Geniculocortical relay of blue-off signals in the primate visual system

Proc Natl Acad Sci U S A. 2006 Dec 19;103(51):19512-7. doi: 10.1073/pnas.0606970103. Epub 2006 Dec 7.

Abstract

A fundamental dichotomy in the subcortical visual system exists between on- and off-type neurons, which respectively signal increases and decreases of light intensity in the visual environment. In primates, signals for red-green color vision are carried by both on- and off-type neurons in the parvocellular division of the subcortical pathway. It is thought that on-type signals for blue-yellow color vision are carried by cells in a distinct, diffusely projecting (koniocellular) pathway, but the pathway taken by blue-off signals is not known. Here, we measured blue-off responses in the subcortical visual pathway of marmoset monkeys. We found that the cells exhibiting blue-off responses are largely segregated to the koniocellular pathway. The blue-off cells show relatively large receptive fields, sluggish responses to maintained contrast, little sign of an inhibitory receptive-field surround mechanism, and negligible functional input from an intrinsic (melanopsin-based) phototransductive mechanism. These properties are consistent with input from koniocellular or "W-like" ganglion cells in the retina and suggest that blue-off cells, as previously shown for blue-on cells, could contribute to cortical mechanisms for visual perception via the koniocellular pathway.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Callithrix / genetics
  • Callithrix / physiology*
  • Color Perception / physiology*
  • Female
  • Male
  • Neurons, Afferent / cytology
  • Neurons, Afferent / physiology
  • Photic Stimulation
  • Polymerase Chain Reaction
  • Polymorphism, Restriction Fragment Length
  • Retinal Ganglion Cells / cytology
  • Retinal Ganglion Cells / physiology
  • Visual Pathways / physiology*
  • Visual Perception / physiology*