“…Indeed, several studies that focused on various brain structures (cerebellar cortex, cerebral cortex, olfactory epithelium, basal forebrain) and neuronal subtypes (granule cells, cortical neuroblasts, tangentially migrating interneurons, luteinizing hormonereleasing hormone neuroblasts, gonadotropin-releasing hormone neuroblasts) have been performed using different protocols (dissociated cells in microchemotaxis chambers, slice preparation). These studies have led to the conclusion that transmitters, GABA and glutamate, acting on several receptor subtypes (GABA A , GABA B , GABA C , NMDA, AMPA) have a crucial modulatory effect on migrating neuroblasts, acting as motility-promoting signals (Behar et al, 1998(Behar et al, , 1999(Behar et al, , 2000(Behar et al, , 2001Hirai et al, 1999;Simonian and Herbison, 2001;Lopez-Bendito et al, 2003), acceleratory signals (Komuro and Rakic, 1993), or stop signals (Behar et al, 1998(Behar et al, , 2000Fueshko et al, 1998;Bless et al, 2000;Simonian and Herbison, 2001;Kihara et al, 2002). However, in contrast to these observations, there is no deficit in cortical layering and synapse formation in mice in which vesicular release has been deleted: munc18-1 mutant mice (Verhage et al, 2000) or munc13-1/2 double knock-out (KO) mice (Varoqueaux et al, 2002).…”