<p dir="ltr">Metacontrol describes outsourcing cognitive control to environmental cues, allowing for efficient instantiation of appropriate cognitive control. While recent years have seen many studies characterizing metacontrol in behavioral terms, relatively little effort has been made to characterize the neural mechanisms underlying metacontrol. Thus, the current dissertation project aimed to investigate the neural systems and interactive features of metacontrol, more specifically, proactive and reactive metacontrol that exert context-appropriate control states in preparatory and just-in-time manners, respectively. Specifically, Study 1 employed a functional magnetic resonance imaging technique and identified brain regions activated under proactive and reactive metacontrol operations. Importantly, the study revealed that the two metacontrol modes were supported by distinct neural systems. Building on the premise that distinct neural systems supporting the two metacontrol modes would enable the concurrent operation of both modes, Study 2 tested whether a preparatory metacontrol mode, proactive metacontrol, can coexist with a just-in-time metacontrol mode, reactive metacontrol. Using electroencephalography, Study 2 revealed that the two metacontrol modes can operate in parallel. Lastly, extending Study 2, Study 3 investigated how proactive metacontrol interacts with reactive metacontrol. Study 3 observed that high preparatory control states during proactive metacontrol benefit reactive metacontrol. Specifically, reactive metacontrol was observed only when penalties were at stake, which promoted heightened preparatory control states. In summary, Study 1 demonstrated that the two metacontrol modes are not only operationally distinctive but also characterized by separate neural systems underlying them. This aligns with the observation from Study 2 showing that the parallel operation of two metacontrol modes is feasible. Lastly, Study 3 suggests that despite the two metacontrol modes being supported by distinct neural systems (as shown in Study 1), they are not entirely independent and can interact with each other. Collectively, these findings reveal the relationship between the two metacontrol modes and elucidate their intricate interactions, thereby deepening our understanding of the neurocognitive mechanisms underlying metacontrol.</p>