Generation of a whole-brain atlas for the cholinergic system and mesoscopic projectome analysis of basal forebrain cholinergic neurons

Significance The cholinergic system plays a critical role in neural modulation of the mammalian brain. Here, we generated a comprehensive atlas of the cholinergic system in the mouse brain via the whole-brain imaging and reconstruction system. In the whole-brain dataset, the cholinergic neurons were divided into three categories including cortical VIP neurons, long-range projection neurons, and brainstem motor neurons. After reconstructing the cholinergic neurons in a subregion of basal forebrain, we found that their projections to the forebrain and midbrain showed neuronal subgroups with distinct projection specificity. Our work presents three-dimensional information about the cholinergic system in the mouse brain, facilitating further studies of the cholinergic system.