Neurosciences Graduate Program, University of California, San Diego, La Jolla, California.
Department of Psychology, University of California, San Diego, La Jolla, California.
J Neurophysiol. 2019 Apr 1;121(4):1410-1427. doi: 10.1152/jn.00015.2019. Epub 2019 Feb 13.
Searching for items that are useful given current goals, or "target" recognition, requires observers to flexibly attend to certain object properties at the expense of others. This could involve focusing on the identity of an object while ignoring identity-preserving transformations such as changes in viewpoint or focusing on its current viewpoint while ignoring its identity. To effectively filter out variation due to the irrelevant dimension, performing either type of task is likely to require high-level, abstract search templates. Past work has found target recognition signals in areas of ventral visual cortex and in subregions of parietal and frontal cortex. However, target status in these tasks is typically associated with the identity of an object, rather than identity-orthogonal properties such as object viewpoint. In this study, we used a task that required subjects to identify novel object stimuli as targets according to either identity or viewpoint, each of which was not predictable from low-level properties such as shape. We performed functional MRI in human subjects of both sexes and measured the strength of target-match signals in areas of visual, parietal, and frontal cortex. Our multivariate analyses suggest that the multiple-demand (MD) network, including subregions of parietal and frontal cortex, encodes information about an object's status as a target in the relevant dimension only, across changes in the irrelevant dimension. Furthermore, there was more target-related information in MD regions on correct compared with incorrect trials, suggesting a strong link between MD target signals and behavior. NEW & NOTEWORTHY Real-world target detection tasks, such as searching for a car in a crowded parking lot, require both flexibility and abstraction. We investigated the neural basis of these abilities using a task that required invariant representations of either object identity or viewpoint. Multivariate decoding analyses of our whole brain functional MRI data reveal that invariant target representations are most pronounced in frontal and parietal regions, and the strength of these representations is associated with behavioral performance.
在当前目标下搜索有用的项目,或者“目标”识别,要求观察者灵活地关注某些对象属性,而忽略其他属性。这可能涉及专注于对象的身份,同时忽略保持身份的变换,例如视角的变化,或者专注于对象的当前视角,同时忽略其身份。为了有效地过滤掉由于不相关维度而产生的变化,执行这两种任务中的任何一种都可能需要高级、抽象的搜索模板。过去的研究在腹侧视觉皮层以及顶叶和额叶皮层的亚区中发现了目标识别信号。然而,在这些任务中,目标状态通常与对象的身份相关,而不是与对象视角等身份正交的属性相关。在这项研究中,我们使用了一项任务,要求受试者根据身份或视角将新的对象刺激识别为目标,其中每个目标都不能从形状等低水平属性来预测。我们在男女两性的人类受试者中进行了功能磁共振成像,并测量了视觉、顶叶和额叶皮层区域中目标匹配信号的强度。我们的多元分析表明,多需求(MD)网络,包括顶叶和额叶皮层的亚区,仅在相关维度中编码与对象状态作为目标相关的信息,而在不相关维度中则不编码。此外,在正确的试验中,MD 区域的目标相关信息比错误的试验更多,这表明 MD 目标信号与行为之间存在很强的联系。 新的和值得注意的是,像在拥挤的停车场中寻找汽车这样的现实世界目标检测任务,既需要灵活性,也需要抽象性。我们使用需要对象身份或视角不变表示的任务来研究这些能力的神经基础。我们对全脑功能磁共振成像数据的多元解码分析表明,不变的目标表示在额叶和顶叶区域最为明显,并且这些表示的强度与行为表现相关。