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Different Processing (different + processing)

Distribution by Scientific Domains
Life Sciences60%

Terms modified by Different Processing

  • different processing condition
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  • different processing parameter
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    Selected Abstracts

    Spectro-temporal sound density-dependent long-term adaptation in cat primary auditory cortex

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2008
    Boris Gourévitch
    Abstract Sensory systems use adaptive strategies to code for the changing environment on different time scales. Short-term adaptation (up to 100 ms) reflects mostly synaptic suppression mechanisms after response to a stimulus. Long-term adaptation (up to a few seconds) is reflected in the habituation of neuronal responses to constant stimuli. Very long-term adaptation (several weeks) can lead to plastic changes in the cortex, most often facilitated during early development, by stimulus relevance or by behavioral states such as attention. In this study, we show that long-term adaptation with a time course of tens of minutes is detectable in anesthetized adult cat auditory cortex after a few minutes of listening to random-frequency tone pips. After the initial post-onset suppression, a slow recovery of the neuronal response strength to tones at or near their best frequency was observed for low-rate random sounds (four pips per octave per second) during stimulation. The firing rate at the end of stimulation (15 min) reached levels close to that observed during the initial onset response. The effect, visible for both spikes and, to a smaller extent, local field potentials, decreased with increasing spectro-temporal density of the sound. The spectro-temporal density of sound may therefore be of particular relevance in cortical processing. Our findings suggest that low stimulus rates may produce a specific acoustic environment that shapes the primary auditory cortex through very different processing than for spectro-temporally more dense and complex sounds. [source]

    Tonotopic representation of missing fundamental complex sounds in the human auditory cortex

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2003
    Takako Fujioka
    Abstract The N1m component of the auditory evoked magnetic field in response to tones and complex sounds was examined in order to clarify whether the tonotopic representation in the human secondary auditory cortex is based on perceived pitch or the physical frequency spectrum of the sound. The investigated stimulus parameters were the fundamental frequencies (F0 = 250, 500 and 1000 Hz), the spectral composition of the higher harmonics of the missing fundamental sounds (2nd to 5th, 6th to 9th and 10th to 13th harmonic) and the frequencies of pure tones corresponding to F0 and to the lowest component of each complex sound. Tonotopic gradients showed that high frequencies were more medially located than low frequencies for the pure tones and for the centre frequency of the complex tones. Furthermore, in the superior,inferior direction, the tonotopic gradients were different between pure tones and complex sounds. The results were interpreted as reflecting different processing in the auditory cortex for pure tones and complex sounds. This hypothesis was supported by the result of evoked responses to complex sounds having longer latencies. A more pronounced tonotopic representation in the right hemisphere gave evidence for right hemispheric dominance in spectral processing. [source]

    Shape-understanding system: A system of experts

    INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 10 2004
    Zbigniew Les
    A shape-understanding system (SUS) that is able to perform different tasks of shape analysis and recognition, based on the ability of the system to understand different concepts of shape at the different levels of cognition, is proposed. This system is an implementation of a shape-understanding method. The proposed method of shape understanding is based on the concept of possible classes of shapes. Possible classes of shape are based on shape models and are viewed as a hierarchical structure at different levels of description. At each level of description the different aspects of shape such as geometrical properties of shape, perceptual properties of figure, or meaningful properties of visual form are incorporated in the shape model. The shape-understanding system consists of different types of experts that perform different processing and reasoning tasks. © 2004 Wiley Periodicals, Inc. Int J Int Syst 19: 949,978, 2004. [source]

    The solubility of ,-synuclein in multiple system atrophy differs from that of dementia with Lewy bodies and Parkinson's disease

    JOURNAL OF NEUROCHEMISTRY, Issue 1 2001
    Bruce C. V. Campbell
    Intracellular inclusions containing ,-synuclein (,SN) are pathognomonic features of several neurodegenerative disorders. Inclusions occur in oligodendrocytes in multiple system atrophy (MSA) and in neurons in dementia with Lewy bodies (DLB) and Parkinson's disease (PD). In order to identify disease-associated changes of ,SN, this study compared the levels, solubility and molecular weight species of ,SN in brain homogenates from MSA, DLB, PD and normal aged controls. In DLB and PD, substantial amounts of detergent-soluble and detergent-insoluble ,SN were detected compared with controls in grey matter homogenate. Compared with controls, MSA cases had significantly higher levels of ,SN in the detergent-soluble fraction of brain samples from pons and white matter but detergent-insoluble ,SN was not detected. There was an inverse correlation between buffered saline-soluble and detergent-soluble levels of ,SN in individual MSA cases suggesting a transition towards insolubility in disease. The differences in solubility of ,SN between grey and white matter in disease may result from different processing of ,SN in neurons compared with oligodendrocytes. Highly insoluble ,SN is not involved in the pathogenesis of MSA. It is therefore possible that buffered saline-soluble or detergent-soluble forms of ,SN are involved in the pathogenesis of other ,SN-related diseases. [source]

    Study of prelocalized graphite/styrene acrylonitrile conducting composites for device applications

    PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2006
    V. K. Sachdev
    Abstract Conductive polymer composites were prepared by compression molding of prelocalized graphite on to styrene acrylonitrile (SAN) particles. The electrical conductivity is found to be strongly dependent on the graphite content. Three different series were prepared for different processing and material parameters. A low percolation threshold has been noticed when only 1 wt% of graphite is incorporated. Resistivity as low as ,14 , cm has been achieved in a composite with SAN resin particles of 180,212 µm size and graphite 10,20 µm at 90 °C, 105 MPa and 15 min. An electrically conducting network of graphite channels has been observed using scanning electron microscopy. V,I characteristic reveals that at a lower percentage of graphite the increase in current with increase in electric field is due to the hopping/tunneling of electrons, while for higher percentages of graphite ohmic behavior similar to metals has been observed. The data has been analyzed using percolation model. The value of the exponent t that determines the increase in electrical conductivity above the percolation threshold is found to be close to the values given in the literature. The theoretically calculated values of conductivity are found to be in satisfactory agreement with the experimental ones. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]