By Kathleen Cullen (Professor, Physiology and Director of McGill’s Aerospace Medical Research Unit)
Aristotle described five senses: sound, sight, touch, smell and taste that provide us with a conscious awareness of the world around us. But he missed one of our most important senses, the vestibular (inner ear) system which contributes to a surprising range of functions from reflexes to the highest levels of perception and consciousness. The brain combines information from the vestibular system, with proprioception (or sense of body position), and vision to adjust for unexpected motion during everyday activities. How does the brain achieve this? How do athletes maintain their balance for very complex motions (imagine an Olympic gymnast doing a back flip on a balance beam)? How do astronauts adapt to Zero-G where input from the vestibular sense is altered? Why do we start to loose our sense of balance as we age? This lecture will discuss recent (and not so recent) theoretical and experimental work that characterizes how single neurons, organized into dedicated circuits, support our ability to stay on our feet.