD Vary widely as the robot approaches obstacles, they still trigger avoidance responses. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词： behaviour insect vision sensory coding mobile robot collision avoidance

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Proprioceptive population coding of limb position in humans

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EXPERIMENTAL BRAIN RESEARCH 2003年第4期149卷 512-519页

作者： Ribot-Ciscar, E Bergenheim, M Albert, F Roll, JP Univ Aix Marseille 1 Fac Sci St Jerome 52 CNRSUMR Neurobiol Integrat & Adapt 6149 Lab Neurobiol Humaine F-13397 Marseille 20 France Natl Inst Working Life Ctr Musculoskeletal Res Umea Sweden

The present study investigates the coding of positions reached in a two-dimensional space by populations of muscle spindle afferents. The unitary activity of 35 primary muscle spindle afferents originating from the tibialis anterior, extensor digitorum longus, extensor hallucis longus, and peroneus lateralis muscles were recorded from the common peroneal nerve by the microneurographic technique. The steady mean frequency of discharge was analyzed during 16 passively maintained positions of the tip of the foot. These positions were equally distant from and circularly arranged around the "neutral" position of the ankle. The results showed that a same position of the foot was differently coded depending on whether it was maintained for several seconds or whether it was attained after a movement. Muscle spindle activity was increased or decreased, respectively, when the previous movement lengthened or shortened the parent muscle;the magnitude of change in activity depended on the amount of lengthening or shortening in relation to movement direction. Each muscle surrounding the ankle joint was shown to encode the different spatial positions following a directional tuning curve. Data were analyzed by using the "neuronal population vector model". This model consists of calculating population vectors representing the mean contribution of each muscle population of afferents to the coding of a particular position, and by finally calculating a sum vector. The direction of the sum vector was shown to accurately describe the direction of a given maintained position compared to the initial position. We conclude that muscle spindle position coding is based on afferent information coming from the whole set of muscles crossing a given joint. A given spatial position is associated with a stable muscle afferent inflow where each muscle makes an oriented and weighted contribution to its coding.

关键词： proprioception muscle afferents sensory coding position sensitivity microneurography

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Blocking sensory inputs to identified antennal glomeruli selectively modifies odorant perception in Drosophila

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JOURNAL OF NEUROBIOLOGY 2003年第1期56卷 1-12页

作者： Devaud, JM Keane, J Ferrús, A CSIC Inst Cajal E-28002 Madrid Spain Univ Sussex Sussex Ctr Neurosci Brighton BN1 9QG E Sussex England

Neural coding of sensory input is a major unsolved issue in neuroscience. Current experimental methods rely on neural activity recording or visualization following sensory stimulation. Most of them, however, do not include behavioral correlates on the actual perception by the animal. We present a novel approach to address olfaction and coding in adult Drosophila. sensory input was selectively blocked in two subsets of sensory neurons that project to different, albeit overlapping, groups of central targets, by means of tetanus toxin expressed under the control of the yeast transcription factor Ga14. Glomeruli DL1, DL2, VM1, and VM4 were tested following stimulation with benzaldehyde, ethyl acetate, propionic acid, butanol, or acetone at various concentrations. The behavioral response was found to be modified in an odorant-specific and a concentration-dependent manner. sensory input to DL2 and, to a minor extent, VM1 and/or VM4, appear to be required for benzaldehyde perception, while acetone is processed through DL1. None of these glomeruli, however, seem necessary for butanol perception. In addition, sexual differences were observed for some stimuli. These results demonstrate the behavioral relevance of odor representation as maps of glomerular activity generated in the antennal lobes following specific sensory input. The strategy used here should be useful to characterize olfactory coding, as new and selective Gal4 lines become available. (C) 2003 Wiley Periodicals, Inc.

关键词： olfaction glomeruli sensory coding tetanus toxin Drosophila

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Natural patterns of neural activity - How physiological mechanisms are orchestrated to cope with real life

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MOLECULAR NEUROBIOLOGY 2003年第1期27卷 13-31页

作者： Kurtz, R Egelhaaf, M Univ Bielefeld Fak Biol Lehrstuhl Neurobiol D-33501 Bielefeld Germany

Physiological mechanisms of neuronal information processing have been shaped during evolution by a continual interplay between organisms and their sensory surroundings. Thus, when asking for the functional significance of such mechanisms, the natural conditions under which they operate must be considered. This has been done successfully in several studies that employ sensory stimulation under in vivo conditions. These studies address the question of how physiological mechanisms within neurons are properly adjusted to the characteristics of natural stimuli and to the demands imposed on the system being studied. Results from diverse animal models show how neurons exploit natural stimulus statistics efficiently by utilizing specific filtering capacities. Mechanisms that allow neurons to adapt to the currently relevant range from an often immense stimulus spectrum are outlined, and examples are provided that suggest that information transfer between neurons is shaped by the system-specific computational tasks in the behavioral context.

