Srinath Ramanujan, Ni Amy M, Marucci Claire, Cohen Marlene R, Brainard David H
equal contribution.
Department of Neurobiology and Neuroscience Institute, The University of Chicago, Chicago, IL 60637, USA.
bioRxiv. 2024 Jun 4:2024.02.14.580134. doi: 10.1101/2024.02.14.580134.
In natural behavior, observers must separate relevant information from a barrage of irrelevant information. Many studies have investigated the neural underpinnings of this ability using artificial stimuli presented on simple backgrounds. Natural viewing, however, carries a set of challenges that are inaccessible using artificial stimuli, including neural responses to background objects that are task-irrelevant. An emerging body of evidence suggests that the visual abilities of humans and animals can be modeled through the linear decoding of task-relevant information from visual cortex. This idea suggests the hypothesis that irrelevant features of a natural scene should impair performance on a visual task only if their neural representations intrude on the linear readout of the task relevant feature, as would occur if the representations of task-relevant and irrelevant features are not orthogonal in the underlying neural population. We tested this hypothesis using human psychophysics and monkey neurophysiology, in response to parametrically variable naturalistic stimuli. We demonstrate that 1) the neural representation of one feature (the position of a central object) in visual area V4 is orthogonal to those of several background features, 2) the ability of human observers to precisely judge object position was largely unaffected by task-irrelevant variation in those background features, and 3) many features of the object and the background are orthogonally represented by V4 neural responses. Our observations are consistent with the hypothesis that orthogonal neural representations can support stable perception of objects and features despite the tremendous richness of natural visual scenes.
在自然行为中，观察者必须从大量无关信息中分离出相关信息。许多研究使用呈现于简单背景上的人工刺激来探究这种能力的神经基础。然而，自然观察存在一系列使用人工刺激无法触及的挑战，包括对与任务无关的背景物体的神经反应。越来越多的证据表明，人类和动物的视觉能力可以通过从视觉皮层对任务相关信息进行线性解码来建模。这一观点提出了一个假设：只有当自然场景的无关特征的神经表征干扰任务相关特征的线性读出时，这些特征才会损害视觉任务的表现，就像在基础神经群体中任务相关和无关特征的表征不正交时所发生的那样。我们使用人类心理物理学和猴子神经生理学，针对参数可变的自然主义刺激来检验这一假设。我们证明：1）视觉区域V4中一个特征（中央物体的位置）的神经表征与几个背景特征的神经表征是正交的；2）人类观察者精确判断物体位置的能力在很大程度上不受那些背景特征中与任务无关变化的影响；3）物体和背景的许多特征由V4神经反应正交表征。我们的观察结果与以下假设一致：尽管自然视觉场景极其丰富，但正交神经表征能够支持对物体和特征的稳定感知。
