Triune Brain

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Triune Brain (German: three-part brain ) is the name of a concept developed in the 1950-60s by the American brain researcher Paul D. MacLean (1913-2007) and published several times under this name from 1970 onwards. It constructs evolutionary processes that seem to be reflected in the functions and structures of the human brain . In this model, MacLean divided the brain into three areas, the “protoreptilian”, “paleomammalian” and “neomammalian” brain.

The triune brain

MacLean's evolutionary biological ( phylogenetic ) concept is an attempt to schematically divide the human brain into anatomy and function according to various stages of development . MacLean took up ideas from James W. Papez and added them.

The pro-reptilian brain

The components of the brain are protoreptilischen the brain stem and midbrain . The protoreptilic brain is the "lowest" and the oldest form of the brain in phylogeny. It controls innate instincts , has only limited ability to learn and does not yet enable social behavior.

The paleomammalian brain

Some of the larger regions of the limbic system according to the usual classification. It corresponds to the paleomammal brain in MacLean's concept. In his Triune model, however, he assigned the thalamus and hypothalamus regions to the protoreptilic brain .

The components of the paleomammal brain are a collection of different structures for which MacLean coined the term limbic system in 1952 . It mainly contains information from inside the body. That's why MacLean called it the “ visceral ” brain. It is nature's first “attempt” to develop an individual awareness . In the paleomammalian brain, memory contents would be formed and colored affectively and emotionally . It also controls the instinctual process.

The neo-mammalian brain

The components of the neomammalian brain are the structures of the neocortex . It works largely regardless of the internal ( endogenous ) signals of the body and the genetically older areas of the brain. It creates cognitive and logical concepts and strategies and modifies the affects and impulses of the paleomammal brain.

Admission within science

The concept was heavily criticized and mostly rejected. The assumptions about the evolution of the brain anatomy of the various classes of vertebrates are flawed and their results are not tenable. The functional division of the brain anatomy is inadmissibly simplified. For example, the data show that the earliest mammals (Mammalia) had already developed a neocortex and that birds and reptiles had brain regions similar to the neocortex. Corresponding to this, the cognitive abilities of some birds, for example in language or tool making, are no less than that of great apes .

However, there are also neuroscientists, such as Jaak Panksepp , who have appreciated MacLean's concept because it is original and has raised interesting questions and food for thought.

Admission outside of science

Since the concept offers a relatively simple model for the much-discussed opposition of mind and feeling, it was picked up and popularized by several well-known writers. Examples are Carl Sagan's book The Dragons of Eden (1977; German: Die Drachen von Eden , 1978) or Arthur Koestler's book The Ghost in the Machine (1967; German: Das Gespenst in der Maschine , 1968).

literature

  • Paul D. MacLean , VA Kral: A Triune Concept of the Brain and Behavior. Ontario Mental Health Foundation 1973, ISBN 0-8020-3299-0 .
  • Paul D. MacLean: The Triune Brain in Evolution: Role in Paleocerebral Functions. Springer Science & Business Media, 1990, ISBN 0-306-43168-8 .
  • Gerald A. Cory, Russell Gardner (Eds.): The Evolutionary Neuroethology of Paul MacLean: Convergences and Frontiers. Praeger Publishers, 2002, ISBN 0-275-97219-4 .
  • Paul D. MacLean: Expanding Lifespan Learning. about a possible next step in evolution. ( education.jhu.edu ( Memento from May 4, 2017 in the Internet Archive ), English)

Individual evidence

  1. ^ Paul D. MacLean : The triune brain, emotion and scientific bias. In: Francis Otto Schmitt (Ed.): The Neurosciences: Second study program. Volume 2, Rockefeller University Press, New York 1970, ISBN 0-87470-014-0 , pp. 336-349.
  2. ↑ GF Streidter: Principles of Brain Evolution. Sinauer Associates, Sunderland MA (USA) 2005, ISBN 0-87893-820-6 .
  3. ↑ Jaak Panksepp : Foreword. In: Gerald A. Cory, Russell Gardner (Eds.): The Evolutionary Neuroethology of Paul MacLean: Convergences and Frontiers. Praeger Publishers, 2002, ISBN 0-275-97219-4 .