Grant: Project Grant

As we move through the world, we experience optic flow - the motions of surfaces and objects across our retina. Studies of human behaviour reveal that optic flow is used for controlling virtually all aspects of locomotion such as walking, navigating through cluttered environments like forests or airport terminals, and when driving motor vehicles. Despite the importance of optic flow, there is a major gap in our understanding of how these signals are processed in the brain to allow for complex locomotion. Thus, optic flow processing in the brain is one of the most important, but least understood aspects of locomotion control. Disruptions to optic flow processing in the brain are associated with common diseases including vertigo, oscillopsia, ataxias and Alzheimer's disease. For example, Alzheimer's patients require much stronger optic flow signals to be able to navigate through a series of hallways to find their rooms. For other patients, such as those with vestibular deficits and visual neglect, presentations of optic flow are effective rehabilitative tools. Improving our understanding of optic flow is therefore essential. The principal challenge to studying optic flow processing in the brain is that we lack an appropriate animal model for research. Mice and rats are often used for studies of vertebrate neurobiology, but they are crepuscular/nocturnal and use information from their whiskers to guide many aspects of their locomotion. We will investigate how optic flow is used to guide movement in different environments, how optic flow signals are processed along the pathway from the midbrain to the cerebellum, and how selective silencing of neurons in this pathway leads to deficits in locomotor ability. The experiments will be performed on the visually-guided flight of small birds, which can be easily studied in the lab. Because birds have the same optic flow pathways as humans, this research will identify specific neural connections as potential treatment targets.