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  • 1.
    el Azazi, Mildred
    et al.
    S:t Erik, Stockholm.
    Wang, Ling
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Wachtmeister, Lillemor
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Background light adaptation of the retinal neuronal adaptive system. II. Dynamic effects2004In: Documenta Ophthalmologica, ISSN 0012-4486, Vol. 109, no 2, p. 201-213Article in journal (Refereed)
    Abstract [en]

    The dynamic effects of continuous exposure to light on the neuronal adaptive system of the retina, as indicated by the oscillatory response (OPs) of the electroretinogram (ERG) were studied in the albino rat. Digitally filtered OPs and the a- and b-waves of the corneal ERG were simultaneously recorded in dark adaptation, during continuous light adaptation to four levels of background light (BGL) changing in steps of two log units from 1.43 x 10(-6) cd/m2, referred to as 'low and high scotopic, low and high mesopic' levels. Exposed to 'high scotopic' BGL the total oscillatory response (SOP) significantly enhanced within the first minute, whereas the amplitudes of the a- and b-waves were unaffected. In 'low mesopic' BGL the SOP increased within the first minute, whereas the a- and b-waves significantly decreased. 'High mesopic' BGL instantaneously and profoundly reduced both the SOP and the slow potentials. The individual OPs changed in amplitudes mainly within the first minute of BGL. In general, the earlier OPs (O1 and O2) reacted more to the two 'scotopic' BGL levels, whereas the later OPs (O3 and 04) were more affected by the relatively brighter two 'mesopic' conditions. In conclusion, the rapid increase of the OPs within the first minute of 'high scotopic' and 'low mesopic' BGL exposure may represent a rudimentary light adaptational effect in the rod-dominated rat retina. These findings also suggest that the neuronal adaptive mechanism of the retina seems to be a robust system, probably attaining preservation of visual abilities in the rat on exposure to light.

  • 2.
    Lundström, Anna-Lena
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Wang, Ling
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Wachtmeister, Lillemor
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Neuronal adaptation in the human retina: a study of the single oscillatory response in dark adaptation and mesopic background illumination.2007In: Acta Ophthalmologica Scandinavica, ISSN 1395-3907, E-ISSN 1600-0420, Vol. 85, no 7, p. 756-763Article in journal (Refereed)
    Abstract [en]

    PURPOSE: The single oscillatory response in complete dark adaptation (DA) and the effect of mesopic illumination were studied in order to investigate the behaviour of the neuronal adaptation system as reflected in the oscillatory potentials (OPs) of the electroretinogram (ERG). METHODS: The rapid oscillatory and slow components (a- and b-waves) of single ERGs were simultaneously recorded in nine healthy, young subjects in response to first flash after both DA of 45 mins and light adaptation to a steady background light (BGL) of low mesopic intensity. RESULTS: Two low-amplitude oscillatory peaks were present in the single response to the first flash recorded in DA. There was no increase in the summed amplitudes of the OPs (SOP) when recorded in the single response to the first flash in mesopic BGL. However, the morphology of the oscillatory response altered. The first OP was reduced and a third oscillatory peak appeared. CONCLUSIONS: We conclude that early, scotopically related OPs may indeed be activated in the single response to the first flash in DA (i.e. without using conditioning flashes). Secondly, on its own, adaptation to mesopic BGL does not seem to trigger enhancement of the overall oscillatory response. The altered single oscillatory response to the first flash apparent in the mesopic BGL comprises a third cone-associated OP and seems to reflect a reorganization of the retinal microcircuitry from a predominantly rod-activated system to one of mixed rod/cone neuronal activity in the inner part of the retina at the level at which individual OPs have their respective origins.

  • 3.
    Wang, Ling
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology. Department of Ophthalmology, Ruijin Hospital, Medicine School of Shanghai, Jiaotong University, Shanghai, China.
    el Azazi, Mildred
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Burstedt, Marie
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Wachtmeister, Lillemor
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    The response of the neuronal adaptive system to background illumination and readaptation to dark in the immature retina2015In: Acta Ophthalmologica, ISSN 1755-375X, E-ISSN 1755-3768, Vol. 93, no 2, p. 146-153Article in journal (Refereed)
    Abstract [en]

    Purpose: Developmental characteristics of the neuronal adaptive system of the retina, focusing on background light (BGL) adaptation and readaptation functions, were studied by measuring the oscillatory response (SOP) of the electroretinogram (ERG).

    Methods: Digitally filtered and conventional ERGs were simultaneously recorded. Rats aged 15 and 17 days were studied during exposure to BGLs of two mesopic intensities and during readaptation to dark.

    Results: Results were compared to adult rats. In ‘low mesopic’ BGL SOP instantly dropped significantly to about half of its dark-adapted (DA) value contrary to mature rats, in which the SOP significantly increased. In ‘high mesopic’ BGL SOP decreased to about 20% and 30% of DA values in immature and adult rats, respectively. The process of recovery of SOP in darkness lacked the transient enhancement immediately as BGL was turned off, characteristic of adult rats. There were no major age differences in adaptive behaviour of a-wave. In young rats, recovery of b-wave was relatively slower.

    Conclusions: Properties of BGL adaptation and readaptation functions of the neuronal adaptive system in baby retina differed compared to the adult one by being less forceful and more restrained. Handling of mesopic illumination and recovery in the dark was immature. Development of these functions of the neuronal adaptive system progresses postnatally and lags behind that of the photoreceptor response and seems to be delayed also compared to that of the bipolar response.

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