Department of Biological Structure.
Washington National Primate Research Center, University of Washington, Seattle, Washington 98195.
J Neurosci. 2022 Jan 26;42(4):631-642. doi: 10.1523/JNEUROSCI.0971-21.2021. Epub 2021 Dec 3.
Texture is an important visual attribute for surface pattern discrimination and therefore object segmentation, but the neural bases of texture perception are largely unknown. Previously, we demonstrated that the responses of V4 neurons to naturalistic texture patches are sensitive to four key features of human texture perception: coarseness, directionality, regularity, and contrast. To begin to understand how distinct texture perception emerges from the dynamics of neuronal responses, in 2 macaque monkeys (1 male, 1 female), we investigated the relative contribution of the four texture attributes to V4 responses in terms of the strength and timing of response modulation. We found that the different feature dimensions are associated with different temporal dynamics. Specifically, the response modulation associated with directionality and regularity was significantly delayed relative to that associated with coarseness and contrast, suggesting that the latter are fundamentally simpler feature dimensions. The population of texture-selective neurons could be grouped into multiple clusters based on the combination of feature dimensions encoded, and those subpopulations displayed distinct temporal dynamics characterized by the weighted combinations of multiple features. Finally, we applied a population decoding approach to demonstrate that texture category information can be obtained from short temporal windows across time. These results demonstrate that the representation of different perceptually relevant texture features emerge over time in the responses of V4 neurons. The observed temporal organization provides a framework to interpret how the processing of surface features unfolds in early and midlevel cortical stages, and could ultimately inform the interpretation of perceptual texture dynamics. To delineate how neuronal responses underlie our ability to perceive visual textures, we related four key perceptual dimensions (coarseness, directionality, regularity, and contrast) of naturalistic textures to the strength and timing of modulation of neuronal responses in area V4, an intermediate stage in the form-processing, ventral visual pathway. Our results provide the first characterization of V4 temporal dynamics for texture encoding along perceptually defined axes.
纹理是表面图案识别和物体分割的重要视觉属性，但纹理感知的神经基础在很大程度上尚不清楚。以前，我们证明了 V4 神经元对自然纹理斑块的反应对人类纹理感知的四个关键特征敏感：粗糙度、方向性、规律性和对比度。为了开始了解从神经元反应的动力学中如何产生不同的纹理感知，在 2 只猕猴（1 只雄性，1 只雌性）中，我们根据反应调制的强度和时间来研究四个纹理属性对 V4 反应的相对贡献。我们发现，不同的特征维度与不同的时间动态相关。具体来说，与方向性和规律性相关的反应调制与粗糙度和对比度相关的反应调制相比显著延迟，这表明后者是更基本的简单特征维度。基于编码的特征维度组合，可以将具有纹理选择性的神经元群体分为多个簇，并且这些子群体表现出不同的时间动态特征，其特征是多个特征的加权组合。最后，我们应用群体解码方法来证明可以从时间上的短时间窗口中获得纹理类别的信息。这些结果表明，不同的感知相关纹理特征的表示在 V4 神经元的反应中随着时间的推移而出现。所观察到的时间组织为解释表面特征的处理如何在早期和中级皮层阶段展开提供了一个框架，并最终为解释感知纹理动态提供了信息。为了阐明神经元反应如何支持我们感知视觉纹理的能力，我们将自然纹理的四个关键感知维度（粗糙度、方向性、规律性和对比度）与 V4 神经元反应的调制强度和时间相关联，V4 是形式处理、腹侧视觉通路的中间阶段。我们的结果提供了 V4 时间动态的首次特征描述，用于沿着感知定义的轴进行纹理编码。
