Neural indicators of numerical abilities in the infant human brain: A systematic review

Infants are thought to possess an innate specific capacity to process numerical information. In this article, we review the past research that has focused on unveiling the timing and localization of the related brain mechanisms with the purpose of depicting a neurodevelopmental blueprint of this capacity from birth. A systematic search of studies published between 1998 and 2023 was conducted. A total of 21 studies with 732 participants (age rage: 30 weeks of gestation to 6 years) met the study selection criterion. EEG, fMRI and fNIRS studies consistently support the existence of brain responses (mainly in the right parietal, bilateral frontal and occipital cortex) that reflect sensitivity to numerical features even before birth. These enable the infant brain to code numerical information independently of other non-numerical magnitude dimensions. Small (<4) or large (>4) numerosities seem to diverge in dissociable brain responses from the second semester of life, suggesting a neurodevelopmental specialization. Variations in the brain’s sensitivity to numerical information across participants and whether they can anticipate the individual’s development of future numerical skills remains uncertain, due to the scarcity of longitudinal studies. Understanding how familial and other contextual factors shape these initial biological predispositions and give rise to typical and atypical trajectories requires further investigation.