Fourier power, subjective distance, and object categories all provide plausible models of BOLD responses in scene-selective visual areas.
Fourier power, subjective distance, and object categories all provide plausible models of BOLD responses in scene-selective visual areas.
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DOI：
10.3389/fncom.2015.00135
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发表时间：
2015
影响因子：
3.2
通讯作者：
Gallant JL
中科院分区：
文献类型：
--
作者：
Lescroart MD;Stansbury DE;Gallant JL
对自然视觉场景的感知激活了人类大脑中的几个功能区域，包括海马旁位置区（PPA），压后复合体（RSC）和枕骨位置区（OPA）。目前尚不清楚这些区域中代表了哪些特定的场景相关特征。先前的研究表明，PPA、RSC和/或OPA可能代表至少三种性质不同的特征类别：（1）与傅立叶功率相关的2D特征;（2）3D空间特征，例如到场景中对象的距离;或（3）抽象特征，例如场景中对象的类别。为了确定这些假设最好地描述了在场景选择性区域的视觉表示，我们采用体素建模（VM）BOLD功能磁共振成像反应引起的一组1386自然场景的图像。VM提供了一种有效的方法来测试竞争的假设，通过比较基于编码模型的大脑活动的预测，实例化每个假设。在这里，我们评估了三种不同的编码模型，它们分别实例化了上面列出的三个假设。我们使用线性回归将每个编码模型拟合到从每个体素记录的fMRI数据，并通过估计其在数据集的保留部分中预测的方差量来评估每个拟合模型。我们发现，基于傅立叶功率或每个场景中对象的主观距离的体素模型预测了基于对象类别的模型预测的大部分方差。此外，这三个模型解释的响应方差在很大程度上是共享的，并且各个模型解释的响应的独特方差很小。基于以往的研究和我们在这里提出的数据的评估，我们得出结论，目前没有很好的基础，有利于任何一个场景选择性区域的视觉表征的三个替代假设。我们为进一步的研究提供建议，可能有助于解决这个问题。
Perception of natural visual scenes activates several functional areas in the human brain, including the Parahippocampal Place Area (PPA), Retrosplenial Complex (RSC), and the Occipital Place Area (OPA). It is currently unclear what specific scene-related features are represented in these areas. Previous studies have suggested that PPA, RSC, and/or OPA might represent at least three qualitatively different classes of features: (1) 2D features related to Fourier power; (2) 3D spatial features such as the distance to objects in a scene; or (3) abstract features such as the categories of objects in a scene. To determine which of these hypotheses best describes the visual representation in scene-selective areas, we applied voxel-wise modeling (VM) to BOLD fMRI responses elicited by a set of 1386 images of natural scenes. VM provides an efficient method for testing competing hypotheses by comparing predictions of brain activity based on encoding models that instantiate each hypothesis. Here we evaluated three different encoding models that instantiate each of the three hypotheses listed above. We used linear regression to fit each encoding model to the fMRI data recorded from each voxel, and we evaluated each fit model by estimating the amount of variance it predicted in a withheld portion of the data set. We found that voxel-wise models based on Fourier power or the subjective distance to objects in each scene predicted much of the variance predicted by a model based on object categories. Furthermore, the response variance explained by these three models is largely shared, and the individual models explain little unique variance in responses. Based on an evaluation of previous studies and the data we present here, we conclude that there is currently no good basis to favor any one of the three alternative hypotheses about visual representation in scene-selective areas. We offer suggestions for further studies that may help resolve this issue.