Multidimensional maturation of oxytocin neurons: A principal component analysis of postnatal development

Oxytocin (Oxt) is a neuropeptide critical for higher brain functions, with its physiological functions dependent on the activity of Oxt‐producing neurons in the paraventricular nucleus (PVN). However, the postnatal maturation process of these neurons remains poorly understood, particularly whether it involves a uniform trajectory or a dynamic functional reorganization. Here, we investigated the electrophysiological maturation of PVN Oxt neurons in rats using a multifaceted approach including electrophysiology, principal component analysis (PCA), and f–I curve fitting. Our analysis revealed a highly heterogeneous maturation timeline for individual electrophysiological parameters. While action potential amplitude and half‐width matured relatively early, the resting membrane potential (RMP) and firing threshold showed a much more protracted maturation. To comprehensively capture this, we applied PCA and found that the first principal component (PC1) exhibited a striking inverted U‐shaped pattern over time. This pattern suggests a dynamic transition through three distinct functional states: an initial immature state, an intermediate transitional state, and a later mature state. Furthermore, f – I curve fitting provided mechanistic insights, identifying a “high‐gain” state around postnatal Day 7, characterized by high firing threshold ( I th ) and gain ( k ). This period temporally overlaps with peak Oxt receptor expression, hinting at a critical window for experience‐dependent circuit refinement. Our findings provide a new perspective on neuronal maturation as a complex process of dynamic functional reorganization. The identified “high‐gain” state may represent a critical period for Oxt system development, offering a crucial foundation for understanding neurodevelopmental disorders and developing targeted early interventions.