**4. Brain imaging evidence**

Recent advances in neuroimaging techniques make it possible to identify the brain-based factors that facilitate successful reading outcomes. Importantly, brain imaging may provide innovative solutions to improve education curriculums and lead to improvements in reading results in young children.

Over the last decades, neuroimaging studies focused on identifying brain markers that are the cause of dyslexia (see reviews: [48, 49]). Although researchers are far from concluding that the brain markers causing dyslexia, we have learned about the neural basis of reading acquisition. For instance, a left-lateralized brain network, including temporoparietal and occipitotemporal cortices, is critical to facilitate skilled reading [50, 51] (see **Figure 1**). High white matter integrity in accurate fasciculus (AF) predicts better reading outcomes in children at risk for dyslexia [52]. AF is a tract connecting Broca's area and Wernicke's area, related to reading ability [53–55] (see **Figure 1**). If neuroimaging measures can identify children at risk for reading difficulties before they even start to learn to read in school, early emergent reading interventions can be applied to help them overcome the risk of developing reading difficulties in school years. Only a limited number of studies have specifically investigated the relationship between emergent reading environments and neuroimaging data.

Hutton et al. used StimQ-P questionnaire [56] to quantify the cognitive simulation at home and identified that functional magnetic resonance imaging (fMRI) data during a storying comprehension task presented stronger activity for those children with higher StimQ-P Reading scores [57]. They reported that higher StimQ Reading scores were associated with stronger activation in occipital cortices, including lateral occipital gyrus and precuneus, which can be attributed to mental imagery evoked during story listening [58]. Their study sample includes nineteen 3- to 5-year-old children from a longitudinal study of healthy brain development. In preschool children listening to stories, greater home reading exposure was positively related to activation of left posterior occipital fusiform, lateral occipital, posterior inferior temporal, posterior middle temporal, posterior cingulate, and angular gyri and left precuneus (household income is controlled). Their finding suggests that

#### **Figure 1.**

*Brain regions and white matter tracts related to reading on a 3D rendered brain. Red: accurate fasciculus (AF), green: superior longitudinal fasciculus (SLF).*

brain-based markers exist as a result of parent-child reading in early childhood. Thus, emergent reading shall be promoted and may help shape the developing brain and better prepare a child for formal reading instructions in school.

Developmental dyslexia (DD) has strong genetic basis [59], and family history of DD can increase a child's chance to develop reading difficulties by 34–56% [60–62]. In order to identify children at risk for DD, familial risk can be used as a good indicator. One group led by Dr. Nadine Gaab in Boston Children's Hospital has done pioneer work in this research field [48, 52, 63–70]. For the first time, they examined the relationship between home literacy environment (HLE) and the neural basis of phonological processing in beginning readers with family history of DD (n = 29, first-degree relative who has reading difficulties) and without family history of DD (n = 21) [67]. This study aimed to identify brain mechanism of how HLE affects reading development in beginning readers. SES was controlled in this study in order to isolate the effects only by HLE. In reading-related brain regions (e.g., left inferior/ middle frontal and right fusiform gyri), stronger correlations between HLE composite scores and brain activations were present in children without familial risk than those with familial risk. In the nonreading-related brain region (e.g., right precentral gyrus), stronger correlations existed in children with familial risk than those without familial risk. These findings suggest that genetic predisposition for DD alters contributions of HLE to brain activation. Specifically, typically developing children can benefit more from better HLE than children with familial risk for DD. Therefore, enhanced HLE is especially important for children with familial risk for DD to have the same impact as for typically developing children.

Shared parent-child reading is one of the important factors in emergent reading. A recent study demonstrated increased activation and functional connectivity in children who are more deeply engaged during shared reading in 22 motherdaughter pairs [71]. The same group also associated shared reading quality scores with brain activation, and they found a positive correlation between shared reading quality scores with activation in left-hemispheric regions supporting expressive and complex language, social-emotional integration, and working memory in 22 healthy, 4-year-old girls from low SES [72]. Their findings suggest that the use of shared parent-child reading is crucial for emergent reading experience, but the quality of this experience has also a strong impact on brain development. Especially for those at-risk families, improvements of the quality of shared reading can promote healthy brain development and better prepare a child for future success in school.

Morken et al. [73] used a longitudinal study design to examine the differences of cortical connectivity in the brain during reading tasks between children with dyslexia and children with typical reading development through dynamic causal modeling (DCM) [74]. They included five regions (inferior frontal gyrus, precentral gyrus, superior temporal gyrus, inferior parietal lobule, and occipitotemporal cortex) in their effective brain connectivity model [74]. They found that effective connectivity between the inferior frontal gyrus and the occipitotemporal cortex during reading tasks changes during reading acquisition. In addition, the group readers with dyslexia presented different developmental trajectory than the control group. The control group actually seemed to downregulate or stabilize connection strength over time, whereas the dyslexia group started out at a level well below the control group, followed by an increase in connectivity from 6 to 8 years and then a downregulation from 8 to 12 years. The general downregulation of connectivity in the control group might reflect that they need these connections to establish reading skills initially, and then, the connections are no longer needed after later automaticity is established. The dyslexia group showed late development of some connections in occipitotemporal cortices. However, they seem to show overcompensation

**229**

*Emergent Reading and Brain Development DOI: http://dx.doi.org/10.5772/intechopen.82423*

develop simultaneously.

