Browsing by Author "Fletcher, Jack M."

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A cognitive dimensional approach to understanding comorbidity among reading disability, math disability, and attention-deficit/hyperactivity disorder
(2015-12) Child, Amanda; Cirino, Paul T.; Fletcher, Jack M.; Willcutt, Erik G.
Reading disability (RD), math disability (MD), and attention-deficit/hyperactivity disorder (ADHD) are common disorders that frequently co-occur in school-aged children. However, it is not yet clear which cognitive factors contribute to the comorbidities between the three disorders and which cognitions are uniquely related to one disorder. Thus, the present study considers how reading, math, and attention outcomes are related to PA, numerosity, WM, and PS. In response to findings that all three disorders exist on a continuum as opposed to representing groups that are fundamentally different from the normative population, this study employed a dimensional approach. Furthermore, in order to elucidate how the cognitive predictors relate to different methods of assessing math and reading ability, both timed and untimed academic outcomes were utilized. Inattention as well as hyperactivity outcomes were also considered. Results from this study support the role of working memory and phonological awareness in the comorbidities between reading, math, and attention outcomes, with a limited role of processing speed. Numerosity was also found to be related to the comorbidity between math and inattention. Results from timed outcomes and hyperactivity were generally similar to those with untimed and inattention outcomes, although hyperactivity was less strongly related to academic and attention outcomes in general. These findings have implications for understanding cognitive deficits that contribute to comorbidities between RD, MD, and ADHD.
A response to recent reanalyses of the National Reading Panel Report: Effects of systematic phonics instruction are practically significant
(Journal of Educational Psychology, 2008-02) Stuebing, Karla K.; Barth, Amy E.; Cirino, Paul T.; Francis, David J.; Fletcher, Jack M.
The authors examine the reassessments of the National Reading Panel (NRP) report (National Institute of Child Health and Human Development, 2000) by G. Camilli, S. Vargas, and M. Yurecko (2003); G. Camilli, P. M. Wolfe, and M. L. Smith (2006); and D. D. Hammill and H. L. Swanson (2006) that disagreed with the NRP on the magnitude of the effect of systematic phonics instruction. Using the coding of the NRP studies by Camilli et al. (2003, 2006), multilevel regression analyses show that their findings do not contradict the NRP findings of effect sizes in the small to moderate range favoring systematic phonics. Extending Camilli et al. (2003, 2006), the largest effects are associated with reading instruction enhanced with components that increase comprehensiveness and intensity. In contrast to Hammill and Swanson, binomial effect size displays show that effect sizes of the magnitude found for systematic phonics by the NRP are meaningful and could result in significant improvement for many students depending on the base rate of struggling readers and the size of the effect. Camilli et al. (2003, 2006) and Hammill and Swanson do not contradict the NRP report, concurring in supporting comprehensive approaches to reading instruction.
A structural model for developmental change in the determinants of reading ability
(1984) Francis, David J.; Sheer, Daniel. E.; Fletcher, Jack M.; Osburn, Hobart G.; Maxwell, Scott E.
Developmentally dependent changes in the neuropsychological correlates of reading achievement were examined via the analysis of linear structural relations, or LISREL (Joreskog, 1976). The study tested the hypothesis that the relative importance of non-verbal/perceptual skills and verbal-conceptual skills in reading changed as a function of development and that non-verbal/perceptual skills became increasingly less important with age. Data were taken from a previously completed six-year longitudinal study of learning disabilities in Alachua County, Florida (Satz, Taylor, Friel, and Fletcher, 1978). A sub-sample of 222 white males from the original study sample was used for the present study. Three measures of non-verbal/perceptual skills and three measures of verbal conceptual skills were collected at each of three measurement periods, namely in Kindergarten, at the end of Grade 2, and at the end of Grade 5. In addition, a standardized test of word recognition and a teacher based report of the child's instructional book level were obtained at the Grade 2 and Grade 5 assessment periods. These 22 measures were incorporated into a three-wave three-factor structural equation model with correlated errors, the parameters of which were estimated via the computer program LISREL V (Joreskog and Sorbom, 1981). The model stipulated that each of the 22 variables loaded on only a single factor, and that each of the non-verbal and verbal skills factors were measured by three variables, while the reading achievement factors were each measured by two variables. [...]
