Modulation of parietal activation by semantic distance in a number comparison task

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Psycholinguistics

Background:

• Number comparison tasks involve processing both the format (notation) and the magnitude (semantic distance) of numbers.
• Previous research suggests distinct cognitive stages for number identification and semantic evaluation.
• Understanding the neural basis of numerical cognition across different notations is crucial.

Purpose of the Study:

• To investigate the neural correlates of number notation (verbal vs. Arabic) during number comparison.
• To identify brain regions sensitive to semantic numerical distance, independent of notation.
• To explore the existence of a shared neural representation for numerical quantity.

Main Methods:

• Event-related functional Magnetic Resonance Imaging (fMRI) and high-density Electroencephalography (ERPs) were employed.
• Participants performed number comparison tasks using both verbal and Arabic number formats.
• Analysis focused on isolating brain activation patterns related to notation and numerical distance.

Main Results:

• Verbal notation (vs. Arabic) showed increased activation in bilateral extrastriate and left precentral cortices.
• Arabic notation (vs. verbal) activated the right fusiform gyrus and bilateral inferoparietal/frontal regions.
• Numerical distance effects, independent of notation, were prominent in parietal areas (intraparietal sulci, precuneus), left middle temporal gyrus, and posterior cingulate.

Conclusions:

• The findings support a distinct neural processing for number notation and semantic quantity.
• A common parietal network, including the intraparietal sulci, underpins the semantic representation of numerical quantity across notations.
• This suggests a shared, notation-independent system for magnitude processing in the brain.