AUTHOR=Bukhari Qasim , Borsook David , Rudin Markus , Becerra Lino TITLE=Random Forest Segregation of Drug Responses May Define Regions of Biological Significance JOURNAL=Frontiers in Computational Neuroscience VOLUME=10 YEAR=2016 URL=https://www.frontiersin.org/journals/computational-neuroscience/articles/10.3389/fncom.2016.00021 DOI=10.3389/fncom.2016.00021 ISSN=1662-5188 ABSTRACT=
The ability to assess brain responses in unsupervised manner based on fMRI measure has remained a challenge. Here we have applied the Random Forest (RF) method to detect differences in the pharmacological MRI (phMRI) response in rats to treatment with an analgesic drug (buprenorphine) as compared to control (saline). Three groups of animals were studied: two groups treated with different doses of the opioid buprenorphine, low (LD), and high dose (HD), and one receiving saline. PhMRI responses were evaluated in 45 brain regions and RF analysis was applied to allocate rats to the individual treatment groups. RF analysis was able to identify drug effects based on differential phMRI responses in the hippocampus, amygdala, nucleus accumbens, superior colliculus, and the lateral and posterior thalamus for drug vs. saline. These structures have high levels of mu opioid receptors. In addition these regions are involved in aversive signaling, which is inhibited by mu opioids. The results demonstrate that buprenorphine mediated phMRI responses comprise characteristic features that allow a supervised differentiation from placebo treated rats as well as the proper allocation to the respective drug dose group using the RF method, a method that has been successfully applied in clinical studies.