MELANOPSIN CONTRIBUTION TO PATTERNS DISCIRMINATION IN DIURNAL AND NOCTURNAL RODENTS

Description du projet

Mieux comprendre le système visuel grâce à la mélanopsine

La mélanopsine est un type de photopigment qui appartient à une famille plus vaste de protéines rétiniennes photosensibles. Des données récentes d’études menées chez des souris montrent que la mélanopsine apporte des informations au cerveau concernant les structures spatiales pendant la journée, complétant ainsi l’activité des cônes dans la représentation d’une plus grande amplitude et de structures plus grossières dans des conditions lumineuses. Le projet MEL-ROD, financé par l’UE, entend déterminer la manière dont le rôle de la mélanopsine dans le soutien de la vision diffère entre les souris nocturnes et les muridés diurnes dotés d’une bonne vision diurne déterminée par les cônes. Le projet prévoit d’utiliser une technologie de pointe qui permettra, pour la première fois, de générer des structures seulement visibles par la mélanopsine.

Objectif

Three types of retinal photoreceptors are responsible for light detection: rods, cones and intrinsically photosensitive retinal ganglion cells (ipRGCs) containing melanopsin. Until recently, it was universally assumed that daytime vision originates with cones, dim light vision with rods, leaving ipRGCs to drive sub-conscious reflex responses to changes in ambient light (e.g. circadian photoentraiment). However, very recent data from mice has revolutionized vision science by showing that melanopsin can also provide the brain with information about the spatial patterns during the day, complementing the activity of cones in the representation of larger amplitude and coarser patterns in brightness. The proposed project is aimed to determine how melanopsin and cones work together to create images in nocturnal mice and in a diurnal murid (Rhabdomys) with strong cone-based daytime vision, respectively. We will take advantage of technological edge in multi-primary visual display (mVDU) design that allows, for the first time, patterns visible only to melanopsin to be generated. We will apply the mVDU technology to in vivo multi-unit electrophysiological recordings from the visual thalamus (the dorsal lateral geniculate nucleus) and behavioural experiments on melanopsin sufficient and deficient mice created by optogenetical manipulation of ipRGCs. We hypothesize that there will be significant differences in the melanopsin contribution to pattern discrimination between chosen night and day active animals due to the difference in their retinal structure (rod-cone ratio). We believe that the proposed research will contribute to better understanding of the visual system and lead to a step change in performance of image capture and display technologies by adjusting their design to take account of melanopsin. The applicant will benefit from the project with new skills, knowledge and the experience to launch her own research group in the future.