“…While it is clear that mAChRs modulate the learning and memory functions of the hippocampus (Deiana et al, ; Thiele, ; Wilson & Fadel, ), the contributions of specific mAChR subtypes in mediating these effects remain unclear. Early immunohistochemical (Hersch & Levey, ; Levey et al, ) and in situ hybridization (Brann, Buckley, & Bonner, ; Buckley et al, ) studies showed predominant M1, M2, and M4 mAChR protein and gene expression within the hippocampus, with G i/o ‐coupled M2 and M4 receptors largely located presynaptically (Levey et al, ; Rouse, Edmunds, Yi, Gilmor, & Levey, ), and G q/11 ‐coupled M1 receptors largely located postsynaptically (Levey et al, ; Rouse et al, ; Volpicelli & Levey, ).…”