Background: An increasing number of studies using a variety of experimental procedures in both animals and humans have demonstrated the significant contribution made by the orbital frontal cortex to the flexible monitoring of actions based on rewards processing. Yet, much remains to be discovered about the role played by this structure in the development of emotional responses and goal-directed behaviors, which are the prerequisites for the development of complex social behavior.

Methods and Results: Three studies will be presented investigating behavioral and cognitive changes following neonatal damage of the orbital frontal cortex in infant rhesus monkeys. The first study demonstrates that neonatal orbital frontal lesions alter the modulation of fear and defensive responses towards threatening social stimuli, indicating poor modulation of social stimuli. These findings were confirmed by a second study showing that these same neonatal lesions disrupted choice selection predicted by affective signals but not by visual signals conveying reward contingency. The last study investigated how the deficits in flexible monitoring of social cues will affect dyadic social interactions. The data indicated a lack of interests in initiating and maintaining social contacts with operated-controls in animals with neonatal orbital frontal lesions.

Discussion: These results are consistent with orbital frontal damage altering the complex and flexible monitoring of the reward values of emotional and social cues to select appropriate actions, even when the damage occurs in infancy. These functional alterations may in turn reduce general motivation to engage in social interactions. These experimental data shed some lights into the crucial role of this cortical area in developmental psychopathology.