**5. Discussion**

around age 8, followed by normalization before age 12. Importantly, the dyslexia group was clearly lagging behind in the development of the brain networks at the age of 8 (emergent reading stage), suggesting emergent reading stage is critical. Younger et al. also used a longitudinal study design and found decreases in connectivity for most connections from the first (T1) to the second (T2) time point about 2–3 years apart, regardless of changes in reading skill in 59 typical developing children [75]. But they found a significant decrease in the dorsal, decoding processing pathway from fusiform gyrus (FG) to inferior parietal lobule (IPL) for the group who improved more from the first to the second time point, suggesting that the improvements in reading skills lead to a decreased reliance on the dorsal pathway (decoding processing pathway) in the brain. The high and low improving groups did not differ in behavioral performance at T1, and high improvers showed greater connectivity between FG and IPL at T1 compared to the low improvers. The dorsal pathway facilitates phonological processing, which is necessary for development of the ventral pathway supporting automatic processing of visual word forms. However, there is no sequential relationship between the two routes. They may

Yu et al. studied 28 children over three stages (pre-reading, beginning reading, and emergent reading) and found decreases in neural activation in the left inferior parietal cortex (LIPC) during an audiovisual phonological processing task [69]. Seed-based brain network analysis revealed increases in connection strength in the brain network of children with above-average gains in phonological processing but decreases in connection strength in the brain network of children with below-average gains in phonological processing measured by Comprehensive Test of Phonological Processing (CTOPP). Moreover, the connection strength between LIPC and the left posterior occipitotemporal cortex (LpOTC, BA 18) at the prereading stage significantly predicted reading skills at the emergent reading stage.

This chapter demonstrates the view of emergent reading and brain imaging evidence supporting advocacy for emergent reading. Emergent reading emphasizes the developmental continuum aspect of learning to read and the importance of

Both behavioral and imaging studies on DD suggest that early reading skills are essential to the later development of reading. Most children start formal reading curriculum in kindergarten; however, at that time, many factors (genetic, SES, HLE, etc.) have already affected the future reading development. Moreover, early

Brain regions (left inferior/middle frontal gyrus, bilateral fusiform gyri, and right anterior superior temporal gyrus) were identified to be especially sensitive to differences of early language/literacy exposure in beginning readers [67]. A richer HLE corresponded to increased brain activations during a phonological processing task [67] and increased brain activations related to high reading proficiency [76] demonstrated the underlying neural basis of reading. Among the children with a familial risk for DD, only around 50% of them will develop DD. The imaging evidence implies that a rich HLE might be one of the protective factors in reading development especially for children with a familial risk for DD. Future longitudinal studies are needed to examine how HLE contributes to the development of reading

Advocating emergent reading can benefit all children who are learning to read and especially those who are also at risk for DD. It is clear that aspects of HLE

networks in the brain and its role as a protective factor in general.

reading-related behaviors occurring before school.

interventions work more effectively.

#### *Emergent Reading and Brain Development DOI: http://dx.doi.org/10.5772/intechopen.82423*

*Early Childhood Education*

brain-based markers exist as a result of parent-child reading in early childhood. Thus, emergent reading shall be promoted and may help shape the developing brain

Developmental dyslexia (DD) has strong genetic basis [59], and family history of DD can increase a child's chance to develop reading difficulties by 34–56% [60–62]. In order to identify children at risk for DD, familial risk can be used as a good indicator. One group led by Dr. Nadine Gaab in Boston Children's Hospital has done pioneer work in this research field [48, 52, 63–70]. For the first time, they examined the relationship between home literacy environment (HLE) and the neural basis of phonological processing in beginning readers with family history of DD (n = 29, first-degree relative who has reading difficulties) and without family history of DD (n = 21) [67]. This study aimed to identify brain mechanism of how HLE affects reading development in beginning readers. SES was controlled in this study in order to isolate the effects only by HLE. In reading-related brain regions (e.g., left inferior/ middle frontal and right fusiform gyri), stronger correlations between HLE composite scores and brain activations were present in children without familial risk than those with familial risk. In the nonreading-related brain region (e.g., right precentral gyrus), stronger correlations existed in children with familial risk than those without familial risk. These findings suggest that genetic predisposition for DD alters contributions of HLE to brain activation. Specifically, typically developing children can benefit more from better HLE than children with familial risk for DD. Therefore, enhanced HLE is especially important for children with familial risk for DD to have