A study of intellectual recovery following closed head injury
(1988) Bailey, Cynthia A.; Fletcher, Jack M.; Francis, David J.; Foorman, Barbara R.; Hayden, Mary Ellen
Previous studies have utilized the WAIS and WAIS-R to assess the level of intellectual functioning after closed head injury, and have found that the Full Scale scores are depressed within the first year, and show a gradual improvement over time. The Verbal scale is usually higher that the Performance scale and exhibits a faster recovery rate. The present study focused on identifying subject variables (such as premorbid IQ and severity of injury) which contribute to the initial depression of IQ scores, and on determining the reasons for the VIQ-PIQ discrepancy. Results indicated that premorbid intellectual levels and severity of injury were correlated with change in IQ scores over time. Also, the interval between injury and readiness to be tested was significantly related to IQ at follow-up. The VIQ-PIQ discrepancy appeared to be an artefact of deficits in visual discrimination and motor programming at baseline. At follow-up there was no overall discrepancy, but visual discrimination was correlated with Performance IQ. Implications of these results will be discussed.
A study of memory in subtypes of learning disabled children
(1982) Ward, Donna Catherine; Sheer, Daniel. E.; Fletcher, Jack M.; Cordua y Cruz, Glenn; Amerikaner, Martin J.
A verbal and nonverbal selective reminding procedure is utilized with three groups of children, ages eight to twelve years. Four memory indices are analyzed on each of the selective reminding tasks to identify the specific component of memory responsible for failure to learn. The three groups of children are identified based on academic achievement and intellectual performance and divided into two experimental groups (Math disabled. Generally disabled) and a Control group.
A test of the cerebellar hypothesis of dyslexia in adequate and inadequate responders to reading intervention
(Journal of the International Neuropsychological Society, 2010-03) Barth, Amy E.; Denton, Carolyn A.; Stuebing, Karla K.; Fletcher, Jack M.; Cirino, Paul T.; Francis, David J.; Vaughn, Sharon
The cerebellar hypothesis of dyslexia posits that cerebellar deficits are associated with reading disabilities and may explain why some individuals with reading disabilities fail to respond to reading interventions. We tested these hypotheses in a sample of children who participated in a grade 1 reading intervention study (n = 174) and a group of typically achieving children (n = 62). At posttest, children were classified as adequately responding to the intervention (n = 82), inadequately responding with decoding and fluency deficits (n = 36), or inadequately responding with only fluency deficits (n = 56). Based on the Bead Threading and Postural Stability subtests from the Dyslexia Screening Test-Junior, we found little evidence that assessments of cerebellar functions were associated with academic performance or responder status. In addition, we did not find evidence supporting the hypothesis that cerebellar deficits are more prominent for poor readers with “specific” reading disabilities (i.e., with discrepancies relative to IQ) than for poor readers with reading scores consistent with IQ. In contrast, measures of phonological awareness, rapid naming, and vocabulary were strongly associated with responder status and academic outcomes. These results add to accumulating evidence that fails to associate cerebellar functions with reading difficulties.
Aberrant spatiotemporal activation profiles associated with math difficulties in children: A magnetic source imaging study
(Neuropsychology, 2008-09) Simos, Panagiotis G.; Kanatsouli, Kassiani; Fletcher, Jack M.; Sarkari, Shirin; Juranek, Jenifer; Cirino, Paul T.; Passaro, Antony D.; Papanicolaou, Andrew C.
