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  • 1
    ISSN: 0168-583X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0304-3991
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Natural Sciences in General , Physics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1106
    Keywords: Key words Human ; Distal-proximal somatotopy ; Index finger ; Palm ; Somatosensory cortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The distal-proximal representation of the finger and palm in the first somatosensory cortex was reexamined. Somatosensory evoked magnetic fields (SEFs) were measured with a 37-channel first-order axial gradiometer system. Sensory stimulus comprising a 20-ms vibration at a frequency of 200 Hz was delivered to five successive sites in 3-cm increments along the distal-proximal direction over the volar surface of the right index finger and palm. Using a single dipole model, the sources and the signal strengths of the main peak (M50) of the SEFs were estimated. All of the sources were located in the 3b area. There were no statistically significant differences between the locations of dipoles evoked by stimulation of different sites. The results support those of our previous study using a 122-channel whole-head planar gradiometer system that orderly distal-proximal representation of the hand, as described in monkeys, is blurred in the adult human somatosensory cortex.
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  • 4
    ISSN: 1432-1106
    Keywords: Tactile air ; Puff stimulation ; Skin sensation ; Somatosensory evoked potentials ; Psychophysical magnitude estimations ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Short air-puff stimuli were applied to the sole of the right foot to obtain both psychophysical and neurophysiological responses. The detection threshold (So) was first determined, and six levels of stimulus intensity above threshold were adopted for magnitude estimation. Somatosensory evoked potentials (SEPs) were also recorded over the foot projection area (2 cm posterior to Cz) for the six stimulus intensities. Six components (N40, P45, N55, P70, N80 and P90) were recorded within 100 ms following stimulation. A power function with an exponent of 0.94 provided an adequate description of the magnitude estimation values as a function of stimulus intensity, as was verified by the high correlation coefficient (r = 0.87; P 〈 0.001). Similarly, stimulus-amplitude functions of P45-N55, N55-P70 and P70-N80 SEP components were well represented by power functions with exponents of 0.62, 0.63 and 0.78, respectively. The SEP latencies as a function of stimulus intensity had negative power functions. The latency functions of the P45 and N55 components had the largest negative power exponents (-0.17 and -0.15) and showed the highest negative correlations (r= -0.70 and-0.71, respectively) with the stimulus intensity. These results suggest that both the amplitude and the latency information encoded in the SEPs may contribute to the magnitude estimation of the stimulus.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1106
    Keywords: Tactile air-puff stimulation ; Human skin sensation ; Stimulus intensity ; Psychophysical magnitude estimations ; Somatosensory evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Brief air-puff stimuli were applied to the volar surface of the right hand to obtain both psychophysical and neurophysiological responses. The detection threshold (So) was first determined (0.56 kg · cm-2±0.20 kg · cm-2, mean±SD) and six levels of the stimulus intensities (So + 0.25 kg · cm-2, So + 1.25 kg · cm-2, So + 2.50 kg · cm-2, So + 3.75 kg · cm-2, So + 5.00 kg · cm-2, and So + 6.25 kg · cm-2) were employed for magnitude estimation using the stimulus level of So + 2.50 kg · cm-2 as the standard stimulus. The subject was asked to estimate numerically the series of stimulus intensities randomly presented. Cortical SEPs were recorded over the hand sensory area in response to a set of 120 air-puffs at the identical intensity level. Thus SEPs for six sets of stimulus intensities given in a random order were obtained from each subject. Six components (N20, P27, N35, P45, N60, and P75) were recorded within 100 ms following stimulation. It was seen that a simple power function with an exponent of 0.81 could be an adequate description of the stimulus-response function for magnitude estimation, as was also revealed by the high correlation coefficient (r=0.98). Similarly, stimulus-amplitude functions of different SEP components were well represented by straight lines in double logarithmic plots. The function of the early P27-N35 had the highest exponent (0.56) and also the highest correlation coefficient (r=0.91). Plotting subjective magnitude on the abscissa produced power functions similar to the stimulus-amplitude functions. However, higher correlations were observed for later components. The amplitudes of the four earlier components correlated with stimulus intensity when the effect of subjective magnitudes was removed. In contrast, the correlation between amplitudes and subjective magnitudes with stimulus intensity held constant was positive and significant for the later three components. These results may indicate that early SEP components represent neural coding of physical intensity while later components are more closely related to the subjective judgment of the stimulus.
