The Development Of The Cortex

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The development of the cortex is a delicate balance between proliferation, differentiation and migration of neural progenitors (NPs). Throughout developmental process, various cellular mechanisms ensure that NPs are differentiating into the correct cell subtypes, migrating to their correct regions, and forming the correct cortical and sub-cortical layers. The cortex is comprised of both excitatory and inhibitory neurons, which interact within neuronal circuits to mediate cortical functions. Though both types of neurons reside in the cortex, they arise from different embryonic brain regions, and from different neural progenitors. Excitatory neurons are generated from neural progenitors residing in the ventricular zone (VZ)/subventricular…show more content…
X94 cells are located exclusively in layers 4 and 5, and martinotti cells can be either calretinin (CR) positive or negative, and are bursting/non-bursting respectively. NPY+ originate from both the MGE and CGE, and can also be SST+. In the adult mouse brain, they are found mostly in layers 2/3/6, but can exist in all layers (Karagiannis et al., 2009). Additionally, they are often activity dependent, and increases expression upon neuronal activity (De Marco Garcia et al., 2011). Failure to form proper cortical layers has been observed in patients with developmental disorders, such as ASDs and SZ(Stoner et al., 2014). Though less populous than excitatory neurons in the neocortex, GABAergic interneurons are essential to the functionality of the nervous system. Though the precise genetic components causing autism still elude us, there are intriguing molecular hypothesis for this disorder. One such hypothesis is the GABAergic hypothesis of autism. There is increasing evidence that deficits in interneurons are related to psychiatric disease. Post-mortem studies of schizophrenia patients revealed reduced GAD67 expression, and decreased PV and GAD67 mRNA (Benes et al., 2007; Curley and Lewis, 2012). Additionally, 30% of patients with ASD have epilepsy, and 30% of patients with epilepsy have ASD. This co-morbidity suggests a potential disruption in the E/I balance of the brain, which often results in epilepsy. Additionally, many ASD risk genes have been associated with
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