The study investigates the relative degree and timing of cortical activation in parietal, temporal, and frontal regions during simple arithmetic tasks in children who experience math difficulties. Real-time brain activity was measured with magnetoencephalography during simple addition and numerosity judgments in students with math difficulties and average or above average reading skills (MD group, N = 14), students with below average scores on both math and basic reading tests (MD/RD group, N = 16) and students with above average scores on standardized math tests (control group, N = 25). Children with MD showed increased degree of neurophysiological activity in inferior and superior parietal regions in the right hemisphere compared to both controls and MD/RD students. Left hemisphere inferior parietal regions did not show the expected task-related changes and showed activity at a significant temporal delay. MD students also showed increased early engagement of prefrontal cortices. Taken together, these findings may indicate increased reliance on a network of right hemisphere parietal (and possibly frontal areas as well) for simple math calculations in students who experience math difficulties but perform within normal range in reading.
Age effects in the recovery of motor, somatosensory, and visual-spatial skills following pediatric head injury
(1988) Thompson, Nora M.; Fletcher, Jack M.; Levin, Harvey S.; Ewing-Cobbs, Linda; Foorman, Barbara R.; Miner, Michael E.; Power, Thomas G.
This prospective, longitudinal study of the recovery of motor, somatosensory, and visual-spatial functions following pediatric closed head injury supports previous literature describing a systematic relationship of performance levels with injury severity. Furthermore, systematic relationships were demonstrated between injury severity and the rate of recovery during the first post-injury year. Age effects were found suggesting greater vulnerability for children on a somatosensory and a constructional task. In addition, adolescents were at greater risk for deficits in fine motor speed and on a grapho-motor task. These age effects lend support to the functional maturation hypothesis. Correlates of recovery from hemiparesis included the type of pathological process and proximity to the corticospinal pathways. Site of injury was not significantly related to performance in most task domains. Differential recovery patterns for speed and accuracy were demonstrated on a somatosensory task. Finally, this study supports the utility of Hierarchical Linear Modelling for assessing the correlates of change.
An examination of short-term memory deficits in nonfluent aphasia
(1987) Feher, Edward P.; Fletcher, Jack M.; Martin, Randi C.; Breitmeyer, Bruno G.; Aker, Joan S.
Martin (1987) has suggested that nonfluent aphasics have reduced ability to hold verbal information in short-term memory (STM) because of difficulty performing rehearsal. Two experiments were performed to test this hypothesis. In Experiment 1, recall of word sets was tested at 0, 5,10, and 20 seconds. More rapid decay was found in nonfluent aphasics than in fluent aphasics and controls, suggesting inability to regenerate information in STM in the nonfluent group. In Experiment 2, STM was compared for easy-to-articulate (EA) and difficult-to-articulate (DA) words. Controls and fluent aphasics showed an EA > DA superiority, assumedly due to more rapid rehearsal of the EA words. Nonfluent aphasics failed to show the EA > DA effect, suggesting impaired ability to use rehearsal. The results of the two experiments support the hypothesis of rehearsal-related STM deficits in nonfluent aphasia. A third experiment compared three measures of rehearsal skill as predictors of STM scores. None of the measures proved to be good predictors, and possible reasons for this finding were discussed. A fourth experiment compared pattern of performance across three STM tasks (serial recall, probe recognition, and missing digit), in an attempt to separate rehearsal-related STM deficits from other types of STM impairment. The serial recall task is known to draw on rehearsal, whereas the other two tasks do not. It was expected that aphasics with rehearsal difficulty would show poorest performance, relative to normals, on serial recall. This prediction was only partially confirmed: aphasics' scores were near the normal range for probe recognition, but well below normal for the serial recall and missing digit tasks. A final experiment tested claims that STM defects account for some aphasics' difficulty with sentence comprehension. Sentence comprehension was compared for two conditions: in the first, a printed sentence was in view during attempted comprehension; in the second, each sentence was presented one word at a time via computer screen. Comparison of performance on the two conditions yielded an estimate of the contribution of STM deficits to comprehension impairment. STM scores predicted performance on syntactically simple sentences with a heavy load of semantic information, but failed to predict performance on three types of syntactically complex sentences. The results suggest that STM defects play a determining role in comprehension impairment only for the former sentence type.
