Tracing the neuroanatomical profiles of reward pathways with markers of neuronal activation.

Functional neuroanatomical tools have played an important role in proposing which structures underlie brain stimulation reward circuitry. This review focuses on studies employing metabolic markers of neuronal and glial activation, including 2-deoxyglucose, cytochrome oxidase, and glycogen phosphorylase, and a marker of cellular activation, the immediate early gene c-fos. The principles underlying each method, their application to the study of brain stimulation reward, and their strengths and limitations are described. The usefulness of this strategy in identifying candidate structures, and the degree of overlap in the patterns of activation arising from different markers is addressed in detail. How these data have contributed to an understanding of the organization of reward circuitry and directed our thinking towards an alternative framework of neuronal arrangement is discussed in the final section.