Hippocampal Neuronal Overflow and Cortical Reconstruction: A Hypothesis on the Formation of Neural Networks Unique to the Human Brain

This study explores the neural basis of humans' unique cognitive abilities, focusing on distinctive features in human infant brain development that differentiate us from other species, particularly the extensive neuronal migration in white matter that continues for nearly 18 months after birth. Traditional views suggest these migrating neurons originate from the ventral telencephalic region during the fetal period, but this cannot adequately explain their scale and duration. Based on existing research evidence, this study proposes the "Hippocampal Neuronal Overflow and Cortical Reconstruction" hypothesis: hippocampal neurogenesis in human infants peaks during the perinatal to early period, and under rich environmental stimulation, the survival rate of new hippocampal neurons significantly increases. When the quantity exceeds the hippocampus's capacity, these neurons overflow and migrate to white matter areas, subsequently distributing throughout the forebrain cortex to form novel neural networks. This hippocampal neuronal overflow phenomenon may be a developmental mechanism unique to humans, becoming a key factor in the development of distinctive neural structures in humans. This special neural network might be closely related to human-specific language abilities, memory transformation mechanisms, and advanced cognitive functions, explaining the fundamental differences in cognitive abilities between humans and other animals. This hypothesis provides a new perspective for understanding the uniqueness of human brain developmental pathways.