title: Visual gravitational motion and the vestibular system in humans.
abstract: The visual system is poorly sensitive to arbitrary accelerations, but accurately detects the effects of gravity on a target motion. Here we review behavioral and neuroimaging data about the neural mechanisms for dealing with object motion and egomotion under gravity. The results from several experiments show that the visual estimates of a target motion under gravity depend on the combination of a prior of gravity effects with on-line visual signals on target position and velocity. These estimates are affected by vestibular inputs, and are encoded in a visual-vestibular network whose core regions lie within or around the Sylvian fissure, and are represented by the posterior insula/retroinsula/temporo-parietal junction. This network responds both to target motions coherent with gravity and to vestibular caloric stimulation in human fMRI studies. Transient inactivation of the temporo-parietal junction selectively disrupts the interception of targets accelerated by gravity.
authors.affiliation: Department of Systems Medicine, University of Rome Tor Vergata Rome, Italy ; Centre of Space Bio-medicine, University of Rome Tor Vergata Rome, Italy ; Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation Rome, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Lacquaniti
authors.affiliation: Department of Systems Medicine, University of Rome Tor Vergata Rome, Italy ; Centre of Space Bio-medicine, University of Rome Tor Vergata Rome, Italy ; Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation Rome, Italy.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Bosco
authors.affiliation: Centre of Space Bio-medicine, University of Rome Tor Vergata Rome, Italy ; Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation Rome, Italy.
authors.forename: Iole
authors.initials: I
authors.lastname: Indovina
authors.affiliation: Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation Rome, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: La Scaleia
authors.affiliation: Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation Rome, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Maffei
authors.affiliation: Department of Cognitive Neuroscience, University of Bielefeld Bielefeld, Germany.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Moscatelli
authors.affiliation: Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation Rome, Italy.
authors.forename: Myrka
authors.initials: M
authors.lastname: Zago
keywords: insula; interception; internal model; microgravity; self-motion; temporo-parietal junction; time perception