Historical Perspective of Prefrontal Research

Abstract

The notion that the cerebral cortex is an essential structure for achieving a variety of cognitive functions is now a common sense. However, this was not the case until the middle of the nineteenth century. Until the eighteenth century, the cerebral cortex was thought to be merely a kind of vascular tissue or a glandular structure. In the early nineteenth century, Franz Joseph Gall established that the cerebral cortex consists of two basic structures, which are gray matter and white matter. He recognized that the gray matter was comprised of a mass of nerve cells while the white matter was comprised of a mass of nerve fibers. Gall also established not only the concept that the brain is an important structure for controlling intelligent functions but also the concept that the cerebral cortex, especially the gray matter, plays essential roles in achieving various complex cognitive behaviors (Zola-Morgan 1995). Thus, Gall contributed significantly to establishing the importance of the cerebral cortex as a central structure for achieving various complex behaviors. This notion was an important step for developing a modern view of cerebral functions, that is, the mental faculties are housed in the cerebral cortex. However, at the same time, he emphasized the idea that had been called organology or phrenology. Gall’s idea of organology was based on the following thoughts: (1) Moral and intellectual faculties are innate; (2) Their exercise and manifestation depend on the cerebral structure; (3) The brain is the organ for all faculties, tendencies, and feelings; and (4) The brain is composed of as many particular organs as there are faculties, tendencies, and feelings (Zola-Morgan 1995). These thoughts were based on his observations of normal individuals and neurological and psychiatry patients. Then, Gall attempted to correlate the physical aspects of the skull with prominent psychological characteristics of human behavior and personality. He determined 27 separate faculties (Organs) and assigned each faculty to each area on the skull, which was a crude form of functional localization of the cerebral cortex. Interestingly, Gall had assigned the following functions to the frontal lobe: memory of things, memory of facts, educability, and perfectibility at Organ 11; comparative sagacity (wisdom) at Organ 20; sense of metaphysics at Organ 21; sense of satire and witticism at Organ 22 (see Zola-Morgan 1995). Functions that Gall assigned to the frontal lobe are amazingly similar to current views of prefrontal functions. However, these are exceptional. He assigned the following functions to the occipital lobe: love of offspring at Organ 2; affection and friendship at Organ 3 (see Zola-Morgan 1995). According to organology, a specific region of the brain was thought to be the center for a specific faculty and the surface of the skull was thought to mirror the development of the underlying brain structure. Therefore, it was expected that highly developed faculty in a particular individual could be estimated by palpating the skull. This idea had been further developed by Johann Gaspard Spurzheim as phrenology movement.