Neuronal ensembles formed rapidly in the prelimbic cortex mediate initial and maintained cocaine-seeking behavior in male and female rats

Substance use disorder is a complex neurobiological disease thought to be partially driven by aberrant forms of learning and memory. The cellular basis of memory is hypothesized to be small subsets of interconnected networks formed during the acquisition of behavior called neuronal ensembles. We interrogate neuronal ensembles by utilizing a dual viral approach that expresses Cre^ERT2 under the control of the c-Fos promoter in conjunction with a Cre-dependent inhibitory DREADD. This approach gives us the temporal specificity to target neuronal ensembles formed during the acquisition of cocaine seeking in the prelimbic cortex. First, we demonstrate that neuronal ensembles in the prelimbic cortex are rapidly recruited and mediate cocaine seeking. Second, we show that the neuronal ensembles formed during behavioral acquisition are an enduring population that continues to be behaviorally relevant once rats are well-trained. Finally, through the combination of retrograde tract tracing and Fos immunohistochemistry, we show that neuronal ensembles in the prelimbic cortex recruit the nucleus accumbens core and shell after behavioral acquisition of cocaine self-administration. Collectively, we show that the prelimbic neuronal ensembles that mediate cocaine seeking are highly specific to context and behavioral conditions and recruit downstream projection targets post-acquisition.