New research demonstrating the role of habit learning in cocaine addicts is now published in Science. You can find the article on the Science website.
Ersche, K.D., Gillan, C.M., Jones, P.M., Williams, G.B., Ward, L.H.E., Luijten, M., de Wit, S., Sahakian, B.J., Bullmore, E.T., Robbins, T.W. (2016). Carrots and sticks fail to change behavior in cocaine addiction. Science. DOI: 10.1126/science.aaf3700