A NEURAL THEORY OF RETINO-CORTICAL DYNAMICS
A NEURAL THEORY OF RETINO-CORTICAL DYNAMICS
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DOI：
10.1016/0893-6080(93)90020-w
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发表时间：
1993-01-01
期刊：
影响因子：
7.8
通讯作者：
OGMEN, H
中科院分区：
文献类型：
--
作者：
OGMEN, H
由于多种因素（眼睛的运动、外部物体的运动、积分时间、聚散度、调节和不均匀的视网膜采样），视网膜编码是高度瞬态、模糊和扭曲的。然而这个问题很少受到关注，因为文献中提出的大多数模型都是围绕静态（或稳态）和均匀聚焦图像的分析而建立的。因此，视觉感知的一个基本问题在于理解从短暂的、模糊的活动中合成现象静态的、敏锐的感知的过程。我们提出了一种连续时间神经理论，提出了视网膜瞬态活动的两个主要作用：首先，我们提出视网膜神经元的非单调行为作为一种简单的记忆形式，自适应地过滤视觉信号以指导注意力机制。其次，我们认为瞬态活动对于实现敏锐的动态感知同时保持良好的光敏感度至关重要。理论分析表明，需要视网膜外的中心偏外反馈解剖结构来锐化视网膜水平的“模糊输出”。这种反馈环路的数学特性表明瞬态复位机制对于避免拖尾是必要的。有人提出，瞬时视网膜细胞通过向较高水平的持续活动分布（视网膜外区域：例如，外侧膝状核（LGN）和/或视觉皮层区域）发送抑制信号来实现重置。在这个理论框架中，视觉系统的连续时间行为可以分为三个主要阶段进行分析。在第一阶段，持续的视网膜信号通过反馈主导的视网膜外环路而变得锐化。当输入移动时，将启动第二阶段。在此阶段，短暂的视网膜细胞快速且短暂地重置视网膜外活动。在第三阶段，视网膜外环路进入前馈模式，从而将视网膜活动的忠实副本转移到它们自己的细胞中。前馈模式由视网膜持续单元的瞬态分量维持。当视网膜单元进入稳态模式时，整个系统返回到第一阶段，其中通过反馈主导的视网膜外环路进行锐化。该理论的预测与各种实验数据进行了比较，重点是掩蔽和运动去模糊现象。
As a result of a variety of factors-the movements of the eyes, those of external objects, integration time, vergence, accommodation, and nonuniform retinal sampling-the retinal encoding is highly transient, blurred, and distorted. Yet this problem received very little attention, for most of the models proposed in the literature are built around the analysis of static (or steady-state) and uniformly focused images. Thus, a fundamental problem in visual perception consists of the understanding of the processes underlying the synthesis of phenomenally static, sharp percepts from transient, blurred activities. We present a continuous-time neural theory that proposes two major roles for the retinal transient activity: First, we propose that the nonmonotonic behavior of retinal neurons serves as a simple form of memory that adaptively filters visual signals to guide attentional mechanisms. Second, we propose that the transient activity is essential in achieving sharp dynamic percepts while preserving a good sensitivity to light. Theoretical analysis shows that an extraretinal on-center off-surround feedback anatomy is required to sharpen the ''blurred output ''from the retinal level. Mathematical properties of such feedback loops indicate that a transient reset mechanism is necessary to avoid smearing. It is proposed that transient retinal cells realize the reset by sending inhibitory signals to sustained activity distributions at higher levels (extraretinal areas: eg., lateral geniculate nucleus (LGN) and/or visual cortical areas). In this theoretical framework, the continuous time behavior of the visual system can be analyzed in three major phases. In the first phase, sustained retinal signals are sharpened by feedback dominant extra-retinal loops. When the input moves, a second phase is engaged. In this phase, transient retinal cells reset rapidly and briefly extra-retinal activities. In the third phase, extra-retinal loops enter a feedforward mode thereby transferring a faithful copy of retinal activity into their own cells. The feedforward mode is maintained by the transient components of the retinal sustained units. When retinal units enter their steady-state mode, the overall system returns to the first phase where sharpening occurs through feedback dominant extra-retinal loops. The predictions of the theory are compared with various experimental data with emphasis on masking and motion deblurring phenomena.