Neural representations of non-symbolic magnitudes show familial specificity in the right intraparietal sulcus.

Parental skills strongly predict children's cognitive development. This is the case even for abilities such as non-symbolic magnitude processing, which are evolutionary old and might be expected to show relatively invariant neural architecture. However, whether this behavioral similarity reflects similar neural representations between parents and children is unknown. Here we combined fMRI with dyadic representational similarity analysis to measure mother-child neural similarity during a numerosity adaptation task. Forty-four mother-child dyads (children's mean age = 8.55 yr) viewed sequences of dot arrays where numerosity remained either constant or varied. We assessed whether neural patterns associated with the numerosity adaptation effect showed greater similarity in familial than non-familial dyads. Results revealed family-specific neural similarity in the right intraparietal sulcus, a core region for non-symbolic magnitude processing. Structural analyses revealed that cortical thickness in this region also showed family-specific similarity, suggesting that functional transmission may partly reflect shared anatomical properties. These findings indicate that even evolutionarily ancient cognitive systems like the approximate number system show intergenerational neural transmission. Together with prior evidence of familial transmission in regions associated with executive functions during mental arithmetic, the present study highlights multiple pathways through which math skills may be transmitted from parents to children.