Asymmetry in electrical activity in frontal regions is measured via EEG. Generally, activity in the right frontal region is thought to reflect withdrawal behavior and negative affect. The left frontal region reflects approach behavior and positive affect. Depression has been associated with decreased relative left FA. These symptoms have been studied, and it has been found that this trait is only modestly heritable. However, this particular endophenotype is still being researched continually to discover its exact relation to depression.