The reference librarians at The Seattle Public Library are pretty darn amazing. They don’t know everything, instead they know where to find everything. As part of an irregular series of posts we salute the talented and dedicated reference staff at your local library. Names and other identifying information have been removed from the questions we showcase. Got a stumper? Click on Ask a Librarian. It’s what we do.
“What part of the brain controls writing (forming letters)? “
We have found some good basic information on the website of the Center for Neuro Skills. This site describes the parietal lobe near the back and top of the head as having the functions of:
Location for visual attention. Location for touch perception. Goal directed voluntary movements. Manipulation of objects. Integration of different senses that allows for understanding a single concept.”
While discussing agraphia (a condition involving the inability to locate the words for writing), Dr. Joseph Rhawn gives a brief definition of how the parietal lobe converts the ability for visual attention into the written word. (Neuropsychiatry, Neuropsychology, Clinical Neuroscience by Rhawn Joseph, Ph.D. (Academic Press, New York, 2000)
Broadly considered, the principle structures include the left frontal lobe (Exner’s Writing Area and Broca’s Expressive Speech area), the left temporal lobe (Wernicke’s receptive speech area), and the superior and inferior parietal lobe. Exner’s and Broca’s area are implicated in the expressive aspects of writing, whereas the temporal and parietal lobe are involved in the comprehension of written words. However, the parietal lobe is also believed to program the frontal motor areas and to supply the anterior region of the brain with the grapheme equivalents of auditory language; i.e. converting or visual images sounds into written symbols.
Presumably the parietal lobe constructs the written-word images (probably via interaction with Wernicke’s area) which and assists in converting these into graphemes. These motor-graphemes (or written word/letter images) are then transmitted to the left frontal convexity (i.e. Broca’s and Exner’s area) for grapheme conversion and motoric expression.”