The Attentional Control of Reading: Insights from Behavior, Imaging and Development

The process by which the initially attention-requiring task of transforming scribbles into meaningful concepts eventually becomes facile remains a central riddle of cognitive neuroscience. This body of work represents an effort to provide forward movement in answering the question of how attentional control mediates the process of reading, both by considering different stages of reading competence (development) and by seeking convergence between types of evidence (behavior and imaging). Inspired by a study published by Balota and colleagues in 2000, the paradigm used throughout this work involves comparing a simple speeded reading task vs. a regularize ( sound out ) task (Balota et al. 2000). In the first data chapter, I replicate the essential findings of the Balota et al. study in 2 young adult cohorts, confirming that stimulus characteristics, including lexicality and frequency, influence reading task performance in a manner that is modulated by top-down attentional control. I furthermore argue that the reaction time (RT) patterns are consistent with 2 distinct mechanisms by which top-down attentional control interacts with reading processes, pathway control and response checking. I then present evidence, motivated by the 2-mechanism hypothesis, that 2 sets of brain regions, including members of previously defined attentional control networks, show separable activity patterns that map nicely onto roles reflecting pathway control and response checking. In the second data chapter, I show that 8-10 year old children, like young adults, can perform the regularize task. Unexpectedly, the early readers are faster than the experienced readers to regularize, and this speed advantage for children holds for both words and pseudowords. Because children are slower than adults across a range of cognitive tasks (e.g., Kail 1991) - with children showing particular immaturity with regard to inhibiting prepotent responses (e.g., Davidson et al. 2006) - the developmental observation is remarkable in and of itself. Complemented by a cadre of post hoc analyses, the age groups differences can also be interpreted as additional support for the 2-mechanism interaction of attention and reading. Together, these results suggest that dissociable subcomponents of attentional control interact with subcomponents of reading processing, and that these interactions are dynamic across skill development and across task demands

Learning, Arts, and the Brain: The Dana Consortium Report on Arts and Cognition

Reports findings from multiple neuroscientific studies on the impact of arts training on the enhancement of other cognitive capacities, such as reading acquisition, sequence learning, geometrical reasoning, and memory

Examining Brain Connectivity and Reading Ability in Children

In this thesis, I investigated the relationship between functional and structural connectivity and reading ability in children. Prior research has tended to use single word reading measures or composite measures, however this is problematic as reading is a complex skill relying on multiple subskills, such as decoding efficiency, sight word reading efficiency, reading comprehension, and rapid automatized naming. As a result, the multi-faceted relationship between brain connectivity and reading ability is not well understood. I aimed to address this issue by considering multiple reading subskills while examining the neural substrates of reading. In Chapter 2, I examined how individual differences in decoding efficiency, sight word reading efficiency, reading comprehension, and rapid automatized naming relate to resting-state functional connectivity from regions of the brain’s reading network. I found that distinct functional networks in both hemispheres of the brain support different components of reading in children. In Chapter 3, I built on these findings to examine how individual differences in the same reading subskills are associated with structural connectivity in reading-related white matter tracts, as measured by diffusion tensor imaging. Similar to Chapter 2, the results of Chapter 3 suggested that different components of reading ability are supported by structural characteristics in distinct bilateral tracts of the brain. Importantly, many of the effects observed in Chapters 2 and 3 were found to be specific to reading subskills and were not associated with more general cognitive abilities. In Chapter 4, I examined how improvements in reading ability are related to changes in structural and functional connectivity, by measuring brain connectivity pre- and post-intervention in a group of children with reading disability. I also investigated whether individual differences in the amount of improvement in reading ability post-intervention was predicted by pre-intervention brain connectivity. I found that gains in reading ability were associated with changes in resting-state functional connectivity, particularly between reading-related regions and frontal regions as well as regions of the default mode network. Changes in white matter microstructure of the right arcuate fasciculus were strongly associated with gains in single word reading abilities. Additionally, results showed that distinct pre-intervention characteristics of resting-state functional connectivity and white matter integrity predicted the magnitude of subsequent gains in reading ability following the reading intervention. Chapter 5 summarizes the findings of this thesis in relation to the current literature and presents recommendations for future research on reading ability and brain connectivity

The Examination of White Matter Microstructure, Autism Traits, and Social Cognitive Abilities in Neurotypical Adults

