Featured Paper of the Month – January 2026
Published in PNAS by Rajtarun Madangopal, Ph.D. and Bruce Hope, Ph.D. of the NIDA IRP Neuronal Ensembles in Drug Addiction Section.
In this study, researchers used single-cell calcium imaging to longitudinally track hundreds of brain cells (neurons) in rats across three phases: when they pressed a lever for food rewards (Training), as they learned to stop pressing when the reward was removed (Extinction), and when they resumed pressing after a small, non-contingent reward was reintroduced (Reinstatement). Analyses showed that distinct and non-overlapping populations – called ensembles – were active during Training and Extinction, to support response execution and inhibition, respectively.










