Direction-selective motion discrimination by traveling waves in visual cortex
Direction-selective motion discrimination by traveling waves in visual cortex
复制标题
DOI：
10.1371/journal.pcbi.1008164
复制
发表时间：
2020-09-01
影响因子：
4.3
通讯作者：
Ermentrout, G. Bard
中科院分区：
文献类型：
--
作者：
Heitmann, Stewart;Ermentrout, G. Bard
众所周知，初级视觉皮层的所谓“简单细胞”优先响应以特定速度和方向穿过视野的定向光条。这种神经元的时空响应被认为是不可分离的，因为它们不能从独立的空间和时间神经机制构建。神经元如何计算不可分离反应的当代理论通常依赖于来自视野不同区域的信号之间的微调传输延迟。然而，这种拖延的存在是有争议的。我们提出了一种替代的神经机制，用于计算不需要传输延迟的不可分离的响应。相反，它依赖于皮质组织的倾向，自发地产生以特定速度和方向传播的神经活动的时空波。我们认为内源性波活动与视觉刺激产生共振，从而引起对视觉运动的方向选择性神经反应。我们在计算机模型中证明了这一原理，并表明对立神经元之间的竞争有力地增强了它们区分向相反方向移动的视觉光栅的能力。初级视觉皮层中的大多数神经元选择性地对具有特定方向并向特定方向移动的光条做出反应。这种神经元的空间和时间响应是不可分离的。神经元如何在不诉诸显式时间延迟的情况下完成计算壮举尚不清楚。我们提出了一种新的神经机制，即视觉皮层计算不可分离的反应，通过产生内源性行波的神经活动，共振的时空签名的视觉刺激。反应的时空特征由皮层中兴奋性和抑制性横向连接的局部拓扑结构定义。我们模拟了内源性行波和视觉刺激之间的相互作用，使用空间分布的兴奋性和抑制性神经元与Wilson-Cowan动力学和周围耦合。我们的模型可靠地检测到以给定速度和方向移动的视觉光栅，前提是我们结合了神经竞争来抑制相反方向的错误运动信号。研究结果表明，内源性行波在视觉皮层可以赋予方向选择性的神经反应，而不诉诸显式的时间延迟。他们还建议在消除虚假的运动信号的功能作用的运动顺应性。
Author summary It is well established that the so-called 'simple cells' of the primary visual cortex respond preferentially to oriented bars of light that move across the visual field with a particular speed and direction. The spatiotemporal responses of such neurons are said to be non-separable because they cannot be constructed from independent spatial and temporal neural mechanisms. Contemporary theories of how neurons compute non-separable responses typically rely on finely tuned transmission delays between signals from disparate regions of the visual field. However the existence of such delays is controversial. We propose an alternative neural mechanism for computing non-separable responses that does not require transmission delays. It instead relies on the predisposition of the cortical tissue to spontaneously generate spatiotemporal waves of neural activity that travel with a particular speed and direction. We propose that the endogenous wave activity resonates with the visual stimulus to elicit direction-selective neural responses to visual motion. We demonstrate the principle in computer models and show that competition between opposing neurons robustly enhances their ability to discriminate between visual gratings that move in opposite directions.The majority of neurons in primary visual cortex respond selectively to bars of light that have a specific orientation and move in a specific direction. The spatial and temporal responses of such neurons are non-separable. How neurons accomplish that computational feat without resort to explicit time delays is unknown. We propose a novel neural mechanism whereby visual cortex computes non-separable responses by generating endogenous traveling waves of neural activity that resonate with the space-time signature of the visual stimulus. The spatiotemporal characteristics of the response are defined by the local topology of excitatory and inhibitory lateral connections in the cortex. We simulated the interaction between endogenous traveling waves and the visual stimulus using spatially distributed populations of excitatory and inhibitory neurons with Wilson-Cowan dynamics and inhibitory-surround coupling. Our model reliably detected visual gratings that moved with a given speed and direction provided that we incorporated neural competition to suppress false motion signals in the opposite direction. The findings suggest that endogenous traveling waves in visual cortex can impart direction-selectivity on neural responses without resort to explicit time delays. They also suggest a functional role for motion opponency in eliminating false motion signals.