Attentional demands of state transitions in posture and balance

以直立姿势安静地站立包括持续受控的平衡状态。这种动态状态可以被认为是稳定的，因为重心(COM)的位置被保持在防止重力拉动的稳定性(LOS)的范围内，并且在身体平衡受到扰动(例如，导致轻微的前移)之后，平衡控制系统将试图通过返回到初始平衡状态来恢复。然而，在正常情况下，人们经常改变自己的姿势，要么是自愿的(例如伸手拿起一个物体)，要么是为了应对环境中的外部因素(例如意外的推力)。这些活动会导致不同姿势状态之间的转换，改变感觉刺激的模式，改变身体各部分的协调性，看起来毫不费力，但仍然需要适当的计划和执行，以保持平衡。在随意的双侧肢体运动中，稳定行为状态之间的转换的动力学已被广泛研究，但很少有人研究姿势和平衡的感觉运动控制中的稳定状态之间的转换。我们将研究预测和反应控制过程的作用，多模式感觉信息的整合，以及在新平衡状态下状态之间的转换和稳定过程中的注意要求。我们将使用行为和功能脑成像来阐明姿势控制的动态和潜在的大脑机制，以及与老年人在适应影响身体姿势的外部变化方面的损伤相关的变化。

Quiet standing in an upright posture comprises a continuously controlled balance state. This dynamical state can be considered as 'steady' in the sense that the position of Centre of Mass (CoM) is kept within the limits of stability (LoS) against the pull of gravity and that following a perturbation to body balance resulting, for example, in slight forward sway, the balance control system will try to recover by returning to the initial balance state. However, in normal circumstances people frequently change their posture either voluntarily (eg reaching to pick up an object) or in response to external factors in the environment (eg an unexpected push). These events, which cause transitions between different postural states with changes in patterns of sensory stimulation and altered coordination of body segments, seem effortless but nevertheless need to be properly planned and executed in order to maintain balance. The dynamics of transitions between steady behavioural states have been extensively investigated in voluntary bilateral limb movements but there has been little research examining transitions between steady states in the sensorimotor control of posture and balance. We will examine the role of predictive and reactive control processes, the integration of multimodal sensory information and the demands on attention during transitions between states and stabilization in the new balance state. We will use behavioural and functional brain imaging to shed light on the dynamics of postural control and the underlying brain mechanisms and the changes that occur associated with elderly impairments in adaptation to external changes affecting body posture.