Li Sheng, Ostwald Dirk, Giese Martin, Kourtzi Zoe
School of Psychology, University of Birmingham, Birmingham B15 2TT, United Kingdom.
J Neurosci. 2007 Nov 7;27(45):12321-30. doi: 10.1523/JNEUROSCI.3795-07.2007.
Despite the importance of visual categorization for interpreting sensory experiences, little is known about the neural representations that mediate categorical decisions in the human brain. Here, we used psychophysics and pattern classification for the analysis of functional magnetic resonance imaging data to predict the features critical for categorical decisions from brain activity when observers categorized the same stimuli using different rules. Although a large network of cortical and subcortical areas contain information about visual categories, we show that only a subset of these areas shape their selectivity to reflect the behaviorally relevant features rather than simply physical similarity between stimuli. Specifically, temporal and parietal areas show selectivity for the perceived form and motion similarity, respectively. In contrast, frontal areas and the striatum represent the conjunction of spatiotemporal features critical for complex and adaptive categorization tasks and potentially modulate selectivity in temporal and parietal areas. These findings provide novel evidence for flexible neural coding in the human brain that translates sensory experiences to categorical decisions by shaping neural representations across a network of areas with dissociable functional roles in visual categorization.
尽管视觉分类对于解释感官体验至关重要，但对于介导人类大脑中分类决策的神经表征却知之甚少。在此，我们运用心理物理学和模式分类方法来分析功能磁共振成像数据，以便在观察者使用不同规则对相同刺激进行分类时，从大脑活动中预测对分类决策至关重要的特征。尽管大量的皮质和皮质下区域网络包含有关视觉类别的信息，但我们表明，这些区域中只有一部分会塑造其选择性，以反映行为上相关的特征，而不是简单地反映刺激之间的物理相似性。具体而言，颞叶和顶叶区域分别对感知到的形状和运动相似性表现出选择性。相比之下，额叶区域和纹状体则代表了对复杂且适应性分类任务至关重要的时空特征的结合，并可能调节颞叶和顶叶区域的选择性。这些发现为人类大脑中的灵活神经编码提供了新证据，这种神经编码通过在视觉分类中具有不同功能作用的区域网络中塑造神经表征，将感官体验转化为分类决策。
