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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. ==History== 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.〔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〕 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.〔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〕 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.〔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.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dual brain theory」の詳細全文を読む スポンサード リンク
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