Using gravity to perceive, move and orient

项目总结 对身体在世界上的方位的准确感知是日常生活的核心，就像平衡问题一样 常见且严重，尤其是在老年人中。计算理论提出，这种能力需要 大脑学习和存储可用于感知和行动的重力的内部表示，以及 研究表明，这个模型是基于视觉、体感和前庭信号的。建议数 实验研究了前庭系统对这一内部模型的产生的贡献 测试相同的神经机制是否提供了用于感知和行动的引力信息。 在目标1中，猕猴将被训练在视觉上辨别它们在地球上的垂直方向 随机倾斜头部/身体姿势，然后在切除双侧前庭器官后进行行为测试。如果 这种操作取消了在倾斜的位置执行这项任务的能力，这将表明前庭 信息对于重力的内部模型是至关重要的。这一目标还将检验视觉定向 辨别通过招募前庭外的感觉线索来适应前庭感受器的丢失，例如 躯体感觉，以及这种补偿是否需要积极的训练。Aim 2将研究如何 依赖重力的前庭信息通过测量手臂运动学和肌肉来影响运动功能 双侧前庭输入摘除前后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情况以及训练在这一补偿中的作用。目标3将 辨别这些重力对知觉和行为的影响是否由共同的丘脑皮质介导 在可逆性前部失活过程中探测AIMS 1和2任务缺陷的通路 丘脑，据报道，那里有重力调节细胞。总而言之，这些实验对于 了解重力对知觉和行动的多感官影响，以及潜在的神经 电路，并揭示运动学习如何有助于从前庭功能障碍中恢复。

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.