Funding and Disclosures
Role of Funding Source: This work was supported by NIH Grants
DA045364, DA031725, and DA045714. The NIH had no role in the writing of
the manuscript or in the decision to submit the manuscript for
publication.
Contributors: MAS and TP developed the idea. TP and JLS
performed the review of the primary literature and wrote the initial
drafts. JLS and MS collaborated on writing the final draft. All authors
approved the final manuscript.
Acknowledgements: The authors wish to thank Dr. Karl Schmidt
for comments on a previous version of this manuscript.
Conflict of Interest: No conflict declared.