Six groups of cholinergic neurons have been identified in the central nervous system (Ch1 –Ch6) [1]. Cholinergic neurons innervating the hippocampus and cerebral cortex arise from basal forebrain nuclei, including the medial septum (MS, Ch1 group), the vertical and horizontal limbs of the diagonal band (Ch2 and Ch3) and the nucleus basalis of Meynert (NBM, Ch4) [2]. Cholinergic neurons arising from the MS project mainly to the hippocampus, a brain region that plays an important role in learning and memory function. The diagonal band projections innervate the anterior cingulate cortex and the olfactory bulb, while the NBM projects to the amygdala and the cerebral cortex. The cholinergic projection from the NBM is widespread, covering the entire cortical mantle [3]. Basal forebrain cholinergic pathways have been implicated in attention, learning, memory and cognitive function. Moreover, the degeneration of basal forebrain cholinergic neurons is a consistent neurochemical hallmark of Alzheimer’s disease.