Kaiser Daniel, Azzalini Damiano C, Peelen Marius V
Center for Mind/Brain Sciences, University of Trento, Rovereto, Trentino, Italy.
Center for Mind/Brain Sciences, University of Trento, Rovereto, Trentino, Italy
J Neurophysiol. 2016 Apr;115(4):2246-50. doi: 10.1152/jn.01074.2015. Epub 2016 Jan 6.
Neuroimaging research has identified category-specific neural response patterns to a limited set of object categories. For example, faces, bodies, and scenes evoke activity patterns in visual cortex that are uniquely traceable in space and time. It is currently debated whether these apparently categorical responses truly reflect selectivity for categories or instead reflect selectivity for category-associated shape properties. In the present study, we used a cross-classification approach on functional MRI (fMRI) and magnetoencephalographic (MEG) data to reveal both category-independent shape responses and shape-independent category responses. Participants viewed human body parts (hands and torsos) and pieces of clothing that were closely shape-matched to the body parts (gloves and shirts). Category-independent shape responses were revealed by training multivariate classifiers on discriminating shape within one category (e.g., hands versus torsos) and testing these classifiers on discriminating shape within the other category (e.g., gloves versus shirts). This analysis revealed significant decoding in large clusters in visual cortex (fMRI) starting from 90 ms after stimulus onset (MEG). Shape-independent category responses were revealed by training classifiers on discriminating object category (bodies and clothes) within one shape (e.g., hands versus gloves) and testing these classifiers on discriminating category within the other shape (e.g., torsos versus shirts). This analysis revealed significant decoding in bilateral occipitotemporal cortex (fMRI) and from 130 to 200 ms after stimulus onset (MEG). Together, these findings provide evidence for concurrent shape and category selectivity in high-level visual cortex, including category-level responses that are not fully explicable by two-dimensional shape properties.
神经影像学研究已经确定了针对有限的一组物体类别的特定类别神经反应模式。例如，面部、身体和场景会在视觉皮层中引发活动模式，这些模式在空间和时间上具有独特的可追溯性。目前存在争议的是，这些明显的类别反应是真正反映了对类别的选择性，还是相反反映了对与类别相关的形状属性的选择性。在本研究中，我们对功能磁共振成像（fMRI）和脑磁图（MEG）数据采用交叉分类方法，以揭示与类别无关的形状反应和与形状无关的类别反应。参与者观看人体部位（手和躯干）以及与人体部位形状紧密匹配的衣物（手套和衬衫）。通过在一个类别内（例如，手与躯干）训练多变量分类器以区分形状，并在另一个类别内（例如，手套与衬衫）测试这些分类器以区分形状，从而揭示与类别无关的形状反应。该分析显示，从刺激开始后90毫秒起，在视觉皮层的大簇区域（fMRI）中存在显著的解码（MEG）。通过在一种形状内（例如，手与手套）训练分类器以区分物体类别（身体和衣物），并在另一种形状内（例如，躯干与衬衫）测试这些分类器以区分类别，从而揭示与形状无关的类别反应。该分析显示，在双侧枕颞叶皮层（fMRI）以及刺激开始后130至200毫秒（MEG）存在显著的解码。总之，这些发现为高级视觉皮层中同时存在的形状和类别选择性提供了证据，包括不能完全由二维形状属性解释的类别水平反应。
