Damage to the Ventromedial Prefrontal Cortex Impairs Learning from Observed Outcomes

Individuals learn both from the outcomes of their own internally generated actions ("experiential learning") and from the observation of the consequences of externally generated actions ("observational learning"). While neuroscience research has focused principally on the neural mechanisms by which brain structures such as the ventromedial prefrontal cortex (vmPFC) support experiential learning, relatively less is known regarding how learning proceeds through passive observation. We explored the necessity of the vmPFC for observational learning by testing a group of patients with damage to the vmPFC as well as demographically matched normal comparison and brain-damaged comparison groups--and a single patient with bilateral dorsal prefrontal damage--using several value-learning tasks that required learning from direct experience, observational learning, or both. We found a specific impairment in observational learning in patients with vmPFC damage manifest in the reduced influence of previously observed rewards on current choices, despite a relatively intact capacity for experiential learning. The current study provides evidence that the vmPFC plays a critical role in observational learning, suggests that there are dissociable neural circuits for experiential and observational learning, and offers an important new extension of how the vmPFC contributes to learning and memory.