McMenamin Brenton W, Deason Rebecca G, Steele Vaughn R, Koutstaal Wilma, Marsolek Chad J
Department of Psychology, University of Maryland, College Park, United States.
Department of Psychology, Texas State University, United States.
Brain Cogn. 2015 Feb;93:54-63. doi: 10.1016/j.bandc.2014.11.007. Epub 2014 Dec 18.
Previous research indicates that dissociable neural subsystems underlie abstract-category (AC) recognition and priming of objects (e.g., cat, piano) and specific-exemplar (SE) recognition and priming of objects (e.g., a calico cat, a different calico cat, a grand piano, etc.). However, the degree of separability between these subsystems is not known, despite the importance of this issue for assessing relevant theories. Visual object representations are widely distributed in visual cortex, thus a multivariate pattern analysis (MVPA) approach to analyzing functional magnetic resonance imaging (fMRI) data may be critical for assessing the separability of different kinds of visual object processing. Here we examined the neural representations of visual object categories and visual object exemplars using multi-voxel pattern analyses of brain activity elicited in visual object processing areas during a repetition-priming task. In the encoding phase, participants viewed visual objects and the printed names of other objects. In the subsequent test phase, participants identified objects that were either same-exemplar primed, different-exemplar primed, word-primed, or unprimed. In visual object processing areas, classifiers were trained to distinguish same-exemplar primed objects from word-primed objects. Then, the abilities of these classifiers to discriminate different-exemplar primed objects and word-primed objects (reflecting AC priming) and to discriminate same-exemplar primed objects and different-exemplar primed objects (reflecting SE priming) was assessed. Results indicated that (a) repetition priming in occipital-temporal regions is organized asymmetrically, such that AC priming is more prevalent in the left hemisphere and SE priming is more prevalent in the right hemisphere, and (b) AC and SE subsystems are weakly modular, not strongly modular or unified.
先前的研究表明，可分离的神经子系统是抽象类别（AC）识别和物体启动（例如，猫、钢琴）以及特定范例（SE）识别和物体启动（例如，一只花斑猫、另一只不同的花斑猫、一架三角钢琴等）的基础。然而，尽管这个问题对于评估相关理论很重要，但这些子系统之间的可分离程度尚不清楚。视觉物体表征广泛分布于视觉皮层，因此，一种用于分析功能磁共振成像（fMRI）数据的多变量模式分析（MVPA）方法对于评估不同类型视觉物体加工的可分离性可能至关重要。在这里，我们使用多体素模式分析来研究视觉物体类别和视觉物体范例的神经表征，该分析针对在重复启动任务期间视觉物体加工区域中引发的大脑活动。在编码阶段，参与者观看视觉物体以及其他物体的印刷名称。在随后的测试阶段，参与者识别那些要么是同范例启动、不同范例启动、单词启动，要么是未启动的物体。在视觉物体加工区域，训练分类器以区分同范例启动的物体和单词启动的物体。然后，评估这些分类器区分不同范例启动的物体和单词启动的物体（反映AC启动）以及区分同范例启动的物体和不同范例启动的物体（反映SE启动）的能力。结果表明：（a）枕颞区域的重复启动是不对称组织的，使得AC启动在左半球更普遍，而SE启动在右半球更普遍；（b）AC和SE子系统是弱模块化而非强模块化或统一的。
