Functional anatomy of idiomatic expressions.

Area of Science:

• Neuroscience
• Psycholinguistics
• Cognitive Science

Background:

• Idiomatic expressions (IE) present unique processing challenges due to their non-literal meanings.
• The neural underpinnings of IE comprehension, including hemispheric lateralization and network independence from spoken language, remain subjects of debate.

Purpose of the Study:

• To investigate the neural correlates of idiomatic expression processing in healthy Spanish speakers.
• To determine the brain structures and lateralization patterns involved in understanding non-literal language.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to scan 21 native Spanish speakers.
• Participants completed a task distinguishing meanings of IE versus literal sentences.
• Data were processed using SPM 12, with laterality indices calculated for group analysis.

Main Results:

• Idiomatic expression processing activated a bilateral network, with a slight rightward bias.
• Key areas included the pars triangularis, Brodmann areas 9 and 10, pars orbitalis, superior frontal, angular, and fusiform gyri (left hemisphere).
• The right hemisphere showed activation in the anterior insula, middle frontal, and superior temporal gyri.

Conclusions:

• Idiomatic expression comprehension relies on fronto-temporal networks in both hemispheres, emphasizing the right hemisphere's role alongside traditional left hemisphere language areas.
• Findings support semantic coding and configuration hypotheses, suggesting simultaneous processing of literal and figurative meanings.
• The observed neural network appears independent of the specific spoken language, offering insights into clinical populations with IE processing deficits.