High-resolution structural and functional retinal imaging in the awake behaving mouse

The laboratory mouse has provided tremendous insight to the underpinnings of mammalian central nervous system physiology. In recent years, it has become possible to image single neurons, glia and vascular cells in vivo by using head-fixed preparations combined with cranial windows to study local networks of activity in the living brain. Such approaches have also succeeded without the use of general anesthesia providing insights to the natural behaviors of the central nervous system. However, the same has not yet been developed for the eye, which is constantly in motion. Here we characterize a novel head-fixed preparation that enables high-resolution adaptive optics retinal imaging at the single-cell level in awake-behaving mice. We reveal three new functional attributes of the normal eye that are overlooked by anesthesia: 1) High-frequency, low-amplitude eye motion of the mouse that is only present in the awake state 2) Single-cell blood flow in the mouse retina is reduced under anesthesia and 3) Mouse retinae thicken in response to ketamine/xylazine anesthesia. Here we show key benefits of the awake-behaving preparation that enables study of retinal physiology without anesthesia to study the normal retinal physiology in the mouse. A high-resolution imaging apparatus that allows functional retinal imaging in awake and free moving mice was developed, allowing the study of the effect of anaesthesia on eye motion, blood flow and retinal thickness.

Automated summary

In recent years, it has been possible to image single neurons, glia, and vascular cells in vivo to study local networks of activity in the living brain. However, a similar method has not yet been developed for the constantly moving eye. In this study, a novel head-fixed preparation was characterized to enable high-resolution retinal imaging at the single-cell level in awake mice. The study revealed new functional attributes of the eye that are overlooked by anesthesia and highlighted the benefits of studying retinal physiology without anesthesia.