Eventually after a whole sequence of these actions you get some sort of reward signal. (fortune.com)
With more reward signal they are more likely to become addicted and have an exaggerated memory of reward associated with taking cocaine. (scientificamerican.com)
New research presented by Dr. Jonathan Britt, from McGill University, helps to better understand how reward signals, such as those produced by addictive drugs, travel through the brain and modify brain circuits. (sciencedaily.com)