Individuals who use cocaine develop an intense craving for the drug. Napier and Patricia Johnson, Ph.D., presented the results of their work on June 24 in San Juan, Puerto Rico, at the annual meeting of The College on Problems of Drug Dependence. Johnson is director of the behavioral laboratory in Loyola's Neuroscience and Aging Institute Division for Research on Drugs of Abuse and a research associate in the pharmacology department of the Loyola University Chicago Stritch School of Medicine. Located at the base of the front of the brain and relatively unexplored until now, the ventral pallidum harbors those processes that help determine how good one feels as a result of some stimulus, such as a drug, and how motivated one is to continue pursuing that stimulus. However, psychostimulants like cocaine appear to increase the release and concentration of dopamine in the ventral pallidum.
Dopamine is a neurotransmitter, a chemical that cells use to send messages to each other.
Specifically, dopamine, released by one brain cell, interacts with another cell by altering the receiving cell's electrical properties. This change in dopamine function is suspected of playing a role in a chronic cocaine user's enhanced motivation to obtain more and more of the drug, Napier said. Cocaine's impact on the ventral pallidum may also alter memory, but the precise nature of the change is unknown at this time, Napier added. Something is encoded in the memory system that motivates a person to want the drug again. Napier is hopeful that her findings will lead to development of treatments that can stem cocaine's effects on the ventral pallidum, particularly the drug's enhancement of dopamine concentrations.