Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom.
Proc Natl Acad Sci U S A. 2011 Jun 28;108(26):10726-31. doi: 10.1073/pnas.1101246108. Epub 2011 Jun 13.
Biological image processing has been hypothesized to adopt a coarse to fine strategy: the image is initially analyzed at a coarse spatial scale, and this analysis is then used to guide subsequent inspection at a finer scale. Neurons in visual cortex often display response characteristics that are consistent with this hypothesis for both monocular and binocular signals. Puzzlingly, measurements in human observers have failed to expose similar coarse to fine dynamics for human pattern vision, questioning the applicability of direct parallels between single neurons and perception. We performed a series of measurements using experimental protocols that were specifically designed to examine this question in more detail. We were able to confirm that, when the analysis is restricted to the linear properties of the perceptual process, no coarse to fine dynamics were evident in the data. However, when the analysis was extended to nonlinear descriptors, a clear coarse to fine structure emerged that consisted of two processes: an early nonlinear process operating on a coarse spatial scale followed by a linear process operating on a fine spatial scale. These results potentially serve to reduce the gap between the electrophysiological and behavioral findings.
图像最初在粗的空间尺度上进行分析，然后利用这种分析来指导后续更精细尺度的检查。对于单眼和双眼信号，视觉皮层中的神经元通常表现出与这一假设一致的反应特征。令人费解的是，人类观察者的测量结果未能揭示出人类模式视觉中类似的从粗到精的动力学特性，这使得人们对单细胞和感知之间的直接类比的适用性产生了质疑。我们采用了一系列实验方案进行测量，这些方案专门用于更详细地研究这个问题。我们能够证实，当分析仅限于感知过程的线性特性时，数据中没有明显的从粗到精的动力学特征。然而，当分析扩展到非线性描述符时，一个清晰的从粗到精的结构出现了，它由两个过程组成：一个在粗空间尺度上运行的早期非线性过程，随后是一个在细空间尺度上运行的线性过程。这些结果可能有助于缩小电生理和行为研究结果之间的差距。
