Level dependent signal flow in the light pupil reflex
Level dependent signal flow in the light pupil reflex
复制标题
光瞳反射中的电平相关信号流
DOI：
10.1007/bf00224857
复制
发表时间：
2004
影响因子：
1.9
通讯作者：
L. Stark
中科院分区：
文献类型：
--
作者：
G. A. Myers;J. A. Gannon;L. Stark
在一系列光强和频率下测量了瞳孔对正弦光刺激的反应。随着平均光强增加，这些反应的相位滞后和等效时间延迟以近似对数线性的方式减小（斜率 = -60毫秒/对数单位）。在较高频率和较高光强下，这种对光强的依赖程度会降低。这种非线性的依赖光强的信号流（LDSF）效应基本上与影响瞳孔大小的目标距离（调节刺激）以及瞳孔大小本身无关。因此，大部分对光强的依赖性可能存在于光 - 瞳孔反射弧的传入通路中，在调节信号在动眼神经核与光信号汇合之前。针对此处以及相关论文（迈尔斯和斯塔克，1993a，b）中描述的LDSF效应提出了一个系统模型。当调整模型参数以拟合瞳孔在一系列光强下对瞬态光刺激的反应时，该模型模拟出随着平均光强增加相位滞后减小，以及随着平均光强增加或刺激频率增加这种LDSF效应降低，而无需进一步改变参数。后一种降低解释了在潜伏期数据中看到的相对较小的对光强的依赖性（-34毫秒/对数单位）。这些数据将表明（迈尔斯和斯塔克，1990b）与在高增益振荡实验中随着平均亮度增加所观察到的瞳孔周期时间缩短（振荡频率增加）是相符的。该模型模拟了瞳孔反应的方向不对称性，即收缩比扩张快，以及对固定平均亮度的光刺激进行正弦调制时的强直性瞳孔收缩，即瓦尔朱 - 特罗尔斯特拉效应。
Pupillary responses to sinusoidal light stimuli were measured over a range of light levels and frequencies. The phase lag and equivalent time delay of these responses were reduced in an approximately loglinear fashion with increasing mean light level (slope=-60ms/log unit). The magnitude of this level dependence is reduced at higher frequencies, and at higher light levels. This nonlinear level dependent signal flow (LDSF) effect is shown to be essentially independent of target distance (accommodative stimulus) which influences pupil size, and of pupil size itself. Thus most of the level dependence probably resides in the afferent path of the light-pupil reflex arc, before the accommodation signal joins the light signal in the Edinger-Westphal nucleus. A systems model is presented to the LDSF effect described here and in the companion papers (Myers and Stark 1993a, b). When parameters of the model are adjusted to fit pupillary responses to transient light stimuli over a range of light levels, the model simulates reduced phase lag in response to increased mean light level, and the reduction in this LDSF effect with increased mean light level or increasing stimulus frequency without further changes in parameters. This latter reduction explains the relatively small level dependence seen in latency data (-34ms/ log unit). These data will be shown (Myers and Stark 1990b) to be commensurate with reduction in pupil cycle time (increased frequency of oscillation) observed in high gain oscillation experiments as mean brightness increases. The model simulates directional asymmetry of pupillary response, with constriction faster than dilation, and tonic pupillary constriction in response to sinusoidal modulation of a light stimulus of fixed average brightness, the Varju-Troelstra effect.