Vision in laboratory rodents—Tools to measure it and implications for behavioral research

Abstract

Mice and rats are nocturnal mammals and their vision is specialized for detection of motion and contrast in dim light conditions. These species possess a large proportion of UV-sensitive cones in their retinas and the majority of their optic nerve axons target superior colliculus rather than visual cortex. Therefore, it was a widely held belief that laboratory rodents hardly utilize vision during day-time behavior. This dogma is being questioned as accumulating evidence suggests that laboratory rodents are able to perform complex visual functions, such as perceiving subjective contours, and that declined vision may affect their performance in many behavioral tasks. For instance, genetic engineering may have unexpected consequences on vision as mouse models of Alzheimer's and Huntington's diseases have declined visual function. Rodent vision can be tested in numerous ways using operant training or reflex-based behavioral tasks, or alternatively using electrophysiological recordings. In this article, we will first provide a summary of visual system and explain its characteristics unique to rodents. Then, we present well-established techniques to test rodent vision, with an emphasis on pattern vision: visual water test, optomotor reflex test, pattern electroretinography and pattern visual evoked potentials. Finally, we highlight the importance of visual phenotyping in rodents. As the number of genetically engineered rodent models and volume of behavioral testing increase simultaneously, the possibility of visual dysfunctions needs to be addressed. Neglect in this matter potentially leads to crude biases in the field of neuroscience and beyond.

Roles of HIFs and VEGF in angiogenesis in the retina and brain

“…With current technology, 3D images of the living human retina, including angiographic images, can be obtained at near-cellular resolution (39)(40)(41). Finally, the high degree of functional localization within the retina and the availability of quantitative psychophysical and electrophysiological tests of retinal function permit precise anatomic mapping and characterization of tissue dysfunction (42,43). Together, these biological and technical attributes have paved the way for an increasingly sophisticated understanding of retinal vascular development, physiology, disease, and response to therapy.…”

Subretinal surgery: functional and histological consequences of entry into the subretinal space

“…When the effect of subretinal treatments for blinding diseases is investigated, a test for retinal function (vision) is a valuable outcome. In animals, vision can be tested in numerous ways using operant training, reflex‐based behavioral tasks or electrophysiological recordings (Leinonen & Tanila ). Training animals to perform learned tasks (operant training) allow testing of all aspects of vision, but it is time‐consuming and some animals cannot be trained (Leinonen & Tanila ).…”

“…In animals, vision can be tested in numerous ways using operant training, reflex‐based behavioral tasks or electrophysiological recordings (Leinonen & Tanila ). Training animals to perform learned tasks (operant training) allow testing of all aspects of vision, but it is time‐consuming and some animals cannot be trained (Leinonen & Tanila ). Domestic pigs gain 5 kg a week on average and behavioral training for weeks or months would mean that the animals would be huge and difficult to handle when the experiments start.…”

“…Several techniques that require little or no training have been established; some of these methods include electrophysiological tests, where electrical activity is recorded upon visual stimulation (Leinonen & Tanila ). An advantage of electrophysiological tests is that they are objective and not easily affected by factors other than retinal function (Leinonen & Tanila ). Electroretinography (ERG) is a relatively non‐invasive and the method is used in both laboratory animals and humans (Leinonen & Tanila ).…”

“…An advantage of electrophysiological tests is that they are objective and not easily affected by factors other than retinal function (Leinonen & Tanila ). Electroretinography (ERG) is a relatively non‐invasive and the method is used in both laboratory animals and humans (Leinonen & Tanila ). Unfortunately, it is not possible in the ERG to differentiate retinal function in separate areas and it can therefore be difficult to correlate functional and morphological parameters (Jansson et al.…”