title: The response of the neuronal adaptive system to background illumination and readaptation to dark in the immature retina.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Ophthalmology, Ruijin Hospital, Medicine School of Shanghai, Jiaotong University, Shanghai, China; Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden.
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Mildred
authors.initials: M
authors.lastname: El Azazi
authors.forename: Anders
authors.initials: A
authors.lastname: Eklund
authors.forename: Marie
authors.initials: M
authors.lastname: Burstedt
authors.forename: Lillemor
authors.initials: L
authors.lastname: Wachtmeister
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D003623:Dark Adaptation / Q000502:physiology*; D004596:Electroretinography; D008027:Light; D055255:Mesopic Vision / Q000502:physiology; D009991:Oscillometry; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000502:physiology*; D055351:Retinal Neurons / Q000528:radiation effects*
keywords: background light adaptation; electroretinogram; immature neuronal adaptive system; oscillatory potentials; readaptation to dark