Personality and the Brain, Part 4
The bossy left hemisphere
Posted Oct 20, 2016
The change in openness that we witnessed in Leigh turns out to require a completely different explanation. In Leigh’s case, the change in openness is primarily due to a change in artistic interest. One factor that may help us explain this change is the damage to the white matter we found in the neurons that carry signals from one side of the brain to the other. When signals cannot travel very fast or efficiently from the left side of the brain to the right side of the brain, people often undergo personality changes.
This has been observed in people with conditions causing progressive nerve cell loss in the left side of the brain. Consider the case of the Canadian biologist Anne Adams. In 1986 Anne took a leave of absence from her job when after her son got into a bad car accident (from which he would eventually recover). With more time on her hands, she started painting and found herself not only good at it, but absolutely fascinated by it. Soon she was spending every day from nine to five in the art studio. It didn’t take long before she quit biology altogether and became a full-time painter.
Then in 1994 Anne became intrigued by the music of the composer Maurice Ravel. She was particularly fascinated with Ravel’s famous one-movement orchestral piece Bolero. It’s one of the best known compositions of classical music. It alternates between two main melodic themes, repeating the pair eight times over 340 bars with increasing volume and layers of instruments. Anne decided to paint an elaborate visual translation of the composition on canvas, calling it Unraveling Bolero.
What Anne didn’t know at the time was that her newfound talent for painting was due to the frontal areas of her brain slowly unraveling. Frontotemporal dementia, which differs from the memory-related form of dementia known as Alzheimer’s, tends to lead to sudden remarkable enhancements in people’s artistic abilities. In frontotemporal dementia, cells in the brain’s frontal and temporal lobes slowly begin to die off, thereby altering the configuration of certain brain circuits and changing the connections between the front and back parts in the left hemisphere of the brain as well as the connections between the two hemispheres.
As it turns out Ravel probably also suffered from frontotemporal dementia when he wrote Bolero. After its premiere at the Paris Opéra in 1928 an audience member was heard shouting that Ravel was mad, to which Ravel responded, “You, my friend, are the only one here who understood the piece.” He later told Spanish-Cuban pianist and composer Joaquín Nin that the work had “no form, properly speaking, no development, no or almost no modulation.” Ravel was indeed going mad but managed to produce his most celebrated piece in the process.
As in the case of folks with frontotemporal dementia, Leigh’s shift in artistic obsession may have been at least partially a result of a decrease in signaling from the left hemisphere to the right. The left frontal areas of the brain and the frontal regions of the temporal cortex normally keep the creative right brain in check through organized thought and decision-making, thereby suppressing its creative activities. It’s micromanagement supreme. When the connections between the two hemispheres deteriorate, however, the artsy right brain regions are no longer censored and become unusually active, which can lead to amazing artistic abilities, especially in the areas of painting and drawing. This is also known in the medical literature as “paradoxical functional facilitation” of the rear right-side parietal cortex, which sits on top of the head, and the rear part of the right-side temporal lobe on the side of the head. These regions are used in accurate copying of images and in drawing internally visualized images. In effect, when the bossy left hemisphere is “shushed” and the creative right brain is allowed to “speak,” artistic talent proliferates.
You can read the next chapter of this true tale tomorrow. Part 3 can be found here. For further information about this and similar cases of extraordinary human ability, you can read our book The Superhuman Mind.