RT Journal Article
SR Electronic
T1 When Up Is Down in 0g: How Gravity Sensing Affects the Timing of Interceptive Actions
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 1969
OP 1973
DO 10.1523/JNEUROSCI.3886-11.2012
VO 32
IS 6
A1 Patrice Senot
A1 Myrka Zago
A1 Anne Le Séac'h
A1 Mohammed Zaoui
A1 Alain Berthoz
A1 Francesco Lacquaniti
A1 Joseph McIntyre
YR 2012
UL http://www.jneurosci.org/content/32/6/1969.abstract
AB Humans are known to regulate the timing of interceptive actions by modeling, in a simplified way, Newtonian mechanics. Specifically, when intercepting an approaching ball, humans trigger their movements a bit earlier when the target arrives from above than from below. This bias occurs regardless of the ball's true kinetics, and thus appears to reflect an a priori expectation that a downward moving object will accelerate. We postulate that gravito-inertial information is used to tune visuomotor responses to match the target's most likely acceleration. Here we used the peculiar conditions of parabolic flight—where gravity's effects change every 20 s—to test this hypothesis. We found a striking reversal in the timing of interceptive responses performed in weightlessness compared with trials performed on ground, indicating a role of gravity sensing in the tuning of this response. Parallels between these observations and the properties of otolith receptors suggest that vestibular signals themselves might plausibly provide the critical input. Thus, in addition to its acknowledged importance for postural control, gaze stabilization, and spatial navigation, we propose that detecting the direction of gravity's pull plays a role in coordinating quick reactions intended to intercept a fast-moving visual target.