Are numbers grounded in a general magnitude processing system? A functional neuroimaging meta-analysis

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Psychology

Background:

• Ongoing debate regarding number processing: number-specific system vs. general magnitude processing system.
• General magnitude system is also used for non-numerical information like physical size, duration, or luminance.
• Need for quantitative analysis to synthesize existing neuroimaging findings.

Purpose of the Study:

• To conduct the first quantitative meta-analysis of neuroimaging studies on numerical and non-numerical magnitude processing.
• To identify overlapping and distinct neural activation patterns for different types of magnitude processing.

Main Methods:

• Utilized Activation Likelihood Estimation (ALE) meta-analysis.
• Analyzed 93 empirical neuroimaging papers.
• Generated probabilistic activation maps for non-numerical, symbolic numerical, and nonsymbolic numerical magnitudes.

Main Results:

• Overlapping activation for symbolic, nonsymbolic, and non-numerical magnitudes found in frontal and parietal lobes.
• Specific activation in the left superior parietal lobule for symbolic numerical magnitudes (e.g., Arabic digits).
• Specific activation in bilateral precuneus for nonsymbolic numerical magnitudes (e.g., dot arrays).
• No parietal regions activated for non-numerical magnitudes were exclusive of numerical magnitude activation.

Conclusions:

• Numbers are processed through a combination of a generalized magnitude system and format-specific number regions.
• Evidence supports a dual mechanism for numerical cognition, integrating general and specialized processing pathways.
• Findings clarify the neural basis of numerical cognition and its relationship to broader sensory magnitude processing.