The inverted neurogenetic gradient of the mammalian isocortex: development and evolution

Aboitiz, Francisco; Morales, Daniver; Montiel, Juan

doi:10.1016/s0006-8993(01)02902-x

Cited by 25 publications

(21 citation statements)

References 88 publications

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“…There were two different telencephalon, topographically organized sensory representations take place in the multilaminar neocortex (36,37). This coincides with the development of a strong commissural system in monotremes, marsupials and placentals (38).…”

Section: Origin Of the Corpus Callosummentioning

confidence: 67%

One hundred million years of interhemispheric communication: the history of the corpus callosum

Aboitiz

Montiel

2003

Braz J Med Biol Res

335

223

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Analysis of regional corpus callosum fiber composition reveals that callosal regions connecting primary and secondary sensory areas tend to have higher proportions of coarse-diameter, highly myelinated fibers than callosal regions connecting so-called higher-order areas. This suggests that in primary/secondary sensory areas there are strong timing constraints for interhemispheric communication, which may be related to the process of midline fusion of the two sensory hemifields across the hemispheres. We postulate that the evolutionary origin of the corpus callosum in placental mammals is related to the mechanism of midline fusion in the sensory cortices, which only in mammals receive a topographically organized representation of the sensory surfaces. The early corpus callosum may have also served as a substrate for growth of fibers connecting higher-order areas, which possibly participated in the propagation of neuronal ensembles of synchronized activity between the hemispheres. However, as brains became much larger, the increasingly longer interhemispheric distance may have worked as a constraint for efficient callosal transmission. Callosal fiber composition tends to be quite uniform across species with different brain sizes, suggesting that the delay in callosal transmission is longer in bigger brains. There is only a small subset of large-diameter callosal fibers whose size increases with increasing interhemispheric distance. These limitations in interhemispheric connectivity may have favored the development of brain lateralization in some species like humans.

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Section: Origin Of the Corpus Callosummentioning

confidence: 67%

One hundred million years of interhemispheric communication: the history of the corpus callosum

Aboitiz

Montiel

2003

Braz J Med Biol Res

335

223

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“…During cortical development, postmitotic neurons migrate toward the CP from the VZ and pass the IZ. Within the CP, radially migrating cells become arranged in an inside-out pattern in which the earlier generated neurons occupy deeper layers, and those generated later become located in more superficial layers (Aboitiz= et al, 2001). These previous reports indicated that the transcripts of ié~êN are located in the VZ, and LPA 1 -expressing cells migrate toward the CP from VZ.…”

Section: Discussionmentioning

confidence: 99%

Application of in Utero Electroporation of G-Protein Coupled Receptor (GPCR) Genes, for Subcellular Localization of Hardly Identifiable GPCR in Mouse Cerebral Cortex

Kim¹,

Kim²,

Hong³

et al. 2014

Molecules and Cells

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Lysophosphatidic acid (LPA) is a lipid growth factor that exerts diverse biological effects through its cognate receptors (LPA 1 -LPA 6 ). LPA 1 , which is predominantly expressed in the brain, plays a pivotal role in brain development. However, the role of LPA 1 in neuronal migration has not yet been fully elucidated. Here, we delivered LPA 1 to mouse cerebral cortex using in utero electroporation. We demonstrated that neuronal migration in the cerebral cortex was not affected by the overexpression of LPA 1 . Moreover, these results can be applied to the identification of the localization of LPA 1 . The subcellular localization of LPA 1 was endogenously present in the perinuclear area, and overexpressed LPA 1 was located in the plasma membrane. Furthermore, LPA 1 in developing mouse cerebral cortex was mainly expressed in the ventricular zone and the cortical plate. In summary, the overexpression of LPA 1 did not affect neuronal migration, and the protein expression of LPA 1 was mainly located in the ventricular zone and cortical plate within the developing mouse cerebral cortex. These studies have provided information on the role of LPA 1 in brain development and on the technical advantages of in utero electroporation.

