We do not simply react to stimuli but guide our behaviors based on previous experience. If the experience was repetitive, it generates habitual behavior to maximize efficacy of goal achievement (Kim et al., 2015 Cell; Kim et al., 2017 Neuron). I aim to investigate the neural codes of this habitual memory with non-human primates, and to find the mechanisms that manipulate habitual behavior. Since habitual behavior arises from well-orchestrated circuits in the cortical and subcortical structures, understanding the neural codes of habitual memory requires a multi-scale approach to elucidate an overall picture of brain circuits as well as the detailed mechanism of each part. I thus use two main techniques: MRI for macro-scale and single-unit recording for micro-scale understanding. Furthermore, using invasive and non-invasive techniques I manipulate habitual memory circuits of the non-human primate (NHP) brain to examine its causal effect on habitual behavior and change of plasticity at the level of the whole brain. Knowledge about the habitual memory circuit is critical to understand how we make habitual decisions. This study is expected to identify a target circuit to control dysfunctional habitual behaviors through brain manipulation such as deep brain stimulation.