Developing Language: The Science Behind Learning to Read

Robert Greenleaf surveys the latest medical research that reveals how the brain decodes the written word.

Early in life, in our quest for survival and meaning, language is learned. By the time most young children enter public school, they have acquired a 17,000+ word vocabulary. The human brain is designed to do this, primarily through auditory input. It is the abstraction of language through the visual sense (reading) that presents a new challenge to our neural networks.

From the second trimester on, the brain is growing dendritic connections between cells at an average rate of 6-700 per second, 40,000 per minute or about sixty million per day. This period of synaptogenesis is the brain’s response to a new and novel existence. Everything is being recorded in attempts to make sense of this world. Somewhere in the convoluted folds, the foundation for reading is forming.

Dr. Kenneth Pugh, Psychiatrist and Medical Researcher at the Haskins Laboratory at Yale, has been studying the neural pathways which are generated in good readers. When the brain is asked to go from the listening and speaking modes to the visual spatial, yet abstract production of reading, new relationships between regions in the cortex are formed. This is true for all written languages. Skilled readers have engineered neural networks, which take the visual sensory input from "eye to meaning" in about 150 milliseconds.

This is done through the dominant path of eye to three posterior gyrus (areas in the back half of the cortex). The lingual, fusiform and angular gyrus collaborate to convert letters into meaning.

Auditorily, the unit of analysis for language is constructed in parts, which are words, or syllables (i.e. "bad" equals one unit, one sound). In skilled readers the unit of analysis is by phoneme (i.e. "bad" equals three distinct units, each having its own sound). As Pugh states, "The number one predictor of reading in grades 2 to 4 is the ability to distinguish parts (phonological awareness)." Here’s what takes place in the human brain as we go from eye to meaning in the reading process. Three primary components called orthographic, phonological, and lexicon are involved. First, the visual input is read in the lingual gyrus of the visual cortex orthographically (the configuration of a straight vertical line intersected medially by two diagonally perpendicular ones, or "K" is identified). Next, this configuration is connected with the sound, or phoneme, which "K" makes in the fusiform gyrus of the temporal lobe. Finally, meaning is determined in collaboration with the angular gyrus in the parietal lobe. It is this interactive relationship which provides the context for meaning, all within a fraction of a second. The key to this process is phonological decoding. While some letter sequences are identified via the more direct lingual to angular routing, they are quite infrequent and slow by comparison. Thus, the core deficit of poor readers appears to be phonological.
Further research using positron emission tomography (P.E.T.) and functional Magnetic Resonance Imaging (fMRI) scanning has demonstrated that the "go to" area for dyslexics and illiterates, was the frontal cortex, the part of the brain where Broca’s area for speech production is located. An increase in blood flow in the frontal region was recorded during reading activity of poor readers, as opposed to the posterior gyrus’ of skilled readers. The frontal region of the cortex is not efficient in decoding phonemic components and performs such tasks far too slowly for meaning to be generated.

Education practitioners for years have encouraged children who are weak in making phonological connections to use meaning or context as an alternative strategy. The recent findings suggest this may prompt a beginning reader to use an inefficient strategy, which is unlikely to support skill development over time. An increased emphasis on phonemic analysis may be more beneficial to the struggling reader. Dr. Pugh clearly states, "The Reading Wars are, in a sense, over. The data is in." There's no longer any dispute as to what works and how it works with building capacity for skillful reading.

Are there implications for reading instruction or for home activities with parents? Yes, some very simple ideas come to mind. Talk to your child right from the start. Speak with a full vocabulary, even though you know they will not understand the meaning. What is more important early on, is the encoding of phonemic capacity through auditory channels. At some later point (+/- 5 years old) the young, developing reader will access the phonological memory as a means of interpreting language in visual forms.

The next work of the Haskins Laboratory at Yale is to observe brain activity when these proven phonemic awareness interventions are applied to see whether the brain engages the areas "deployed" by competent decoders.

References
Pugh, Kenneth. Interview at the Haskins Laboratory, Yale University on June 4, 1999.
Levitt, Pat. Presentation at the Rhode Island Hospital, Neurology Grand Rounds, with subsequent interview, May 5, 1999.
Levitt, Pat. "Reinoso, Blesilda and Jones, Leisl. "The Critical Impact of Early Cellular Environment on Neuronal Development," Preventive Medicine, 27, 180-183, Article No. PM970273, 1998.
Salovey, Peter and Mayer, John D. "Emotional Intelligence," Imagination, Cognition and Personality, Vol. 9(3), 185-211, p. 185-211, 1990.
Society for Neuroscience "Brain Briefings," 11 Dupont Circle, Northwest, Suite 500, Washington D.C. 20036, 202-462-6688, www.sfn.org/briefings.

Dr. Robert K. Greenleaf, Program Planning Specialist, Northeast and Islands Regional Educational Laboratory at Brown University, Providence, Rhode Island.