This study investigated the neural correlates of scientific innovation induced by heuristic prototypes. We hypothesized that forming novel associations and the automatic activation of heuristic prototype might be the critical processes behind scientific innovation. The results of Experiments 1 and 2 showed that the LG (BA18) and precuneus (BA31) might be involved in scientific innovation induced by a heuristic prototype.
In 1994 
, Blagrove and Tucker found that “frequent lucid dreamers scored 13.2% higher than non-lucid dreamers on Domino's 
creativity adjective check list” (quoted from 
). Moreover, Bischof and Bassetti 
indicated that the right inferior LG might play a key role in dream experience. Obviously, these results suggest that LG is probably related to the process of creativity. In addition, Jung et al. 
found the cortical thickness of LG is associated with (negative correlation) composite creativity index scores. Moreover, Stoppel et al. 
found that LG was activated when novel stimuli presented in the spatially unattended visual field. The researchers' interpretation of this finding was that LG might represent the “novelty detector at early perceptual level” (quoted from 
). The LG (BA18) was activated more under NSI than under OSI in Experiment 1, and the further correlation analysis showed a positive correlation between the mean beta-values of the LG and the behavioral accuracy of NSI. As Experiment 2 also showed, the LG (BA18) displayed stronger activity under NSI than under OSI conditions. Therefore, it was suggested that the LG might be involved in forming novel associations, whereby a creative method is used to resolve problems by applying heuristic prototypes.
The precuneus (BA31) (NSI - OSI) was also activated in Experiment 2. However, observed from the , it was found that, relative to the case of OSI, the NSI had been found to exhibit less deactivation (or stronger activation). Moreover, mean beta-values of the precuneus of NSI correlated extremely well with the behavior accuracy of NSI. Thus, it was speculated that the less deactivation in the precuneus of NSI might be associated with heuristic creativity. Similarly, Takeuchi et al. 
found that “the higher the creativity scores, the less the deactivation during the task in precuneus”. However, the precuneus belong to the default model network (DMN), which exhibited task-induced deactivation (TID) 
. Furthermore, McKiernan et al. argued that the magnitude of TID in the precuneus that were deactivated might reflect the reallocation of cognitive load 
. Accordingly, Takeuchi et al. pointed out that “the reduced TID in the precuneus among creative subjects may indicate that they are unable to inhibit cognitive activity irrelevant to the task performance” 
. And the stronger activation (or less deactivation) in the precuneus in creative subjects may “actually help them in associating two isolated ideas” 
. In our study, participants would obtain a method to resolve the NSI problem as soon as they activated the relative and effective prototype. Interestingly, it was unclear how the related heuristic prototype was activated (or retrieved) automatically from memory. One explanation might be a specific junction between the characteristics of a heuristic prototype (such as the spider silk example given in the Methods
) and its specific function (strength and elasticity) and an unrealized function in the problem (Kevlar has higher tensile strength but it is not very stretchy. How to make it more so?). It is most likely that the function of the heuristic prototype (strength and elasticity) is consistent with the unrealized function (it is not very stretchy), thus causing automatic activation of the characteristics of the heuristic prototype which could help solve the problem. Thus, the stronger activation in the precuneus of NSI might be involved in the automatic retrieval of heuristic information (i.e., automatic activation of the heuristic prototype from the irrelevant cognitive activity and may allow heuristic prototype and problem to combine), which might be the most important process in scientific creativity. In a similar vein, it has been postulated that the precuneus is related to the information retrieval from memory 
To the best of our knowledge, this work is the first fMRI study to have investigated the brain activation of critical cognitive processes (i.e., automatic activation of heuristic prototype and forming novel associations) behind scientific innovation. Moreover, the real-life scientific innovations used in our experiments have higher ecological validity than those tasks (riddles, remote association tasks and so on) used in many studies. That is, the fMRI results might be valuable in revealing the neural basis of heuristic creativity. To summarize, the main purpose of this study was to investigate the neural correlates of scientific innovation induced by heuristic prototype. It was hypothesized that the neural correlates of the automatic activation and forming novel associations in innovation are distinctive. As the hypothesis indicated, the results showed that the LG might be involved in forming novel associations using heuristic information, while the precuneus might be involved in the automatic activation of the heuristic prototype.