Remarkable progress has been made in understanding the neural systems influencing reading and reading disability. In large measure, this progress reflects the development of functional neuroimaging—in particular, functional magnetic resonance imaging (fMRI), a technology that assesses increases in blood flow in specific brain regions that are activated while subjects carry out cognitive tasks, such as reading. Increased blood flow brings more oxygenated blood, which the magnetic scanner detects.
A range of studies that we have reviewed (Shaywitz, 2003) converge to demonstrate three left-hemisphere neural systems for reading (see fig. 1, p. 76). Brain imaging further demonstrates differences in activation patterns between good and struggling readers at all ages. Nonimpaired younger children demonstrate significantly greater activation in the three left-hemisphere neural systems than do dyslexic children. In dyslexic children, anterior regions appear to compensate over time, so differences between older nonimpaired and dyslexic children are confined to the two posterior regions (Shaywitz et al., 2002). These data converge with reports from many investigators that show that the left-hemisphere posterior brain systems in dyslexic children fail to function properly during reading (Price & Mechelli, 2005; Shaywitz, 2003). One of these systems, in the left occipito-temporal region, appears to play an important role in skilled, fluent reading and has been labeled theword form area (see Dehaene, Cohen, Sigman, & Vinckier, 2005).
Figure 1. Neural Systems for Reading
Unfortunately, Willis seems to have missed this progress. She seems unaware that, although brain imaging studies of dyslexia are relatively recent, neural systems influencing reading were first proposed more than a century ago based on studies of adults who suffered a stroke with subsequent acquired alexia, the sudden loss of the ability to read. These neuropathological studies, which implicated left-hemisphere post-erior regions, have now been confirmed using functional brain imaging. It is a pity that Willis has misread and failed to assimilate the reports and achievements on the neurobiology of reading and dyslexia from neuroscientists around the world and has also seriously misread and misinterpreted papers from our own research group. Willis's article demonstrates little understanding of how functional brain imaging works. For example, she cites the term subtraction analysis but seems unaware that all neuroscientists (including our research group) using functional brain imaging employ this method. She seems unaware that the tasks used by neuro-scientists (including our research group) studying reading and dyslexia involve reading real words or decoding pseudowords, the very basis of reading new or unfamiliar words.
Willis proposes a garbled picture of how children read, a view that scientific evidence does not support. She mis-interprets papers (for example, Sowell's paper describes anatomic changes in the brain from childhood to old age, not electrical changes in the brain) and implies that other papers relate to humans when in fact they relate to mice (Pawlak, Magarinos, Melchor, McEwen, & Strickland, 2003); rats (Introini-Collison, Miyazaki, & McGaugh, 1991); sea slugs (Brembs, Lorenzetti, Reyes, Baxter, & Byrne, 2002); or monkeys (Nader et al., 2002) At other times, she cites papers that are simply opinion pieces with no supportive data (such as Wunderlich, Bell, & Ford, 2005).
Perhaps even more important, Willis ignores the almost three decades of research predating brain imaging that has converged to indicate that the successful beginning reader must recognize that the letters and letter strings (the orthography) represent the sounds of spoken language. To read, a child has to develop the insight that spoken words can be pulled apart into the elemental particles of speech (phonemes) and that the letters in a written word represent these sounds (Shaywitz, 2003). Such awareness is largely missing in dyslexic children and adults (Bruck, 1992; Shaywitz, 2003; Torgesen & Wagner, 1995). Results from large and well-studied populations with reading disability confirm that in young school-age children (Fletcher et al., 1994; Stanovich & Siegel, 1994) as well as in adolescents (Shaywitz et al., 1999) a deficit in phonology represents the most robust and specific correlate of reading disability (Morris et al., 1998; Ramus et al., 2003). Such findings form the basis for the most successful and evidence-based approaches to reading instruction and to interventions for struggling readers (National Reading Panel, 2000).
Effective reading instruction and intervention programs provide children with systematic instruction in each of five crucial components of reading: (1) phonemic awareness (the ability to focus on and manipulate phonemes, or speech sounds, in spoken syllables and words); (2) phonics (understanding how letters are linked to sounds to form letter-sound correspondences and spelling patterns); (3) fluency; (4) vocabulary; and (5) comprehension strategies. The goal is for children to develop the skills that will enable them to read and understand the meaning of both familiar and unfamiliar words they encounter so that they may learn to read effortlessly and look forward to a lifetime of enjoyment as readers.
Willis seems unaware of the fMRI studies examining whether the neural systems for reading are malleable and whether the disruption in these systems in struggling readers can be modified by an effective reading intervention. Compared with struggling readers who received other types of intervention, children who received an intervention focused on evidence-based application of the alphabetic principle not only improved their reading but also demonstrated increased activation in the neural systems for reading (Shaywitz et al., 2004). Other investigators (reviewed in Shaywitz & Shaywitz, 2005) have found that effective reading intervention influences neural systems in the brain.
These data demonstrate that the provision of evidence-based reading intervention at an early age improves reading fluency and facilitates the development of those neural systems that support skilled reading. Because large-scale studies to date have focused on younger children, relatively little data are available on the effect of these training programs on older children. The data on younger children, however, are extremely encouraging (Foorman, Brier, & Fletcher, 2003; Shaywitz, 2003; Torgesen et al., 1999), indicating that using evidence-based methods can remediate, and may even prevent, reading difficulties in primary school–age children.
