We are surrounded by various appetitive stimuli that positively motivate us to behave and aversive stimuli that negatively motivate us not to behave. In order to take action in a conflict situation where we face both appetitive and aversive stimuli, we need a willpower: an ability to make an effort to overcome difficulties to achieve goals. However, neural mechanisms of willpower are not well understood.
We set up a behavioral paradigm in which mice needed to explore an experimental context where they might receive electric shocks in order to obtain sucrose solution. Fiber photometry using Ca²⁺-sensitive fluorescent protein GCaMP6 showed that neuronal pathway from the medial prefrontal cortex (mPFC) to the periaqueductal gray (PAG) was activated when mice started moving to obtain sucrose solution. Optogenetic activation and inhibition of the mPFC-PAG pathway shortened and prolonged the latency to obtain sucrose in a conflict situation, respectively. Interestingly, in a no-conflict context where mice could obtain sucrose solution without fear of being shocked, optogenetic activation and inhibition of the mPFC-PAG pathway had no effect on the latency to obtain sucrose. These results suggest that the mPFC-PAG activity promotes animals to seek rewards in a conflict context.