Developmental continuity in the neural representations of number.

Thesis (Ph. D.)--University of Rochester. Department of Brain and Cognitive Sciences, 2018.The acquisition of formal mathematics is a uniquely human ability that supports success in the fields of science, technology, engineering, and medicine. Theories of brain evolution suggest that these formal mathematical concepts are grounded in evolutionarily-primitive numerosity representations in the intraparietal sulcus (IPS). Although some studies of cognitive development and some neuroimaging studies with adults and older children suggest that this might be the case, we are missing important data on how the developing brain represents number prior to and in the earliest stages of acquiring mathematics. The present work fills this gap by combining behavioral and neuroimaging approaches to test children in the critical age range of 3 to 8 years. The overarching hypothesis is that if evolutionarily-primitive numerosity representations support the acquisition of formal mathematics, then there should be continuity in the neural representations that underlie numerical development in early childhood. First, I show that the IPS represents numerosities using evolutionarily-primitive mechanisms by 3 to 6 years of age (Chapter 2). Then, across two studies, I show that the intraparietal sulcus represents exact, symbolic numerical concepts in early childhood and is also important for the acquisition of these early mathematical concepts (Chapters 3 & 4). Together these three studies demonstrate developmental continuity in the neural representations of numerical sets, words, and symbols in the intraparietal sulcus. This finding is consistent with the prediction that the acquisition of mathematics builds on evolutionarily-primitive numerosity representations in the intraparietal sulcus and suggests that evolutionary constraints shape children’s learning of mathematical concepts