Finally, in addition to the ability of ACh to modulate neuronal activity acutely in adulthood, ACh can also alter a number of processes in neuronal development, and the molecular basis for a number of these developmental effects of ACh signaling have been elucidated recently. For example, one fundamental role for ACh signaling through nAChRs is to regulate the timing of expression of the chloride transporter that is necessary for the ability of GABA to hyperpolarize, and therefore inhibit, central neurons (Liu et al., 2006). Disrupting nAChR signaling delays the switch from GABA-mediated excitation to inhibition. Recent studies have also shown that nAChRs contribute to the maturation of GABAergic (Kawai et al., 2002; Zago et al., 2006) and glutamatergic (Lozada et al., 2012a, b) synapses, highlighting an important role for ACh signaling in synaptic development, as well as neuronal pathfinding and target selection (reviewed in (Role and Berg, 1996). In addition, signaling through nAChRs is also important for establishing critical periods for activity-dependent shaping of visual cortical function (Morishita et al., 2010) and maturation of thalamocortical (Aramakis and Metherate, 1998; Aramakis
