The period reveals a shift toward understanding pain as a centrally modulated neural process, with central nervous system circuits mediating analgesia through brainstem pathways, spinal gates, and targeted brain stimulation. Opioid analgesia becomes highly site- and dose-dependent within the central nervous system, while psychological and cognitive factors—such as anxiety, expectation, placebo effects, and hypnosis—restructure pain experiences and analgesic responses. Methodological progress—standardized experimental pain methods, animal models, and brain-stimulation-based paradigms—provides controlled platforms for studying analgesia and neuromodulation, enabling clearer mappings of central processing and conscious perception of pain. Historical Significance: The period culminates in pivotal breakthroughs that unified neurophysiological mechanisms with quantification of pain. The Gate Control Theory reframed pain as a dynamic interaction of neural gates modulating nociceptive input, guiding decades of research on neuromodulation and spinal and brain interventions. Groundbreaking demonstrations of dorsal column stimulation and focal brain stimulation established practical neuromodulation strategies, while the McGill Pain Questionnaire introduced a multidimensional framework for reliable, standardized pain measurement, shaping both clinical practice and research. These milestones linked neuroanatomy, subjective experience, and measurement, solidifying a neuromodulation-and-assessment paradigm for future exploration.