Biology subjects

Ozernov-Palchik, O.

Publications and source records attributed to Ozernov-Palchik, O..

5 recordsLinked to original sources

bioRxiv2024

Precision fMRI reveals that the language network exhibits adult-like left-hemispheric lateralization by 4 years of age

In adults, left hemisphere (LH) damage often leads to aphasia, but many cases of early damage leave linguistic processing intact, with a functional language system developing in the right hemisphere. To explain this early apparent equipotentiality of the two hemispheres for language, some have proposed that the language system is more bilateral during early development and becomes increasingly left-lateralized with age. We examined language lateralization using fMRI in two large developmental cohorts (total n=273 children aged 4-16 years; n=107 adults). Strong, adult-like LH lateralization (in response magnitude and activation volume) was evident by age 4, although other features of the LH language network showed protracted development, including the magnitude of language response and the strength of functional connectivity. Thus, although the RH can take over language function in some cases of early brain damage, this plasticity occurs in spite of adult-level LH bias present by age 4 years.

neuroscience↗

bioRxiv2021

Longitudinal changes in brain activation underlying reading fluency

Reading fluency - the speed and accuracy of reading connected text - is foundational to educational success. The current longitudinal study investigates the neural correlates of fluency development using a connected-text paradigm with an individualized presentation rate. Twenty-six children completed a functional MRI task in 1st/2nd grade (time 1) and again 1-2 years later (time 2). There was a longitudinal increase in activation in the ventral occipito-temporal (vOT) cortex from time 1 to time 2. This increase was also associated with improvements in reading fluency skills and modulated by individual speed demands. These findings highlight the reciprocal relationship of the vOT region with reading proficiency and its importance for supporting the developmental transition to fluent reading. These results have implications for developing effective interventions to target increased automaticity in reading.

neuroscience↗

bioRxiv2020

Distinct neural substrates of individual differences in components of reading comprehension in adults with or without dyslexia

Reading comprehension is a complex task that depends on multiple cognitive and linguistic processes. According to the updated Simple View of Reading framework, in adults, individual variation in reading comprehension can be largely explained by combined variance in three component abilities: (1) decoding accuracy, (2) fluency, and (3) language comprehension. Here we asked whether the neural correlates of the three components are different in adults with dyslexia as compared to typically-reading adults and whether the relative contribution of these correlates to reading comprehension is similar in the two groups. We employed a novel naturalistic fMRI reading task to identify the neural correlates of individual differences in the three components using whole-brain and literature-driven regions-of-interest approaches. Across all participants, as predicted by the simple view framework, we found distinct patterns of associations with linguistic and domain-general regions for the three components, and that the left-hemispheric neural correlates of language comprehension in the angular and posterior temporal gyri made the largest contributions to explaining out-of-scanner reading comprehension performance. These patterns differed between the two groups. In typical adult readers, better fluency was associated with greater activation of left occipitotemporal regions, better comprehension with lesser activation in prefrontal and posterior parietal regions, and there were no significant associations with decoding. In adults with dyslexia, better fluency was associated with greater activation of bilateral inferior parietal regions, better comprehension was associated with greater activation in some prefrontal clusters and lower in others, and better decoding skills were associated with lesser activation of bilateral prefrontal and posterior parietal regions. Extending the behavioral findings of skill-level differences in the relative contribution of the three components to reading comprehension, the relative contributions of the neural correlates to reading comprehension differed based on dyslexia status. These findings reveal some of the neural correlates of individual differences in the three components and the underlying mechanisms of reading comprehension deficits in adults with dyslexia.

neuroscience↗

bioRxiv2019

Putative protective neural mechanisms in pre-readers with a family history of dyslexia who subsequently develop typical reading skills

Developmental dyslexia is a learning disability characterized by difficulties in word reading. While the prevalence in the general public is around 10-12%, an increased prevalence of 40-60% has been reported for children with a familial risk. Neural atypicalities in the reading network have been observed in children with (FHD+) compared to without (FHD-) a family history of dyslexia, even before reading onset. Despite the hereditary risk, about half of FHD+ children develop typical reading abilities (FHD+Typical) but the underlying neural characteristics and the developmental trajectories of these favorable reading outcomes remain unknown. Utilizing a retrospective, longitudinal approach, this is the first study to examine whether potential protective neural mechanisms are present before reading onset in FHD+Typical. Functional and structural brain characteristics were examined in 69 pre-readers who subsequently developed typical reading abilities (35 FHD+Typical/34 FHD-Typical) using MRI/fMRI. Searchlight-based multivariate pattern analyses identified distinct activation patterns during phonological processing between FHD+Typical and FHD-Typical in right inferior frontal (RIFG) and left temporo-parietal (LTPC) regions. Hypoactivation in LTPC was further demonstrated in FHD+Typical compared to FHD-Typical, suggesting that this previously reported neural characteristic of dyslexia is primarily associated with familial risk. Importantly, FHD+Typical pre-readers exhibited higher activation in RIFG than FHD-Typical, which was associated with increased interhemispheric functional and structural connectivity. These results suggest that putative protective neural mechanisms are already established in FHD+Typical pre-readers and may therefore support their successful reading development. Further studies are needed to investigate the functional significance and developmental trajectories of these neural mechanisms as well as their enabling factors, which has the potential to inform the design of early preventative/remediation strategies.

neuroscience↗

bioRxiv2019

Multifactorial pathways facilitate resilience among kindergarteners at risk for dyslexia: A longitudinal behavioral and neuroimaging study

Recent efforts have focused on screening methods to identify children at risk for dyslexia as early as preschool/kindergarten. Unfortunately, while low sensitivity leads to under-identification of at-risk children, low specificity can lead to over-identification, resulting in inaccurate allocation of limited educational resources. The present study focused on children identified as at-risk in kindergarten who do not subsequently develop dyslexia to specify factors associated with better reading outcomes among at-risk children. Early screening was conducted in kindergarten and a subset of children was tracked longitudinally until second grade. Potential protective factors were evaluated at cognitive-linguistic, environmental, and neural levels. Relative to at-risk kindergarteners who subsequently developed dyslexia, those who did not were characterized by significantly higher socioeconomic status (SES), speech production accuracy, and microstructure of the posterior right-hemispheric superior longitudinal fasciculus (SLF). A positive association between microstructure of the right SLF and subsequent decoding skills was found to be specific to at-risk children and not observed among typical controls. Among at-risk children, several kindergarten-age factors were found to significantly contribute to the prediction of subsequent decoding skills: microstructure of the posterior right SLF, age, gender, SES, and phonological awareness. These findings suggest that putative compensatory mechanisms are already present by the start of kindergarten. The right SLF, in conjunction with the cognitive-linguistic and socioeconomic factors identified, may play an important role in facilitating reading development among at-risk children. This study has important implications for approaches to early screening, and assessment strategies for at-risk children.

neuroscience↗