Hemispheric speech lateralisation in the developing brain is related to motor praxis ability

Area of Science:

• Neuroscience
• Developmental Psychology
• Cognitive Science

Background:

• Functional brain asymmetries like hand dominance and speech lateralization are well-studied in adults.
• The developmental trajectory of these lateralizations in typically developing children remains debated.
• Understanding the emergence of these asymmetries is crucial for developmental neuroscience.

Purpose of the Study:

• To investigate the relationship between hand dominance and speech laterality in children.
• To examine how these functional asymmetries vary with age in typically developing children.
• To explore the link between motor skill performance and cerebral lateralization.

Main Methods:

• 148 typically developing children (aged 3-10 years) completed a pegboard task for hand dominance assessment.
• A subset of 38 children underwent functional Transcranial Doppler (fTCD) imaging during a speech task.
• A lateralization index (LI) was calculated to quantify hemispheric activation during speech production.

Main Results:

• No significant main effect of age was found on speech laterality scores.
• Younger children exhibited a larger performance difference between their hands on the motor task.
• A significant interaction revealed that a smaller hand performance difference was associated with greater left hemisphere speech activation.

Conclusions:

• Both handedness and speech lateralization seem relatively determined by age 3.
• Atypical cerebral lateralization is linked to greater hand skill performance differences, irrespective of age.
• These findings suggest shared neural systems underlie handedness and speech lateralization development.