O'Toole Alice J, Natu Vaidehi, An Xiaobo, Rice Allyson, Ryland James, Phillips P Jonathon
The University of Texas at Dallas, USA.
The University of Texas at Dallas, USA.
Neuroimage. 2014 May 1;91:1-11. doi: 10.1016/j.neuroimage.2014.01.038. Epub 2014 Jan 29.
The neural organization of person processing relies on brain regions functionally selective for faces or bodies, with a subset of these regions preferring moving stimuli. Although the response properties of the individual areas are well established, less is known about the neural response to a whole person in a natural environment. Targeting an area of cortex that spans multiple functionally-selective face and body regions, we examined the relationship among neural activity patterns elicited in response to faces, bodies, and people in static and moving displays. When both stimuli were static or moving, pattern classification analyses indicated highly discriminable responses to faces, bodies, and whole people. Neural discrimination transferred in both directions between representations created from moving or static stimuli. It transferred also to stimuli experienced across static and dynamic presentations (one static and the other dynamic). In both transfer cases, however, discrimination accuracy decreased relative to the case where the representations were both created and tested with static or moving forms. Next, we examined the relative contribution of activity pattern and response magnitude to discrimination by comparing classifiers that operated with magnitude-normalized scans with classifiers that retained pattern and magnitude information. When both stimuli were moving or static, response magnitude contributed to classification, but the spatially distributed activity pattern accounted for most of the discrimination. Across static and moving presentations, activity pattern accounted completely for the discriminability of neural responses to faces, bodies, and people, with no contribution from response magnitude. Combined, the results indicate redundant and flexible access to person-based shape codes from moving and static presentations. The transfer of shape information across presentation types that preferentially access dorsal and ventral visual processing streams indicates that a common shape code may ground functional divisions in the processing of face and body information.
对人的加工的神经组织依赖于对面孔或身体具有功能选择性的脑区,其中一部分脑区更倾向于运动刺激。尽管各个区域的反应特性已得到充分证实,但对于自然环境中整个人体的神经反应了解较少。针对跨越多个功能选择性面孔和身体区域的皮质区域,我们研究了在静态和动态展示中,对面孔、身体和人的神经活动模式之间的关系。当两种刺激都是静态或动态时,模式分类分析表明对面孔、身体和整个人体有高度可区分的反应。神经辨别在由动态或静态刺激创建的表征之间双向转移。它也转移到在静态和动态呈现(一个静态和另一个动态)中经历的刺激。然而,在这两种转移情况下,辨别准确率相对于表征均以静态或动态形式创建和测试的情况有所下降。接下来,我们通过比较对幅度归一化扫描进行操作的分类器与保留模式和幅度信息的分类器,研究了活动模式和反应幅度对辨别的相对贡献。当两种刺激都是动态或静态时,反应幅度有助于分类,但空间分布的活动模式占辨别作用的大部分。在静态和动态呈现中,活动模式完全决定了对面孔、身体和人的神经反应的可辨别性,反应幅度没有作用。综合来看,结果表明从动态和静态呈现中对基于人的形状编码有冗余且灵活的获取方式。形状信息在优先访问背侧和腹侧视觉处理流的呈现类型之间的转移表明,一个共同的形状编码可能是面孔和身体信息处理中功能划分的基础。