A University of Texas at Dallas neuroscientist is trying to pinpoint these neurological changes at the microscopic level and, in the process, learn more about the nature of addiction. Synapses are gaps between brain cells, or neurons, where molecules called neurotransmitters pass electrical and chemical signals from one cell to another. “We’re trying to provide a better understanding of the neurotransmission side of the compulsions that define addiction, to understand which neurons are relevant on the network level,” Kroener said. “In the last couple of years, we’ve realized that even within certain brain areas, not all neurons do the same thing,” Kroener said. “Only some neurons in the prefrontal cortex will be involved in drug-taking behavior, for instance.