Scaling in Reflexive and Volitional Eye Movements

反射性和意志性眼动的缩放

• 批准号: 6864418
• 负责人: MARK J SHELHAMER
• 金额: $ 16.03万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-03-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6864418
• 关键词: cerebellum; clinical research; eye movements; human subject; mathematical model; memory; neurophysiology; nystagmus; oculomotor nerve; reflex; saccades; semicircular duct; visual stimulus

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.

描述（由申请人提供）：该项目涉及两种类型的眼球运动（眼跳，OKN），重点是对视觉刺激的反应时间。扫视是在扫描视觉场景时做出的快速运动。对同步目标的扫视有一个特征性的潜伏期：随着起搏频率的增加，扫视变得更加具有预期性。OKN（视动性眼震）发生在场景的宽视野运动中，是前庭和眼功能的指标。在OKN期间，眼睛跟踪场，并通过向相反方向快速移动间歇性地重置其位置。眼睛位置波形看起来像一个波动的曲线。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，随机动态相对于确定性动态的主导地位使其合理。如果受试者主动跟随场景（“看眼震”），OKN与受试者只是直视前方（“凝视眼震”）时不同。这可能反映了不同程度的自反性和意志控制。 在第一个子项目中，将研究以相同速度扫视的缩放特性。许多系统具有特征性的缩放行为，例如可变性作为序列长度的幂律函数增加，反映了一种类型的统计长期记忆。将使用参数程序评估扫视潜伏期的缩放，并以图形方式进行验证。目标是评估扫视是反应性或预测性的范围内的缩放（分别为正或负的扫视）。有证据表明，预测机制中的缩放行为与非预测（“反应”）机制中的缩放行为不同。这种关系可以将反射/意志行为与预测/反应行为联系起来。证据也提出了改变缩放小脑患者。第二个子项目将对OKN快相间隔进行类似的分析。 有证据表明，缩放取决于意志与反射行为的程度。这种意志/反射的混合可以通过刺激不同类型的OKN（水平与扭转，“看”与“凝视”）来改变，并用于验证缩放与行为的关系。 结果将广泛适用于生理系统，可以描述的统计标度律，并表现出自反和意志行为和预测的组合系统。由于缩放随病理变化，可能会产生评估前庭或眼神经病理的新方法。