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.

Interaction of brain areas of visual and vestibular simultaneous activity with fMRI

“…The ten selected areas to determine the relative BOLD signal changes were labeled using the names indicated in the probabilistic cytoarchitectonic maps from the SPM Anatomy Toolbox (Eickhoff et al 2005(Eickhoff et al , 2006a(Eickhoff et al , 2007. BA 18-Lingual gyrus; hOC3v(V3v)-Lingual gyrus; hOC4(V4)-Fusiform gyrus; hOC5(V5)-Middle occipital gyrus; IPC(PFcm)-Supramarginal gyrus; Insula(Ig2)-Insula; Lobule VI(Hem)-Cerebellum; BA 44-Inferior frontal gyrus; BA 45-Middle frontal gyrus; BA 6-Superior frontal gyrus and coworkers formulated a hypothesis that the integration of estimating the effects of gravity involves connections between spatiotemporal visual areas and temporo-parietalinsular regions, which are involved in multisensory integration (Lacquaniti et al 2013). …”

Direction-dependent arm kinematics reveal optimal integration of gravity cues

“…The neural representation of gravity is thought to solve this ambiguity by multisensory statistical inference (Angelaki et al, 1999; Merfeld et al, 1999; Angelaki et al, 2004; Laurens et al, 2013b). An internal model of gravity has been shown to benefit the anticipation of a free falling object motion (Zago and Lacquaniti, 2005; Zago et al, 2008; Lacquaniti et al, 2013), as well as the visual perception of allocentric vertical (Van Pelt et al, 2005; De Vrijer et al, 2008; Elmore et al, 2014). However, whether and how an internal model of gravity benefits the planning and execution of skilled movement remains unknown.…”

Fourier decomposition of spatial localization errors reveals an idiotropic dominance of an internal model of gravity

“…e.g., Green & Angelaki, 2010;Harris et al, 2011;Lacquaniti et al, 2013;Oman, 2003). Increasingly more, the perception of gravity has been acknowledged as a prime factor in structuring our apprehension of space and notable breakthroughs have been made in identifying neural structures involved in its processing (Angelaki & Cullen, 2008;Angelaki et al, 2004;Hess & Angelaki, 1999;Merfeld, Zupan, & Peterka, 1999).…”

“…Aubert's effect). Of importance, outcomes found with time-to-contact tasks and timing of interceptive actions strongly suggest that an internalized model of earth's gravitational acceleration is furthermore involved in the processing of visual sensory information (Indovina et al, 2005;Lacquaniti & Maioli, 1989;Lacquaniti et al, 2013;Moscatelli & Lacquaniti, 2011;Zago et al, 2004; see Baurés et al, 2007; for a critical review and Zago et al, 2008; for a response), even under microgravity conditions (McIntyre et al, 2001).…”