Orbitofrontal thickness, retention of fear extinction, and extraversion.

People differ in their personality traits and in their ability to modulate fear. Does our personality determine how well we extinguish conditioned fear responses? Or is the opposite true? Herein, we examine the relationships between personality traits, memory for fear extinction, and cortical thickness as a measure of brain structure. We found that in healthy humans, extinction retention and thickness of the medial orbitofrontal cortex are positively correlated with extraversion. Path analysis indicates that extinction retention mediates the relationship between the medial orbitofrontal cortex thickness and extraversion, thereby illustrating one path through which brain structure influences personality.