Plug and Play Integration of a New Sensory Channel in Evolution
1 Molecular and Systemic Neurophysiology - RWTH Aachen
2 Bernstein Center Freiburg and Faculty of Biology
Color vision is a crucial visual characteristic that significantly impacts behavior. Most mammalian species, including mice, have dichromatic cone vision. Trichromatic color vision likely emerged in evolution by integrating an additional opsin with different spectral sensitivity into the retina. Through early X-chromosome inactivation, heterozygous primate females acquired trichromatic color vision with the addition of a second cone sensitive to middle-to-long wavelengths. Subsequently, downstream networks were adjusted to process the new visual inputs. Understanding the exact steps required to integrate a new information channel into existing visual processing circuits is essential for comprehending the functional adaptations of the nervous system during evolution. In this study, we investigate this question by characterizing transgenic mice with trichromatic vision. We utilized a genetically modified mouse line that expresses the human L-opsin (B6.129-Opn1mwtm1(OPN1LW)Nat/J mice) in the mouse retina. Using in vivo two-photon microscopy, we measured the responses of neurons in layer 2/3 of the primary visual cortex to visual stimuli containing short (S), middle (M), and long (L) wavelength light, examining color responsiveness and opponency. Our results demonstrate strong UV-green color opponency, providing new insights into how trichromatic color vision may have evolved from dichromatic ancestors. Additionally, this example offers a broader understanding of the evolution of sensory perception and computation.