Phase Transition Models of Oculomotor Control

描述(由申请人提供)：许多物理系统显示出 以相变为代表的行为：当“控制参数”变化时， 行为在两个(或多个)不同的稳定状态或模式之间发生变化。 最近，这种相变的例子已经在 生理系统。例如，当受试者轻拍每个人的食指时 手有两种稳定的模式：一种是手指同步敲击，另一种是手指同步敲击 在这个过程中，他们在反相中敲击。这两种模式是健壮的(稳定的)， 随着敲击频率的系统化，行为会从一个改变到另一个 多种多样。 此行为显示了相变的许多共同特征：每个 模式对扰动是稳健的，当控制时有更大的可变性 参数(频率)在过渡点附近，存在滞后现象 当从上面和下面接近时，过渡点是不同的 (减少或增加频率)。 我们将研究类似类型的相变的眼动行为。 眼球运动领域的数学建模是相当复杂的，但 对相变行为的分析还没有尝试过。拟议中的工作 因此，这是对动眼行为的一个方面进行模拟的尝试 地址。本文提出的模型将对改进现有的 模型，了解观察到的行为，并预测新的行为。 研究计划包括三项主要工作。首先，分析了 周期性扫视以寻找多个稳定状态的证据，类似于 上面提到的手指敲击工作。初步数据表明， 在这个系统中确实可能发生转变：作为目标跳跃频率 增加，扫视从落后于目标(正延迟)变为 预测目标(负延迟)，并且存在更大的可变性 在过渡频率附近。该系统的工作将包括进一步 对这一效应的验证、滞后的检查和对 摄动和数学模型的公式(以及现有的分析 模型)来重现相变。第二个努力是研究 眼跳和前庭-眼反射(VOR)的相互作用，寻找模式 产生的流畅和快速的眼球运动之间的协调性 频率的函数。最后，我们将对其他前庭进行调查 以及可能表现出相变行为的动眼行为和模型。 这个项目是高风险的，因为眼球运动系统可能会避免这样的阶段 而是平稳地表现出分级的行为变化，使阶段 过渡模式不合适。这项工作代表了PI的新方向 因为他过去的工作没有涉及到独特的数学公式 是这项研究所必需的。

DESCRIPTION (provided by applicant): Many physical systems exhibit patterns of behavior typified by phase transitions: as a "control parameter" varies, the behavior changes between two (or more) distinct stable states or modes. Recently, examples of such phase transitions have been demonstrated in physiological systems. For example, when subjects tap the index fingers of each hand, there are two stable modes: one in which the fingers tap in phase and one in which they tap in counter-phase. These two modes are robust (stable), and the behavior changes from one to the other as tapping frequency is systematically varied. This behavior exhibits a number of features common to phase transitions: each mode is robust to perturbations, there is increased variability when the control parameter (frequency) is near the transition point, and there is hysteresis such that the transition point is different when approached from above versus below (decreasing or increasing frequency). We will investigate oculomotor behavior for similar types of phase transitions. Mathematical modeling in the oculomotor field is quite sophisticated, yet analysis of phase-transition behaviors has not been attempted. The proposed work is thus an attempt to model an aspect of oculomotor behavior that has not been addressed. The modeling proposed here will have value in improving existing models, understanding observed behaviors, and predicting new ones. The research plan consists of three main efforts. First is the analysis of periodic saccades for evidence of multiple stable states, in analogy to the finger tapping work referred to above. Preliminary data suggests that phase transitions may indeed occur in this system: as target jumping frequency increases, saccades change from lagging the target (positive latency) to anticipating the target (negative latency), and there is increased variability near the transition frequency. Work on this system will involve further verification of this effect, examination of hysteresis and the response to perturbations, and formulation of mathematical models (and analysis of existing models) to reproduce the phase transitions. The second effort is a study of the interaction of saccades and the VOR (vestibulo-ocular reflex), looking for modes of coordination between the resulting smooth and fast eye movements as a function of frequency. Finally, we will carry out a survey of other vestibular and oculomotor behaviors and models for those which might exhibit phase transition behaviors. This project is high risk because the oculomotor system may avoid such phase transitions but rather exhibit smoothly graded behavioral changes, making phase transition models inappropriate. The work represents a new direction for the PI because his past work has not dealt with the unique mathematical formulations required for this study.