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  • 6
    ISSN: 1432-1106
    Keywords: Air-puff stimulation ; Primary afferent population response ; Cerebral somatosensory population response ; Time-integral ; Input-output relation ; Decelerating power function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study examined input-output relation of the somatosensory system in response to mechanical air-puff stimuli applied to the volar aspect of the tip of the index finger. Compound sensory nerve action potentials (SNAPs) from the median nerve at the wrist and cerebral somatosensory evoked potentials (SEPs) were simultaneously recorded at six levels of stimulus intensity above threshold. Using the time-integral of the SNAPs and SEPs as measures of peripheral and central neural activity, a strongly accelerating power function with an exponent of 1.35 was found to describe peripheral neural function, while central neural function was described by a negatively accelerating function with a power exponent of 0.50, suggesting suppression of SEPs by recruitment of units with increasing stimulus intensity. It was concluded that input-output relation of the somatosensory system can be described by a decelerating power function with the exponent of 0.37.
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  • 7
    ISSN: 1432-1106
    Keywords: Tactile air-puff stimulation ; Face ; Stimulus intensity ; Somatosensory evoked potentials ; Psycho-physical magnitude estimations ; Mechanical properties of the skin ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Air-puff stimuli were applied to the skin of the face to obtain psychophysical and neurophysiological responses. Six levels of stimulus intensity above threshold were adopted for numerical magnitude estimation and for recording somatosensory evoked potentials (SEPs). A power function with an exponent of 0.71 provided an adequate description of the magnitude estimation values as a function of stimulus intensity, as was verified by the high correlation coefficient (r=0.86, P 〈 0.001). Six SEP components (N15, P20, N30, P40, N50 and P65) were recorded during the 100 ms following stimulation. Stimulus-amplitude functions of the various SEP components were well represented by power functions. The P20-N30 component had the highest power exponent (0.66) and also the highest correlation coefficient (r=0.55, P 〈 0.001). The SEP latencies as a function of stimulus intensity had negative power functions. The latency function of the P20 component had the largest negative power exponent (-0.10) and showed the highest negative correlation (r = — 0.62) with the stimulus intensity. These results suggest that processing of intensity information occurs at a relatively early stage within the central nervous system, and that both the amplitude and latency information encoded in the SEPs may contribute to stimulus processing.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Tissues of the central nervous system (CNS) of cynomolgus monkeys were examined by electron microscopy after intraspinal inoculation of enterovirus 71 (E71). A characteristic finding was the appearance of numerous membrane-bound vesicles (Mbvs) in affected motoneurons. Similar Mbvs were also present in E71-infected cynomolgus monkey kidney (CMK) cells in culture. Virus-like particles were found within or around Mbvs in motoneurons as well as in infected CMK cells in culture. Neither Mbvs nor E71 antigens as detected by immunofluorescence were found in supporting tissues, vascular endothelim, or inflammatory cells. Quite similar findings had been seen in poliovirus infections. It was suggested that the appearance of Mbvs in the cytoplasm of motoneuron is the direct results of virus multiplication in E71 infection as in poliovirus infection.
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  • 9
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Biological and biochemical characters of seven enterovirus 71 (E71) isolates were compared. Four isolates (two from patients with hand, foot and mouth disease [HFMD] and two from patients with encephalitis) grew in cynomolgus monkey kidney cells both at 39.5 and 35° C. However, the remaining three strains (from patients with HFMD) grew at 35° C, but not at 39.5° C. Three temperature-resistant and two temperature-sensitive strains were tested for neurovirulence in monkeys. Temperature-resistant strains were shown to be neurovirulent, whereas temperature-sensitive strains were less neurovirulent. The results suggest correlation between temperature-sensitive growth and neurovirulence in monkeys of E71. Variation in the electrophoretic mobility of the viral polypeptides was detected in three out of seven strains. The fingerprinting of oligonucleotides generated from the viral genome showed similar patterns in two isolates from patients with HFMD and one from patient with encephalitis and variable patterns in each genomic map of remaining four strains. These variations of polypeptide patterns and of oligonucleotide maps could not be correlated with pathogenicity (encephalitis or HFMD), temperature-sensitive growth and neurovirulence in monkeys.
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  • 10
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Six cynomolgus monkeys were inoculated subcutaneously with enterovirus 71 (E71), isolated from the stools of a patient with hand, foot and mouth disease (HFMD). Clinical symptoms were observed in three of the six monkeys. One monkey showed complete paralysis of the lower extremities and two animals showed weakness in the hind limbs 4 to 7 days after inoculation. Lesions were found in the central nervous system (CNS) of all six monkeys. Mild to moderate vascular lesions, perivascular cuffings, degeneration and disappearance of the neurons and meningial lymphocytic infiltration were observed in the grey and/or white matter of the spinal cord, medulla oblongata, cerebral cortex and brain stem. No virus was recovered from the CNS or liver of any of the six monkeys. However, serum neutralizing antibody titers had risen in monkeys inoculated with E71.
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