Introduction to Vestibular Cognition Special Issue: Progress in Vestibular Cognition.

“How many senses do you have?” Most of us would probably respond with the traditional five senses we were taught in school: sight, hearing, smell, taste and touch. However, there is an additional sensory modality that is essential in almost all our behaviours. The vestibular system is a sophisticated set of organs located in the inner ear. It comprises the semicircular canals, which detect rotational movements of the head in three-dimensional space, and the otolith organs, which code translational acceleration, including the orientation of the head relative to the gravitational vertical. Most scientists consider the vestibular system as an organ specialized for balance, orientation and control of eye movements. However, vestibular inputs are always on and turn out to be involved in almost all our interactions with the external world in ways that go far beyond these fundamental reflexes. Vestibular signals have extensive projections throughout the cerebral cortex, and can potentially influence any behaviours that involve relating to external space. Over the last decade, emerging studies have demonstrated that sensory information provided by the vestibular system is deeply involved in several cognitive processes. This special issue, which contains both reviews and original articles, focuses on vestibular effects on higher cortical function and seeks to provide a comprehensive overview of the key findings on vestibular cognition. In our special issue, we distinguish specific cognitive sub-functions and highlight how basic vestibular input contributes to each. The broad range of