Artemenko Christina, Coldea Andra, Soltanlou Mojtaba, Dresler Thomas, Nuerk Hans-Christoph, Ehlis Ann-Christine
LEAD Graduate School & Research Network, University of Tübingen, Tübingen, Germany.
Department of Psychology, University of Tübingen, Tübingen, Germany.
Exp Brain Res. 2018 Apr;236(4):1129-1138. doi: 10.1007/s00221-018-5204-8. Epub 2018 Feb 14.
In our daily lives, we are constantly exposed to numbers and letters. However, it is still under debate how letters and numbers are processed in the brain, while information on this topic would allow for a more comprehensive understanding of, for example, known influences of language on numerical cognition or neural circuits shared by numerical cognition and language processing. Some findings provide evidence for a double dissociation between numbers and letters, with numbers being represented in the right and letters in the left hemisphere, while the opposing view suggests a shared neural network. Since processing may depend on the task, we address the reported inconsistencies in a very basic symbol copying task using functional near-infrared spectroscopy (fNIRS). fNIRS data revealed that both number and letter copying rely on the bilateral middle and left inferior frontal gyri. Only numbers elicited additional activation in the bilateral parietal cortex and in the left superior temporal gyrus. However, no cortical activation difference was observed between copying numbers and letters, and there was Bayesian evidence for common activation in the middle frontal gyri and superior parietal lobules. Therefore, we conclude that basic number and letter processing are based on a largely shared cortical network, at least in a simple task such as copying symbols. This suggests that copying can be used as a control condition for more complex tasks in neuroimaging studies without subtracting stimuli-specific activation.
在我们的日常生活中，我们不断接触数字和字母。然而，字母和数字在大脑中是如何被处理的仍存在争议，而关于这一主题的信息将有助于更全面地理解，例如，语言对数字认知的已知影响，或数字认知与语言处理所共有的神经回路。一些研究结果为数字和字母之间的双重分离提供了证据，数字在右半球表征，字母在左半球表征，而相反的观点则认为存在一个共享的神经网络。由于处理过程可能取决于任务，我们使用功能近红外光谱技术（fNIRS）在一个非常基本的符号复制任务中解决所报告的不一致问题。fNIRS数据显示，数字和字母复制都依赖于双侧额中回和左下额回。只有数字在双侧顶叶皮层和左上颞回引起额外激活。然而，在复制数字和字母之间未观察到皮层激活差异，并且有贝叶斯证据表明额中回和顶上小叶存在共同激活。因此，我们得出结论，基本的数字和字母处理至少在像复制符号这样的简单任务中是基于一个很大程度上共享的皮层网络。这表明在神经成像研究中，复制可以用作更复杂任务的对照条件，而无需减去特定刺激的激活。
