Syntax without language: neurobiological evidence for cross-domain syntactic computations

Area of Science:

• Neuroscience
• Cognitive Science
• Linguistics

Background:

• Human languages predominantly use relative, non-rigid syntactic rules, unlike rigid distance-based rules.
• The left inferior frontal gyrus (IFG), or Broca's area, is implicated in processing non-rigid syntax in language.
• The specificity of this neural mechanism to language is questioned due to analogous structures in other cognitive domains.

Purpose of the Study:

• To investigate whether the neural basis for non-rigid syntactic processing is language-specific.
• To compare brain activity for rigid versus non-rigid syntax acquisition in both language and visuo-spatial domains.

Main Methods:

• Event-related functional magnetic resonance imaging (fMRI) was used on 16 healthy Italian native speakers.
• Participants underwent tasks involving the acquisition of rigid and non-rigid syntax in the visuo-spatial domain.
• Data were compared with a prior study examining rigid and non-rigid syntax in the language domain.

Main Results:

• Acquisition of non-rigid syntax, in both visuo-spatial and language domains, activated Brodmann Area 44 of the left IFG.
• Acquisition of rigid syntax did not activate this area in either domain.
• The observed domain-independent effect in the left IFG was modulated by performance improvement.

Conclusions:

• A single neural mechanism, a "grammar without words," underlies non-rigid syntactic processing across different cognitive functions.
• The left IFG (Brodmann Area 44) plays a domain-independent role in processing abstract, non-rigid grammatical structures.
• This suggests a unified neural architecture for abstract rule-based cognition, not limited to language.