title: Developmental origin of the neuronal subtypes that comprise the amygdalar fear circuit in the mouse.
abstract: We have taken a genetic-based fate-mapping approach to determine the specific contributions of telencephalic progenitors to the structures that comprise the amygdalar fear circuit including the central (CA), lateral (LA), and basolateral (BLA) amygdala. Our data indicate that progenitors in the ventral pallium (VP) contribute projection neurons to the LA and BLA but not the CA. Rather, the CA appears to derive, at least in part, from progenitors located in the ventral lateral ganglionic eminence (vLGE). Diverse groups of interneurons populate these amygdalar nuclei, and as predicted our data support the notion that they originate from subpallial progenitors. A rather specific population of amygdalar interneurons, the intercalated cells (ITCs), is known to play a fundamental role in fear-related behaviors. However, no information on their specific origin has, as yet, been provided. Our findings suggest that the ITCs arise from the dorsal lateral ganglionic eminence (dLGE) and migrate in the lateral migratory stream to populate the paracapsular regions as well as the main intercalated mass of the amygdala (IA). Germ-line Gsx2 mutants are known to exhibit an expansion of the VP into the LGE and a concomitant reduction in the dLGE and vLGE. Accordingly, Gsx2 conditional mutants display a significantly enlarged LA and a significant reduction in ITCs both within the paracapsular regions and the IA. Additional support for a dLGE origin of the ITCs was obtained in conditional mutants of the dLGE gene Sp8. Thus, our findings indicate diverse origins for the neuronal components that comprise the amygdalar fear circuit.
authors.affiliation: Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio 45229, USA.
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Waclaw
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Ehrman
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pierani
authors.forename: Kenneth
authors.initials: K
authors.lastname: Campbell
mesh_terms: D000367:Age Factors; D000679:Amygdala / Q000166:cytology* / Q000254:growth & development*; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D001931:Brain Mapping; D004268:DNA-Binding Proteins / Q000235:genetics; D004622:Embryo, Mammalian; D005239:Fear; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics; D060850:LIM-Homeodomain Proteins; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000145:classification / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; C103403:Dbx1 protein, mouse; C501120:Dlx5 protein, mouse; C109498:Gsh2 protein, mouse; D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; D009419:Nerve Tissue Proteins; C490035:Sp8 protein, mouse; D014157:Transcription Factors; C485184:enhanced green fluorescent protein; C063843:insulin gene enhancer binding protein Isl-1; D049452:Green Fluorescent Proteins