Role of the monkey orbitofrontal cortex in processing the choice history during reward-based decision-making

Decision-making is typically influenced by past choices. Previous studies have shown that the activity of neurons in the orbitofrontal cortex (OFC), which is involved in reward value coding, can be modulated by the reward values of previously chosen options. To further explore how the OFC processes the history of choice-related factors (HCF) from past choices, we analyzed the neuronal activity recorded in the monkey OFC during a decision-making task in which the monkeys could choose between two options based on their reward values. We found that the activity of over 70% of neurons was better explained by models that incorporated HCF than by models without it. The activity of these neurons during current choice was influenced by HCF in the previous trial. Additionally, some types of HCF were represented in these neurons between trials, suggesting that this information was maintained in the OFC and used to guide future decisions. Furthermore, a significant difference was observed in the choice reaction times between trials sorted by HCF. Pharmacological inactivation of the OFC by muscimol infusion eliminated such behavioral differences. These results indicate that HCF-modulated OFC activity contributes to the behavioral bias during current decision-making.