Morton Mitchell P, Denagamage Sachira, Hudson Nyomi V, Nandy Anirvan S
bioRxiv. 2024 Mar 11:2023.08.15.553380. doi: 10.1101/2023.08.15.553380.
A prevailing assumption in our understanding of how neurons in the primary visual cortex (V1) integrate contextual information is that such processes are spatially uniform. Conversely, perceptual phenomena such as visual crowding, the impaired ability to accurately recognize a target stimulus among distractors, suggest that interactions among stimuli are distinctly non-uniform. Prior studies have shown flankers at specific spatial geometries exert differential effects on target perception. To resolve this discrepancy, we investigated how flanker geometry impacted the representation of a target stimulus in the laminar microcircuits of V1. Our study reveals flanker location differentially impairs stimulus representation in excitatory neurons in the superficial and input layers of V1 by tuned suppression and untuned facilitation of orientation responses. Mechanistically, this effect can be explained by asymmetrical spatial kernels in a normalization model of cortical activity. Strikingly, these non-uniform modulations of neural representation mirror perceptual anisotropies. These results establish the non-uniform spatial integration of information in the earliest stages of cortical processing as a fundamental limitation of spatial vision.
在我们对初级视觉皮层（V1）中的神经元如何整合上下文信息的理解中，一个普遍的假设是这些过程在空间上是均匀的。相反，诸如视觉拥挤等感知现象，即在干扰物中准确识别目标刺激的能力受损，表明刺激之间的相互作用明显是非均匀的。先前的研究表明，特定空间几何形状的侧翼对目标感知有不同的影响。为了解决这一差异，我们研究了侧翼几何形状如何影响V1层状微电路中目标刺激的表征。我们的研究表明，侧翼位置通过对方向反应的调谐抑制和非调谐促进，对V1浅层和输入层兴奋性神经元中的刺激表征有不同程度的损害。从机制上讲，这种效应可以用皮层活动归一化模型中的不对称空间核来解释。引人注目的是，这些对神经表征的非均匀调制反映了感知各向异性。这些结果表明，在皮层处理的最早阶段，信息的非均匀空间整合是空间视觉的一个基本限制。
