Lateralization of brain function
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The human brain has two halves, called the left and right hemispheres. These two halves of the brain are not exactly alike. For most tasks, both sides of the brain work together. But each side of the brain specializes in some things and works harder on those things than the other side. The term brain lateralization, or lateralization of brain function, means that the different halves do things differently.
The Brain's Hemispheres
A deep groove called the longitudinal fissure separates the brain into its two hemispheres (halves). The two hemispheres are connected by the corpus callosum, a bundle of nerve fibers. The corpus callous allows the right and left hemispheres to communicate with each other, and to work together.
Both the left and right hemispheres look and work in similar ways. The large parts of both hemispheres are exactly the same on both sides. But in the smaller parts, there are some differences.
Sometimes, the brain is different for left-handed and right-handed people. For example, there are two areas in the brain that are very important for speech: Broca's area and Wernicke's area. These two areas are in the left hemisphere for about 95% of right-handed people, but only about 70% of left-handed people.[1]
How Are the Two Hemispheres Different?
Popular articles on psychology often say that each side of the brain does things that the other does not. For example, a common mistake is the idea that the left side of the brain does all of a person's "logical thinking" (like solving math problems), while the right brain does all the "creative thinking" (like painting or drawing).[2] It is often said that a person who is creative is "right-brained," while a person who is more logical or "book-smart" is "left-brained."[3]
The truth is that both hemispheres work together on both logical and creative thinking.[4][5] However, in different people, one hemisphere may work harder than the other on different kinds of thinking, or other tasks.
For example, in about 95% of right-handed people, the left hemisphere is dominant when it comes to language - meaning that for these people, their language abilities are controlled mostly by the left hemisphere. The right hemisphere helps too, but not as much as the left hemisphere.[6]
Brain Injury
Sometimes, people have brain injuries that hurt or destroy part of the brain. With very bad injuries, an entire hemisphere may be destroyed. Sometimes that hemisphere's jobs can be done by part of the other hemisphere. However, this is not always possible. It depends on the area that was damaged and the patient's age.[7]
Sometimes, a brain injury damages pathways that carry information from one area to another. In some people, the brain can create other, less direct pathways (like detours). These new 'detours' may help the brain continue to carry information between the areas that were separated by the brain injury.
References
- ↑ Griggs, Richard A. Psychology: a concise introduction. p. 69.
- ↑ Nielsen, Jared A. et al. An evaluation of the left-brain vs. right-brain hypothesis with resting state functional connectivity magnetic resonance imaging. PLOS ONE 2013.
- ↑ Goswami U (2006). "Neuroscience and education: from research to practice?". Nat Rev Neurosci. 7 (5): 406–11. doi:10.1038/nrn1907. PMID 16607400.
{{cite journal}}: Cite has empty unknown parameter:|1=(help) - ↑ Westen et al 2006 Psychology: Australian and New Zealand edition. John Wiley p.107
- ↑ Toga A.W. & Thompson P.M (2003). "Mapping brain asymmetry". Nature Reviews Neuroscience. 4 (1): 37–48. doi:10.1038/nrn1009. PMID 12511860.
- ↑ BBC News: Regarding different languages. http://www.bbc.co.uk/news/health-11181457
- ↑ Pulsifer M.B.; et al. (2004). "The cognitive outcome of hemispherectomy in 71 children". Epilepsia. 45 (3): 243–254. doi:10.1111/j.0013-9580.2004.15303.x. PMID 15009226.
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