The purpose of this study was to examine the relationships among mentalizing abilities, self-reported autism traits, and two white matter tracts, uncinate fasciculus (UF) and inferior longitudinal fasciculus (ILF), in neurotypical adults. UF and ILF were hypothesized to connect brain regions implicated in a neuroanatomical model of mentalizing. Data were available for 24 neurotypical adults (mean age = 21.92 (4.72) years; 15 women). Tract-based spatial statistics (TBSS) was used to conduct voxelwise cross-participant comparisons of fractional anisotropy (FA) values in UF and ILF as predicted by mentalizing abilities and self-reported autism traits. Self-reported autism traits were positively related to FA values in left ILF. Results suggest that microstructural differences in left ILF are specifically involved in the expression of subclinical autism traits in neurotypical individuals

Structural properties of the ventral reading pathways are associated with morphological processing in adult English readers

Morphological processing, the ability to extract information about word structure, is an essential component of reading. Functional MRI studies have identified several cortical regions involved in morphological processing, but the white matter pathways that support this skill remain unknown. Here, we examine the relationship between behavioral measures of morphological processing and microstructural properties of white matter pathways. Using diffusion MRI (dMRI), we identified the major ventral and dorsal reading pathways in a group of 45 adult English readers. The same participants completed a behavioral battery that included a morphological task and measures of phonological and orthographic processing. We found significant correlations between morphological processing skill and microstructural properties of the ventral, but not dorsal, pathways. These correlations were detected primarily in the left hemisphere, and remained significant after controlling for phonological or orthographic measures, suggesting some level of cognitive specificity. Morphological processing of written words thus appears to rely on ventral pathways, primarily in the left hemisphere. This finding supports the contribution of morphological processing to lexical access and comprehension of complex English words

Multimodal principal component analysis to identify major features of white matter structure and links to reading

The role of white matter in reading has been established by diffusion tensor imaging (DTI), but DTI cannot identify specific microstructural features driving these relationships. Neurite orientation dispersion and density imaging (NODDI), inhomogeneous magnetization transfer (ihMT) and multicomponent driven equilibrium single-pulse observation of T1/T2 (mcDESPOT) can be used to link more specific aspects of white matter microstructure and reading due to their sensitivity to axonal packing and fiber coherence (NODDI) and myelin (ihMT and mcDESPOT). We applied principal component analysis (PCA) to combine DTI, NODDI, ihMT and mcDESPOT measures (10 in total), identify major features of white matter structure, and link these features to both reading and age. Analysis was performed for nine reading-related tracts in 46 neurotypical 6–16 year olds. We identified three principal components (PCs) which explained 79.5% of variance in our dataset. PC1 probed tissue complexity, PC2 described myelin and axonal packing, while PC3 was related to axonal diameter. Mixed effects regression models did not identify any significant relationships between principal components and reading skill. Bayes factor analysis revealed that the absence of relationships was not due to low power. Increasing PC1 in the left arcuate fasciculus with age suggest increases in tissue complexity, while increases of PC2 in the bilateral arcuate, inferior longitudinal, inferior fronto-occipital fasciculi, and splenium suggest increases in myelin and axonal packing with age. Multimodal white matter imaging and PCA provide microstructurally informative, powerful principal components which can be used by future studies of development and cognition. Our findings suggest major features of white matter undergo development during childhood and adolescence, but changes are not linked to reading during this period in our typically-developing sample

Post-stroke deficit prediction from lesion and indirect structural and functional disconnection

Behavioural deficits in stroke reflect both structural damage at the site of injury, and widespread network dysfunction caused by structural, functional, and metabolic disconnection. Two recent methods allow for the estimation of structural and functional disconnection from clinical structural imaging. This is achieved by embedding a patient's lesion into an atlas of functional and structural connections in healthy subjects, and deriving the ensemble of structural and functional connections that pass through the lesion, thus indirectly estimating its impact on the whole brain connectome. This indirect assessment of network dysfunction is more readily available than direct measures of functional and structural connectivity obtained with functional and diffusion MRI, respectively, and it is in theory applicable to a wide variety of disorders. To validate the clinical relevance of these methods, we quantified the prediction of behavioural deficits in a prospective cohort of 132 first-time stroke patients studied at 2 weeks post-injury (mean age 52.8 years, range 22-77; 63 females; 64 right hemispheres). Specifically, we used multivariate ridge regression to relate deficits in multiple functional domains (left and right visual, left and right motor, language, spatial attention, spatial and verbal memory) with the pattern of lesion and indirect structural or functional disconnection. In a subgroup of patients, we also measured direct alterations of functional connectivity with resting-state functional MRI. Both lesion and indirect structural disconnection maps were predictive of behavioural impairment in all domains (0.16 < R2 < 0.58) except for verbal memory (0.05 < R2 < 0.06). Prediction from indirect functional disconnection was scarce or negligible (0.01 < R2 < 0.18) except for the right visual field deficits (R2 = 0.38), even though multivariate maps were anatomically plausible in all domains. Prediction from direct measures of functional MRI functional connectivity in a subset of patients was clearly superior to indirect functional disconnection. In conclusion, the indirect estimation of structural connectivity damage successfully predicted behavioural deficits post-stroke to a level comparable to lesion information. However, indirect estimation of functional disconnection did not predict behavioural deficits, nor was a substitute for direct functional connectivity measurements, especially for cognitive disorders

