Roles of retinal circuits in the innate visual behaviors of mice

Much of brain science is concerned with understanding the neural circuits that underlie specific behaviors. While the mouse has become a favorite experimental subject, the behaviors of this species are still poorly explored, posing a challenge for understanding the neural basis for visual behaviors. We approach this problem first, by exploring the visual responses of mice of mice to visual stimuli, second by genetically ablating specific cell types in the retina and testing the effects on visual behaviors. We show that mice respond to the visual display of an approaching object by either initiating escape or by freezing for an extended period. We then use genetic means to ablate specific cell classes in the retina to dissect the roles of these classes in the looming avoidance behavior and two other visual behaviors: optokinetic reflex (OKR) and pupillary light reflex (PLR). We show that a class of cells including the alpha retinal ganglion cells are necessary for the looming avoidance behavior, while this class has minor roles in the pupillary constriction and optokinetic reflex. By contrast another cell class, starburst amacrine cells, are crucial for the optokinetic reflex and are dispensable for the looming avoidance and pupil reflexes. Our results suggest that mouse retina possesses neural circuits that are specialized for specific visual functions, such as avoiding an aerial predator, moving head to minimize retinal slip and constricting the pupil to limit light input to the retina.