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At least 289 records · Page 16Linked to original sources
PubMed2006

The role of ARX in cortical development.

The ARX protein (encoded by the aristaless-related homeobox gene) is a member of the paired class of homeoproteins. More precisely, it is a member of the Aristaless subclass of proteins with a glutamine residue (Q) at the critical position 50 of the homeodomain (Q50). Through identification of diverse inherited or de novo mutations, genetic investigations of X-linked mental retardation conditions have demonstrated the implication of ARX in a wide spectrum of disorders extending from phenotypes with severe neuronal migration defects, such as lissencephaly, to mild forms of X-linked mental retardation without apparent brain abnormalities. These investigations have recently directed attention to the role of this gene in brain development. Analysis of its spatiotemporal localization profile have revealed expression mainly in telencephalic structures at all stages of development. Interestingly, in adult, ARX expression becomes restricted to a population of GABAergic neurons. Although the identification of the target genes regulated by ARX remains a crucial step to better understanding its role during brain development, studies of the role of ARX orthologs in different models have indicated that it is essential for important developmental processes such as proliferation, cell differentiation and neuronal migration.

Animals↗
PubMed2003

Environmental noise retards auditory cortical development.

The mammalian auditory cortex normally undergoes rapid and progressive functional maturation. Here we show that rearing infant rat pups in continuous, moderate-level noise delayed the emergence of adultlike topographic representational order and the refinement of response selectivity in the primary auditory cortex (A1) long beyond normal developmental benchmarks. When those noise-reared adult rats were subsequently exposed to a pulsed pure-tone stimulus, A1 rapidly reorganized, demonstrating that exposure-driven plasticity characteristic of the critical period was still ongoing. These results demonstrate that A1 organization is shaped by a young animal's exposure to salient, structured acoustic inputs-and implicate noise as a risk factor for abnormal child development.

Acoustic Stimulation↗
PubMed1973

Visual experience without lines: effect on developing cortical neurons.

Kittens were reared in a planetarium-like visual environment that lacked straight line contours. Cortical neurons were subsequently highly sensitive to spots of light but not to straight lines, in marked contrast to those from a normal cat. If linear contour processing is an innate function it appears to be subject to substantial modification by early visual experience.

Action Potentials↗
PubMed2005

BDNF acutely modulates synaptic transmission and calcium signalling in developing cortical neurons.

Brain-derived neurotrophic factor (BDNF), like other neurotrophins, has long-term effects on neuronal survival and differentiation; furthermore, BDNF has been reported to exert an acute potentiation of synaptic activity and are critically involved in long-term potentiation(LTP). We found that BDNF rapidly induced potentiation of synaptic activity and an increase in the intracellular Ca2+ concentration in cultured cortical neurons. Within minutes of BDNF application to cultured cortical neurons, spontaneous firing rate was dramatically increased as was the frequency and amplitude of excitatory spontaneous postsynaptic currents (EPSCs). Fura-2 recordings showed that BDNF acutely elicited an increase in intracellular calcium concentration ([Ca2+]i). This effect was partially dependent on extracellular Ca2+. In calcium-free perfusion medium a substantial calcium signal remained which disappeared after loading of cortical neurons with 5 microM U-73122. BDNF-induce Ca2+ transients were completely blocked by K252a and partially blocked by Cd2+. The results demonstrate that BDNF can enhance synaptic transmission and induce directly a rise in [Ca2+]i that require two routes: the release of Ca2+ from intracellular calcium stores and influx of extracellular Ca2+ mainly through voltage-dependent Ca2+ channels in cultured cortical neurons.

Animals↗
PubMed2001

NeuroD homologue expression during cortical development in the human brain.

Neurogenesis and neuronal differentiation are determined by the NeuroD homologues, transcription factors belonging to a family of basic helix-loop-helix proteins. The authors used in situ hybridization with full-length riboprobes for NeuroD1, NeuroD2, and NeuroD3 to describe the expression of the NeuroD homologues in a gestational sequence of human fetal brains. Acridine orange histofluorescence was used to differentiate neuronal from non-neuronal cell precursors. At the earliest gestational age examined (gestational week 16), signals for all three homologues could be identified but that for NeuroD3 was most intense. Peak expression of NeuroD1 and NeuroD2 followed at gestational weeks 19 and 20, respectively. Although similar to the expression of these homologues in the mouse cerebrum, notable differences were observed. Specifically, signals for all three homologues were detected in the marginal zone and the ventricular zone, including the ganglionic eminence. The temporal order of expression in the human is similar to that in the mouse, in spite of these anatomic differences. These data are consistent with NeuroD3 serving as a determination factor, which commits the post-mitotic progenitor cell to a neuronal fate, whereas NeuroD1 and NeuroD2 appear more likely to play a role in neuronal differentiation.

Basic Helix-Loop-Helix Proteins↗
PubMed2005

Giant intracranial teratoma and lack of cortical development in a fetus. Case report.

Antenatal diagnosis of an intracranial neoplasm is extremely rare. The authors describe a case in which a 21-week-old fetus was found, by using fetal ultrasonography, to have a large intracranial mass. Fetal magnetic resonance (MR) images, obtained at 21 and 25 weeks' gestation, supported the diagnosis of a teratoma. As the tumor increased in size, near-complete brain atrophy ensued. Premature labor was induced, and a nonviable fetus died within minutes of delivery. Postmortem analysis confirmed a teratoma occupying a major portion of the intracranial space. In cases in which abnormal brain development is suspected in a fetus, the use of fetal MR imaging can give a clearer picture of the pathological entity, which may allow for a more accurate diagnosis. The usefulness of fetal MR imaging in monitoring brain development and tumor growth during treatment planning is discussed.

Adult↗