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"Understanding the Brain", The Birth of a Learning Science, 2007, page 114, 115
“Is There One ‘Left-Brain’ & Another ‘Right-Brain’?” (2)
A Myth that Began in the 19th Century
A Myth that Began in the 19th Century
This “left brain/right brain” opposition originated in the First neurophysiology research. Intellectual capacities were often then described in two classes: critical and analytical aptitudes, on the one hand, and creative and synthetic aptitudes, on the other.
One of the major doctrines of neurophysiology from the 19th century associated each class to a hemisphere. In 1844, Arthur Ladbroke Wigan published A New View of Insanity: Duality of the Mind. He describes the two hemispheres of the brain as independent, and attributes to each one its own will and way of thinking: they usually work together but in some diseases they can work against each other.
This idea caught the imagination with the publication of Robert Louis Stevenson’s famous The Strange Case of Doctor Jekyll and Mister Hyde in 1866 which exploits the idea of a cultivated left hemisphere that opposes a primitive and emotional right hemisphere, which easily loses all control.
Paul Broca, a French neurologist, went beyond fiction to localise different roles in the two hemispheres. In the 1860s, he examined postmortem the brains of more than 20 patients whose language functions had been impaired. 
In all the brains examined, he noticed lesions in the frontal lobe of the left hemisphere, whereas the right hemisphere was still intact. He concluded that the Production of spoken language had to be located in the front part of the left hemisphere.
This was completed a few years later, by the German neurologist Carl Wernicke who also examined postmortem brains of those who had had language development disorders; he suggested that the capacity to Understand language is situated in the temporal lobe of the left hemisphere.
Thus, Broca and Wernicke associated the same hemisphere of the brain, the left, to two essential components of processing language – comprehension and oral production.
One of the major doctrines of neurophysiology from the 19th century associated each class to a hemisphere. In 1844, Arthur Ladbroke Wigan published A New View of Insanity: Duality of the Mind. He describes the two hemispheres of the brain as independent, and attributes to each one its own will and way of thinking: they usually work together but in some diseases they can work against each other.
This idea caught the imagination with the publication of Robert Louis Stevenson’s famous The Strange Case of Doctor Jekyll and Mister Hyde in 1866 which exploits the idea of a cultivated left hemisphere that opposes a primitive and emotional right hemisphere, which easily loses all control.
Paul Broca, a French neurologist, went beyond fiction to localise different roles in the two hemispheres. In the 1860s, he examined postmortem the brains of more than 20 patients whose language functions had been impaired. 
In all the brains examined, he noticed lesions in the frontal lobe of the left hemisphere, whereas the right hemisphere was still intact. He concluded that the Production of spoken language had to be located in the front part of the left hemisphere.
This was completed a few years later, by the German neurologist Carl Wernicke who also examined postmortem brains of those who had had language development disorders; he suggested that the capacity to Understand language is situated in the temporal lobe of the left hemisphere.
Thus, Broca and Wernicke associated the same hemisphere of the brain, the left, to two essential components of processing language – comprehension and oral production.
Brain Autopsy
Diagram of the Left Cerebral Hemisphere
Photograph of the Left Hemisphere "Normal"
Photograph of the Left Hemisphere "With the Damaged Broca's Area" 
Diagram of the Left Cerebral Hemisphere
Photograph of the Left Hemisphere "Normal"
Photograph of the Left Hemisphere "With the Damaged Broca's Area" 
"Understanding the Brain", The Birth of a Learning Science, 2007, page 114, 115
(To be continued...)
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