Dual brain theory
||This article needs attention from an expert in Neurology. (August 2010)|
The dual brain theory claims that the two cerebral hemispheres of the brain may sense and react to the environment independently from one another and that as a result of emotionally traumatic experience, one half may dominate the other in order to reduce the traumatized hemisphere's exposure.
This theory is an extension of split-brain studies of epileptic patients having the corpus callosum severed in order to reduce seizures, but it has recently begun to be studied in patients who have experienced traumatic events without any kind of brain surgery. In essence, this theory can apply to anyone.
Studies of healthy people with intact corpora callosa also indicate differing abilities or emotional responses associated with the two hemispheres. Studies using the Wada test and others are cited. In addition the theory draws upon research by Werner Wittling, Stuart Dimond, Roger Drake, Patrizio Tessoldi, Ryan Hansen, H. Edward Fouty and Stephen E. Levick.
The first instances of this theory began during the nineteenth century. According to the theory, every person has two perfectly formed brains, each of which can be substituted for the other in case of some traumatic, unilateral brain injury. In this time, it was thought that each side of the brain was associated with a specific gender: the left corresponding with masculinity and the right with femininity and each half could function independently. The right side of the brain was seen as the inferior and thought to be prominent in women, savages, children, criminals, and the insane. A prime example of this can be seen in Robert Louis Stevenson’s Strange Case of Dr. Jekyll and Mr. Hyde.
Scientists of the time disagreed on whether these cases of hemisphere imbalance could be cured, but some did believe that there was an analogy between muscular exertion and brain activity, meaning a person could physically strengthen one side of their brain.
These studies continued up until about the 1920s before they died out because psychiatrists turned to psychological explanations and neurologists emphasized holistic brain dynamics. The brain duality was revived through in the 1960s with Roger Sperry’s split-brain experiments. In one of Sperry’s studies, he showed a split-brain patient a picture to his right brain and the left hemisphere, responsible for verbal responses, could not articulate what was being seen. But the patient’s left hand, connected to the right brain, was able to give a thumbs-up or thumbs-down showing whether he approved of the picture or not.
The process that is mainly used to treat severe epileptic patients is corpus callosotomy. It usually involves the surgeon cutting the front two-thirds of the corpus callosum in hopes that it will greatly reduce the frequency of seizures. Later on, the remaining one-third can also be cut creating a complete severing of the two halves of the brain. This splitting of the two hemispheres of the brain usually leads to this dual brain theory, but of course, it can still occur in those with intact brains.
Dual brain and psychology
One of the biggest, if not the biggest, aspects of the dual brain theory is how it affects a person psychologically. The idea of having two independently thinking brains can affect how a person learns and how they function socially. Also, the way a person thinks changes drastically after a person experiences the dual brain effect.
When a person experiences this dual brain phenomenon, either with an intact brain or from a split brain, there are some changes that occur in their everyday lives as they function in society.
Of Two Minds
Dr. Fredric Schiffer developed the dual brain model of psychology in his work with understanding how and when each half of the brain of a patient was dominating. One important aspect of this model is that often the two minds in a person are quite different. In most cases he found that one mind tended to be more mature, reasonable, and living in the present. The other mind was often immature in its cognitive and emotional aspects. It was often this second mind that tended to be stuck back in the thought of whatever traumatic experience the patient had experienced.
To test this, Dr. Fredric Schiffer claims to have experimented with lateralizing glasses which restrict patients to one side of the visual field or the other, in turn stimulating the associated hemisphere. Schiffer claims this allowed some patients to experience the world through the more submissive or immature self and to compare differing experiences and changes in emotional moods, simply by switching between glasses. The glasses are fabricated simply by taping over the right or left halves of both lenses of typical safety glasses. The glasses function according to the properties of the optic tract, whereby the right halves of both retinas (which see the left side of the field of view) are each connected to the right hemisphere, and the left halves (which see the right side of the field of view) are each connected to the left hemisphere, via optic nerves, which partially cross at the optic chiasm. Theoretically, the patient could then relativize experience and escape from a single viewpoint or life experience. In this manner a patient, through counseling, might begin a rapport between hemispheres in order to lead a more balanced and fruitful life.
- Lateralization of brain function
- Left brain interpreter
- Eye dominance
- Robert Louis Stevenson's Jekyll and Hyde and the Double Brain, SEL Studies in English Literature 1500-1900 46.4 (2006) 879-900, Anne Stiles
- Medicine, Mind, and the Double Brain by Anne Harrington, Review by: Philip J. Pauly, Science , New Series, Vol. 239, No. 4838 (Jan. 22, 1988), p. 422
- Fredric Schiffer, Affect changes observed with right versus left lateral visual field stimulation in psychotherapy patients: Possible physiological, psychological, and therapeutic implications, Comprehensive Psychiatry, Volume 38, Issue 5, September–October 1997, Pages 289-295, ISSN 0010-440X, 10.1016/S0010-440X(97)90062-6.
- Schiffer, Fredric. Of Two Minds: The Revolutionary Science of Dual-brain Psychology. New York: Free, 1998. Print.
- Traumatology Review of Fredric Schiffer's "Of Two Minds: The Revolutionary Science of Dual-Brain Psychology", New York, Free Press, 1998
- 1. Schiffer F, Johnston AL, Ravichandran C, Polcari A, Teicher MH, Webb RH, Hamblin MR. Psychological benefits 2 and 4 weeks after a single treatment with near infrared light to the forehead: a pilot study of 10 patients with major depression and anxiety. Behav Brain Funct. 2009 Dec 8;5:46.
- 2. Schiffer F, Teicher MH, Anderson C, Tomoda A, Polcari A, Navalta CP, Andersen SL: Determination of hemispheric emotional valence in individual subjects: A new approach with research and therapeutic implications. Behavioral and Brain Functions 2007, 3:13 3. Schiffer F, Glass I, Lord J, Teicher MH: Prediction of clinical outcomes from rTMS in depressed patients with lateral visual field stimulation: a replication. The Journal of Neuropsychiatry and Clinical Neurosciences, 2008 Spring;20(2):194-200 4.
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|In major viscera||Situs solitus||Situs ambiguus||Situs inversus|