The neural basis of hyperlexic reading: an FMRI case study

Area of Science:

• Neuroscience
• Developmental Psychology
• Clinical Linguistics

Background:

• Autism spectrum disorders (ASD) are associated with diverse cognitive profiles.
• Hyperlexia, characterized by precocious reading ability, is a rare but notable feature in some children with ASD.
• Existing theories on hyperlexia often focus on either left or right hemisphere functions, creating a dichotomy.

Observation:

• A 9-year-old boy with autism spectrum disorder and hyperlexia, reading 6 years above his age, was studied using functional magnetic resonance imaging (fMRI).
• The study examined neural activity during covert reading to understand the basis of his advanced reading skills.

Findings:

• The hyperlexic boy showed increased activity in the left inferior frontal and superior temporal cortices compared to controls.
• Greater activity was observed in the right inferior temporal sulcus when compared to reading age-matched controls.
• These results indicate simultaneous engagement of left hemisphere (phonological) and right hemisphere (visual) systems during hyperlexic reading.

Implications:

• This study reconciles contradictory theories of hyperlexia by demonstrating a dual-hemisphere neural basis.
• Precocious reading in hyperlexia is linked to hyperactivation of the left superior temporal cortex.
• Findings offer new insights into the neurobiology of reading development and variations in autism spectrum disorders.