PMC:4429232 / 5967-9184 JSONTXT

{"project":"0_colil","denotations":[{"id":"26029038-7840420-565781","span":{"begin":230,"end":234},"obj":"7840420"},{"id":"26029038-10929318-565782","span":{"begin":244,"end":248},"obj":"10929318"},{"id":"26029038-21647397-565783","span":{"begin":260,"end":264},"obj":"21647397"},{"id":"26029038-25291080-565784","span":{"begin":283,"end":287},"obj":"25291080"},{"id":"26029038-21647397-565785","span":{"begin":1062,"end":1066},"obj":"21647397"},{"id":"26029038-25291080-565786","span":{"begin":1085,"end":1089},"obj":"25291080"},{"id":"26029038-21647397-565787","span":{"begin":1354,"end":1358},"obj":"21647397"},{"id":"26029038-803518-565788","span":{"begin":1573,"end":1577},"obj":"803518"},{"id":"26029038-21647397-565789","span":{"begin":2020,"end":2024},"obj":"21647397"},{"id":"26029038-24105342-565790","span":{"begin":2040,"end":2044},"obj":"24105342"},{"id":"26029038-23884180-565791","span":{"begin":2364,"end":2368},"obj":"23884180"},{"id":"26029038-24671134-565792","span":{"begin":2370,"end":2374},"obj":"24671134"},{"id":"26029038-16766701-565793","span":{"begin":2496,"end":2500},"obj":"16766701"},{"id":"26029038-18331905-565794","span":{"begin":2523,"end":2527},"obj":"18331905"},{"id":"26029038-19726493-565795","span":{"begin":2544,"end":2548},"obj":"19726493"},{"id":"26029038-3455589-565796","span":{"begin":2740,"end":2744},"obj":"3455589"},{"id":"26029038-3950076-565797","span":{"begin":2815,"end":2819},"obj":"3950076"},{"id":"26029038-24105342-565798","span":{"begin":2959,"end":2963},"obj":"24105342"},{"id":"26029038-23334497-565799","span":{"begin":2985,"end":2989},"obj":"23334497"}],"text":"It is generally accepted that in the reptilian ancestor of mammals the medial, dorsal and lateral cortices were laminated but were made only by three layers, an organization that is also called allocortex (Figure 1B; Nieuwenhuys, 1994; Reiner, 2000; Shepherd, 2011; Fournier et al., 2015). In mammals, this type of cortex is still present in two structurally and functionally well conserved regions that border the neocortex: the hippocampus, a MP derivative, and the piriform cortex, a LP derivative that receive a direct input from the olfactory bulb. In the allocortex the more superficial layer I is a plexiform layer where extrinsic and intrinsic projections meet the apical dendrites of pyramidal neurons whose cell bodies settle in layers II and III (Haberly, 1990; Ulinsky, 1990). In general, the cellular density is higher in layer II than in layer III particularly in the piriform/lateral cortex and the hippocampus. The neocortex shares with allocortex the basic microcircuits, but it stands out for the higher number of neurons and layers (Shepherd, 2011; Fournier et al., 2015). In many respects the neocortex can be described as a double allocortex, with two couples of pyramidal layers, namely upper (II,III,IV; UL) and deeper (V,VI, DL), each below a plexiform layer carrying extrinsic inputs, namely layer I and IV (Figure 1B; Shepherd, 2011). In primary sensory areas the layer IV is enriched in stellate cells, a glutamatergic cell type that lack apical tufts and output projections and is specialized in receiving thalamic inputs (Sanides, 1969; Jones, 1975). By contrast, most of the glutamatergic neurons in the other layers possess an apical dendrite directed to layer I and output connections emerging at the opposite pole of the cell body (Figure 1B). The UL neurons axons are mainly involved in cortico-cortical connectivity and include homotopic and heterotopic callosal projections to the contralateral hemisphere, while DL neurons target various subcortical structures (Figure 1B; Shepherd, 2011; Greig et al., 2013). To understand the evolution of the neocortex we should thus first disclose the developmental mechanisms that triggered the multiplication of cellular and plexiform layers. As expected, comparative studies shows that in respect to reptiles, the mammalian DP progenitors have an increased proliferation (Nomura et al., 2013, 2014) that include the appearance of a well defined layer of intermediate progenitor cells: the SVZ (Martínez-Cerdeño et al., 2006; Abdel-Mannan et al., 2008; Cheung et al., 2010). In mammals, this increase in cell proliferation is accompanied by a distinct pattern of migration of neuroblasts that passes older cells (n.b. in both piriform cortex and neocortex; Bayer, 1986) rather than accumulating below them as in reptiles (Goffinet et al., 1986; Figure 1C). Since cortical neurons are generally considered to be already committed to a specific cell type at their birth (Greig et al., 2013; Rouaux and Arlotta, 2013), a major point to understand the emergence of the neocortex will be to unravel the evolution of the developmental program set up by dorsal pallium progenitors and regulating the production of neocortical glutamatergic neurons."}

