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  • 1
    Electronic Resource
    Electronic Resource
    Luminance detectors in the olivary pretectal nucleus and their relationship to the pupillary light reflex in the rat. II. Studies using sinusoidal light (1985)
    Springer
    Experimental brain research 59 (1985), S. 83-90 
    Details
    ISSN: 1432-1106
    Keywords: Pretectal luminance detectors ; Pupillary responses ; Iris sphincter muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The luminance detectors in the olivary pretectal nucleus, which are likely candidates mediating the pupillary light reflex, responded to all frequencies of sinusoidally modulated light up to 12–25 Hz. At low frequencies (0.05–4.0 Hz) the luminance detectors responded with modulated firing to different stimulation rates. The modulation depth of the cell response increased with the increase in stimulation frequency up to 20 Hz, then rapidly fell. There was a delay between the peak intensity of the stimulus and the peak firing of cell response of about 30–40 ms. The amplitudes of the consensual pupil responses to the same sinusoidal stimulus, on the other hand, decreased with an increase in frequency and no discernible response was recorded above 2 Hz. The pupil responses were little affected by sympathectomy. The differences in the frequency response characteristics of luminance detectors and the pupil were attributed to the sluggish dynamic properties of the pupil muscles. This was demonstrated using an electronic model of the iris muscle which modified the responses of the luminance detectors giving output waveforms broadly resembling pupil responses to square and sinusoidally modulated lights.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237669
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Out of Africa and back again (2000)
    Springer
    International journal of anthropology 15 (2000), S. 185-189 
    Details
    ISSN: 1824-3096
    Keywords: H. erectus ; H. ergaster ; artefacts ; migrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract If the genusHomo did indeed originate in Africa, then it must have spread by about 2 m.y. ago into Asia where it is represented at 1.8 m.y. ago byHomo erectus fossils. This latter species in turn eventually spread back into Africa, as indicated by the 1.4 m.y. old OH 9 calvaria from Olduvai, and into Europe, as indicated by the 800,000 year old Ceprano calvaria from Italy. These hominids are associated only with Oldowan style artefacts of cores, choppers and flakes and were apparently not conversant with Acheulean handaxe technology. It seems that they most probably evolved viaHomo heidelbergensis into the Neanderthals. Meanwhile, a completely separate development originating withHomo ergaster of about 1.7 m.y. ago in Africa and possessing Acheulean handaxe technology evolved via such forms as Ndutu and Steinheim intoHomo sapiens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02445133
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    Paper (German National Licenses)
    Fulltext
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