Clozapine Induces Neuronal Activation in the Medial Prefrontal Cortex in a Projection Target-Biased Manner.

The medial prefrontal cortex (mPFC) is associated with various behavioral controls via diverse projections to cortical and subcortical areas of the brain. Dysfunctions and modulations of this circuitry are related to the pathophysiology of schizophrenia and its pharmacotherapy, respectively. Clozapine is an atypical antipsychotic drug used for treatment-resistant schizophrenia and is known to modulate neuronal activity in the mPFC. However, it remains unclear which prefrontal cortical projections are activated by clozapine among the various projection targets. To identify the anatomical characteristics of neurons activated by clozapine at the mesoscale level, we investigated the brain-wide projection patterns of neurons with clozapine-induced c-Fos expression in the mPFC. Using a whole-brain imaging and virus-mediated genetic tagging of activated neurons, we found that clozapine-responsive neurons in the mPFC had a wide range of projections to the mesolimbic, amygdala and thalamic areas, especially the mediodorsal thalamus. These results may provide key insights into the neuronal basis of the therapeutic action of clozapine.