An experimental study of scheduling and duration of "Tier 2" first-grade reading intervention
(Journal of Research on Educational Effectiveness, 2011-05) Denton, Carolyn A.; Cirino, Paul T.; Barth, Amy E.; Romain, Melissa A.; Vaughn, Sharon; Wexler, Jade; Francis, David J.; Fletcher, Jack M.
This study compared the effects on reading outcomes of delivering supplemental, small-group intervention to first-grade students at risk for reading difficulties randomly assigned to one of three different treatment schedules: extended (4 sessions per week, 16 weeks; n = 66), concentrated (4 sessions per week, 8 weeks; n = 64), or distributed (2 sessions per week, 16 weeks; n = 62) schedules. All at-risk readers, identified through screening followed by 8 weeks of oral reading fluency (ORF) progress monitoring, received the same Tier 2 reading intervention in groups of 2 to 4 beginning in January of Grade 1. Group means were higher in word reading and ORF at the final time point relative to pretest; however, the groups did not differ significantly on any reading outcome or on rates of adequate intervention response. Of potential covariates, site, age, free lunch status, program coverage rate, and tutor were significantly related to student outcomes; however, the addition of these variables in multivariate models did not substantially change results. Rates of adequate intervention response were lower than have been reported for some first-grade interventions of longer duration.
Arithmetic error and neuropsychological test profiles among arithmetic disabled groups : external validation of academic subtypes
(1986) Dowell, Richard Edward, Jr.; Fletcher, Jack M.; Copeland, Donna P.; Francis, David J.; Foorman, Barbara R.
Neuropsychological deficits and arithmetic error types among learning disabled (Lp) children have been related to academic achievement patterns and attributed to a common underlying disability. A disability-based explanation predicts that groups of children showing similar (different) subtype patterns will exhibit similar (different) neuropsychological and arithmetic error patterns. Fifty-seven children, aged 8-16 years, with a history of a LD or cranial radiation therapy (CRT) were classified into four groups; A LD (arithmetic impaired), RA LD (reading and arithmetic impaired), A CRT, and N CRT (not subtype A). Neuropsychological composites representing ability areas were computed from intellectual, memory, and psychomotor test scores. Arithmetic errors were scored on the WRAT Arithmetic test using procedures adapted from Strang and Rourke (1985) and converted to composite scores. Profile analyses on composite scores compared groups showing similar (A LD vs A CRT) and different (A LD vs RA LD, A CRT vs N CRT) subtype patterns. Results indicated no significant group profile differences and did not support study predictions. The failure to replicate previous findings is discussed.
Attention and memory in children and adolescents with traumatic brain injury
(1988) Kaufmann, Paul M.; Fletcher, Jack M.; Breitmeyer, Bruno G.; Ewing-Cobbs, Linda; Foorman, Barbara R.; Levin, Harvey S.; Miner, Michael E.
Attention and memory were investigated in fifty-two children and adolescents at one and two years following closed-head injury. Subjects were divided into three injury severity groups (mild, moderate, and severe) based on neurological criteria. Attention and memory skills were assessed using the following battery: 1) WISC-R Digit Span, 2) Continuous Performance Task, 3) Continuous Recognition Memory, and 4) Verbal Selective Reminding Task. Subjects with more severe brain injuries had a greater degree of attention and memory impairment. Children under 13 years of age demonstrated greater impairment on the CPT when compared to adolescents. Deficits were most pronounced on tasks requiring selective attention and inhibition of responses to distracting stimuli. Attention skills made a significant contribution to overall memory performance. These results support the view that attention is a prerequisite skill for memory. There was no evidence of greater sparing of attention in younger children. Implications for new learning and development were discussed.
Attention in spina bifida myelomeningocele: Relations with brain volume and integrity
(NeuroImage: Clinical, 2015-03) Kulesz, Paulina A.; Treble-Barna, Amery; Williams, Victoria J.; Juranek, Jenifer; Cirino, Paul T.; Dennis, Maureen; Fletcher, Jack M.
