Additive contributions of melanopsin and both cone types provide broadband sensitivity to mouse pupil control.

Our data reveal a key difference in the sensory control of the mouse pupil relative to another major target of ipRGCs-the circadian clock. Whereas the latter uses colour information to help estimate time of day, the mouse pupil instead sums signals across cone opsin classes to provide broadband spectral sensitivity to changes in illumination. As such, while the widespread co-occurrence of chromatic responses and melanopsin input in the PON supports a close association between colour discrimination mechanisms and NIF visual processing, our data suggest that colour opponent PON cells in the mouse contribute to functions other than pupil control.