title: A fundamental step-transition in retinal function at low light intensities.
abstract: There appears to be a fundamental step-transition in retinal function at low light intensities, close to the scotopic-mesopic transition. This step-transition is observed for elements of the retinal dark-light switch, which has been described in the chicken retina. Over the same range of light intensities, there is a step-transition in photoreceptor retinomotor movements and in the coupling of horizontal and All amacrine cells, which suggests a switch in retinal circuitry from rod-processing to cone-processing regimes. A similar step-transition in pineal function suggests that the retinal step-transition signals to the central circadian systems. Finally, this step-transition may also inhibit eye growth, and thus be responsible for the reported diurnal rhythm in eye growth. Disturbances to this step-transition may be the initial cause of disordered eye growth in the form-deprivation myopia paradigm.
authors.affiliation: Centre for Visual Science and Research School of Biological Sciences, Australian National University, Canberra, Australia. ian.morgan@anu.edu.au
authors.forename: I G
authors.initials: IG
authors.lastname: Morgan
authors.forename: M K
authors.initials: MK
authors.lastname: Boelen
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D000818:Animals; D004298:Dopamine / Q000378:metabolism; D008027:Light; D055537:Light Signal Transduction / Q000502:physiology*; D008550:Melatonin / Q000096:biosynthesis; D010870:Pineal Gland / Q000378:metabolism / Q000528:radiation effects; D012160:Retina / Q000502:physiology* / Q000528:radiation effects; D014795:Visual Pathways; D014796:Visual Perception
chemical_list: D008550:Melatonin; D004298:Dopamine