information:extraction
How the brain reads

Several researchers and neuroscientists have attempted to explain how the brain reads. They have written articles and books, and created websites and YouTube videos to help the average consumer.

Neuroscientist Stanislas Dehaene says that a few simple truths should be accepted by all, namely: a) all children have similar brains, are well tuned to systematic grapheme-phoneme correspondences, "and have everything to gain from phonics – the only method that will give them the freedom to read any text", b) classroom size is largely irrelevant if the proper teaching methods are used, c) it is essential to have standardized screening tests for dyslexia, followed by appropriate specialized training, and d) while decoding is essential, vocabulary enrichment is equally important.

A study conducted at the Medical University of South Carolina (MUSC) in 2022 indicates that "greater left-brain asymmetry can predict both better and average performance on a foundational level of reading ability, depending on whether the analysis is conducted over the whole brain or in specific regions". There have been correlations between specific brain regions in the left hemisphere of the cerebral cortex during different reading activities.

Although it is not included in most meta-analytical studies, the sensorimotor cortex of the brain is the most active region of the brain during reading. This is often disregarded because it is associated solely with movement; However, a 2014 fMRI study involving adults and children participants, where bodily movement was restricted, demonstrated strong evidence revealing that this region may be correlated with automatic word processing and decoding. The results of this study found this portion of the brain to be highly active in persons who were learning/struggling to read (children, those diagnosed with dyslexia, and those new to the English language) and less active in fluent adult readers.

The occipital and parietal lobes, or more specifically fusiform gyrus, include the brain's visual word form area (VWFA). The VWFA is believed to be responsible for the brain's ability to read visually. This area of the brain tends to be activated when words are presented orthographically, as found in a study in 2002 where participants were presented with word and non-word stimuli. During presentation of word stimuli, this portion of the brain was extremely active; however, during presentation of stimuli that did not involve graphemes the brain was less active. Participants with dyslexia remained outliers, with this area of the brain being consistently underactive in both scenarios.

The two major regions of the brain associated with phonological skills are the temporal-parietal region and the Perisylvian Region. In an fMRI study conducted in 2001, participants were presented with written words, verbal frequency words, and verbal pseudo-words. The dorsal (upper) portion of the temporal-parietal region was the most active during the pseudo-words and the ventral (lower) portion was more active during frequency words, except subjects diagnosed with dyslexia, who showed no impairment to their ventral region but under-activation in the dorsal portion.

The Perisylvian Region, which is the portion of the brain believed to connect Broca's and Wernicke's area, is another region that is highly active during phonological activities where participants are asked to verbalize known and unknown words. Damage to this portion of this brain directly affects a person's ability to speak cohesively and with sense; furthermore, this portion of the brain activity remains consistent for both dyslexic and non-dyslexic readers.

The inferior frontal region is a much more complex region of the brain, and its association with reading is not necessarily linear, for it is active in several reading-related activities. Several studies have recorded its activity in association with comprehension and processing skills, as well as spelling and working memory. Although the exact role of this portion of the brain is still debatable, several studies indicate that this area of the brain tends to be more active in readers who have been diagnosed with dyslexia and less active when treatment is successfully undergone.

In addition to regions on the cortex, which is considered gray matter on fMRI's, there are several white matter fasciculus that are also active during different reading activities. These three regions are what connect the three respected cortex regions as the brain reads, thus are responsible for the brain's cross-model integration involved in reading. Three connective fasciculus that are prominently active during reading are the following: the left arcuate faciculus, the left inferior longitudinal faciculus, and the superior longitudinal fasciculus. All three areas are found to be weaker in readers diagnosed with dyslexia.

The cerebellum, which is not a part of the cerebral cortex, is also believed to play an important role in reading. When the cerebellum is impaired, victims struggle with many executive functioning and organizational skills both inside and outside of their reading ability. In a synthetic fMRI study, specific activities that displayed significant cerebellum involvement included automation, word accuracy, and reading speed.