Letter fluency in 7-8-year-old children is related to the anterior, but not posterior, ventral occipito-temporal cortex during an auditory phonological task

Previous studies have shown that reading skill in 3- to 6-year-old children is related to the automatic activation of the posterior left ventral occipitotemporal cortex (vOT) during spoken language processing, whereas 8- to 15-year-old children and adult readers activate the anterior vOT. However, it is unknown how children who are between these two age groups automatically activate orthographic representations in vOT for spoken language. In the current study, we recruited 153 7- to 8-year-old children to fill the age gap from previous studies. Using functional magnetic resonance imaging (fMRI), we measured children\u27s reading-related skills and brain activity during an auditory phonological task with both a small (i.e. onset) and a large (i.e. rhyme) grain size condition. We found that letter fluency, but not reading accuracy, was correlated with activation in the anterior vOT for the rhyme condition. There were no reading-related skill correlations for the posterior vOT or for activation during the onset condition in this age group. Our findings reveal that automatic activation in the anterior vOT during spoken language processing already occurs in higher skilled 7- to 8-year-old children. In addition, increases in naming automaticity is the primary determinant of the engagement of vOT during phonological awareness tasks

Analysis of Pseudohomophone Orthographic Errors through Functional Magnetic Resonance Imaging (fMRI)

The study of orthographic errors in a transparent language such as Spanish is an important topic in relation to writing acquisition because in Spanish it is common to write pseudohomophones as valid words. The main objective of the present study was to explore the possible differences in activation patterns in brain areas while processing seudohomophone orthographic errors between participants with high (High Spelling Skills (HSS)) and low (Low Spelling Skills (LSS)) spelling orthographic abilities. We hypothesize that (a) the detection of orthographic errors will activate bilateral inferior frontal gyri, and that (b) this effect will be greater in the HSS group. Two groups of 12 Mexican participants, each matched by age, were formed based on their results in a group of spelling-related ad hoc tests: HSS and LSS groups. During the fMRI session, two experimental tasks were applied involving correct and pseudohomophone substitution of Spanish words. First, a spelling recognition task and second a letter searching task. The LSS group showed, as expected, a lower number of correct responses (F(1, 21) = 52.72, p <.001, η2 = .715) and higher reaction times compared to the HSS group for the spelling task (F(1, 21) = 60.03, p <.001, η2 = .741). However, this pattern was reversed when the participants were asked to decide on the presence of a vowel in the words, regardless of spelling. The fMRI data showed an engagement of the right inferior frontal gyrus in HSS group during the spelling task. However, temporal, frontal, and subcortical brain regions of the LSS group were activated during the same task

Hippocampal Influences on Movements, Sensory, and Language Processing: A Role in Cognitive Control?

Beyond its established role in declarative memory function, the hippocampus has been implicated in varied roles in sensory processing and cognition, particularly those requiring temporal or spatial context. Disentangling its known role in memory from other cognitive functions can be challenging, as memory is directly or indirectly involved in most conscious activities, including tasks that underlie most experimental investigations. Recent work from this lab has examined the directional influence from the hippocampus on cortical areas involved in task performance, including tasks requiring movements, sensory processing, or language judgments. The hippocampus shows preferential connectivity with relevant cortical areas, typically the region critically involved in task performance, raising the possibility that the hippocampus plays a role in cognitive control. Minimal criteria for a role in cognitive control are proposed, and hippocampal connectivity with sensorimotor cortex during a non-mnemonic motor task is shown to meet this standard. Future directions for exploration are discussed

Neural Correlates of Orthographic Access in Mandarin Chinese Writing: An fMRI Study of the Word-Frequency Effect

Writing is an essential tool for human communication and involves multiple linguistic, cognitive, and motor processes. Chinese, a logographic writing system, differs remarkably from the writing systems of alphabetic languages. The neural substrates of Chinese writing are largely unknown. Using functional magnetic resonance imaging (fMRI) in a copying task, this study probed the neural underpinnings of orthographic access during Mandarin Chinese writing by employing the word-frequency effect. The results showed that writing low-frequency characters evoked greater activation in the bilateral superior/middle/inferior frontal gyrus, superior/inferior parietal lobule, and fusiform gyrus than writing high-frequency characters. Moreover, psychophysiological interaction (PPI) analysis demonstrated that the word-frequency effect modulated functional connectivity within the frontal-occipital networks and the parietal-occipital networks. Together, these findings illustrate the neural correlates of orthographic access for Mandarin Chinese writing, shedding new light on the cognitive architecture of writing across various writing systems

Brain Mechanisms Underlying Visuo-Orthographic Deficits in Children With Developmental Dyslexia

Multiple hypotheses have been proposed to explain the reading difficulty caused by developmental dyslexia (DD). The current study examined visuo-orthographic processing in children with dyslexia to determine whether orthographic deficits are explainable based solely on visual deficits. To identify orthographic-specific, visual perception-specific, and overlapping deficits, we included two tasks (lexical and perceptual) in three Chinese subject groups: children with DD, age-matched controls (AC), and reading matched controls (RC) using functional magnetic resonance imaging (fMRI). We found that the left precuneus showed decreased activation across both tasks for the DD group compared to the two control groups, thus reflecting visual processing deficits in children with DD, which also affects orthographic processing. Furthermore, we found that the functional connectivity between left middle occipital gyrus (LMOG) and left inferior frontal gyrus (IFG) was decreased in the DD group compared to AC and RC for only the lexical task. This suggests a weaker association between orthography and phonology for children with DD. In addition, the children with DD showed decreased functional connectivity between the LMOG and right parahippocampal gyrus for only the visual perceptual task, thereby indicating a weaker association between visual regions for DD during visual symbol processing. Taken together, our findings suggest that the observed orthographic processing deficit in DD might be driven by both a basic visual deficit, and a linguistic deficit

