Growth and development of the precuneus in humans from birth to early adulthood.

The precuneus is a main node of the brain organization, and it is crucial to autonoetic consciousness, body awareness, imagination, and the construction of the self. In humans, it displays a remarkable individual variation, which functional consequences are not yet known. Comparative analyses suggest that the expansion of these areas may have had an evolutionary relevance in Homo sapiens. In this study, we analyzed the MRI scans of 220 individuals ranging from birth to early adulthood, to investigate the morphological changes of the precuneus along ontogeny. Size changes are only detected between birth and 2-3 years of age. In terms of shape, there is a minor increase in dorsal expansion in the same period, although the mean effect is moderate, and general trends are obscured by the pronounced variability. The remarkable individual differences in precuneus morphology are already established at birth. The dorsal extension is a major determinant of such variability in all age groups, although the analysis reveals multiple factors involved. Importantly, the dorsal and ventral regions of the precuneus are largely independent. Longitudinal studies will be necessary to test the details of its morphological changes through ontogeny, as well as surveys investigating its development in prenatal stages.