Our brain is divided in two hemispheres. Within this structure comes a unique kind of processing called contralateral processing. Contralateral processing explains that the brain processes on the opposite side of the body. So, the left arm is controlled by the right side of the brain while the right arm is controlled by the left side of the brain. The corpus collosum is a mass of neural fibers that is located in between the two hemispheres. The corpus collosum is the communication site between the left and right hemisphere of the brain.
Because of this hemispheric specialization, there is lateralization between the two hemispheres. Lateralization refers to the specialization of some cognitive processes on one side of the brain. In class, we discussed that the left side of the brain is linked to spoken and written language, mathematical thinking, logical thought processes, analysis of detail, reading, and right-hand control. While, the right side of the brain is linked to art, creativity, imagination, insight, holistic thought, music, and left-hand control.
Because the left-handed population only takes up 10% of the world population, most of the studies were done on right-handed people. When left-handed people were studied, it was found that there was less lateralization in their brains. In other words, left-handed people tend to use both the left and right regions of the brain instead of only one side (also called bilateral language function or reversed lateralization) For example, Oxford conducted a study to compare left-handed and right-handed people on brain lateralization during face perception. Face perception, in right-handed individuals, is processed on the right side of the brain. But, they found that left-handers tend to use both regions of the brain when they see a face.
When I was looking into anxiety treatment options, I decided to look into how each medication would work in my brain. I was interested to see how there is a common theme of increasing activity on the left hemisphere with medication. The left hemisphere is associated with motivation. So, it would make sense that medication would increase activity in this area of the brain.
As I am a left-handed person, I was interested to dive into the idea that there could be less lateralization of my brain, especially when looking at medication. A 2012 study published in the journal PLoS ONE explains that motivation shows more activity in the right hemisphere for left handed people, while the opposite is true of right-handed people. Because anxiety treatment is usually targeting to increase neural activity in the left hemisphere, the attempt would be to increase motivation for right-handed people. Because this research proposes that left-handed peoples’ brains organize emotion differently than the majority, I talked to my doctor about the effectiveness of each proposed anxiety medication. I was able to be in a more engaged part of the conversation as my doctor and I talked about how this could affect my prescribed medication.
Sources:
Willems, R. M., Van der Haegen, L., Fisher, S. E., & Francks, C. (2014). On the other hand: including left-handers in cognitive neuroscience and neurogenetics. Nature Reviews Neuroscience, 15(3), 193.
Brookshire, G., & Casasanto, D. (2012). Motivation and motor control: hemispheric specialization for approach motivation reverses with handedness. PLoS One, 7(4), e36036.
File:Brain Lateralization.svg. (2018, November 22). Wikimedia Commons, the free media repository. Retrieved 00:30, September 19, 2019 from https://commons.wikimedia.org/w/index.php?title=File:Brain_Lateralization.svg&oldid=328835878.
This is a really awesome perspective! I love the way you used the example of anxiety medication, I never really considered the way certain medications are targeting areas of the brain that may not be functioning equally for all people. As a right-handed person myself, I never considered the idea that left-handed people are experiencing more differences besides just “they write with their other hand”. It’s fascinating how both brain hemispheres are utilized in the case of someone who is left-handed, and I would love to know how split-brain patients adjust to the split if they are left-handed.