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Neurodevelopmental trajectories of audiovisual letter and number word processing throughout elementary school
Poster Session A, Wednesday, September 30, 11:00 am - 1:00 pm, Wangari Maathai
This poster is part of the Sandbox Series.
Sarah V. Di Pietro1,2, Iliana I. Karipidis1,2, Silvia Brem1,2; 1University Hospital of Psychiatry Zurich, 2University of Zurich
A central feature of both reading and mathematics is the acquisition of arbitrary symbol–meaning mappings, whereby visual symbols are linked to domain-specific representational systems, including phonological codes in reading and magnitude- and verbal representations in numerical cognition. Letter-speech sound and symbolic number processing recruit partially overlapping fronto-parietal and occipitotemporal networks that specialize throughout development (Moeller et al., 2015; Di Pietro et al, 2023). While audiovisual integration has been extensively studied in reading acquisition, less is known about the development of audiovisual symbolic number processing. Moreover, few studies have directly compared developmental trajectories across reading- and mathematics-related symbolic processing in the same longitudinal cohort. Understanding shared and domain-specific neural mechanisms underlying audiovisual symbol processing may provide important insights into the development of scholastic skills, such as reading and arithmetic fluency. The present study therefore aims to investigate neurodevelopmental trajectories of auditory, visual and audiovisual symbolic processing across elementary school. Approximately 100 children participated at up to five time points: end of kindergarten, middle and end of first grade, second grade, and fifth grade. Children completed an implicit audiovisual target detection task during fMRI (Fraga-González et al, 2021; Karipidis et al, 2017; 2018; 2021) including the presentation of visual symbols, auditory stimuli, congruent audiovisual pairs, and incongruent audiovisual pairs in both linguistic (letters/speech sounds) and numerical (Arabic numbers/number words) domains. This design allows for the assessment of unimodal processing, multisensory integration, and congruency effects across developmental stages and symbolic domains. Neural measures are related to behavioral indices of reading and arithmetic fluency. Previous findings from the separate domain-specific activation analyses suggested both shared and domain-specific developmental trajectories (Di Pietro et al, 2023; 2026). Across domains, unimodal visual and auditory processing recruited occipitotemporal and superior temporal regions from kindergarten onward, indicating early-established sensory and phonological processing systems. In contrast, audiovisual congruency and incongruency effects emerged more gradually throughout development, particularly toward the end of primary school, suggesting prolonged maturation of multisensory integration and cognitive control mechanisms. These findings suggested potentially distinct developmental trajectories across symbolic domains, both in the timing of specialization and in the neural regions involved. Letter-speech sound processing may show earlier specialization of language-related regions, whereas symbolic number processing may involve more gradual recruitment of parietal regions implicated in numerical representations. Across domains, skill-related differences were most pronounced around the end of first grade, suggesting a critical developmental window during which audiovisual symbol mappings become increasingly automatized and shaped by formal instruction. Together, these findings motivate a direct longitudinal comparison of audiovisual symbolic processing across reading- and mathematics-related domains. In addition to familiar letters and Arabic numbers, we will include meaningless falsefonts to investigate the influence of familiarity with symbols on the developmental trajectories (Pleisch et al, 2019). Planned combined activation and connectivity analyses will directly test whether shared fronto-parietal mechanisms and connections support audiovisual integration across symbolic systems or whether domain-specific developmental trajectories emerge as a function of learning experience and academic specialization.
Topic Areas: Language Development/Acquisition, Multisensory or Sensorimotor Integration