Color signals in retina and lateral geniculate nucleus of marmoset monkeys.

Abstract

Marmosets show sex-linked polymorphism of color vision, whereby all males and some females show dichromatic ("redgreen color-blind") vision based on two classes of photoreceptor sensitive to short or medium wavelength bands. Most female marmosets by contrast express three photoreceptor classes, one sensitive to short wavelengths and two classes in the mediumlong wavelength sensitivity band. We used this 'natural knock-out' to study the organization of color vision pathways in primates. We review here results from our and other laboratories showing how the primordial dichromatic blue-yellow pathway is characterized by selective connections to short wavelength sensitive cones in the retina and that signals for blue-yellow color vision travel through an ancient part of the subcortical visual pathway called the koniocellular system. Signals serving red-green color vision by contrast are tightly linked to retinal circuits serving high-resolution spatial vision at the fovea and show little sign of specific patterns of connections with medium-and long-wavelength sensitive cones. Routine trichromatic color vision thus is based on converging signals from two quite distinct retinal and subcortical pathways.

Retinorecipient areas in the common marmoset (Callithrix jacchus): An image-forming and non-image forming circuitry

“…Each cell type differs dramatically in terms of their morphological, physiological, and connectional features, representing distinct parallel channels for visual processing ( Mitchell and Leopold, 2015 ). The P pathways provide high-acuity vision and red-green color vision ( Lennie and Movshon, 2005 ; Martin and Grünert, 2013 ), while the visual inputs conducted by the M channel provide for spatial and motion analysis ( Lee et al, 2010 ; Percival et al, 2014 ). A third pathway involves cells located in the K layers, which form another chromatic channel that mediates blue/yellow opponency discrimination ( Wässle, 2004 ; Szmajda et al, 2006 , 2008 ; Roy et al, 2009 ).…”

“…Consistent with previous findings in macaques, DLG layers of the marmoset receive input from specific classes of RGCs. Although melanopsinergic intrinsically photosensitive RGCs (ipRGCs), a heterogenous subpopulation that mediate NIF functions, send axonal projections to the DLG ( Szmajda et al, 2008 ), the three best-understood retinogeniculate pathways originate from the parasol, midget, and small bistratified cells ( Martin and Grünert, 2013 ). Most of the RGCs are of the midget type, and project to P layers of the DLG ( Goodchild et al, 1996 ; Gomes et al, 2005 ; Jusuf et al, 2006 ).…”

“…Most of the RGCs are of the midget type, and project to P layers of the DLG ( Goodchild et al, 1996 ; Gomes et al, 2005 ; Jusuf et al, 2006 ). These cells are described as having sustained responses to photic stimuli ( Ghosh and Grünert, 1999 ), selectivity to chromatic (red/green) signals ( Martin and Grünert, 2013 ), and a small soma with a single primary dendrite that branches densely into small dendritic fields, as a main morphological feature ( Szmajda et al, 2005 ; Masri et al, 2017 ). The second largest class of RGCs is that of parasol cells ( Chan et al, 2001 ; Gomes et al, 2005 ; Eriköz et al, 2008 ), which are morphologically characterized by two-four dendrites emerging from a large soma, forming a large branched dendritic tree ( Szmajda et al, 2005 ; Masri et al, 2017 ).…”

Colour Vision: Random Retina of Butterflies Explained

“…While many questions regarding human, and generally primate, colour vision are also still open, here we know quite a bit about the neural processing of colour-opponent signals (see e.g. [17]).…”