Using gravity to perceive, move and orient

项目摘要 准确感知身体在世界中的方向是日常生活的核心，就像平衡问题一样 常见且严重，尤其是老年人。计算理论提出，这种能力需要 大脑学习和存储重力的内部表示，可用于感知和行动，以及 研究表明，该模型基于视觉、躯体感觉和前庭信号。拟议 实验研究前庭系统对该内部模型的产生的贡献， 测试是否相同的神经机制提供用于感知和行动的重力信息。 在目标1中，猕猴将被训练在视觉上区分地球垂直方向， 随机的头部/身体倾斜位置，然后在双侧移除前庭器官后进行行为测试。如果 这种操作消除了在倾斜位置执行该任务的能力，这将表明前庭 信息对于重力的内部模型至关重要。这一目标也将研究如何视觉定位 辨别通过募集前庭外感觉线索来适应前庭感受器损失，例如 躯体感觉，以及主动训练是否是这种补偿所必需的。目标2将研究如何 重力依赖性前庭信息通过测量手臂运动学和肌肉运动学来影响运动功能 在双侧前庭输入去除之前和之后，来自激动肌和拮抗肌的活动。这一目标 还将测量前庭损伤后的适应性以及训练在这种补偿中的作用。目标3将 区分这些重力对知觉和动作的影响是否是由共同的丘脑皮层介导的， 通过在前额叶可逆性失活期间探测目标1和2任务中的缺陷， 丘脑，那里有重力调节细胞的报道。综合起来，这些实验对于 理解重力对感知和行动的多感官影响，以及潜在的神经系统 以及揭示运动学习如何帮助前庭功能障碍的恢复。

PROJECT SUMMARY Accurate perception of the body’s orientation in the world is central to everyday life, as balance problems are common and serious, especially in older adults. Computational theory proposes that this ability requires the brain to learn and store an internal representation of gravity that can be used for perception and action, and research has shown that this model is based on visual, somatosensory, and vestibular signals. The proposed experiments investigate the contribution of the vestibular system to the generation of this internal model and test whether the same neural mechanisms provide the gravitational information used for perception and action. In Aim 1, macaques will be trained to visually discriminate the earth-vertical orientation while they are in random head/body tilt positions and then behaviorally tested after bilateral removal of the vestibular organs. If this manipulation abolishes the ability to perform this task at tilted positions, that will indicate that vestibular information is critical for the internal model of gravity. This aim will also examine how visual orientation discrimination adapts to vestibular receptor loss by recruiting extra-vestibular sensory cues, such as somatosensation, and whether active training is necessary for this compensation. Aim 2 will examine how gravity-dependent vestibular information affects motor function by measuring arm kinematics and muscle activity from agonist and antagonist muscles before and after bilateral removal of vestibular inputs. This aim will also measure adaptation after vestibular injury and the role of training in this compensation. Aim 3 will distinguish whether these gravity effects on perception and action are mediated by a shared thalamocortical pathway by probing for deficits in the tasks of Aims 1 and 2 during reversible inactivation of the anterior thalamus, where gravity-tuned cells have been reported. Taken together, these experiments are important for understanding the multisensory influences of gravity on perception and action, as well as the underlying neural circuits, and for revealing how motor learning can aid recovery from vestibular dysfunction.