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Existing methods of measuring melanopsin's functional response in humans can only return a measure of a post-cortical interpretation of the intrinsic photoresponse. There is physiological ex vivo evidence to suggest that the retinal activity of melanopsin can differ from its cortical interpretation. We developed an in vivo method for isolating the multifocal neuroretinal responses originating from melanopsin signalling in humans (7 males, 1 female). These electrical responses can be decomposed into three separable components; (1) a very fast positive potential with timing on the scale of melanopsin's phototransduction cascade; (2) a slow and sustained negative-going, depolarisation consistent with the inherent spiking response of melanopsin; and (3) a positive potential following the onset of the spiking response that is a candidate for the intraretinal response to melanopsin activation. It was possible to manipulate the duration of the sustained signal component by introducing ambient illumination during the test and thereby, demonstrate in vivo melanopsin's photochemical tristability. A topographical map of the melanopsin electrical response was then created using melanopsin-directed multifocal stimuli and we show that the amplitude of each waveform component maps strongly with the eccentric cell density of melanopsin-containing, intrinsically photosensitive retinal ganglion cells. We demonstrate the ability of this technique to generalise to any photoreceptor class by mapping the retinal responses of the rod- and cone-directed multifocal electroretinogram and which may find clinical applications in ophthalmic diseases. These findings show that the amplitude, timing and polarity of the melanopsin response are distinctly unique compared with the rod and cone neuroretinal electrical responses.<b>Significance Statement</b> The melanopic light response is important for both vision and the regulation of many nonvisual functions, including circadian photoentrainment, the pupillary light reflex, and mood. A dysfunction of the melanopsin response in ophthalmic or neurodegenerative disease leads to negative health outcomes. The challenge is to develop non-invasive tests of melanopsin signalling independent of cortical processing. We introduce a non-invasive electroretinographic technique to measure photoreceptor-isolated electrical responses from melanopsin, rods, or cones across focal retinal areas. The waveform components originating from melanopsin are found to map to physiological properties measured in ex vivo non-human primate retina. The ability to measure topographic retinal maps of an isolated photoreceptor response can be a powerful tool for diagnostic investigations in clinical settings.