Laboratory Exercise : Vestibular

The vestibular system is arguably the most ancient sensory system. Its evolution became an invaluable acquisition enabling vertebrates to move about in their environment. The peripheral vestibular apparatus, the semicircular canals and the otolith organs, evolved early and relatively completely. Thus, their structure and function are similar across the vertebrate phyla. Labyrinthine enteroceptors report the magnitudes and directions of angular and linear motion of the head as an animal translates and rotates through space. This information is transmitted to the central nervous system as a frequency code of impulses carried by the VIIIth cranial nerve. The code is subsequently combined with information from other sensory systems that converge on vestibular nuclear sites to compute a central estimate or vectorial representation of head and body position and motion in space called the gravitoinertial vector.