Identification of tool use acquisition-associated genes in the primate neocortex.

Japanese macaques are able to learn how to use rakes to take food after only a few weeks of training. Since tool-use training induced rapid morphological changes in some restricted brain areas, this system will be a good model for studying the neural basis of plasticity in human brains. To examine the mechanisms of tool-use associated brain expansion on the molecular and cellular level, here, we performed comprehensive analysis of gene expressions with microarray. We identified various transcripts showing differential expression between trained and untrained monkeys in the region around the lateral and intraparietal sulci. Among candidates, we focused on genes related to synapse formation and function. Using quantitative reverse transcription-polymerase chain reaction and histochemical analysis, we confirmed at least three genes (ADAM19, SPON2, and WIF1) with statistically different expression levels in neurons and glial cells. Comparative analysis revealed that tool use-associated genes were more obviously expressed in macaque monkeys than marmosets or mice. Thus, our findings suggest that cognitive tasks induce structural changes in the neocortex via gene expression, and that learning-associated genes innately differ with relation to learning ability.