Whole-brain mapping reveals the divergent impact of ketamine on the dopamine system.

Ketamine is a multifunctional drug with clinical applications as an anesthetic, pain management medication, and a fast-acting antidepressant. However, it is also recreationally abused for its dissociative effects. Recent studies in rodents are revealing the neuronal mechanisms mediating its actions, but the impact of prolonged exposure to ketamine on brain-wide networks remains less understood. Here, we develop a sub-cellular resolution whole-brain phenotyping approach and utilize it in male mice to show that repeated ketamine administration leads to a dose-dependent decrease in dopamine neurons in midbrain regions linked to behavioral states, alongside an increase in the hypothalamus. Additionally, diverse changes are observed in long-range innervations of the prefrontal cortex, striatum, and sensory areas. Furthermore, the data support a role for post-transcriptional regulation in enabling ketamine-induced neural plasticity. Through an unbiased, high-resolution whole-brain analysis, this study provides important insights into how chronic ketamine exposure reshapes brain-wide networks.