Psychology Department, Stanford University, Stanford, CA, 94305, USA.
Psychology Department, Stanford University, Stanford, CA, 94305, USA.
Neuroimage. 2018 Jul 15;175:188-200. doi: 10.1016/j.neuroimage.2018.03.064. Epub 2018 Mar 28.
A region in the posterior inferior temporal gyrus (ITG), referred to as the number form area (NFA, here ITG-numbers) has been implicated in the visual processing of Arabic numbers. However, it is unknown if this region is specifically involved in the visual encoding of Arabic numbers per se or in mathematical processing more broadly. Using functional magnetic resonance imaging (fMRI) during experiments that systematically vary tasks and stimuli, we find that mathematical processing, not preference to Arabic numbers, consistently drives both mean and distributed responses in the posterior ITG. While we replicated findings of higher responses in ITG-numbers to numbers than other visual stimuli during a 1-back task, this preference to numbers was abolished when participants engaged in mathematical processing. In contrast, an ITG region (ITG-math) that showed higher responses during an adding task vs. other tasks maintained this preference for mathematical processing across a wide range of stimuli including numbers, number/letter morphs, hands, and dice. Analysis of distributed responses across an anatomically-defined posterior ITG expanse further revealed that mathematical task but not Arabic number form can be successfully and consistently decoded from these distributed responses. Together, our findings suggest that the function of neuronal regions in the posterior ITG goes beyond the specific visual processing of Arabic numbers. We hypothesize that they ascribe numerical content to the visual input, irrespective of the format of the stimulus.
后颞下沟（ITG）的一个区域，被称为数字形式区（NFA，这里是 ITG-numbers），与阿拉伯数字的视觉处理有关。然而，尚不清楚该区域是否专门参与阿拉伯数字的视觉编码本身，还是更广泛的数学处理。通过在系统改变任务和刺激的实验中使用功能磁共振成像（fMRI），我们发现数学处理而不是对阿拉伯数字的偏好，一致地驱动了后部 ITG 的平均和分布式反应。虽然我们复制了在 1 次回任务中 ITG-numbers 对数字的反应高于其他视觉刺激的发现，但当参与者进行数学处理时，这种对数字的偏好就消失了。相比之下，在加法任务中比其他任务显示出更高反应的 ITG 区域（ITG-math）在包括数字、数字/字母形态、手和骰子在内的广泛刺激中保持了对数学处理的这种偏好。对解剖定义的后部 ITG 广阔范围的分布式反应进行分析进一步表明，数学任务而不是阿拉伯数字形式可以成功且一致地从这些分布式反应中解码出来。总之，我们的发现表明，后部 ITG 中神经元区域的功能不仅仅局限于阿拉伯数字的特定视觉处理。我们假设它们将数值内容归因于视觉输入，而与刺激的格式无关。