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“…Dynamic patterns of mitotically active neuronal precursors, known as 'neurogenetic gradients' (3) have been described in several brain regions, including the neocortex (4,5), the dorsal midbrain colliculi (6), and the dopaminergic region of the ventral midbrain (7). In the mammalian diencephalon, in particular the thalamus (formerly known as dorsal thalamus), two main neurogenetic gradients have been described: from posterior to anterior and from lateral to medial (8,9).…”

mentioning

confidence: 99%

Her6 regulates the neurogenetic gradient and neuronal identity in the thalamus

Scholpp

Delogu²,

Gilthorpe³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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During vertebrate brain development, the onset of neuronal differentiation is under strict temporal control. In the mammalian thalamus and other brain regions, neurogenesis is regulated also in a spatially progressive manner referred to as a neurogenetic gradient, the underlying mechanism of which is unknown. Here we describe the existence of a neurogenetic gradient in the zebrafish thalamus and show that the progression of neurogenesis is controlled by dynamic expression of the bHLH repressor her6. Members of the Hes/Her family are known to regulate proneural genes, such as Neurogenin and Ascl. Here we find that Her6 determines not only the onset of neurogenesis but also the identity of thalamic neurons, marked by proneural and neurotransmitter gene expression: loss of Her6 leads to premature Neurogenin1-mediated genesis of glutamatergic (excitatory) neurons, whereas maintenance of Her6 leads to Ascl1-mediated production of GABAergic (inhibitory) neurons. Thus, the presence or absence of a single upstream regulator of proneural gene expression, Her6, leads to the establishment of discrete neuronal domains in the thalamus.diencephalon ͉ Hes1 ͉ mash1 ͉ ngn1 ͉ zona limitans intrathalamica N eurogenesis in the developing vertebrate CNS is regulated with a high degree of temporal and spatial precision, with stereotypic patterns of neuronal differentiation and extensive neuronal migration (1, 2). Dynamic patterns of mitotically active neuronal precursors, known as 'neurogenetic gradients' (3) have been described in several brain regions, including the neocortex (4, 5), the dorsal midbrain colliculi (6), and the dopaminergic region of the ventral midbrain (7). In the mammalian diencephalon, in particular the thalamus (formerly known as dorsal thalamus), two main neurogenetic gradients have been described: from posterior to anterior and from lateral to medial (8,9). In rodents, all thalamic neurons are generated in about 6 days, and the orthogonal gradients of glutamatergic neurogenesis sweep across the boundaries of future nuclei. The underlying molecular mechanisms responsible for generating the neurogenetic gradients of the thalamus are unknown.The major constituent of the thalamus is a population of excitatory neurons generated in the caudal thalamus (cTh), whereas a minor population of inhibitory neurons is generated in the rostral thalamus (rTh). The latter is thought to give rise to the reticular nucleus and the ventral lateral geniculate nucleus, including the intergeniculate leaflet (10). During development, this rostro-caudal partitioning is seen in the expression domains of proneural basic helix-loop-helix (bHLH) genes: the achaete-scute-like complex genes (Ascl formerly known as Mash in mouse and Zash in zebrafish) mark the GABAergic rTh and the prethalamus (PTh) and the Neurogenin genes (Neurog, formerly known as Ngn) mark the glutamatergic cTh (2,11,12). Several lines of evidence show that these genes function as determinants of transmitter phenotype: in the mouse telencephalon, Neurog1/2 are required to ...

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The inverted neurogenetic gradient of the mammalian isocortex: development and evolution

Cited by 25 publications

References 88 publications

One hundred million years of interhemispheric communication: the history of the corpus callosum

One hundred million years of interhemispheric communication: the history of the corpus callosum

Application of in Utero Electroporation of G-Protein Coupled Receptor (GPCR) Genes, for Subcellular Localization of Hardly Identifiable GPCR in Mouse Cerebral Cortex

Her6 regulates the neurogenetic gradient and neuronal identity in the thalamus

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