Neural processing of vision and language in kindergarten is associated with prereading skills and predicts future literacy.

The main objective of this longitudinal study was to investigate the neural predictors of reading acquisition. For this purpose, we followed a sample of 54 children from the end of kindergarten to the end of second grade. Preliterate children were tested for visual symbol (checkerboards, houses, faces, written words) and auditory language processing (spoken words) using a passive functional magnetic resonance imaging paradigm. To examine brain-behavior relationships, we also tested cognitive-linguistic prereading skills at kindergarten age and reading performance of 48 of the same children 2 years later. Face-selective response in the bilateral fusiform gyrus was positively associated with rapid automatized naming (RAN). Response to both spoken and written words at preliterate age was negatively associated with RAN in the dorsal temporo-parietal language system. Longitudinally, neural response to faces in the ventral stream predicted future reading fluency. Here, stronger neural activity in inferior and middle temporal gyri at kindergarten age was associated with higher reading performance. Our results suggest that interindividual differences in the neural system of language and reading affect literacy acquisition and thus might serve as a marker for successful reading acquisition in preliterate children.

Structural gray matter features and behavioral preliterate skills predict future literacy - A machine learning approach.

When children learn to read, their neural system undergoes major changes to become responsive to print. There seem to be nuanced interindividual differences in the neurostructural anatomy of regions that later become integral parts of the reading network. These differences might affect literacy acquisition and, in some cases, might result in developmental disorders like dyslexia. Consequently, the main objective of this longitudinal study was to investigate those interindividual differences in gray matter morphology that might facilitate or hamper future reading acquisition. We used a machine learning approach to examine to what extent gray matter macrostructural features and cognitive-linguistic skills measured before formal literacy teaching could predict literacy 2 years later. Forty-two native German-speaking children underwent T1-weighted magnetic resonance imaging and psychometric testing at the end of kindergarten. They were tested again 2 years later to assess their literacy skills. A leave-one-out cross-validated machine-learning regression approach was applied to identify the best predictors of future literacy based on cognitive-linguistic preliterate behavioral skills and cortical measures in a priori selected areas of the future reading network. With surprisingly high accuracy, future literacy was predicted, predominantly based on gray matter volume in the left occipito-temporal cortex and local gyrification in the left insular, inferior frontal, and supramarginal gyri. Furthermore, phonological awareness significantly predicted future literacy. In sum, the results indicate that the brain morphology of the large-scale reading network at a preliterate age can predict how well children learn to read.

Neural correlates of affective contributions to lexical decisions in children and adults.

The goal of the present study was to investigate whether 6-9-year old children and adults show similar neural responses to affective words. An event-related neuroimaging paradigm was used in which both age cohorts performed the same auditory lexical decision task (LDT). The results show similarities in (auditory) lexico-semantic network activation as well as in areas associated with affective information. In both age cohorts' activations were stronger for positive than for negative words, thus exhibiting a positivity superiority effect. Children showed less activation in areas associated with affective information in response to all three valence categories than adults. Our results are discussed in the light of computational models of word recognition, and previous findings of affective contributions to LDT in adults.

Neuroimaging of valence decisions in children and adults.

To date, the neural underpinnings of affective components in language processing in children remain largely unknown. To fill this gap, the present study examined behavioural and neural correlates of children and adults performing the same auditory valence decision task with an event-related fMRI paradigm. Based on previous findings in adults, activations in anterior and posterior cingulate cortex, orbitofrontal cortex and left inferior frontal gyrus were expected for both positive and negative valence categories. Recent behavioural findings on valence decisions showed similar ratings and reaction time patterns in children and adults. This finding was successfully replicated in the present study. On a neural level, our analysis of affective language processing showed activations in regions associated with both semantic (superior and middle temporal and frontal) and affective (anterior and posterior cingulate, orbitofrontal and inferior frontal, insula and amygdala) processing. Neural activations in children and adults were systematically different in explicit affective word processing. In particular, adults showed a more distributed semantic network activation while children recruited additional subcortical structures.

Same Same But Different: Processing Words in the Aging Brain.

