The rise and fall of rapid occipito-temporal sensitivity to letters: Transient specialization through elementary school

Abstract

Letters, foundational units of alphabetic writing systems, are quintessential to human culture. The ability to read, indispensable to perform in today’s society, necessitates a reorganization of visual cortex for fast letter recognition, but the developmental course of this process has not yet been characterized. Here, we show the emergence of visual sensitivity to letters across five electroencephalography measurements from kindergarten and throughout elementary school and relate this development to emerging reading skills. We examined the visual N1, the electrophysiological correlate of ventral occipito-temporal cortex activation in 65 children at varying familial risk for dyslexia. N1 letter sensitivity emerged in first grade, when letter sound knowledge gains were most pronounced and decayed shortly after when letter knowledge is consolidated, showing an inverted U-shaped development. This trajectory can be interpreted within an interactive framework that underscores the influence of top-down predictions. While the N1 amplitudes to letters correlated with letter sound knowledge at the beginning of learning, no association between the early N1 letter response and later reading skills was found. In summary, the current findings provide an important reference point for our neuroscientific understanding of learning trajectories and the process of visual specialization during skill learning.

Visual occipito-temporal sensitivity to digits through elementary school

“…This section largely overlaps with that of our recent report (Fraga-González et al, 2021). EEG data were recorded at 1 kHz sampling rate using an MR-compatible 128-channel EEG system (Net Amps 400, EGI HydroCelGeodesic Sensor Net) during functional magnetic resonance imaging (fMRI) in a Philips Achieva 3T scanner (Philips Medical Systems, Best, The Netherlands).…”

“…The current study combines longitudinal and cross-sectional samples from a larger group of Germanspeaking children who took part in a large project with simultaneous EEG/fMRI sessions, behavioral tests and a grapheme-phoneme intervention training (Karipidis et al, 2017(Karipidis et al, , 2018Pleisch et al, 2019;Mehringer et al, 2020;Wang et al, 2020;Fraga González et al, 2021). Here, we focus on data from kindergarten (T1), middle of first grade (T2), end of first grade (T3), middle of second grade (T4), and middle of fifth grade (T5) of elementary school.…”

“…We aim to clarify the trajectory of this sensitivity across five time points from kindergarten through elementary school, covering the early and possibly most crucial period in learning basic number processing skills. To examine parallels with literacy acquisition, we include the analysis of N1 amplitudes to letters, which was the focus of previous work (Fraga-González et al, 2021). These developmental analyses are followed by an examination of the associations between N1 sensitivity to numbers and cognitive performance, with a special focus on arithmetic skills.…”

ERP Correlates of Altered Orthographic-Phonological Processing in Dyslexia

“…This coarse-grade sensitivity emerges during reading acquisition. Although this is absent in kindergarten children (Maurer et al, 2005b), it emerges after one year of reading instruction (Eberhard-Moscicka et al, 2015;Varga et al, 2020) and follows an inverted U shape pattern which peaks during reading acquisition and then declines over instruction (Fraga-González et al, 2021). The N1 for print is more pronounced over the left posterior-occipital regions (Maurer et al, 2005a;Yoncheva et al, 2010), and this left lateralization is enhanced with reading experience.…”

“…According to the phonological mapping hypothesis, the left lateralization is driven by automatized grapheme-phoneme mapping . Typically, children show a bilateral effect for letter strings (Maurer et al, 2006;Kast et al, 2010); however, recent studies found that left lateralization can be found as early as one year (Varga et al, 2020; van de Walle de Ghelcke et al, 2021) or even half a year of reading instruction (Pleisch et al, 2019; altough lateralization is less clear for single letters, see Fraga-González et al, 2021).…”