title: Light-dependent changes in outer retinal water diffusion in rats in vivo.
abstract: OBJECTIVE
  To test the hypothesis that in rats, intraretinal light-dependent changes on diffusion-weighted magnetic resonance imaging (MRI) in vivo are consistent with known retinal layer-specific physiology.
  
  
  METHODS
  In male Sprague-Dawley rats, retinal morphology (thickness, extent, surface area, volume) and intraretinal profiles of the apparent diffusion coefficient (ADC, i.e., water mobility) parallel and perpendicular to the optic nerve were measured in vivo using quantitative MRI methods during light and dark stimulation.
  
  
  RESULTS
  The parallel ADC in the posterior half of the avascular, photoreceptor-dominated outer retina was significantly higher in light than dark, and this pattern was reversed (dark>light) in the anterior outer retina. The perpendicular ADC in the posterior outer retina was similar in light and dark, but was significantly higher in dark than light in the anterior outer retina. No light-dark changes in the inner retina were noted.
  
  
  CONCLUSIONS
  We identified light-dependent intraretinal diffusion changes that reflected established stimulation-based changes in outer retinal hydration. These findings are expected to motivate future applications of functional diffusion-based MRI in blinding disorders of the outer retina.
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University, Detroit, MI 48201, USA.
authors.forename: David
authors.initials: D
authors.lastname: Bissig
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Berkowitz
mesh_terms: D000818:Animals; D003623:Dark Adaptation; D004058:Diffusion; D008027:Light; D008279:Magnetic Resonance Imaging; D008297:Male; D009900:Optic Nerve / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000502:physiology* / Q000648:ultrastructure; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water