Brain Lateralization and Language Reflection
by Andrea Watson | October 9, 2020
Traditionally, we think of the “speech center” for the brain as being located in the left hemisphere. In fact, over ninety-five percent of people who are right handed have dominant left hemispheres when it comes to speech (Kalat, 2013). It is thought that the hippocampal formation in the left hemisphere in the left medial temporal lobe plays a critical role in the lateralization of language. When a brain is young, the synaptic density is greater than it is in the adult brain. Progressive localization of function occurs throughout development as neural nets constrict, the number of synapses declines, and processing becomes more efficient (Knecht, 2004).
Convergence of sensory information and the projections from the hippocampus to the frontal and temporal cortex are thought to put the hippocampus in a unique position to bind information and consolidate new memories. When damage such as brain lesions occurs, it is possible for language to shift from the damaged to the intact hemisphere. The language shifts to and can be processed by cortical regions that are adjacent to classical language areas. This transhemispheric reorganization happens more readily in children than in adults, perhaps because for children, language is still being acquired and the mental lexicon is still growing. Adult brains are not exempt, however. After aphasia caused by cerebral artery infarction, some degree of language recovery can be achieved through cortical reorganization. Learning is the best way for this to happen (Knecht, 2004).
While considering brain lateralization, it is important to avoid generalizing too much. Kalat explains to the reader that although the concept of a person being “right brained’ is fairly common in the way we generally perceive brain function, at least one premise that this is based on is doubtful. The workings of the human brain rely upon both hemispheres to work in harmony. While it is true that the hemispheres have been specialized for specific functions and some tasks require one hemisphere to work harder than the other, it is not true that a person depends on just one part of his or her brain. In all things but those that are most simple, including language, cooperation between hemispheres is essential (Kalat, 2013).
References
Kalat, J.W. (2013). Biological psychology, (11th ed.). Belmont, CA: Wadsworth, Cengage
Learning.
Knecht, S. (2004). Does language lateralization depend on the hippocampus?. Brain: A Journal Of Neurology, 127(Pt 6), 1217-1218.
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