Corpus Callosum and Word Reading in Adult Survivors of Childhood Posterior Fossa Tumors

Adult survivors of childhood posterior fossa tumors can experience reading difficulties related to white matter integrity. Previously, reading was shown to be related to cortical white matter tracts, however information transfer across the corpus callosum (CC) may also play a role in reading. The current study used both macro- and microstructural measures of the WM structure of the corpus callosum. The current study examined how white matter volume and fractional anisotropy (FA) in five divisions of the CC was related to degree of neurological risk and reading skill, and tested two mediation models predicting reading. Participants included 20 adult survivors of childhood posterior fossa tumor and 23 healthy controls. Volume and FA were measured in five divisions of the mid-sagittal corpus callosum. Total intracranial vault was used as a covariate in volume analyses. FA was reduced in CC1 and volume was reduced in each subregion in survivors. Volume but not FA was related to degree of neurological risk. Results identified that reduced volume in CC1 and CC5, and FA in CC5 appear to be specifically related to reading skill in line with the cortical reading regions that connect in these subregions of the CC. Mediation models indicate that processing speed is the mechanism by which volume is related to reading skill. These findings have implications for addressing processing speed in reading interventions in survivors and provide insight into the interhemispheric connections in the reading network

Regional Gray Matter Correlates of Perceived Emotional Intelligence

Coping with stressful life events requires a degree of skill in the ability to attend to, comprehend, label, communicate and regulate emotions. Individuals vary in the extent to which these skills are developed, with the term ‘alexithymia’ often applied in the clinical and personality literature to those individuals most compromised in these skills. Although a frontal lobe model of alexithymia is emerging, it is unclear whether such a model satisfactorily reflects brain-related patterns associated with perceived emotional intelligence at the facet level. To determine whether these trait meta-mood facets (ability to attend to, have clarity of and repair emotions) have unique gray matter volume correlates, a voxel-based morphometry study was conducted in 30 healthy adults using the Trait Meta Mood Scale while co-varying for potentially confounding sociodemographic variables. Poorer Attention to Emotion was associated with lower gray matter volume in clusters distributed primarily throughout the frontal lobe, with peak correlation in the left medial frontal gyrus. Poorer Mood Repair was related to lower gray matter volume in three clusters in frontal and inferior parietal areas, with peak correlation in the left anterior cingulate. No significant volumetric correlations emerged for the Clarity of Emotion facet. We discuss the localization of these areas in the context of cortical circuits known to be involved in processes of self-reflection and cognitive control

Regional Gray Matter Correlates of Perceived Emotional Intelligence

Coping with stressful life events requires a degree of skill in the ability to attend to, comprehend, label, communicate and regulate emotions. Individuals vary in the extent to which these skills are developed, with the term ‘alexithymia’ often applied in the clinical and personality literature to those individuals most compromised in these skills. Although a frontal lobe model of alexithymia is emerging, it is unclear whether such a model satisfactorily reflects brain-related patterns associated with perceived emotional intelligence at the facet level. To determine whether these trait meta-mood facets (ability to attend to, have clarity of and repair emotions) have unique gray matter volume correlates, a voxel-based morphometry study was conducted in 30 healthy adults using the Trait Meta Mood Scale while co-varying for potentially confounding sociodemographic variables. Poorer Attention to Emotion was associated with lower gray matter volume in clusters distributed primarily throughout the frontal lobe, with peak correlation in the left medial frontal gyrus. Poorer Mood Repair was related to lower gray matter volume in three clusters in frontal and inferior parietal areas, with peak correlation in the left anterior cingulate. No significant volumetric correlations emerged for the Clarity of Emotion facet. We discuss the localization of these areas in the context of cortical circuits known to be involved in processes of self-reflection and cognitive control