Systematic efforts – to identify cell populations, reveal the RNA repertoires of every cell type and state, and identify molecular markers for each population – would help to understand the functions and interactions of cells in the brain, including the roles of distinct cell types in disease. High-throughput single-cell RNA-seq (scRNA-seq) now enables RNA profiling in thousands of individual cells in complex tissue (Han et al., 2018; Klein et al., 2015; Macosko et al., 2015; Rosenberg et al., 2018; Zheng et al., 2017). To date, single-cell gene expression studies have yielded cell-type classifications in the mouse cerebral cortex (Tasic et al., 2016; Zeisel et al., 2015), retina (Shekhar et al., 2016), hypothalamic arcuate nucleus (Campbell et al., 2017), entopeduncular nucleus (Wallace et al., 2017) and amygdala (Wu et al., 2017).
