Howard Fields received his MD and PhD in Neuroscience at Stanford in 1965-66. After Internal Medicine training at Bellevue Hospital in New York, he spent three years as a research neurologist at Walter Reed Army Institute of Research. Following clinical training in neurology at the Boston City Hospital Service of Harvard Medical School in 1972, he joined the faculty of the University of California San Francisco. Fields major interests are in nervous system mechanisms of pain and substance abuse with a focus on how endogenous opioids contribute to these mechanisms. He was a founder of the UCSF pain management center and has made major contributions to understanding and treating neuropathic pain. His group was the first to demonstrate the clinical effectiveness of opioids for neuropathic pain and of topical lidocaine for post-herpetic neuralgia. In laboratory studies he discovered and elucidated a pain modulating neural circuit that is required for opioids to produce analgesia. He also discovered that placebo analgesia is blocked by an opioid antagonist. Recently, his laboratory has discovered nerve cells in the striatum that selectively encode the magnitude of a reward. They have also shown how the neurotransmitter dopamine contributes to motivation and reward based choice. Current work is focused on the neurobiology of opioid reward.