The orbitofrontal cortex is the smallest part of the frontal lobe in the brain. Located within the cranial cavity directly behind the eyes, this region of the prefrontal cortex is involved in a large part of the decision-making process. Part of this brain structure plays a role in the creation of pleasurable or unpleasant sensations evoked by many flavors and smells. During tests that measure brain activity, it is seen to be highly active throughout tasks that involve learning new information.
Different parts of the orbitofrontal cortex control several aspects of learning and behavior. The medial part, or middle of this brain structure, helps the brain process the reward aspect of behavior reinforcement. Lateral or side portions of it helps the brain to process the punishment value of actions. Interactions between the reward and punishment processors in the orbitofrontal cortex are an important factor in a person’s ability to learn from mistakes and change destructive behavior patterns.
Within the orbitofrontal cortex, the emotions and the thinking process combine to influence the daily decisions a person makes. Damage caused by an injury or by the growth of a lesion in it may cause changes in the behavior of a person. Behavior patterns may alter because of the significant impact the cortex has on the valuation of actions, objects, or people. The orbitofrontal cortex is also involved in many of the brain processes that exist in the minds of people with addictions, including the cravings for the unhealthy substance or activity.
Historically, treatment for personality disorders and psychosis involved the surgical excision of portions of the orbitofrontal cortex. The procedure, called a frontal lobotomy, was used when other methods of treatment failed. People that underwent a frontal lobotomy often reported feeling emotionally flat after the operation, however the post-surgical absence of disruptive behavior patterns and a reduction in the symptoms of psychosis often validated the invasive brain surgery.
Another part of the orbitofrontal cortex plays a role in the formation of food preferences. The taste of food can cause a pleasurable response or an unpleasant sensation that originates in the cortex. Even sensory information related to the texture of a food is relayed through it. A decision of whether or not to consume the same food again is an example of the integration of sensory information into the thinking process by this brain structure.
The test used by scientists to measure the activity in the orbitofrontal cortex is called a functional magnetic resonance imaging (fMRI) scan. It measures the changes in blood flow within the brain throughout different types of activities. During a period of increased stimulation, the fMRI images show that blood flow is amplified in the prefrontal cortex.