Marc Lewis, PhD is a developmental neuroscientist and professor of developmental psychology, recently at the University of Toronto (1989 to 2010) and presently at Radboud University Nijmegen in the Netherlands. His recent book, Memoirs of an Addicted Brain, blends the story of his former drug use and addiction with an up-to-date account of how different drugs affect the brain and how addiction results from self-perpetuating changes in brain structure and function. His "popular science" blog at Psychology Today is @AddictedBrain on Twitter. His personal blog, http://www.memoirsofanaddictedbrain.com/, includes an ongoing and often lively dialogue among reader/participants who have struggled with or studied addiction.