RT Journal Article
SR Electronic
T1 Visual responses in the lateral geniculate nucleus of dichromatic and trichromatic marmosets (Callithrix jacchus)
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 7892
OP 7904
DO 10.1523/JNEUROSCI.15-12-07892.1995
VO 15
IS 12
A1 T Yeh
A1 BB Lee
A1 J Kremers
A1 JA Cowing
A1 DM Hunt
A1 PR Martin
A1 JB Troy
YR 1995
UL http://www.jneurosci.org/content/15/12/7892.abstract
AB New-world primates such as the marmoset (Callithrix jacchus) show polymorphism for the middle- to long-wavelength sensitive cone pigments. Each X-chromosome carries a gene for only one of three possible pigments. All males are thus dichromats, but some females will be trichromats. We have investigated the responses of cells of the parvocellular (PC) and magnocellular (MC) systems within animals from a single marmoset family. The middle- to long-wavelength pigment of dichromats was identified physiologically. Trichromats could readily be distinguished from dichromats by the presence of a high proportion of red-green opponent PC-cells. The physiological classification of phenotypes was confirmed with genetic analysis. The pattern of inheritance was consistent with current genetic models. In trichromatic females, the properties of cells resembled in detail those of cells from the PC- and MC-pathways of the macaque. In dichromats, cell responses resembled those of trichromats (except for the lack of opponency in PC-cells); PC-cells showed sustained and MC-cells transient responses, with a lower contrast gain for the former type. One difference was that a proportion of PC-cells in dichromats showed strong rod input even at high levels of retinal illuminance. Thus, in trichromatic marmosets the presence of two middle- to long-wave pigments appears to permit the elaboration of all the physiological properties associated with trichromacy.