The human visual cortex response to melanopsin-directed

37 The photopigment melanopsin supports reflexive visual functions in people, such as pupil con38 striction and circadian photoentrainment. What contribution melanopsin makes to conscious 39 visual perception is less studied. We devised a stimulus that targeted melanopsin separately 40 from the cones using pulsed (3 s) spectral modulations around a photopic background. Pupil41 lometry confirmed that the melanopsin stimulus drives a retinal mechanism distinct from lu42 minance. In each of four subjects, a functional MRI response in area V1 was found. This 43 response scaled with melanopic contrast and was not easily explained by imprecision in the 44 silencing of the cones. Twenty additional subjects then observed melanopsin pulses and pro45 vided a structured rating of the perceptual experience. Melanopsin stimulation was described 46 as an unpleasant, blurry, minimal brightening that quickly faded. We conclude that isolated 47 stimulation of melanopsin is likely associated with a response within the cortical visual path48 way and with an evoked conscious percept. 49 Human cortical responses to melanopsin 2/22 . CC-BY-ND 4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/138768 doi: bioRxiv preprint first posted online May. 17, 2017;