Spatial Stereoresolution for Depth Corrugations May Be Set in Primary Visual Cortex
Spatial Stereoresolution for Depth Corrugations May Be Set in Primary Visual Cortex
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DOI：
10.1371/journal.pcbi.1002142
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发表时间：
2011-08-01
影响因子：
4.3
通讯作者：
Read, Jenny C. A.
中科院分区：
文献类型：
--
作者：
Allenmark, Fredrik;Read, Jenny C. A.
立体“3D”深度感知要求视觉系统提取双眼图像之间的双目视差。基于已知的初级视觉皮质(V1)的生理学，当前的几个模型通过计算左眼和右眼图像之间的分段额叶平行局部互相关来实现这一过程。检测器检查局部互相关的“窗口”的大小与V1神经元的感受野大小相对应。这个基本模型成功地捕捉到了人类深度感知的许多方面。特别是，这解释了人类对正弦深度波纹的低立体分辨率，这表明立体分辨率的限制可能是在初级视觉皮质。该模型的一个重要特征反映了V1神经元的一个关键特性，即初始视差编码是由调谐到局部均匀视差斑块的检测器执行的。这种探测器对方波深度波纹的响应比对几乎到处倾斜的正弦波纹的响应更好，因为方波深度波纹局部是平的。因此，对于任何给定的窗口大小，当前的模型预测方波差异波纹的性能比高幅度正弦波波纹的性能更好。我们最近已经证明，这一预测并不成立：人类在方波和正弦波纹上的表现并不比在正弦波纹上更好，即使在高波幅下也是如此。这一预测的失败提出了一个问题，即立体分辨率是否实际上可能是在大脑皮层处理的后期阶段设定的，可能涉及到调节到视差倾斜或曲率的神经元。在这里，我们扩展了局部互相关模型，以包括现有的生理和心理物理证据，表明具有更大感受野的神经元可以检测到更大的差异(大小/差异相关)。我们发现，这一简单的修改成功地使模型与人类的结果相一致，证实了视差栅格的立体分辨率确实可能受到初级视觉皮质接受野大小的限制。
Stereo "3D" depth perception requires the visual system to extract binocular disparities between the two eyes' images. Several current models of this process, based on the known physiology of primary visual cortex (V1), do this by computing a piecewise-frontoparallel local cross-correlation between the left and right eye's images. The size of the "window" within which detectors examine the local cross-correlation corresponds to the receptive field size of V1 neurons. This basic model has successfully captured many aspects of human depth perception. In particular, it accounts for the low human stereoresolution for sinusoidal depth corrugations, suggesting that the limit on stereoresolution may be set in primary visual cortex. An important feature of the model, reflecting a key property of V1 neurons, is that the initial disparity encoding is performed by detectors tuned to locally uniform patches of disparity. Such detectors respond better to square-wave depth corrugations, since these are locally flat, than to sinusoidal corrugations which are slanted almost everywhere. Consequently, for any given window size, current models predict better performance for square-wave disparity corrugations than for sine-wave corrugations at high amplitudes. We have recently shown that this prediction is not borne out: humans perform no better with square-wave than with sine-wave corrugations, even at high amplitudes. The failure of this prediction raised the question of whether stereoresolution may actually be set at later stages of cortical processing, perhaps involving neurons tuned to disparity slant or curvature. Here we extend the local cross-correlation model to include existing physiological and psychophysical evidence indicating that larger disparities are detected by neurons with larger receptive fields (a size/disparity correlation). We show that this simple modification succeeds in reconciling the model with human results, confirming that stereoresolution for disparity gratings may indeed be limited by the size of receptive fields in primary visual cortex.