Structure and function of the prefrontal cortex

Abstract

  The prefrontal cortex (PFC) , which is most developed in humans among mammals, plays important roles in: (1) cognitive/executive control of behavior, (2) theory of mind/social behavior, and (3) emotional and motivational control of behavior. There are two kinds of functional axis within PFC: up-down and anterior-posterior axes. As for the up-down axis, the lateral PFC (upper part) is more concerned with role (1), the medial PFC (middle part) with role (2), and the ventral (orbital) PFC (lower part) with role (3). As for the anterior-posterior axis, the more anterior area within PFC is concerned with more abstract and higher information processing. The ventromedial PFC, which consists of the anterior parts of both the ven tral and medial PFC, is specifically concerned with emotion-motivation based decision-making. The most anterior part of PFC is called the frontal pole. The lateral part of the frontal pole is unique to humans, and plays the most important role in abstract and complex cognitive operations. In our studies using monkeys as subjects, we have found that: (1) there are PFC neurons that are related to social behavior by coding the winning and losing of face-to-face competition, and are considered to be related to facilitating competitive behavior, (2) the regional cerebral blood flow (as measured by PET) increases during rest compared with during cognitive task performance in the medial PFC, which is a major part of the default network, (3) do pamine, which is the most important neurotransmitter for cognitive operations in PFC, shows a decreased release in the lateral PFC and increased release in the medial PFC during rest compared with during cogni tive task performance. The increase of dopamine during rest in the medial PFC is considered to be related to internal thought processes.