The medial frontal gyrus is located in the frontal lobe of the mammalian brain. The gyrus is one of the "bumps" on the outer part of the cortex, which is the surface of the brain. The medial frontal gyrus is named as it is because it is in the frontal lobe near the center or midline of the brain. As a result of a large body of research, many scientists who study the function of different areas of the brain believe the medial frontal gyrus is associated with executive mechanisms and decision-making abilities.
This cortical landmark is considered a "higher processing unit" of the brain because it receives information that has often already been processed in some way. The input that comes to the medial frontal gyrus also comes from different areas in the brain, indicating that the gyrus is associated with information integration from different processing units. For example, when it receives information indicating a fear response from the arousal-associated areas of the brain in combination with a visual stimulus that indicates a large object is moving closer, a more appropriate response can be elicited from the medial frontal gyrus than if it had only received an indicator of fear. This information-rich attribute allows this area of the brain to form better responses than if it weren't receiving information from so many other areas.
The previously processed information that is received and processed by the medial frontal gyrus is often also given different weights in terms of the importance of the information due to the physiological arousal associated with the accumulation of that information. This ability, in part, is a result of the incoming timing of different stimuli from different cortical areas. Neural processing of incoming information also often includes filtration to get rid of excess physiological noise by the fact that most sensory input systems have a lateral inhibition circuit. These circuits reduce peripheral information noise and, as a result, important or relevant information signals are amplified.
Some scientists believe the medial frontal gyrus is activated when a person is lying, as multiple functional magnetic resonance imaging (fMRI) studies have indicated. Other scientists believe it is activated with decision-making and is just as active when a person is lying as when they are telling the truth. Still others believe that the two are essentially inseparable because a person can be just as certain of a lie as they can of the truth.