ABSTRACT
A variety of techniques have been used to study pain and nociception at molecular, cellular, and system levels. However, the invasiveness of most of these techniques, such as single unit electrophysiology and anatomical tracing, limit their application to animal studies. Although a large body of information has already been derived by such animal studies, there still exists the dilemma of how to link human perception to brain activity in awake humans. The development of brain-imaging techniques
has filled this gap to some extent and has begun to uncover brain mechanisms underlying many human conditions.
