Scaling in Reflexive and Volitional Eye Movements

描述(由申请人提供)：这个项目涉及两种类型的眼睛运动(眼跳，OKN)，重点是对视觉刺激的反应时间。扫视是扫描视觉场景时的快速动作。对周期性起搏的目标的眼跳有一个特征的延迟：随着起搏率的增加，眼跳变得更具预见性。视动性眼球震颤是伴随着场景的大范围运动而发生的，是前庭和眼球运动功能的指标。在OKN过程中，眼睛跟踪场地，并间歇性地通过向相反方向快速移动来重新设置位置。眼睛位置的波形看起来像一个波动的锯齿。OKN不是周期性的；模型通常依赖于变化的统计特征，最近的工作表明，随机动力学相对于确定性动力学的主导地位使得这一点是合理的。如果受试者主动跟随场景(“注视眼球震颤”)，OKN就不同于当受试者只是直视前方(“凝视眼球震颤”)。这可能反映了不同程度的条件反射和意志控制。 在第一个子项目中，将研究周期性节奏的扫视的缩放特性。许多系统具有特征的缩放行为，使得变异性作为序列长度的幂函数增加，反映了一种统计的长期记忆。眼跳延迟的调整将使用参数程序进行评估，并以图形方式进行验证。我们的目标是评估在眼跳是反应性或预测性(潜伏期分别为正或负)的范围内的缩放。证据表明，在预测性区域和非预测性(“反应性”)区域中的比例行为是不同的。这种关系可以将反身性/意志行为与预测性/反应性行为联系起来。小脑患者的鳞片改变的证据也被提出。第二个子项目将对OKN快相间期进行类似的分析。证据表明，比例的变化取决于意志行为与反射行为的程度。通过刺激不同类型的OKN(水平和扭转，“注视”和“凝视”)，可以改变这种意志/反射混合，并用来验证比例与行为的关系。 这些结果将广泛适用于可用统计标度定律描述的生理系统，以及表现出自反性和意志性行为和预测相结合的系统。由于鳞片随病理而变化，因此可能产生评估前庭或动眼神经病理的新方法。

DESCRIPTION (provided by applicant): This project addresses two types of eye movement (saccades, OKN), with emphasis on timing in response to visual stimuli. Saccades are rapid movements made when scanning a visual scene. Saccades to periodically-paced targets have a characteristic latency: as pacing rate increases saccades become more anticipatory. OKN (optokinetic nystagmus) occurs with wide-field motion of a scene, and is an indicator of vestibular and oculomotor function. During OKN, the eyes track the field, and intermittently reset their position by moving rapidly in the opposite direction. The eye position waveform looks like a fluctuating sawtooth. OKN is not periodic; models typically rely on statistical characterization of the variations, and recent work indicates that the dominance of random vs. deterministic dynamics makes this reasonable. If a subject actively follows the scene ("look nystagmus"), OKN is different from when a subject simply stares straight ahead ("stare nystagmus"). This may reflect different degrees of reflexive and volitional control. In the first sub-project, scaling properties of periodically-paced saccades will be studied. Many systems have a characteristic scaling behavior, such that variability increases as a power-law function of sequence length, reflecting a type of statistical long-term memory. Scaling of saccade latencies will be assessed with a parametric procedure, and verified graphically. The goal is to assess scaling over the range where saccades are reactive or predictive (latencies positive or negative, respectively). Evidence is that scaling behavior in the predictive regime is different from that in the non-predictive ("reactive") regime. This relationship can link reflexive/volitional behaviors to predictive/reactive behaviors. Evidence is also presented for altered scaling in cerebellar patients. The second sub-project will apply similar analyses to OKN fast-phase intervals. Evidence indicates that scaling is altered depending on the degree of volitional vs. reflexive behavior. This volitional/reflexive mix can be altered through stimulation of different types of OKN (horizontal vs. torsional, "look" vs. "stare"), and used to verify the relationship of scaling to behavior. The results will be widely applicable to physiologic systems that can be described by statistical scaling laws, and to systems which exhibit combinations of reflexive and volitional behavior and prediction. Since scaling changes with pathology, new means to assess vestibular or oculomotor pathology may result.