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  • 1995-1999  (3)
  • One-handed catching  (2)
  • Neurodegeneration  (1)
Materialart
Erscheinungszeitraum
  • 1995-1999  (3)
Jahr
  • 1
    ISSN: 1432-0533
    Schlagwort(e): Neurodegeneration ; Epilepsy ; Kainic acid fos ; Gliosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Periodic acid-Schiff (PAS)-positive deposits have been demonstrated in the central nervous system (CNS) of patients suffering from a wide variety of neurodegenerative disorders including Alzheimer's disease, presenile dementia, Parkinson's disease, diabetes mellitus, myoclonic epilepsy, and cerebral palsy. The etiology of these deposits and their relationship to mechanisms of progressive neurodegeneration is unknown. In the present study, we demonstrate that the kainic acid model of limbic status epilepticus provides a useful system for the study of PAS-positive staining. The relationship between PAS-positive deposition, induction of fos-like immunoreactivity (FLI), neuronal necrosis, reactive gliosis, and blood-brain barrier breakdown following the kainic acid induction of status epilepticus was investigated. Epileptiform activity was elicited in rats by intraperitoneal administration of 10 mg/kg kainic acid and brains were examined 3, 5, 12, 24, 72, and 168 h after drug injection. Four distinct types of PAS-positive staining in rat brain were observed: type 1, extracellular matrix (ECM) or blood vessel associated-material; type 2, granular deposits; type 3, glial labelling; and type 4, neuronal labelling. Results demonstrated that the four types of PAS-positive staining were differentially associated with specific markers of neuropathology: (1) type 1 ECM staining and type 3 glia were preferentially localized to edematous tissue; (2) the majority of type 3 glia were identified as reactive astrocytes, while a minority of appeared to be proliferating microglia; (3) type 1 blood vessels labelled hemorrhaging vasculature; (4) early deposition of type 2 granules was predictive of subsequent cell loss; (5) chronic type 2 granular deposits and type 4 neuronal labelling not associated with cell death could be predicted by early changes in FLI; and (6) chronic deposition of all four forms of PAS-positive material was correlated with earlier, transient blood-brain barrier compromise. The results support the growing literature that local carbohydrate metabolism may be one of a constellation of parameters important to the development of progressive neurodegeneration.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 129 (1999), S. 369-377 
    ISSN: 1432-1106
    Schlagwort(e): Key words Adaptation ; Selection ; Re-calibration ; Timing ; One-handed catching ; Binocular information
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract   A pre-exposure, exposure, post-exposure design was used to assess the adaptation of the timing of a one-handed catch during telestereoscopic viewing. More specifically, it was examined whether the adaptation involved: (1) ignoring binocular sources of information and selecting other information, or (2) a recalibration of the coupling between the effected binocular information and the catching movement, and (3), if it is recalibration, whether it is restricted to the manipulated binocular information. To test these hypotheses, subjects (n=16) were assigned to one of two groups, each group performing three blocks of 15 trials in the dark with only the ball visible. In the exposure condition, both groups were required to catch balls under binocular telestereoscopic viewing. In the pre-exposure and post-exposure conditions, subjects performed under binocular and monocular viewing, respectively. Kinematics of the grasping movement were recorded. It was predicted that, in the case of a selection process, no afterfeffects would occur in the post-exposure condition, whereas, in the case of recalibration, aftereffects would occur. Moreover, if the recalibration is restricted to the manipulated information, only the group that was provided with binocular vision during the pre- exposure and post-exposure conditions would show aftereffects. Significant condition (pre-exposure, exposure, post-exposure) by block (first three trials, last three trials) effects were found for the moments of grasp onset, peak opening velocity and hand closure, indicating that the hand was opened and closed earlier in the first three trials of telestereoscopic viewing. This coincided with an increase in catching failures. In addition, for the moments of hand closure and peak closing velocity, negative aftereffects were found in the post-exposure condition. The hand was closed later in the first three trials after removal of telestereoscope. With respect to the presence of the aftereffects, no differences were found between the groups. It was concluded that adaptation to telestereoscopic viewing in the timing of a one-handed catch is due to the recalibration of the coupling between information and movement, rather than a selection of another source of information. Moreover, it is likely that the recalibration was not restricted to the single, manipulated information. Rather, the recalibration involves multiple binocular and monocular optical and oculomotor sources of information.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 129 (1999), S. 362-368 
    ISSN: 1432-1106
    Schlagwort(e): Key words Binocular ; Monocular ; Disparity ; Vergence ; One-handed catching
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The aim of this study was to examine the role of binocular and monocular information sources in specifying time-to-contact. More specifically, it was investigated whether the timing of the one-handed catch is consistent with a binocular tau-function strategy. Subjects (n=8) were required to time their grasp to catch a ball approaching with a constant spatial trajectory. The ball approached at three different constant velocities (1.5, 2.0 and 2.5 m/s). Vergence and disparity were manipulated through subjects wearing a telestereoscope to increase the effective interocular separation, under both binocular and monocular viewing. Subjects performed 24 trials in each of the four conditions. Subjects’ started the opening of the hand earlier in the binocular telestereoscope condition when a ball approached with velocity of 1.5 m/s. They then closed the hand earlier in the binocular telestereoscope condition at all ball approach velocities. There were no effects of telestereoscope on the timing of hand opening and closing under monocular viewing. This finding suggests the use of the binocular information in timing the grasp. However, there were effects of approach velocity under all conditions of monocular and binocular viewing. Subjects’ closed the hand earlier as a function of increasing approach velocity. Together, the effects of the telestereoscope and approach velocity indicate that timing of the one-handed catch is not consistent with the use of a binocular ”tau-function” variable. Rather, it is concluded that multiple sources of monocular and binocular information contribute to the regulation of timing.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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