Evidence Of Distinctive Structural Alterations That Differentiate Adhd Boys With And Without A Comorbid Reading Disability

Attention deficit hyperactivity disorder (ADHD) and reading disability (RD) are neurodevelopmental disorders that often co-occur. Children with ADHD and co-occurring RD (ADHD/+RD) tend to show greater cognitive deficits than children with ADHD alone (ADHD/-RD). However, the extents to which comorbid RD impact structural alteration in children with ADHD have never been investigated. The overall goal of this study was to assess structural alterations in the subcortical, cortical and white matter that may differentiate ADHD/-RD from ADHD/+RD. The general hypothesis was that ADHD/+RD would show extensive alterations in regions implicated in ADHD than ADHD/-RD as well as show additional abnormalities in regions associated with RD. To this end, structural MRI and DTI scans obtained from 22 ADHD/-RD boys, 15 ADHD/+RD boys and 29 healthy control (HC) boys comparable in age and IQ were analyzed to assess alterations in striatal morphology, cortical thickness and white matter integrity. Analysis of the striatum showed greater and widespread alterations in the caudate in ADHD/+RD relative to ADHD/-RD but not putamen where the alterations were only seen in ADHD/-RD. Similarly, ADHD/+RD showed significantly thinner cortex in the regions associated with attention and cognitive control as well as additional regions associated with reading relative to ADHD/-RD and HC. Finally, analysis of DTI parameters showed greater extent of alteration in white matter architecture of the frontostriatal fiber tracts. Together, these findings provide evidence of excessive disturbances in the frontostriatal and frontoparietal networks that regulate executive functions, attention and cognitive control. Furthermore, there is evidence of additional alterations in the regions associated with reading skills. Overall, the results indicate a distinctive profile of structural alterations that differentiate ADHD/-RD from ADHD/+RD relative to HC and may underpin the greater neuropsychological impairments observed in ADHD/+RD

Die Stabilität neuroplastischer Veränderungen nach dem Lernen der Morse-Signal-Sprachübermittlung

Der Zusammenhang von Lernen komplexer Inhalte mit neuroplastischen Veränderungen wurde oft beschrieben, aber eine Zuordnung der neuroplastischen Veränderungen zu spezifischen Mechanismen von synaptischen Anpassungen oder Neurogenese wird in den meisten Studien nicht explizit vorgenommen. In dieser Arbeit wird in drei verschiedenen Experimenten Ergebnisse zum Erlernen einer Sprachfertigkeit erarbeitet, die durch die Kombination von Messungen der Veränderungen von Leistung, neuronalen Aktivierungsmustern und Hirnvolumenverteilungen die Zuordnung der verantwortlichen Mechanismen für leistungsrelevante Aktivierungs- und Volumenveränderungen ermöglicht. Im ersten Experiment wurde dargestellt, wie durch das Entschlüsseln einiger bekannter Morse-Signale eine Aktivierung von Sprachrepräsentation ausgelöst wurde. Im zweiten Experiment wurde untersucht, welche Hirnregionen nach absolviertem Lerntraining sich in Aktivierungsmustern und Hirnvolumenverteilung veränderten im Vergleich zu Probanden ohne Lerntraining. Zugleich wurde dargestellt, wie sich die frontalen und parietalen Veränderung von Aktivierungsmustern und die parietalen Hirnvolumenveränderungen annäherten. Im dritten Experiment wurde untersucht, wie stabil die Veränderungen von frontalen und parietalen Aktivierungsmustern und cerebellären Volumenverteilungen nach dem Lerntraining nach einem längeren Zeitraum aufgefunden werden konnten. Mit diesen Erkenntnissen aus dem Zeitverlauf von Lernleistungen, Aktivierungsmustern, Hirnvolumenverteilungen und den Lokalisationen der regionalen Veränderungen ist eine Zuordnung zu den möglichen Mechanismen der Veränderungen möglich. In Zusammenschau mit dem Wissenstand über die Lokalisationen, der Stabilität und der Integration von Neurogenese im erwachsenen menschlichen Hirn kann somit festgestellt werden, dass demnach Veränderungen in frontalen Regionen nicht einer Neurogenese im erwachsenen Hirn zugeordnet werden können, dass Veränderungen nur dann einer Neurogenese zugeordnet werden können, wenn eine Lernphase über eine Spanne von über einem Jahr erstreckt. Damit bleiben als mögliche Erklärungen von Veränderungen für diese Studie wie für die meisten anderen Studien zu lerninduzierten Veränderungen Mechanismen von synaptischer Sprossung und axonalen Anpassungen, die für die Veränderungen von Leistung, Aktivierungsmustern und Volumenveränderungen verantwortlich sind