Nieder Andreas
Department of Animal Physiology, University of Tuebingen, Tuebingen, Germany.
Curr Opin Neurobiol. 2009 Feb;19(1):99-108. doi: 10.1016/j.conb.2009.04.008. Epub 2009 May 15.
Symbol systems such as numbers and language are of paramount importance to human cognition. In number theory, numbers are symbolic signs embedded in a system of higher-order sign-sign relations. During ontogeny, numerical competence passes through different referential sign relations with increasing complexity, from an iconic to an indexical and finally symbolic stage. Animals such as nonhuman primates are constrained to indexical reference. However, because symbolic reference emerges from indexical reference, behavioral and neuronal representations of semantic sign-numerosity associations in animals can elucidate the precursors of symbol systems. A neurobiological explanation of how numerical signs take their meaning is proposed by suggesting that neurons in the granular prefrontal cortex, a novel brain structure evolved in primates, enable high-order associations and establish links between nonsymbolic numerosities and arbitrary signs.
诸如数字和语言之类的符号系统对人类认知至关重要。在数论中，数字是嵌入高阶符号-符号关系系统中的符号标记。在个体发育过程中，数字能力会经历不同的、越来越复杂的指称符号关系，从图像阶段到索引阶段，最终发展到符号阶段。诸如非人类灵长类动物等动物则局限于索引指称。然而，由于符号指称源自索引指称，动物中语义符号-数量关联的行为和神经元表征可以阐明符号系统的前身。通过提出灵长类动物中进化出的一种新型脑结构——颗粒状前额叶皮质中的神经元能够实现高阶关联并在非符号数量与任意符号之间建立联系，从而对数符号如何获得其意义给出了一种神经生物学解释。
