Pain Perception and Modulation: Fundamental Neurobiology and Recent Advances.

Chronic pain is a major mental health burden with significant individual and societal impact. A major challenge in clinical practice is the considerable variability in treatment responses, reflecting the complexity of associated biopsychosocial factors and their neurobiological underpinnings. This narrative review presents an up-to-date overview of neural structures, circuits, and neurochemical systems involved in pain perception and modulation, integrating foundational and recent findings from human and animal studies. We outline current models of nociceptive processing and pain perception, emphasizing dynamic interactions between ascending nociceptive input, descending modulation, and distributed cortical networks. Additionally, we describe mechanisms at spinal, subcortical, and cortical levels, along with neuroplastic changes in chronic pain. Finally, we review key neuromodulators, including opioids, monoamines, cannabinoids, and GABA. Together, these insights support the development of personalized pain management strategies grounded in systems-level neurobiology.