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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 39 (1980), S. 125-132 
    ISSN: 1432-1106
    Keywords: Cat ; Visual cortex ; Luxotonic sustained responses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neuronal responses to continuous, diffuse white light or darkness were studied in cortical visual areas 17, 18, 19 and Clare-Bishop of the unanesthetized cat. In contrast to squirrel monkeys and macaques in which about 40 or 25% of the units in striate cortex are luxotonic (response to continuous light or darkness sustained〉2.0 min), all of the visual areas in the cat had fewer than 4.0% of the units exhibiting such luxotonic activity. The functional basis of this difference may be related to differences between the two species in the quantitative balance of antagonistic receptive field properties.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 39 (1980), S. 11-16 
    ISSN: 1432-1106
    Keywords: Visual cortex ; Rabbit ; Primate ; Spontaneous activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The firing frequency of a population of 213 units in striate and circumstriate cortex of the moderately restrained rabbit was studied under the influence of alternating 1-min periods of darkness versus steady, diffuse, featureless illumination. The intent was to determine whether luxotonic responses, so prominent in striate cortex of primates, are indeed absent in rabbits. Such was the case, there being only transient occurrences in three units where the continuing rate of discharge in darkness was double that in the light. There were, however, much more modest differences in rate of continuing discharge in light versus darkness, and for 46% of the units discharging 〉 1/s this difference exceeded 10% and/or 1/s. The rate of discharge in any case did not provide a reliable index as to the characteristics of a unit's receptive field in response to patterned visual stimuli. The nature and function of luxotonic activity in primates still not being understood, it cannot be decided whether its absence in rabbits represents a true qualitative or merely a quantitative difference between species.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Psychiatric patients undergoing the psychosurgical operation of stereotactic subcaudate tractotomy were infused intravenously with either saline or L-tryptophan (15 mg/kg/h). Plasma, lumbar cerebrospinal fluid (CSF), ventricular CSF and a specimen of frontal cortex were collected. The relationships of plasma concentrations of substances claimed to influence brain tryptophan concentration (total tryptophan, free tryptophan, large neutral amino acids) with the concentration of tryptophan in the cortex and CSF were investigated. Tryptophan infusion resulted in plasma tryptophan values comparable to those found after oral doses used in treating depression or insomnia, and about sixfold increases of tryptophan in the cerebral cortex. Increased brain 5-hydroxytryptamine synthesis was indicated by significant rises of CSF 5-hydroxyindoleacetic acid. The concentration of plasma free tryptophan was a better predictor than plasma total tryptophan of cortex tryptophan concentration. As all correlation coefficients of plasma versus brain or plasma versus ventricular CSF tryptophan concentrations were decreased when allowance was made for differences of concentration of large neutral amino acids, the results suggest that the role of these substances within their physiological range as inhibitors of tryptophan transport to the brain may previously have been overemphasised.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 24 (1984), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Neuroradiology 19 (1980), S. 257-263 
    ISSN: 1432-1920
    Keywords: Computed tomography ; Cerebral abscess ; Postoperative patient ; Ring enhancement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Nine cases of patients in whom intracranial infection was suspected after operation are presented. Lesions with ring enhancement were seen in all of these patients. The differentiation of enhancement, seen as a normal postoperative phenomenon, from residual neoplasia and cerebral abscess can be difficult. This can be resolved by serial and sequential-delayed CT, and thus unnecessary re-exploration may be prevented.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1615-6110
    Keywords: Ascolichens ; Ascomycetes ; Lichenothrix riddlei ; Cyanophyceae ; Scytonema ; Distribution ; anatomy ; fine structure ; Flora of New Zealand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lichenothrix riddlei is reported from two widely separate localities in New Zealand. It was previously known only from the South Eastern states of U.S.A. Light and electron microscopy show its sterile fungal partner to belong to the ascomycetes. Apparently as a consequence of lichenization, the variation in breadth of the trichomes of theScytonema phycobiont is greater than normal. A thin, probably gelatinous layer, covering the fungal cells and the algal sheath in the interstices between them, can be demonstrated by electron microscopy. In the contact region with the algal cells, the otherwise two layered wall of the haustoria is reduced to one layer only. In the fungal protoplast conspicuous stacks of ER-like membranes can be found.
    Type of Medium: Electronic Resource
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