title: Rod and cone pathway signaling and interaction under mesopic illumination.
abstract: This study investigates the time-course and post-receptoral pathway signaling of photoreceptor interactions when the rod (R) and three cone (L, M, S) photoreceptor classes contribute to mesopic vision. A four-primary photostimulator independently controls photoreceptor activity in human observers. The first experiment defines the temporal adaptation response of receptoral (L-, S-cone, rod) and post-receptoral (LMS, LMSR, +L-M) signaling and interactions. Here we show that nonopponent cone-cone interactions (L-cone, LMS, LMSR) have monophasic temporal response patterns whereas opponent signals (+L-M, S-cone) show biphasic response patterns with slower recovery. By comparison, rod-cone interactions with nonopponent signals have faster adaptation responses and reduced sensitivity loss whereas opponent rod-cone interactions are small or absent. Additionally, the rod-rod interaction differs from these interaction types and acts to increase rod sensitivity due to temporal summation but with a slower time course. The second experiment shows that the temporal profile of the rod signal alters the relative rod contributions to the three primary post-receptoral pathways. We demonstrate that rod signals generate luminance (+L+M) signals mediated via the MC pathway with all rod temporal profiles and chromatic signals (L/L+M, S/L+M) in both the PC and KC pathways with durations >75 ms. Thus, we propose that the change in relative weighting of rod signals within the post-receptoral pathways contributes to the sensitivity and temporal response of rod and cone pathway signaling and interactions.
authors: Institute of Health and Biomedical Innovation and School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia. andrew.zele@qut.edu.au
authors: Andrew J
authors: AJ
authors: Zele
authors: Michelle L
authors: ML
authors: Maynard
authors: Beatrix
authors: B
authors: Feigl
mesh_terms: D000328:Adult; D002450:Cell Communication; D003118:Color Perception / Q000502:physiology; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D006801:Humans; D008027:Light; D055255:Mesopic Vision / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods*; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D055258:Rod-Cone Interaction / Q000502:physiology*; D015398:Signal Transduction