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  • Amblyopia  (1)
  • Area 17  (1)
  • Cushing's disease  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 34 (1979), S. 273-286 
    ISSN: 1432-1106
    Schlagwort(e): Stimulus velocity ; Single cell responses ; LGN ; Area 17 ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Neuronal responses to moving visual stimuli were recorded in the lateral geniculate nucleus (LGN) and area 17 of cats. Response duration (DE), number of spikes (NT), and mean frequency (FM) were estimated from the response histograms and analysed for their dependence on stimulus velocity. In the LGN, for about 2/3 of cells these response parameters changed monotonically with velocity up to about 100 °/s. In 1/3 of the cells, the response frequency was tuned to velocity. The speed at which individual cells reached a peak or plateau firing rate was correlated with their receptive field size. In area 17, most neurones were tuned to velocity. Nine out of 59 cells were insensitive to stimulus speed in that they responded equally well at stimulus velocities up to about 10 °/s. The results suggest that at higher levels in the nervous system information about velocity is represented in discrete groups of neurones. It is pointed out that different response parameters may be relevant for different perceptual phenomena associated with movement. The significance of integrational properties and lateral inhibition of nerve cells for the development of complex response properties is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 377 (1978), S. 201-207 
    ISSN: 1432-2013
    Schlagwort(e): Contrast sensitivity ; Spatial distortion ; Neural dysfunction ; Amblyopia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In this investigation contrast threshold measurements are compared with supra-threshold perception for a group of human amblyopes. The results indicate that human amblyopia involves, in some cases, not only loss of sensitivity but spatial distortion. Thus a new group of amblyopes can now be identified in which only distortion occurs. These results have important physiological implications for both the normal and abnormal visual systems. Neurophysiologists investigating visual loss from deprivation should assess whether similar distortions occur in animals. This question may hold the answer to whether the present animal models are relevant to the human condition.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-1076
    Schlagwort(e): Growth hormone ; Cortisol ; Glucocorticoid therapy ; Cushing's disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Cortisol and growth hormone (GH) secretion (spontaneous variations at night and the release induced by insulin hypoglycaemia) were investigated in 69 children and adolescents. Statistical analysis of approximately 600 pairs of cortisol and GH values in this study demonstrated that physiological fluctuations of cortisol do not alter GH secretion. A review of the literature shows that GH secretion is consistently depressed in Cushing's disease of central origin and in Cushing's syndrome due to adrenal carcinoma. When acutely administered, doses higher than 100 mg of cortisol (or equivalent amounts of other steroids) per adult are necessary to block GH secretion and the hormones have to be given several hours previously. In long-term steroid treatment, suppression of GH is observed in only 1 out of 3 patients. The effect apparently does not persist beyond elimination of the last dose, i.e. generally not longer than 12 to 24 h. These data can be taken as a rationale for intermittent or alternating dosage schedules, and for the use of short acting derivatives if long-term, high-dose steroid treatment is necessary in children. It remains to be established whether growth deficiency in exogenous hypercortisolism is due to suppression of GH secretion, decreased production of somatomedins, direct antagonism of the action of somatomedins on growing cartilage, or a combination of these mechanisms.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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