{"project":"2_test","denotations":[{"id":"26029038-7840420-38462687","span":{"begin":230,"end":234},"obj":"7840420"},{"id":"26029038-10929318-38462688","span":{"begin":244,"end":248},"obj":"10929318"},{"id":"26029038-21647397-38462689","span":{"begin":260,"end":264},"obj":"21647397"},{"id":"26029038-25291080-38462690","span":{"begin":283,"end":287},"obj":"25291080"},{"id":"26029038-21647397-38462691","span":{"begin":1062,"end":1066},"obj":"21647397"},{"id":"26029038-25291080-38462692","span":{"begin":1085,"end":1089},"obj":"25291080"},{"id":"26029038-21647397-38462693","span":{"begin":1354,"end":1358},"obj":"21647397"},{"id":"26029038-803518-38462694","span":{"begin":1573,"end":1577},"obj":"803518"},{"id":"26029038-21647397-38462695","span":{"begin":2020,"end":2024},"obj":"21647397"},{"id":"26029038-24105342-38462696","span":{"begin":2040,"end":2044},"obj":"24105342"},{"id":"26029038-23884180-38462697","span":{"begin":2364,"end":2368},"obj":"23884180"},{"id":"26029038-24671134-38462698","span":{"begin":2370,"end":2374},"obj":"24671134"},{"id":"26029038-16766701-38462699","span":{"begin":2496,"end":2500},"obj":"16766701"},{"id":"26029038-18331905-38462700","span":{"begin":2523,"end":2527},"obj":"18331905"},{"id":"26029038-19726493-38462701","span":{"begin":2544,"end":2548},"obj":"19726493"},{"id":"26029038-3455589-38462702","span":{"begin":2740,"end":2744},"obj":"3455589"},{"id":"26029038-3950076-38462703","span":{"begin":2815,"end":2819},"obj":"3950076"},{"id":"26029038-24105342-38462704","span":{"begin":2959,"end":2963},"obj":"24105342"},{"id":"26029038-23334497-38462705","span":{"begin":2985,"end":2989},"obj":"23334497"}],"text":"It is generally accepted that in the reptilian ancestor of mammals the medial, dorsal and lateral cortices were laminated but were made only by three layers, an organization that is also called allocortex (Figure 1B; Nieuwenhuys, 1994; Reiner, 2000; Shepherd, 2011; Fournier et al., 2015). In mammals, this type of cortex is still present in two structurally and functionally well conserved regions that border the neocortex: the hippocampus, a MP derivative, and the piriform cortex, a LP derivative that receive a direct input from the olfactory bulb. In the allocortex the more superficial layer I is a plexiform layer where extrinsic and intrinsic projections meet the apical dendrites of pyramidal neurons whose cell bodies settle in layers II and III (Haberly, 1990; Ulinsky, 1990). In general, the cellular density is higher in layer II than in layer III particularly in the piriform/lateral cortex and the hippocampus. The neocortex shares with allocortex the basic microcircuits, but it stands out for the higher number of neurons and layers (Shepherd, 2011; Fournier et al., 2015). In many respects the neocortex can be described as a double allocortex, with two couples of pyramidal layers, namely upper (II,III,IV; UL) and deeper (V,VI, DL), each below a plexiform layer carrying extrinsic inputs, namely layer I and IV (Figure 1B; Shepherd, 2011). In primary sensory areas the layer IV is enriched in stellate cells, a glutamatergic cell type that lack apical tufts and output projections and is specialized in receiving thalamic inputs (Sanides, 1969; Jones, 1975). By contrast, most of the glutamatergic neurons in the other layers possess an apical dendrite directed to layer I and output connections emerging at the opposite pole of the cell body (Figure 1B). The UL neurons axons are mainly involved in cortico-cortical connectivity and include homotopic and heterotopic callosal projections to the contralateral hemisphere, while DL neurons target various subcortical structures (Figure 1B; Shepherd, 2011; Greig et al., 2013). To understand the evolution of the neocortex we should thus first disclose the developmental mechanisms that triggered the multiplication of cellular and plexiform layers. As expected, comparative studies shows that in respect to reptiles, the mammalian DP progenitors have an increased proliferation (Nomura et al., 2013, 2014) that include the appearance of a well defined layer of intermediate progenitor cells: the SVZ (Martínez-Cerdeño et al., 2006; Abdel-Mannan et al., 2008; Cheung et al., 2010). In mammals, this increase in cell proliferation is accompanied by a distinct pattern of migration of neuroblasts that passes older cells (n.b. in both piriform cortex and neocortex; Bayer, 1986) rather than accumulating below them as in reptiles (Goffinet et al., 1986; Figure 1C). Since cortical neurons are generally considered to be already committed to a specific cell type at their birth (Greig et al., 2013; Rouaux and Arlotta, 2013), a major point to understand the emergence of the neocortex will be to unravel the evolution of the developmental program set up by dorsal pallium progenitors and regulating the production of neocortical glutamatergic neurons."}