Table 1.

John Liebeskind’s studies and the concepts they addressed

Year	Studies	Concepts
1971	Stimulation produced analgesia	Pain inhibitory systems
1972–1973	Dissecting analgesia/reward	Analgesia vs. abuse
1972–1976	Naloxone blocks SPA	Endorphins
1976	SPA for visceral pain	Visceral vs. somatic pain
1977–1978	Enkephalin is epileptogenic	Therapeutic window
1979–1985	Analgesia from stress and seizures	Natural inhibition of pain
1983–1984	Stress inhibits immune function	Psychoneuroimmunology
1991	Pain inhibits immune function	Pain can kill
1979–1991	Effects of learning, pain, and NMDA receptors on opiate tolerance	Tolerance is not simply receptor desensitization
1993–1995	Gender influences on analgesia	Gender dependent effects
1985–1996	Genetic studies of analgesia	Variance and mechanism

NMDA, N-methyl-d-aspartate; SPA, stimulation-produced analgesia.