gms | German Medical Science

Objective: To understand the integration of a new information channel into existing visual processing circuits using two-photon imaging of visual responses in cortex of awake mice.

Materials and Methods: To investigate the neural mechanisms underlying trichromatic color vision, characterization of transgenic mice expressing the human L-opsin (B6.129-Opn1mwtm1(OPN1LW)Nat/J) in the mouse retina was performed. Using in-vivo two-photon microscopy, the responses of neurons in layer 2/3 of the primary visual cortex (V1) to visual stimuli containing short (S), middle (M), and long (L) wavelength light were recorded, examining color responsiveness and opponency. Additionally, the cone-ratio and -distribution were investigated with qPCR and MEA recordings respectively.

Results: Clear color-dependent responses in mouse V1 were shown. In addition, strong UV-green color opponency was demonstrated, suggesting that mice are also able to discriminate these two colors. As a further aim, red-green color opponency will also be tested in the transgenic trichromatic mice to test if the integration of a new opsin can lead to the development of new color opponent mechanisms.

Discussion: The results provide valuable insights into the evolutionary processes involved in the development of trichromatic color vision. Furthermore, they could offer a broader understanding of how the nervous system adapts to novel sensory inputs.

Acknowledgements: This work was supported by the DFG funded RTG InnoRetVision 2610.