Where and How Are Original and Valuable Ideas Generated? tDCS of the Generation-Related Posterior Temporal Lobe and the Executive Control-Related Prefrontal Cortex.

Creativity is generally defined as the ability to generate innovative thoughts that are both original and valuable. Previous studies have suggested that the temporal lobe, related to memory extraction and construction, is responsible for generating creative ideas and that the executive system supports the generation of creative ideas. However, the causal relationships between these structures and the novelty index as well as the appropriateness index of generated ideas have not been revealed. It is still largely unknown where and how original and valuable ideas are generated. In this study, the transcranial direct current stimulation technique was used to selectively manipulate the activity of the generation-related right temporoparietal junction (TPJ) (experiment 1) and the executive control-related left dorsolateral prefrontal cortex (DLPFC) (experiment 2). Then, both the novelty and appropriateness indexes of generated ideas were analyzed during insight problem-solving. The results showed that anodal stimulation of the right TPJ increased both the novelty and appropriateness indexes of creative ideas, whereas anodal stimulation of the left DLPFC increased the novelty index but not the appropriateness index of creative ideas. These findings suggest that the posterior temporal lobe takes both the novelty and appropriateness attributes into account to generate ideas, while the executive control system can effectively regulate the novelty attribute of generated ideas but ineffectively addresses the inappropriateness attribute. The current study indicates complementary mechanisms in the process of generating original and valuable ideas.