This study investigated the relations of tectal volume and superior parietal cortex, as well as alterations in tectocortical white matter connectivity, with the orienting and executive control attention networks in individuals with spina bifida myelomeningocele (SBM). Probabilistic diffusion tractography and quantification of tectal and superior parietal cortical volume were performed on 74 individuals aged 8–29 with SBM and a history of hydrocephalus. Behavioral assessments measured posterior (covert orienting) and anterior (conflict resolution, attentional control) attention network functions. Reduced tectal volume was associated with slower covert orienting; reduced superior parietal cortical volume was associated with slower conflict resolution; and increased axial diffusivity and radial diffusivity along both frontal and parietal tectocortical pathways were associated with reduced attentional control. Results suggest that components of both the orienting and executive control attention networks are impaired in SBM. Neuroanatomical disruption to the orienting network appears more robust and a direct consequence of characteristic midbrain dysmorphology; whereas, executive control difficulties may emerge from parietal cortical anomalies and reduced frontal and parietal cortical–subcortical white matter pathways susceptible to the pathophysiological effects of congenital hydrocephalus.
Brain mechanisms for reading and language processing in spina bifida meningomyelocele: A combined magnetic source- and structural magnetic resonance imaging study
(Neuropsychology, 2011-09) Simos, Panagiotis G.; Papanicolaou, Andrew C.; Martinez Castillo, Eduardo; Juranek, Jenifer; Cirino, Paul T.; Rezaie, Roozbeh; Fletcher, Jack M.
Objective: The development of the ability to process spoken and written language depends upon a network of left hemisphere temporal, parietal, and frontal regions. The present study explored features of brain organization in children with spina bifida meningomyelocele (SBM) and shunted hydrocephalus, who commonly present with precocious development of word reading skills and preservation of vocabulary and grammar skills. Method: Eight children with SBM were compared with 15 IQ and reading-level matched, typically developing controls on MRI-based morphometric and Magnetic Source Imaging-derived neurophysiological profiles. Results: Children with SBM showed reduced magnetic activity in left inferior parietal regions during spoken word recognition and pseudoword reading tasks. We also noted reduced surface area/volume in inferior parietal and posterior temporal regions in SBM and increased gray matter volumes in left middle frontal regions and gyral complexity in left posterior temporal and inferior parietal regions. Conclusions: A complex pattern of changes in cortical morphology and activation may serve as evidence for structural and functional brain reorganization ensuring preservation of language and decoding abilities in children with SBM.
Characteristics of a spina bifida population including North American Caucasian and Hispanic individuals
(Birth Defects Research Part A: Clinical and Molecular Teratology, 2008-10) Au, Sing Kit; Tran, Phong X.; Tsai, Chester C.; O'Byrne, Michelle R.; Lin, Jone-Ing; Morrison, Alanna C.; Hampson, Amy W.; Cirino, Paul T.; Fletcher, Jack M.; Ostermaier, Kathryn K.; Tyerman, Gayle H.; Doebel, Sabine; Northrup, Hope
BACKGROUND. Meningomyelocele (MM) is a common human birth defect. MM is a disorder of neural development caused by contributions from genes and environmental factors that result in the neural tube defect and lead to a spectrum of physical and neurocognitive phenotypes. METHODS. A multi-disciplinary approach has been taken to develop a comprehensive understanding of MM through collaborative efforts from investigators specializing in genetics, development, brain imaging, and neurocognitive outcome. Patients have been recruited from five different sites: Houston and the Texas-Mexico border area; Toronto, Canada; Los Angeles, California; and Lexington, Kentucky. Genetic risk factors for MM have been assessed by genotyping and association testing using the transmission disequilibrium test. RESULTS. A total of 509 affected child/parent trios and 309 affected child/parent duos have been enrolled to date for genetic association studies. Subsets of the patients have also been enrolled for studies assessing development, brain imaging, and neurocognitive outcomes. The study recruited two major ethnic groups with 45.9% Hispanics of Mexican descent and 36.2% North American Caucasians of European descent. The remaining patients are African American, South and Central American, Native American and Asian. Studies of this group of patients have already discovered distinct corpus callosum morphology and neurocognitive deficits that associate with MM. We have identified maternal MTHFR 667T allele as a risk factor for MM. In addition, we also found that several genes for glucose transport and metabolism are potential risk factors for MM. CONCLUSIONS. The enrolled patient population provides a valuable resource for elucidating the disease characteristics and mechanisms for MM development.
