猴前额叶皮层神经元在序列计数操作中的作用

Numerical ability is an important basis for intelligence. It has been known that monkeys have a ability to count items presented simultaneously (cardinality concept), and neurons in the prefrontal and prietal cortex could represent cardinality. However, we do not know whether monkeys also have an capability to count sequentuially presented items (ordinality concept), and how neurons in the prefrontal cortex represent ordinality. Previously, we found that rhesus monkeys can count sequentuially presented items from 1 up to 7, and inactivation of the ventral prefrontal cortex impairs the the sequential counting performance. The present study attempts to study how individual neurons or neuroanl assembly in the ventral prefrontal cortex encode ordinality and sequential couning performance. This study is of importance for understanding the neuronal mechanisms of numerical ability.

数能力是智力的重要基础。前人研究表明，猴具有对时间上同时呈现的物体进行"计数"的能力（基数概念），前额叶和后顶叶神经元能够对基数进行编码。然而，猴是否能够对时间上先后呈现的物品进行计数（序数概念），尚缺乏有力的实验证据。我们先前的研究表明，猴对时间上序列呈现的物品具有计数能力，能够从"1"数到"7"；可逆性地失活前额叶皮层腹侧部，猴的计数能力受到损伤。本项目拟在猴前额叶皮层记录神经元放电的活动，分析单个和集群神经元在序列计数过程中的编码模式。本工作对理解数能力的神经元机制，具有重要的理论意义。

计数是一种高级而复杂的数能力。计数活动的实施要求操作者不仅具有对元素数量（基数）做出反应的能力，更需要对序列出现的元素次序（序数）做出合适反应的能力。研究表明，动物具有基数能力，但是否具有序数能力存在争议。本项目中，我们训练4只猴进行序数计数任务，并在猴前额叶皮层埋置多通道微电极同步记录神经元的放电活动。我们的结果表明，猴对序列呈现的元素具有计数能力，而且能够从“1”数到“6”。电生理研究也发现，猴前额叶皮层存在有相当比例的神经元对计数活动进行编码。