Brain-wide mapping reveals temporal and sexually dimorphic opioid actions

The field of neuroscience has been transformed by recent advances in spatial mapping of neuronal activity across whole cleared brains. Rapid adoption of these techniques requires computational workflows that can facilitate experiments comparing multiple conditions across large cohorts of individuals. We therefore developed a scalable approach for anatomical mapping of c-Fos positive cells in whole brain and applied it to map the response to the prototypic opioid, morphine. The analysis revealed distinct patterns of morphine-induced regional brain activation across both time and sex. These results support the multi-wave model of opioid-induced brain activation. Male mice displayed higher c-Fos expression than females in several key brain regions including nucleus accumbens, central amygdalar nucleus, ventral pallidum, prelimbic area, anterior cingulate area, and olfactory tubercle. Overall, this workflow can be applied to not only examine spatiotemporal actions of drugs of abuse on neuronal activity across the brain, but also mapping neuronal activity more generally.