Figure 5

Reward in the human orbitofrontal cortex (OFC). Neuroimaging studies have revealed that the OFC is a heterogeneous brain region, where the different parts are engaged in different aspects of reward. Here, the focus is on the difference between activity in the medial OFC, which appears to monitor and evaluate the reward value (A–D), while the mid-anterior OFC (mid-OFC) contains activity encoding the subjective experience of pleasure (E–H). A) The activity in medial OFC is correlated with subjective ratings of pleasant and unpleasant smell [66]. B) Similarly, the activity in medial OFC is correlated with monetary wins and losses with no behavioural consequences [69]. C) Activity in the medial OFC is also tracking reward value over time, as shown in a neuroimaging study of the changing over minutes of pleasure of methamphetamine in drug-naïve participants [70]. D) The medial OFC also tracks the reward value of cute baby faces on faster timescales over milliseconds within 130 ms [71]. E) In contrast, activity in mid-OFC correlates with the subjective pleasure of food in a study of selective satiety [33]. F) Similarly, a study of supra-additive effects of pure taste combining the umami tastants monosodium glutamate and inosine monophosphate found subjective synergy effects in mid-OFC [72]. G) The synergy of supra-additive effects combining retronasal odour (strawberry) with pure sucrose taste solution was found in the mid-OFC [65]. H) Further, mid-OFC also became active when using deep brain stimulation in the PAG for the relief of severe chronic pain [73].