Salillas Elena, Benavides-Varela Silvia, Semenza Carlo
Department of Psychology and Sociology, University of Zaragoza, Zaragoza, Spain.
Department of Developmental Psychology and Socialisation, University of Padova, Padua, Italy.
Front Hum Neurosci. 2023 Oct 27;17:1288154. doi: 10.3389/fnhum.2023.1288154. eCollection 2023.
In 1974, Roger Sperry, based on his seminal studies on the split-brain condition, concluded that math was almost exclusively sustained by the language dominant left hemisphere. The right hemisphere could perform additions up to sums less than 20, the only exception to a complete left hemisphere dominance. Studies on lateralized focal lesions came to a similar conclusion, except for written complex calculation, where spatial abilities are needed to display digits in the right location according to the specific requirements of calculation procedures. Fifty years later, the contribution of new theoretical and instrumental tools lead to a much more complex picture, whereby, while left hemisphere dominance for math in the right-handed is confirmed for most functions, several math related tasks seem to be carried out in the right hemisphere. The developmental trajectory in the lateralization of math functions has also been clarified. This corpus of knowledge is reviewed here. The right hemisphere does not simply offer its support when calculation requires generic space processing, but its role can be very specific. For example, the right parietal lobe seems to store the operation-specific spatial layout required for complex arithmetical procedures and areas like the right insula are necessary in parsing complex numbers containing zero. Evidence is found for a complex orchestration between the two hemispheres even for simple tasks: each hemisphere has its specific role, concurring to the correct result. As for development, data point to right dominance for basic numerical processes. The picture that emerges at school age is a bilateral pattern with a significantly greater involvement of the right-hemisphere, particularly in non-symbolic tasks. The intraparietal sulcus shows a left hemisphere preponderance in response to symbolic stimuli at this age.
1974年，罗杰·斯佩里基于他对裂脑症的开创性研究得出结论，认为数学几乎完全由语言占主导地位的左半球维持。右半球只能进行总和小于20的加法运算，这是完全由左半球主导的唯一例外。对偏侧化局灶性病变的研究也得出了类似的结论，但书面复杂计算除外，在这种计算中，需要空间能力根据计算程序的特定要求将数字显示在正确的位置。五十年后，新的理论和工具的贡献带来了一幅更为复杂的图景，即虽然右利手人群中左半球在数学的大多数功能上占主导地位得到了证实，但一些与数学相关的任务似乎是在右半球进行的。数学功能偏侧化的发展轨迹也已得到阐明。本文将对这一系列知识进行综述。右半球并非仅仅在计算需要一般空间处理时提供支持，其作用可能非常具体。例如，右顶叶似乎存储了复杂算术程序所需的特定于运算的空间布局，而像右岛叶这样的区域在解析包含零的复数时是必要的。即使对于简单任务，也发现了两个半球之间复杂的协同作用：每个半球都有其特定作用，共同得出正确结果。至于发展情况，数据表明在基本数字处理方面右半球占主导地位。在学龄期出现的情况是一种双侧模式，右半球的参与程度明显更高，特别是在非符号任务中。在这个年龄段，顶内沟对符号刺激的反应显示出左半球占优势。
