Responses of V1 neurons to two-dimensional hermite functions.
Responses of V1 neurons to two-dimensional hermite functions.
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DOI：
10.1152/jn.00498.2005
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发表时间：
2006
影响因子：
2.5
通讯作者：
J. Victor;F. Mechler;M. A. Repucci;K. Purpura;T. Sharpee
中科院分区：
文献类型：
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作者：
J. Victor;F. Mechler;M. A. Repucci;K. Purpura;T. Sharpee
初级视皮层神经元被广泛认为是进行一维特征分析的定向滤波器或能量检测器。通常认为，与这幅图的主要偏差包括增益控制和调制影响。在这里，我们研究了单神经元的感受野（RF）特性与局部的二维刺激，二维厄米函数（TDH）。TDH可以被分组为不同的完整的正交基，其在对比度能量、空间范围和空间频率内容上匹配，但在二维形式上不同，因此可以用于探测空间特定的非线性。在这里，我们使用两个这样的基地：笛卡尔TDH，这类似于渐晕光栅和棋盘，和极性TDH，这类似于渐晕环和飞镖。在63个孤立单位中，51个对TDH刺激有反应。在37/51个单位中，我们发现总体响应大小（21/51）或明显的RF形状（28/51）存在显著差异，这取决于使用的基组。由于TDH刺激的性质，这些发现与简单的前馈非线性和许多能量模型的变体不一致。相反，它们意味着非线性的存在，不是本地的空间或空间频率。显示这些差异的单位在猫和猴中，在简单和复杂的细胞中，以及在颗粒上、颗粒下和颗粒层中，存在相似的程度。因此，我们发现了一个广泛分布的神经生理学基板的二维空间分析的最早阶段的皮层处理。此外，调谐到TDH功能的群体模式表明，V1神经元不仅采样方向，而且以均匀的方式采样二维形式的更大空间。
Neurons in primary visual cortex are widely considered to be oriented filters or energy detectors that perform one-dimensional feature analysis. The main deviations from this picture are generally thought to include gain controls and modulatory influences. Here we investigate receptive field (RF) properties of single neurons with localized two-dimensional stimuli, the two-dimensional Hermite functions (TDHs). TDHs can be grouped into distinct complete orthonormal bases that are matched in contrast energy, spatial extent, and spatial frequency content but differ in two-dimensional form, and thus can be used to probe spatially specific nonlinearities. Here we use two such bases: Cartesian TDHs, which resemble vignetted gratings and checkerboards, and polar TDHs, which resemble vignetted annuli and dartboards. Of 63 isolated units, 51 responded to TDH stimuli. In 37/51 units, we found significant differences in overall response size (21/51) or apparent RF shape (28/51) that depended on which basis set was used. Because of the properties of the TDH stimuli, these findings are inconsistent with simple feedforward nonlinearities and with many variants of energy models. Rather, they imply the presence of nonlinearities that are not local in either space or spatial frequency. Units showing these differences were present to a similar degree in cat and monkey, in simple and complex cells, and in supragranular, infragranular, and granular layers. We thus find a widely distributed neurophysiological substrate for two-dimensional spatial analysis at the earliest stages of cortical processing. Moreover, the population pattern of tuning to TDH functions suggests that V1 neurons sample not only orientations, but a larger space of two-dimensional form, in an even-handed manner.