A stream of cells migrating from the caudal telencephalon reveals a link between the amygdala and neocortex

Abstract

The amygdaloid complex consists of diverse nuclei that belong to distinct functional systems, yet many issues about its development are poorly understood. Here, we identify a stream of migrating cells that form specific amygdaloid nuclei in mice. In utero electroporation showed that this caudal amygdaloid stream (CAS) originated in a unique domain at the caudal telencephalic pole that is contiguous with the dorsal pallium, which was previously thought to generate only neocortical cells. The CAS and the neocortex share mechanisms for specification (transcription factors Tbr1, Lhx2 and Emx1/2) and migration (reelin and Cdk5). Reelin, a critical cue for migration in the neocortex, and Cdk5, which is specifically required for migration along radial glia in the neocortex, were both selectively required for the normal migration of the CAS, but not for that of other amygdaloid nuclei. This is first evidence of a dorsal pallial contribution to the amygdala, demonstrating a developmental and mechanistic link between the amygdala and the neocortex.

Global view of the functional molecular organization of the avian cerebrum: mirror images and functional columns

“…For example, the ER81 gene expression pattern used to support the hypothesis of homology between the avian arcopallium and mammalian layer V cortical neurons Dugas-Ford et al, 2012) is also expressed in the basal lateral amygdala (Nomura et al, 2009). In turn, the basal lateral amygdala and other pallial amygdala regions have been proposed to developmentally derive from pallial cells that are similar to the cortex (Swanson, 2000;Deussing and Wurst, 2007;Remedios et al, 2007;Soma et al, 2009). Conversely, the EMX1 gene expression pattern used to support the hypothesis of homology of the ventral pallial region of birds (hyperstriatum ventrale; our MD) and mammalian ventral claustrum (Smith-Fernandez et al, 1998;Puelles et al, 2000; Aboitiz, 2011) is also expressed in the mammalian cortex, and is also high in both avian MV and MD, where just like for GRIA1, FOXP1, and other mesopallium marker genes, the LMI boundary is not always seen with mesopallium enriched genes.…”

Contribution of Genoarchitecture to Understanding Forebrain Evolution and Development, with Particular Emphasis on the Amygdala

“…Therefore, using single genes or combinations of genes for identifying homologous structures disregarding the topological framework of the neural tube often leads to erroneous interpretations. We will focus on the amygdala, a telencephalic center involved in the control of emotions and social behavior that has been found at least in all tetrapods [reviews by Moreno and González, 2006;Martínez-García et al, 2007]; its development has been investigated in depth using genetic and fate map tools in recent years [Puelles et al, 2000;Medina et al, 2004;Remedios et al, 2004Remedios et al, , 2007Tole et al, 2005;Moreno and González, 2007a, b;Medina, 2008, 2009;García-López et al, 2008;Moreno et al, 2008aMoreno et al, , b, 2009Abellán et al, , 2010Hirata et al, 2009;Soma et al, 2009;García-Moreno et al, 2010;Waclaw et al, 2010;Bupesh et al, 2011a, b]. Since the amygdala in different tetrapods also appears to include neurons derived from extratelencephalic domains [Bardet et al, 2008;Abellán et al, 2010;García-Moreno et al, 2010], we will start with a brief summary of some aspects of forebrain development that help to understand its basic divisions and organization.…”

Calcium/calmodulin-dependent serine protein kinase (CASK), a protein implicated in mental retardation and autism-spectrum disorders, interacts with T-Brain-1 (TBR1) to control extinction of associative memory in male mice

“…[21][22][23][24] Interaction with TBR1 likely contributes to the role of CASK in development. In addition to neurodevelopment, TBR1 also serves as an immediate early gene in response to synaptic stimulation to upregulate glutamate receptor, ionotropic, N-methyl-d-aspartate receptor subunit 2B (Grin2b, also known as Nmdar2b) expression in mature neurons.…”