Rod and cone contributions to the a-wave of the electroretinogram of the macaque
Rod and cone contributions to the a-wave of the electroretinogram of the macaque
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DOI：
10.1113/jphysiol.2002.030304
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发表时间：
2003-03-01
影响因子：
5.5
通讯作者：
Frishman, LJ
中科院分区：
文献类型：
--
作者：
Robson, JG;Saszik, SM;Frishman, LJ
记录麻醉后的暗适应猕猴对甘兹菲尔德刺激的视网膜电图（ERG），并对视杆和视锥驱动的受体和感受器后成分进行分离和建模。测试刺激是短暂的（< 4.1 ms）闪光。在杆饱和背景消失后不久，通过传递刺激来隔离锥体驱动组件。杆驱动分量是通过从混合杆-锥体 ERG 中减去锥驱动分量而得出的。当能量足够低时，杆驱动 a 波前缘的初始部分与刺激能量成线性比例，并且在刺激后不到约 12 ms 的时间内，它可以通过包含分布式延迟和三个级联低通滤波器元件的线性模型很好地描述。添加具有双曲函数和指数函数之间的中间特征的简单静态饱和非线性足以将该模型的应用扩展到对高能量刺激的饱和响应的大部分前沿。没有必要假设涉及任何其他非线性，或者模型的非线性阶段之后有任何重要的低通滤波器。负的视网膜内成分促成了视杆细胞驱动的 a 波的后半部分。通过阻断离子型谷氨酸受体抑制该成分后，直到第一个过零时间的整个 a 波与刺激能量成比例，并且通过将杆模型的响应与描述杆双极细胞响应前沿的模型的响应相加来很好地描述。负的视网膜内成分基本上消除了杆状双极细胞成分的早期部分，并且对于中等能量的刺激，使得光感受器电流看起来是a波前沿的唯一重要成分。锥体驱动的 a 波的前缘包括一个持续到峰值的慢相，并且通过杆抑制背景或通过谷氨酸类似物顺式哌啶-2,3-二羧酸 (PDA) 降低振幅。因此，慢相代表除了由视锥细胞本身产生的α波的快速分量之外还存在的感受器后分量。在高刺激能量下，它在刺激后不到 5 秒内出现。锥体驱动的a波的前缘被充分建模为类似于视杆细胞的锥体光感受器模型的输出和通过锥体输出的单次积分获得的感受器后信号的总和。此外，锥体模型中静态非线性级的输出经过时间常数不超过1 ms的低通滤波器。总之，在解释暗适应 ERG 的杆状和锥状驱动 a 波的前缘时，必须考虑感受器后成分。
The electroretinogram (ERG) of anaesthetised dark-adapted macaque monkeys was recorded in response to ganzfeld stimulation and rod- and cone-driven receptoral and postreceptoral components were separated and modelled. The test stimuli were brief (< 4.1 ms) flashes. The cone-driven component was isolated by delivering the stimulus shortly after a rod-saturating background had been extinguished. The rod-driven component was derived by subtracting the cone-driven component from the mixed rod-cone ERG. The initial part of the leading edge of the rod-driven a-wave scaled linearly with stimulus energy when energy was sufficiently low and, for times less than about 12 ms after the stimulus, it was well described by a linear model incorporating a distributed delay and three cascaded low-pass filter elements. Addition of a simple static saturating non-linearity with a characteristic intermediate between a hyperbolic and an exponential function was sufficient to extend application of the model to most of the leading edge of the saturated responses to high energy stimuli. It was not necessary to assume involvement of any other non-linearity or that any significant low-pass filter followed the non-linear stage of the model. A negative inner-retinal component contributed to the later part of the rod-driven a-wave. After suppressing this component by blocking ionotropic glutamate receptors, the entire a-wave up to the time of the first zero-crossing scaled with stimulus energy and was well described by summing the response of the rod model with that of a model describing the leading edge of the rod-bipolar cell response. The negative inner-retinal component essentially cancelled the early part of the rod-bipolar cell component and, for stimuli of moderate energy, made it appear that the photoreceptor current was the only significant component of the leading edge of the a-wave. The leading edge of the cone-driven a-wave included a slow phase that continued up to the peak, and was reduced in amplitude either by a rod-suppressing background or by the glutamate analogue, cis-piperidine-2,3-dicarboxylic acid (PDA). Thus the slow phase represents a postreceptoral component present in addition to a fast component of the a-wave generated by the cones themselves. At high stimulus energies, it appeared less than 5 ins after the stimulus. The leading edge of the cone-driven a-wave was adequately modelled as the sum of the output of a cone photoreceptor model similar to that for rods and a postreceptoral signal obtained by a single integration of the cone output. In addition, the output of the static non-linear stage in the cone model was subject to a low-pass filter with a time constant of no more than 1 ms. In conclusion, postreceptoral components must be taken into account when interpreting the leading edge of the rod- and cone-driven a-waves of the dark-adapted ERG.