Nirody Jasmine A
J Comput Neurosci. 2014 Jun;36(3):401-14. doi: 10.1007/s10827-013-0480-6.
The sequential analysis of information in a coarse-to-fine manner is a fundamental mode of processing in the visual pathway. Spatial frequency (SF) tuning, arguably the most fundamental feature of spatial vision, provides particular intuition within the coarse-to-fine framework: low spatial frequencies convey global information about an image (e.g., general orientation), while high spatial frequencies carry more detailed information (e.g., edges). In this paper, we study the development of cortical spatial frequency tuning. As feedforward input from the lateral geniculate nucleus (LGN) has been shown to have significant influence on cortical coarse-to-fine processing, we present a firing-rate based thalamocortical model which includes both feedforward and feedback components. We analyze the relationship between various model parameters (including cortical feedback strength) and responses. We confirm the importance of the antagonistic relationship between the center and surround responses in thalamic relay cell receptive fields (RFs), and further characterize how specific structural LGN RF parameters affect cortical coarse-to-fine processing. Our results also indicate that the effect of cortical feedback on spatial frequency tuning is age-dependent: in particular, cortical feedback more strongly affects coarse-to-fine processing in kittens than in adults. We use our results to propose an experimentally testable hypothesis for the function of the extensive feedback in the corticothalamic circuit.
以从粗到细的方式对信息进行顺序分析是视觉通路中的一种基本处理模式。空间频率（SF）调谐可以说是空间视觉最基本的特征，在从粗到细的框架内提供了特别的直观理解：低空间频率传达有关图像的全局信息（例如，大致方向），而高空间频率携带更详细的信息（例如，边缘）。在本文中，我们研究皮质空间频率调谐的发展。由于已证明来自外侧膝状体核（LGN）的前馈输入对皮质从粗到细的处理有重大影响，我们提出了一种基于发放率的丘脑皮质模型，该模型包括前馈和反馈成分。我们分析了各种模型参数（包括皮质反馈强度）与反应之间的关系。我们证实了丘脑中继细胞感受野（RFs）中中心和周边反应之间拮抗关系的重要性，并进一步描述了特定的LGN RF结构参数如何影响皮质从粗到细的处理。我们的结果还表明，皮质反馈对空间频率调谐的影响是年龄依赖性的：特别是，皮质反馈对小猫从粗到细处理的影响比对成年动物的影响更强。我们利用我们的结果为皮质丘脑回路中广泛反馈的功能提出了一个可通过实验检验的假设。