Reading is not only one of the most appreciated leisure activities of the elderly but it clearly helps older people to maintain functional independence, which has a significant impact on life quality. Yet, very little is known about how aging affects the neural circuits of the processes that underlie skilled reading. Therefore, the aim of the present study was to systematically investigate the neural correlates of sublexical, orthographic, phonological and lexico-semantic processing in the aging brain. Using functional magnetic resonance imaging, we recorded brain activity of younger (N = 20; 22-35 years) and older (N = 38; 65-76 years) adults during letter identification, lexical decision, phonological decision and semantic categorization. Older and younger adults recruited an identical set of reading-related brain regions suggesting that the general architecture of the reading network is preserved across the lifespan. However, we also observed age-related differences in brain activity in the subcomponents of the reading network. Age-related differences were most prominent during phonological and orthographic processing possibly due to a failure of older adults to inhibit non-optimal reading strategies. Neural effects of aging were also observed outside reading-related circuits, especially in frontal midline regions. These regions might be involved because of their important role in memory, attention and executive control functions and their potential role in resting-state networks.

Neurofunctionally dissecting the reading system in children.

The reading system can be broken down into four basic subcomponents in charge of prelexical, orthographic, phonological, and lexico-semantic processes. These processes need to jointly work together to become a fluent and efficient reader. Using functional magnetic resonance imaging (fMRI), we systematically analyzed differences in neural activation patterns of these four basic subcomponents in children (N=41, 9-13 years) using tasks specifically tapping each component (letter identification, orthographic decision, phonological decision, and semantic categorization). Regions of interest (ROI) were selected based on a meta-analysis of child reading and included the left ventral occipito-temporal cortex (vOT), left posterior parietal cortex (PPC), left inferior frontal gyrus (IFG), and bilateral supplementary motor area (SMA). Compared to a visual baseline task, enhanced activation in vOT and IFG was observed for all tasks with very little differences between tasks. Activity in the dorsal PPC system was confined to prelexical and phonological processing. Activity in the SMA was found in orthographic, phonological, and lexico-semantic tasks. Our results are consistent with the idea of an early engagement of the vOT accompanied by executive control functions in the frontal system, including the bilateral SMA.

Dyslexia risk gene relates to representation of sound in the auditory brainstem.

Dyslexia is a reading disorder with strong associations with KIAA0319 and DCDC2. Both genes play a functional role in spike time precision of neurons. Strikingly, poor readers show an imprecise encoding of fast transients of speech in the auditory brainstem. Whether dyslexia risk genes are related to the quality of sound encoding in the auditory brainstem remains to be investigated. Here, we quantified the response consistency of speech-evoked brainstem responses to the acoustically presented syllable [da] in 159 genotyped, literate and preliterate children. When controlling for age, sex, familial risk and intelligence, partial correlation analyses associated a higher dyslexia risk loading with KIAA0319 with noisier responses. In contrast, a higher risk loading with DCDC2 was associated with a trend towards more stable responses. These results suggest that unstable representation of sound, and thus, reduced neural discrimination ability of stop consonants, occurred in genotypes carrying a higher amount of KIAA0319 risk alleles. Current data provide the first evidence that the dyslexia-associated gene KIAA0319 can alter brainstem responses and impair phoneme processing in the auditory brainstem. This brain-gene relationship provides insight into the complex relationships between phenotype and genotype thereby improving the understanding of the dyslexia-inherent complex multifactorial condition.

Drifting through Basic Subprocesses of Reading: A Hierarchical Diffusion Model Analysis of Age Effects on Visual Word Recognition.

Reading is one of the most popular leisure activities and it is routinely performed by most individuals even in old age. Successful reading enables older people to master and actively participate in everyday life and maintain functional independence. Yet, reading comprises a multitude of subprocesses and it is undoubtedly one of the most complex accomplishments of the human brain. Not surprisingly, findings of age-related effects on word recognition and reading have been partly contradictory and are often confined to only one of four central reading subprocesses, i.e., sublexical, orthographic, phonological and lexico-semantic processing. The aim of the present study was therefore to systematically investigate the impact of age on each of these subprocesses. A total of 1,807 participants (young, N = 384; old, N = 1,423) performed four decision tasks specifically designed to tap one of the subprocesses. To account for the behavioral heterogeneity in older adults, this subsample was split into high and low performing readers. Data were analyzed using a hierarchical diffusion modeling approach, which provides more information than standard response time/accuracy analyses. Taking into account incorrect and correct response times, their distributions and accuracy data, hierarchical diffusion modeling allowed us to differentiate between age-related changes in decision threshold, non-decision time and the speed of information uptake. We observed longer non-decision times for older adults and a more conservative decision threshold. More importantly, high-performing older readers outperformed younger adults at the speed of information uptake in orthographic and lexico-semantic processing, whereas a general age-disadvantage was observed at the sublexical and phonological levels. Low-performing older readers were slowest in information uptake in all four subprocesses. Discussing these results in terms of computational models of word recognition, we propose age-related disadvantages for older readers to be caused by inefficiencies in temporal sampling and activation and/or inhibition processes.