摘要：SummaryTo evaluate the nature of interactions between visual pathways transmitting the slower melanopsin and faster rod and cone signals, we implement a temporal phase summation paradigm in human observers using photoreceptor-directed stimuli. We show that melanopsin stimulation interacts with and alters both rod-mediated and cone-mediated vision regardless of whether it is perceptually visible or not. Melanopsin-rod interactions result in either inhibitory or facilitatory summation depending on the temporal frequency and photoreceptor pathway contrast sensitivity. Moreover, by isolating rod vision, we reveal a bipartite intensity response property of the rod pathway in photopic lighting that extends its operational range at lower frequencies to beyond its classic saturation limits but at the expense of attenuating sensitivity at higher frequencies. In comparison, melanopsin-cone interactions always lead to facilitation. These interactions can be described by linear or probability summations and potentially involve multiple intraretinal and visual cortical pathways to set human visual contrast sensitivity.Graphical abstractDisplay OmittedHighlights•Melanopsin ipRGCs support vision independent of the rod and cone signals•Rod pathways mediate robust visual responses in daylight•Temporal contrast sensitivity is contingent on the melanopsin excitation level•Visual performance is collectively regulated by melanopsin, rod and cone pathwaysApplied sensory psychophysics; Cellular neuroscience; Sensory neuroscience