关键词： adaptation calcium imaging cricket cercal system dendritic processing in vivo stimulation motion vision photoreceptor sensory coding synaptic transmission temporal filtering

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Single trial fMRI reveals significant contralateral bias in responses to laser pain within thalamus and somatosensory cortices

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NEUROIMAGE 2003年第3期18卷 740-748页

作者： Bingel, U Quante, M Knab, R Bromm, B Weiller, C Büchel, C Univ Hamburg Sch Med Dept Neurol Cognit Neurosci Lab Hamburg Germany Univ Hamburg Sch Med Dept Physiol Hamburg Germany

Pain is processed in multiple brain areas, indicating the complexity of pain perception. The ability to locate pain plays a pivotal role in immediate defense and withdrawal behavior. However, how the brain localizes nociceptive information without additional information from somatotopically organized mechano-receptive pathways is not well understood. We used single-trial functional magnetic resonance imaging (fMRI) to assess hemodynamic responses to right and left painful stimulation. Thulium-YAG-(yttrium-aluminium-granate)-laser-evoked pain stimuli, without concomitant tactile component, were applied to either hand in a randomized order. A contralateral bias of the BOLD response was investigated to determine areas involved in the coding of the side of stimulation, which we observed in primary (SI) and secondary (SII) somatosensory cortex, insula, and the thalamus. This suggests that these structures provide spatial information of selective nociceptive stimuli. More importantly, this contralateral bias of activation allowed functionally segregated activations within the SII complex, the insula, and the thalamus. Only distinct subregions of the SII complex, the posterior insula and the lateral thalamus, but not the remaining SII complex, the anterior insula and the medial thalamus, showed a contralaterally biased representation of painful stimuli. This result supports the hypothesis that sensory-discriminative attributes of painful stimuli, such as those related to body side, are topospecifically represented within the forebrain projections of the nociceptive system and highlights the concept of functional segregation and specialization within these structures. (C) 2003 Elsevier Science (USA). All rights reserved.

关键词： pain nociception single-trial fMRI laser neuroimaging sensory coding SI SII somatosensory cortex post insula thalamus lateralization somatotopy

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Colour and luminance selectivity of spatial and temporal interactions in orientation perception

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VISION RESEARCH 2003年第27期43卷 2885-2893页

作者： Clifford, CWG Pearson, J Forte, JD Spehar, B Univ Sydney Sch Psychol Visual Percept Unit Colour Form & Mot Lab Sydney NSW 2006 Australia Natl Vis Res Inst Carlton Vic 3053 Australia Univ New S Wales Sch Psychol Sydney NSW 2052 Australia

Previous studies have commented upon the similar phenomenology of simultaneous and successive interactions in the perception of orientation. These similarities have been taken as evidence of common mechanisms underlying the simultaneous tilt illusion (TI) and the successive tilt aftereffect (TAE). We measured the TI and TAE for four subjects for combinations of test and inducing stimuli modulated along either the same or orthogonal axes of colour space within the L + M + S, L-M colour-luminance plane. The largest TI and TAE were found when test and inducer were modulated along the same axis of colour space. The TI consistently showed greater selectivity for colour/luminance than the TAE. The results are discussed in relation to the known chromatic properties of the primate visual pathways. Specifically, we suggest that both the TI and TAE involve colour- and luminance-specific neurons in primary visual cortex as well as cue-invariant mechanisms in extrastriate cortex. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： adaptation visual cortex human psychophysics tilt illusion tilt aftereffect sensory coding

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A paradox of temporal perception revealed by a stimulus oscillating in colour and orientation

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VISION RESEARCH 2003年第21期43卷 2245-2253页

作者： Clifford, CWG Arnold, DH Pearson, J Univ Sydney Sch Psychol Visual Percept Unit Colour Form & Mot Lab Sydney NSW 2006 Australia UCL Dept Psychol London WC1E 6BT England UCL Inst Cognit Neurosci London WC1E 6BT England

Psychophysical experiments with stimuli oscillating concurrently in colour and orientation revealed an apparently paradoxical dissociation between the perceived simultaneity of stimulus changes and the perceptual pairing of the events demarked by those changes. When subjects were required to report whether changes in colour and orientation were simultaneous, judgements were generally accurate within +/-10 ms. When subjects were required to report which colour was paired predominantly with which orientation, judgements showed a systematic temporal bias of up to 50 ms in favour of colour. This dissociation between different temporal judgements concerning the same stimulus sequence is not predicted by any of the current models of binding in conscious vision. We propose an account of these data based on the temporal response properties of colour- and orientation-selective model neurons such that the perceived pairing of visual attributes is modelled as the cross-correlation of time-varying neural response profiles and thus reflects both neuronal latencies and the rate of rapid adaptation rather than simply the temporal pattern of responses to stimulus transitions. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： colour vision spatial vision time perception human psychophysics visual cortex sensory coding computational model perceptual binding

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