“…Acetylcholine plays a critical developmental role in brain maturation (Lauder and Schambra, 1999;Weiss et al, 1998;Slotkin, 2004), initially promoting cell division, and subsequently promoting the switch from replication to differentiation (Slotkin, 1998(Slotkin, , 1999. In rodents, inappropriate stimulation of nAChRs by nicotine during prenatal development produces reductions in brain cell number, size, and surface area (Roy et al, 1998;Slotkin, 1998Slotkin, , 1999, prolonged reductions in cholinergic neural transmission (Zahalka et al, 1992;Navarro et al, 1989), and alters the subsequent response to nicotine challenge (Navarro et al, 1988;Seidler et al, 1992;Levin et al, 1993Levin et al, , 1996.…”