Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA.
Neuron. 2013 Dec 18;80(6):1508-18. doi: 10.1016/j.neuron.2013.09.029.
A fundamental challenge for maintaining spatial orientation and interacting with the world is knowledge of our orientation relative to gravity, i.e., head tilt. Sensing gravity is complicated because of Einstein's equivalence principle, in which gravitational and translational accelerations are physically indistinguishable. Theory has proposed that this ambiguity is solved by tracking head tilt through multisensory integration. Here we identify a group of Purkinje cells in the caudal cerebellar vermis with responses that reflect an estimate of head tilt. These tilt-selective cells are complementary to translation-selective Purkinje cells, such that their population activities sum to the net gravitoinertial acceleration encoded by the otolith organs, as predicted by theory. These findings reflect the remarkable ability of the cerebellum for neural computation and provide quantitative evidence for a neural representation of gravity, whose calculation relies on long-postulated theoretical concepts such as internal models and Bayesian priors.
维持空间定向和与世界交互的一个基本挑战是我们相对于重力的方向的知识，即头部倾斜。由于爱因斯坦等效原理，感知重力变得很复杂，根据该原理，引力和平移加速度在物理上是不可区分的。理论提出，通过多感觉整合来跟踪头部倾斜可以解决这种歧义。在这里，我们确定了小脑蚓部尾部的一群浦肯野细胞，其反应反映了头部倾斜的估计。这些倾斜选择性细胞与平移选择性浦肯野细胞互补，因此它们的群体活动总和为耳石器官编码的净重力惯性加速度，这与理论预测一致。这些发现反映了小脑进行神经计算的惊人能力，并为重力的神经表示提供了定量证据，其计算依赖于长期假设的理论概念，如内部模型和贝叶斯先验。