Cognitive and behavioral attention in children with math difficulties
(Child Neuropsychology, 2013) Gold, Alanna B.; Ewing-Cobbs, Linda; Cirino, Paul T.; Fuchs, Lynn S.; Stuebing, Karla K.; Fletcher, Jack M.
Cognitive assessments and behavioral ratings of attention were used to examine the relation of inattention to math performance in children. Third grade students with math difficulties (MD; n = 17) and math and reading difficulties (MDRD; n = 35) were administered the Attentional Network Test (ANT), as well as achievement and intelligence measures. Strengths and Weaknesses of ADHD-Symptoms and Normal-Behavior-IV (SWAN-IV) Inattention ratings were collected from teachers. Two comparison groups were also recruited: a typically achieving group (n = 23) and a group that responded to a math-tutoring intervention (responders; n = 54). On the ANT, children with MD and MDRD did not perform significantly different than typically achieving children or responders on measures of alerting and orienting attention and executive control. All subgroups did demonstrate performance patterns that were expected on the ANT. However, performance across blocks of the task was inconsistent, suggesting poor reliability. There were no relations between ANT performance and SWAN-IV behavioral inattention scores, though behavioral ratings of inattention correlated significantly with math performance. Children with MD and MDRD may have more difficulty with distraction and attention to detail in contextual situations, as opposed to impulsive responding in these settings. The lack of relation between cognitive attention and math performance may suggest that either the ANT does not assess the relevant attention constructs associated with math difficulties or may parallel studies of attention deficit/hyperactivity disorder (ADHD) in which cognitive and behavioral assessments are weakly related.
Cognitive and Behavioral Rating Measures of Executive Function as Predictors of Academic Outcomes in Children
(2014-12) Gerst, Elyssa Hope; Cirino, Paul T.; Fletcher, Jack M.; Yoshida, Hanako
The present study aimed to compare the interrelations of cognitive (or performance-based) versus behavioral rating measures four specific domains of Executive Function (EF), and to relate these to academic outcomes in children. The goal of this study was to examine the relation between cognitive and behavioral rating measures of EF on a 1:1 basis, within a constricted age range in typically developing children. Ninety-six 4th and 5th grade students were assessed with cognitive and behavioral rating measures (teacher reports) within four EF domains (working memory, planning, inhibition and shift). Relations between both measurement types within each EF domain were modest (range r = |.19 to .25|), and their relation to measures of reading comprehension and math performance were moderate (range r = |.29 to .55|). All regression models within each EF domain (working memory, planning, inhibition, and shift) were significant (p < .05) with and without the inclusion of relevant covariates (phonological decoding, education program, and/or age). Final models with all relevant covariates and EF measures were significant (p < .05) in the prediction of reading comprehension and math, with working memory particularly important for reading comprehension and inhibition particularly important for math. Cognitive measures and behavioral ratings of EF were only modestly related to each other, though each was contributory to the prediction of both reading comprehension and math.
