Delle Monache Sergio, La Scaleia Barbara, Finazzi Agrò Anna, Lacquaniti Francesco, Zago Myrka
Laboratory of Neuromotor Physiology, IRCCS Santa Lucia Foundation, Rome, 00179, Italy.
Department of Systems Medicine and Centre of Space Bio-medicine, University of Rome Tor Vergata, Rome, 00133, Italy.
Sci Rep. 2025 Mar 26;15(1):10394. doi: 10.1038/s41598-025-94512-1.
The motion of objects and ourselves along the vertical is affected by gravitational acceleration. However, the visual system is poorly sensitive to accelerations, and the otolith organs do not disassociate gravitational and inertial accelerations. Here, we tested the hypothesis that the brain estimates the duration of vertical visual motion and self-motion by means of an internal model of gravity predicting that downward motions are accelerated and upward motions are decelerated by gravity. In visual sessions, a target moved up or down while participants remained stationary. In vestibular sessions, participants were moved up or down in the absence of a visual target. In visual-vestibular sessions, participants were moved up or down while the visual target remained fixed in space. In all sessions, we verified that participants looked straight-ahead. We found that downward motions of either the visual target or the participant were systematically perceived as lasting less than upward motions of the same duration, and vice-versa for the opposite direction of motion, consistent with the predictions of the internal model of gravity. In visual-vestibular sessions, there was no significant difference in the average estimates of duration of downward and upward motion of the participant. However, there was large inter-subject variability of these estimates.
物体和我们自身沿垂直方向的运动受重力加速度影响。然而，视觉系统对加速度的敏感度较低，耳石器官也无法区分重力加速度和惯性加速度。在此，我们检验了这样一个假设：大脑通过一个重力内部模型来估计垂直视觉运动和自我运动的持续时间，该模型预测向下的运动会因重力而加速，向上的运动会因重力而减速。在视觉实验中，参与者静止不动时，一个目标上下移动。在前庭实验中，参与者在没有视觉目标的情况下上下移动。在视觉 - 前庭实验中，参与者上下移动时，视觉目标在空间中保持固定。在所有实验中，我们都确保参与者直视前方。我们发现，视觉目标或参与者的向下运动在系统上被感知为持续时间短于相同持续时间的向上运动，反之，对于相反方向的运动也是如此，这与重力内部模型的预测一致。在视觉 - 前庭实验中，参与者向下和向上运动持续时间的平均估计值没有显著差异。然而，这些估计值在个体间存在很大差异。
