From "Gig" to Genes: The enduring legacy of Seymour Levine in developmental stress neurobiology.

The concept that early life experiences profoundly program adult physiology and behavior is now a cornerstone of neurobiology, a paradigm shift largely founded on the visionary work of Seymour "Gig" Levine. This review traces the intellectual lineage from Levine's pioneering behavioral and physiological studies to the modern molecular era, underscoring his indispensable contribution to understanding developmental stress. Levine's initial elegant experiments established the critical regulatory role of maternal care and the hypothalamic-pituitary-adrenal (HPA) axis, culminating in the discovery of the Stress Hyporesponsive Period (SHRP)-a crucial, sensitive window for developmental programming. Building on this legacy, subsequent research, including my own, has utilized advanced molecular tools to bridge the gap from these macroscopic observations to precise mechanistic detail. I highlight the role of gene-by-environment (G × E) interactions, particularly involving HPA axis modulators like FKBP51 and CRH signaling, in shaping vulnerability. Furthermore, I discuss how Levine's implicit recognition of individual differences has evolved into a central focus on biological sex differences, the match/mismatch hypothesis of adaptive programming, and the use of deep phenotyping to unravel the molecular bases of resilience and vulnerability. Ultimately, the journey from "Gig" to "Genes" provides a foundational understanding that is crucial for developing effective, targeted strategies to promote mental health and resilience across the lifespan.