Corpus callosum microstructure and auditory interhemispheric transfer in spina bifida myelomeningocele
(2014-08) Bradley, Kailyn A. L.; Fletcher, Jack M.; Hannay, H. Julia; Hernandez, Arturo E.; Juranek, Jenifer
The purpose of this study was to evaluate if early disruption in corpus callosum development due to spina bifida myelomeningocele (SBM) contributes to plastic reorganization of interhemispheric white matter. Additionally, this study evaluated if diffusion tensor imaging measures of integrity of the interhemispheric temporal tract specifically had functional relevance and predicted performance on a task that required auditory communication between hemispheres, dichotic listening. T1-weighted and diffusion tensor imaging data was acquired on a group of people with SBM (n = 76) and a typically developing group (n = 27). Probabilistic tractography was performed to isolate the interhemispheric white matter connecting auditory processing regions in both hemispheres. Behavioral performance was assessed on a consonant-vowel dichotic listening task in a subset of these participants (SBM, n = 45; TD, n = 15). The key finding from this study was that atypical development of the corpus callosum in SBM does result in re-routing of interhemispheric temporal connections through alternate commissures, particularly the anterior commissure. These re-routed fibers were present in people with SBM and a hypoplastic, or thin posterior corpus callosum, as well as those with more severe underdevelopment, partial agenesis. Additionally, microstructural integrity was reduced in the interhemispheric temporal tract in SBM, as indicated by lower fractional anisotropy and axial diffusivity, and higher radial diffusivity. Examination of macrostructure and microstructure of the tract and dichotic performance suggests that these re-routed connections through the anterior commissure are not compensatory, but maladaptive. Preservation of the normative pattern on the dichotic listening task in people with SBM is the result of connections between temporal lobes through the posterior corpus callosum, and not the anterior commissure. Lastly, abnormal AD was associated with atypical left ear performance on the dichotic listening task, suggesting that reduced integrity of the auditory interhemispheric tract adversely affected dichotic performance in SBM. Given persistent hypotheses about the role of the anterior commissure and other potential compensatory connections, this study has important implications for understanding of the effects of early corpus callosum maldevelopment, especially when partial agenesis is involved.
Cortical Thickness and Gyrification in Children with Developmental Dyslexia
(2015-05) Williams, Victoria; Fletcher, Jack M.; Juranek, Jenifer; Stuebing, Karla K.; Sharp, Carla
Prior research has demonstrated a pattern of atypical neural structure and function within regions of the left hemisphere reading network in individuals with dyslexia compared to controls. However, studies of pediatric dyslexia are sparse, demonstrate variability in dyslexia classification, and yield inconsistent associations between cortical metrics and reading ability. This study investigated cortical metrics in typically developing readers (n=39) and children with dyslexia (n=37) as determined by deficient single word reading ability. Whole-brain vertex-wise analyses, performed using FreeSurfer, evaluated cortical thickness and local gyrification between reading groups, controlling for age. Following multiple comparison correction, readers with dyslexia demonstrated reduced cortical thickness within previously identified critical reading areas including: bilateral inferior-temporal, inferior-frontal, and occipito-parietal regions, along with left anterior cingulate cortex. In readers with dyslexia, thinner cortex was accompanied by increased gyrification in the cuneus and left inferior temporal cortex. The convergence of thinner and more gyrified cortex within the left inferior temporal region in children with dyslexia may reflect its early temporal role in processing word forms, and highlights the importance of the ventral stream for successful decoding. Reading fluency scores demonstrated a positive association with cortical thickness in right inferior frontal and bilateral inferior temporal cortices, while reading comprehension was significantly correlated with thickness across all regions.
Cortico-cerebellar connectivity in reading impaired children: A probabilistic tractography study
(2014-08) Fernandez, Vindia; Fletcher, Jack M.; Juranek, Jenifer; Stuebing, Karla; Tackett, Jennifer L.
Very little is known about cortico-cerebellar connectivity as it relates to individuals with dyslexia. Building on previous findings of decreased volume in the anterior lobe of the cerebellum, we utilized novel cerebellar segmentation procedures and probabilistic tractography to examine tracts that originate in the anterior lobe of the cerebellum and project to cortical regions typically associated with reading: the temporoparietal region (TP), occipitotemporal region (OT), and inferior frontal region (IF) in 29 children with impaired single-word readings skills and 27 typical readers. We found greater FA for the poor readers in the tracts terminating in the TP and IF regions. In the OT region, differential FA trajectories were identified such that FA was greater for the older poor readers. Additionally, behavioral correlations were found primarily within the group of typical readers. FA was inversely related to decoding. Behavioral measures were associated predominantly with TP and OT regions. This study provides evidence for discrete, regionally-bound functions of the cerebellum and suggests that the projections from the anterior cerebellum appear to have a regulatory effect on cortical functions important for reading.