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arXiv 2103.09954q-bio.NCphysics.bio-ph
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初级视觉皮层特征映射的分析模型

Analytic model for feature maps in the primary visual cortex

Xiaochen Liu, Peter A. Robinson

摘要:

提出了一个简洁的分析模型来描述初级视觉皮层(V1)简单细胞的方位偏好(OP)和眼优势(OD)特征及其布局。该模型由三个部分组成:(i)各向异性拉普拉斯算子(AL),其表示局部神经对视觉输入方向的敏感性;(ii)感受野(RF)算子,其模拟在零点几毫米尺度上投射到给定V1细胞的各向异性空间RF,并与AL算子组合以给出总体OP算子;以及(iii)描述这些算子的参数如何在V1上近似周期性地变化的映射。所提出的模型的参数最大化神经响应在一个给定的OP与OP调谐曲线拟合实验结果。结果表明,AL算符的各向异性对OP选择性没有显著影响,而OP选择性主要由RF各向异性决定,这与Hubel和Wittlefield关于V1单胞的取向调谐宽度与其RF的伸长成反比的结论一致.一个简化的OP-OD映射,然后构造描述的近似周期OP-OD结构的V1在一个紧凑的形式。具体而言,地图近似保留其占主导地位的空间傅立叶系数,这是足以重建的OP-OD地图的整体结构。这种表示是一种比较适合于分析观测映射的形式,并可用于V1神经场论。独立模拟的V1结构的应用表明,观察到的不规则性的地图对应于一个循环中的傅立叶空间中的主导系数的传播。

英文摘要:

A compact analytic model is proposed to describe the combined orientation preference (OP) and ocular dominance (OD) features of simple cells and their layout in the primary visual cortex (V1). This model consists of three parts: (i) an anisotropic Laplacian (AL) operator that represents the local neural sensitivity to the orientation of visual inputs; (ii) a receptive field (RF) operator that models the anisotropic spatial RF that projects to a given V1 cell over scales of a few tenths of a millimeter and combines with the AL operator to give an overall OP operator; and (iii) a map that describes how the parameters of these operators vary approximately periodically across V1. The parameters of the proposed model maximize the neural response at a given OP with an OP tuning curve fitted to experimental results. It is found that the anisotropy of the AL operator does not significantly affect OP selectivity, which is dominated by the RF anisotropy, consistent with Hubel and Wiesel's original conclusions that orientation tuning width of V1 simple cell is inversely related to the elongation of its RF. A simplified OP-OD map is then constructed to describe the approximately periodic OP-OD structure of V1 in a compact form. Specifically, the map is approximated by retaining its dominant spatial Fourier coefficients, which are shown to suffice to reconstruct the overall structure of the OP-OD map. This representation is a suitable form to analyze observed maps compactly and to be used in neural field theory of V1. Application to independently simulated V1 structures shows that observed irregularities in the map correspond to a spread of dominant coefficients in a circle in Fourier space.

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