Center for Mind/Brain Sciences, University of Trento, Trento, 38068, Italy.
Sci Rep. 2019 Jan 18;9(1):239. doi: 10.1038/s41598-018-37429-2.
Categories describe semantic divisions between classes of objects and category-based models are widely used for investigation of the conceptual system. One critical issue in this endeavour is the isolation of conceptual from perceptual contributions to category-differences. An unambiguous way to address this confound is combining multiple input-modalities. To this end, we showed participants person/place stimuli using name and picture modalities. Using multivariate methods, we searched for category-sensitive neural patterns shared across input-modalities and thus independent from perceptual properties. The millisecond temporal resolution of magnetoencephalography (MEG) allowed us to consider the precise timing of conceptual access and, by confronting latencies between the two modalities ("time generalization"), how latencies of processing depends on the input-modality. Our results identified category-sensitive conceptual representations common between modalities at three stages and that conceptual access for words was delayed by about 90 msec with respect to pictures. We also show that for pictures, the first conceptual pattern of activity (shared between both words and pictures) occurs as early as 110 msec. Collectively, our results indicated that conceptual access at the category-level is a multistage process and that different delays in access across these two input-modalities determine when these representations are activated.
类别描述了对象类之间的语义划分，基于类别的模型被广泛用于研究概念系统。在这一努力中，一个关键问题是将概念与感知对类别差异的贡献分开。解决这种混淆的一种明确方法是结合多种输入模式。为此，我们使用名称和图片模式向参与者展示了人与地点的刺激。我们使用多元方法搜索了跨输入模式共享的、与感知属性无关的类别敏感神经模式。脑磁图（MEG）的毫秒时间分辨率使我们能够考虑概念访问的精确时间，并通过比较两种模式之间的潜伏期（“时间泛化”），了解处理潜伏期如何取决于输入模式。我们的结果在三个阶段确定了模态之间共享的类别敏感的概念表示，并且与图片相比，单词的概念访问延迟了约 90 毫秒。我们还表明，对于图片，第一个概念活动模式（在单词和图片之间共享）早在 110 毫秒时就出现了。总的来说，我们的结果表明，类别水平的概念访问是一个多阶段的过程，并且这两种输入模式之间的访问延迟不同，决定了这些表示何时被激活。
