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  • Electronic Resource  (2)
  • 1975-1979  (2)
  • Development  (1)
  • Spatial vision in cat  (1)
Material
  • Electronic Resource  (2)
Years
  • 1975-1979  (2)
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 31 (1978), S. 193-206 
    ISSN: 1432-1106
    Keywords: Kitten LGN ; Development ; Visual acuity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The spatial resolving power and receptive field properties of ‘sustained’ cells in layers A and A1 of the lateral geniculate nucleus (LGN), which received inputs from the area centralis of the retina in kittens of 3–16 weeks of age had been studied. The basic concentric organisation of receptive fields of ‘sustained’ LGN cells receiving inputs from the area centralis appeared to be already laid out at 3 weeks in kittens. Spatial resolving power of the cells determined using the highest spatial frequency of a sinusoidal grating resolved by cells as a measure of cellular visual acuity, however, developed gradually to the level of adult LGN cells during the sensitive period (3–12 weeks). Although this development occurred alongside the process of maturation of ocular alignment and the refractive state of the eyes, following the clearing of the embryonic vasculature of the ocular media from the 4th week onward, it depended on the enhancement of distinct inhibitory surround mechanisms taking place during the 6th–11th week. The course of development of spatial resolution of ‘sustained’ LGN cells receiving inputs from the area centralis of the retina runs parallel with the developmental curve of visual acuity in kittens obtained by visually evoked responses or by behavioural techniques by previous workers. The neural mechanisms which subserve high visual acuity are therefore already determined at the LGN before the inputs of the two eyes are mixed at the visual cortex.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 34 (1979), S. 11-26 
    ISSN: 1432-1106
    Keywords: Convergent squint ; Amblyopia ; Spatial vision in cat ; Contrast sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Visual acuity and contrast sensitivity were measured behaviourally in normal adult cats and cats reared with monocular convergent squint from 3, 6, 8, 12, and 24 weeks of age. The visual acuity of the squinting eye was significantly lower than that of the non-squinting eye in cats with squint from 3, 6, and 8 weeks of age. No significant difference in acuity between eyes was found in the 12- and 24-week squinting cats and in the controls. Contrast thresholds at all spatial frequencies tested (range 0.13–2.0 c/ °) were higher in the squinting eye than in the non-squinting eye of cats with squint from 3 and 6 weeks of age, but differences were greater at the higher spatial frequencies. In the 8-week squinting cat, contrast thresholds were increased only at higher spatial frequencies. No significant differences in contrast sensitivity were found in the cat with squint from 24 weeks of age and in the controls. The degree of disturbance of spatial vision in squinting cats was most related to the age at onset of the squint, i.e., the earlier the onset, the more profound the amblyopia. The period of susceptibility extended from about 3 to 12 weeks of age. When compared with data on the development of visual acuity in kittens, the pattern of results from the present study suggests that convergent squint can arrest the development of spatial vision.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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