Orbitofrontal cortex processing: neurophysiology and neuroimaging

The functioning of the orbitofrontal cortex is described. It is shown that it receives information about what stimulus is present from the sensory pathways, and represents this in terms of its reward value. There are reward outcome neurons (responding to taste and pleasant and unpleasant touch); expected value neurons (responding to visual stimuli according to the expected reward that they predict); and non-reward 'error' neurons that respond when an expected reward is less than expected. There are also neurons that respond to face identity and face expression, and to vocalization. The medial orbitofrontal cortex represents rewards and its activations are related to the pleasantness of stimuli. The lateral orbitofrontal cortex represents punishers and not receiving expected rewards (non-reward). Economic reward value is represented. An anterior region, the ventromedial prefrontal cortex, is implicated in decision-making between rewards of different value. The orbitofrontal cortex represents the reward and punishment value of stimuli, and not actions. Outputs of the orbitofrontal cortex to the cingulate cortex are involved in learning what actions to take to obtain rewards; and to the striatum for stimulus-response, habit, learning.