Shared parent-child reading is one of the important factors in emergent reading. A recent study demonstrated increased activation and functional connectivity in children who are more deeply engaged during shared reading in 22 motherdaughter pairs [71]. The same group also associated shared reading quality scores with brain activation, and they found a positive correlation between shared reading quality scores with activation in left-hemispheric regions supporting expressive and complex language, social-emotional integration, and working memory in 22 healthy, 4-year-old girls from low SES [72]. Their findings suggest that the use of shared parent-child reading is crucial for emergent reading experience, but the quality of this experience has also a strong impact on brain development. Especially for those at-risk families, improvements of the quality of shared reading can promote healthy brain development and better prepare a child for future success in

Morken et al. [73] used a longitudinal study design to examine the differences of cortical connectivity in the brain during reading tasks between children with dyslexia and children with typical reading development through dynamic causal modeling (DCM) [74]. They included five regions (inferior frontal gyrus, precentral gyrus, superior temporal gyrus, inferior parietal lobule, and occipitotemporal cortex) in their effective brain connectivity model [74]. They found that effective connectivity between the inferior frontal gyrus and the occipitotemporal cortex during reading tasks changes during reading acquisition. In addition, the group readers with dyslexia presented different developmental trajectory than the control group. The control group actually seemed to downregulate or stabilize connection strength over time, whereas the dyslexia group started out at a level well below the control group, followed by an increase in connectivity from 6 to 8 years and then a downregulation from 8 to 12 years. The general downregulation of connectivity in the control group might reflect that they need these connections to establish reading skills initially, and then, the connections are no longer needed after later automaticity is established. The dyslexia group showed late development of some connections in occipitotemporal cortices. However, they seem to show overcompensation

and better prepare a child for formal reading instructions in school.

the same impact as for typically developing children.

**228**

school.

around age 8, followed by normalization before age 12. Importantly, the dyslexia group was clearly lagging behind in the development of the brain networks at the age of 8 (emergent reading stage), suggesting emergent reading stage is critical.

Younger et al. also used a longitudinal study design and found decreases in connectivity for most connections from the first (T1) to the second (T2) time point about 2–3 years apart, regardless of changes in reading skill in 59 typical developing children [75]. But they found a significant decrease in the dorsal, decoding processing pathway from fusiform gyrus (FG) to inferior parietal lobule (IPL) for the group who improved more from the first to the second time point, suggesting that the improvements in reading skills lead to a decreased reliance on the dorsal pathway (decoding processing pathway) in the brain. The high and low improving groups did not differ in behavioral performance at T1, and high improvers showed greater connectivity between FG and IPL at T1 compared to the low improvers. The dorsal pathway facilitates phonological processing, which is necessary for development of the ventral pathway supporting automatic processing of visual word forms. However, there is no sequential relationship between the two routes. They may develop simultaneously.

Yu et al. studied 28 children over three stages (pre-reading, beginning reading, and emergent reading) and found decreases in neural activation in the left inferior parietal cortex (LIPC) during an audiovisual phonological processing task [69]. Seed-based brain network analysis revealed increases in connection strength in the brain network of children with above-average gains in phonological processing but decreases in connection strength in the brain network of children with below-average gains in phonological processing measured by Comprehensive Test of Phonological Processing (CTOPP). Moreover, the connection strength between LIPC and the left posterior occipitotemporal cortex (LpOTC, BA 18) at the prereading stage significantly predicted reading skills at the emergent reading stage.

## **5. Discussion**

This chapter demonstrates the view of emergent reading and brain imaging evidence supporting advocacy for emergent reading. Emergent reading emphasizes the developmental continuum aspect of learning to read and the importance of reading-related behaviors occurring before school.

Both behavioral and imaging studies on DD suggest that early reading skills are essential to the later development of reading. Most children start formal reading curriculum in kindergarten; however, at that time, many factors (genetic, SES, HLE, etc.) have already affected the future reading development. Moreover, early interventions work more effectively.

Brain regions (left inferior/middle frontal gyrus, bilateral fusiform gyri, and right anterior superior temporal gyrus) were identified to be especially sensitive to differences of early language/literacy exposure in beginning readers [67]. A richer HLE corresponded to increased brain activations during a phonological processing task [67] and increased brain activations related to high reading proficiency [76] demonstrated the underlying neural basis of reading. Among the children with a familial risk for DD, only around 50% of them will develop DD. The imaging evidence implies that a rich HLE might be one of the protective factors in reading development especially for children with a familial risk for DD. Future longitudinal studies are needed to examine how HLE contributes to the development of reading networks in the brain and its role as a protective factor in general.

Advocating emergent reading can benefit all children who are learning to read and especially those who are also at risk for DD. It is clear that aspects of HLE

(e.g., shared reading) before a child entering kindergarten or preschool benefit the later reading development.
