Researchers based in Munich, Tuebingen and Tuebingen developed an open-source camera that captures natural habitats just like rodents.Animals have evolved to adapt to their environment over time, increasing their survival chances and reproductive potential. The sensory systems that allow species to perceive their environment also have diverse aspects. These adaptations have created features like the position of the eyes and relative acuity between different regions of retina.Our knowledge about the evolution of visual systems in mammals remains limited. Professor Laura Busse, of Ludwig-Maximilians-Universitaet's Department of Biology II in Munich, says that the mouse has been the most popular model for studying the processing of visual information over the past 10 to 15 years. This is a surprising result, considering that the rodents sensed the world primarily through their nose and whiskers. But color vision in mammals has been shown to affect the ability to choose mating partners, find food, and evade predators.Busse is a member the transregional Collaborative Research Center (1233) on "Robust vision." The term "robust," as it is used here, refers to the fact that animals, including humans, can draw inferences even from very limited visual information. Busse, in collaboration with Professor Thomas Euler of Tuebingen University and the Coordinating University of the CRC, decided to fill this gap by studying the visual inputs and the processing of neuronal signs in mice."A camera that captures mouse viewDichromate is a state in which mice have two types (the cone cells that are responsible to color vision) of their retinas. These cells are sensitive to electromagnetic radiation, and can detect wavelengths between 510 nanometers and 350 nanometers (nm), respectively. Busse says, "We wanted to find out what color information was available to mice in natural habitats and whether the presence of these colors could explain the functional characteristics the neural circuits of the mouse retina."The teams from Munich and Tuebingen worked together to create an open-source, low-cost camera that, unlike other cameras, could cover the ultraviolet and green spectral areas to which the mouse retina is sensitive. The camera's hand-held is equipped with a handheld gimbal that automatically aligns the frame to avoid any unintentional changes in perspective.Researchers used the camera to capture the environment as it appeared to a mouse at various times of day in fields with clear signs of their presence. Busse says that UV light is sensitive in the mouse's upper hemisphere, which can see the sky. The lower half of the mouse's retina is oriented towards ground and shows higher sensitivity to UV light. These two spectral regions closely correspond to the color statistics of natural environments, which are preferred by mouse populations. This adaptation may be due to evolutionary processes. It could help animals see birds of prey from the sky and take evasive actions. This conjecture is confirmed by experiments using artificial neural nets, which mimic the processing characteristics in cone cells of the mouse retina.
