Lesion-symptom mapping reveals differential relationships between language and precise versus approximate numeracy.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neurology

Background:

• Numeracy, essential for mathematical processing, comprises approximate (quantity estimation) and precise (exact quantity) skills.
• Aphasia, a language disorder common after stroke, frequently co-occurs with numeracy deficits, but their neural underpinnings are poorly understood.

Purpose of the Study:

• To investigate the neural basis of approximate and precise numeracy in relation to language ability in stroke survivors.
• To determine if distinct brain regions underlie approximate versus precise numeracy deficits and their association with aphasia.

Main Methods:

• Support Vector Regression Lesion-Symptom Mapping (SVR-LSM) analysis was used.
• The study included 104 individuals with chronic left hemisphere stroke.

Main Results:

• Precise numeracy showed significant neural overlap with language processing regions and correlated with aphasia severity.
• Approximate numeracy did not significantly relate to language areas or aphasia.
• Distinct neural correlates were identified: approximate numeracy linked to the intraparietal sulcus (IPS), angular gyrus (AG), precentral gyrus, and anterior fusiform gyrus; precise numeracy associated with the inferior frontal gyrus (IFG), AG, anterior temporal cortex, caudate nucleus, thalamus, and posterior temporal regions.

Conclusions:

• Precise and approximate numeracy have distinct neural patterns and relationships with language processing.
• Damage to specific brain regions differentially impacts precise and approximate numeracy, with precise numeracy showing a strong link to aphasia severity.