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SCHIZOPHRENIA: AN ETIOLOGICAL SPECULATION THOMAS P. MILLAR* In his book, An Adaptive Competence Theory ofNeurosis, this author has formulated a theory of neurosis in the following terms [I]. Neurosis is a life-style manifestation of inadequate mentation that results from the partial failure of functional maturation of the neomammillary , or cortical, brain. As a consequence, paleomammillary, or limbic, mentation retains an unwarranted degree of input into wholebrain function and behavioral choice. The failure of full functional maturation of the neomammalian brain is a result of deficient postnatal training rather than inadequate nurturance and is expressed in defective cognitive control of the whole mind and in consequent adaptive malfunctioning. While the psychopathology of schizophrenia may be explained in terms of the same psychobiological constructs, the etiology points in quite another direction. Schizophrenia is not, in this author's view, at one end of a spectrum of mental disorder, the other end of which is occupied by the neuroses. The derangements that make up the clinical picture of schizophrenia reach so much more deeply into the mental processes that they cannot be explained in terms of degree of neurobiological maturation. What are these derangements, and how may they be accounted for in terms ofemerging psychobiological understanding? There are five principal characteristics of schizophrenia that are essential to this overview. These are (1) schizophrenia, the split between affect and ideation; (2) thought disorder; (3) hallucinations; (4) catatonia and other motor manifestations ; and (5) the praecox onset of the dementia. Before examining these in detail, perhaps it would be helpful to review , albeit briefly, the psychobiological constructs we shall be using to formulate our etiological speculation.»Address: Suite 23-659 Clyde Avenue, West Vancouver, British Columbia, V7T 1C8, Canada.© 1987 by The University of Chicago. AU rights reserved. 0031-5982/87/3004-0540$01.00 Perspectives in Biology and Medicine, 30, 4 · Summer 1987 \ 597 Psychobiological Constructs MacLean, in his concept of the triume brain, has shown us how the human brain contains within it the evolutionary remnants of three brains [2]. The first of these, the reptilian or R-complex brain, is located in the upper brain stem, where its ancient, instinctual self-preservative role, though overshadowed in man, continues to express itself in behaviors that tend to be imitative and repetitive—gestural or motor expressions related to basic biological drives, performed without conscious choice. The second, or paleomammillary brain, occupies the limbic structures. Its mode offunction is emotional. In lower animals, this means matching perceptions to templates, which then activate the emotions basic to four responses—fear leading to flight, rage leading to attack, lust leading to mating behavior, or, finally, hunger leading to feeding behavior. The mode of mentation arising from this brain is emotionally mediated and also out of awareness. The third evolutionary development produced the neomammillary brain, which brought memory and reason into the equation and provided a cortex capable of cognition—that is, the mental manipulation of accumulated data as the ultimate determiner of behavioral choice. From his studies of animal behavior as well as neural anatomy, MacLean put together this overview of neurobiology. In so doing, he has opened the floodgates to new understanding. With Sperry in the lead, a variety of researchers studying brain hemispheres , functionally separated from one another by surgical division of the corpus callosum, have shown us that the arrangements in man's neomammillary brain are quite complex. For example, the right brain, while capable of certain cognition, does so in a holistic, global, and symbolic style and further seems to share with the limbic brain, albeit in much less primitive terms, the mode of mentation in which emotion is a major determinant of final behavior choice. Further, except in the special case ofsplit-brain subjects, the ruminations of the right brain remain out of awareness [3]. The left brain is the thinking brain—that is, it conducts cognition that is more linear than holistic and that reaches conclusions based on logic. Emotion does not play a part in the mentation that the left brain contributes to behavior choice. The left brain's evolutionary development is the story of an increasing capacity to manipulate abstractions, abstractions that are derived initially from perceptions but...


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