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

Brett A. Szmajda, Péter Buzás, Thomas FitzGibbon, Paul R. Martin

Research output: Contribution to journalArticle

53 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)19512-19517
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number51
Publication statusPublished - Dec 19 2006


  • Blue cones
  • Color vision
  • Koniocellular pathway
  • Lateral geniculate nucleus
  • Short-wavelength-sensitive cones

ASJC Scopus subject areas

  • General

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