Funding for this research was provided by:
National Institute on Drug Abuse (T32-037202, P30-DA29926, R01-DA015186)
Received: 25 August 2018
Accepted: 19 December 2018
First Online: 2 January 2019
Compliance with ethical standards
: Neither author has any conflicts of interest other than research and training support from the NIH-NIDA.