Modality and morphology: what we write may not be what we say

Area of Science:

• Cognitive Neuroscience
• Linguistics
• Neurology

Background:

• Written language is a recent human invention, not hardwired by genetics.
• The neural basis for reading and writing is not fully understood.
• It's debated whether written language relies on spoken language areas or develops dedicated neural substrates.

Purpose of the Study:

• To investigate the neural independence of written and spoken language.
• To determine if deficits in spoken and written language co-occur or can be dissociated.
• To explore the role of morpho-orthographic operations in written language processing.

Main Methods:

• Case study of five individuals with aphasia.
• Documented double dissociations in language production.
• Assessed disruption in the production of grammatical affixes in speaking versus writing.

Main Results:

• Observed a double dissociation: some patients had writing deficits affecting affixes while speaking was intact, and vice versa.
• Demonstrated that written and spoken language systems are significantly independent.
• Highlighted the distinct nature of morpho-orthographic operations.

Conclusions:

• Written language processing, particularly morpho-orthographic aspects, involves neural systems largely independent of spoken language.
• Findings support the existence of dedicated neural substrates for written language.
• Implications for educational and rehabilitative strategies for individuals with written language impairments.