Structure and function of word laterality in early childhood

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Cognitive Neuroscience

Background:

• Brain regions often show lateralization, with specialized functions favoring one hemisphere.
• The visual word form area (VWFA) specializes in processing written words and develops post-literacy, typically showing left-hemisphere dominance in adults.
• Understanding the development of VWFA lateralization offers insights into brain plasticity and reading acquisition.

Purpose of the Study:

• To investigate the neural factors contributing to the development of word laterality in children.
• To examine the roles of structural connectivity and regional activation within the language network in shaping VWFA lateralization.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to identify the VWFA and language regions based on their responses to visual word and auditory stimuli, respectively.
• Diffusion-weighted imaging and probabilistic tractography were employed to quantify white matter structural connectivity between the VWFA and language areas.
• Reading children aged 4-13 years were scanned to assess developmental trajectories.

Main Results:

• VWFA word laterality was significantly predicted by an interaction: stronger leftward lateralization of the VWFA was associated with left-lateralized temporal language regions and robust structural connectivity between them.
• This suggests that the integration of connectivity and activation patterns in temporal language areas influences the development of the reading network's lateralization.
• Both structural connections and activation patterns in connected regions appear crucial for developing functional brain lateralization.

Conclusions:

• The findings elucidate the developmental interplay between structural connectivity and functional activation in establishing hemispheric specialization for reading.
• This research provides a deeper understanding of the neural circuitry underlying reading acquisition and brain development.
• The study underscores the importance of the left-hemisphere language network's connectivity and lateralization in shaping the visual word form area's specialization.