title: Melanopsin-driven increases in maintained activity enhance thalamic visual response reliability across a simulated dawn.
abstract: Twice a day, at dawn and dusk, we experience gradual but very high amplitude changes in background light intensity (irradiance). Although we perceive the associated change in environmental brightness, the representation of such very slow alterations in irradiance by the early visual system has been little studied. Here, we addressed this deficit by recording electrophysiological activity in the mouse dorsal lateral geniculate nucleus under exposure to a simulated dawn. As irradiance increased we found a widespread enhancement in baseline firing that extended to units with ON as well as OFF responses to fast luminance increments. This change in baseline firing was equally apparent when the slow irradiance ramp appeared alone or when a variety of higher-frequency artificial or natural visual stimuli were superimposed upon it. Using a combination of conventional knockout, chemogenetic, and receptor-silent substitution manipulations, we continued to show that, over higher irradiances, this increase in firing originates with inner-retinal melanopsin photoreception. At the single-unit level, irradiance-dependent increases in baseline firing were strongly correlated with improvements in the amplitude of responses to higher-frequency visual stimuli. This in turn results in an up to threefold increase in single-trial reliability of fast visual responses. In this way, our data indicate that melanopsin drives a generalized increase in dorsal lateral geniculate nucleus excitability as dawn progresses that both conveys information about changing background light intensity and increases the signal:noise for fast visual responses.
authors.affiliation: Faculty of Life Sciences, University of Manchester, M13 9PT Manchester, United Kingdom;
authors.forename: Riccardo
authors.initials: R
authors.lastname: Storchi
authors.affiliation: Faculty of Life Sciences, University of Manchester, M13 9PT Manchester, United Kingdom;
authors.forename: Nina
authors.initials: N
authors.lastname: Milosavljevic
authors.affiliation: Faculty of Life Sciences, University of Manchester, M13 9PT Manchester, United Kingdom;
authors.forename: Cyril G
authors.initials: CG
authors.lastname: Eleftheriou
authors.affiliation: Faculty of Life Sciences, University of Manchester, M13 9PT Manchester, United Kingdom;
authors.forename: Franck P
authors.initials: FP
authors.lastname: Martial
authors.affiliation: Department of Neurophysiology and Chronobiology, Institute of Zoology, Jagiellonian University, 30-387 Krakow, Poland.
authors.forename: Patrycja
authors.initials: P
authors.lastname: Orlowska-Feuer
authors.affiliation: Faculty of Life Sciences, University of Manchester, M13 9PT Manchester, United Kingdom;
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bedford
authors.affiliation: Faculty of Life Sciences, University of Manchester, M13 9PT Manchester, United Kingdom;
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Brown
authors.affiliation: Faculty of Life Sciences, University of Manchester, M13 9PT Manchester, United Kingdom;
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: Montemurro
authors.affiliation: Faculty of Life Sciences, University of Manchester, M13 9PT Manchester, United Kingdom;
authors.forename: Rasmus S
authors.initials: RS
authors.lastname: Petersen
authors.affiliation: Faculty of Life Sciences, University of Manchester, M13 9PT Manchester, United Kingdom; robert.lucas@manchester.ac.uk.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lucas
mesh_terms: D000818:Animals; D005829:Geniculate Bodies / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D017299:Rod Opsins / Q000502:physiology*; D014785:Vision, Ocular; D000099210:Melanopsin
chemical_list: D017299:Rod Opsins; D000099210:Melanopsin
keywords: DREADD; irradiance; melanopsin; neural coding; silent substitution