Search results for "CORTEX"
showing 10 items of 1827 documents
miR379-410 cluster miRNAs regulate neurogenesis and neuronal migration by fine-tuning N-cadherin
2014
N-cadherin-mediated adhesion is essential for maintaining the tissue architecture and stem cell niche in the developing neocortex. N-cadherin expression level is precisely and dynamically controlled throughout development; however, the underlying regulatory mechanisms remain largely unknown. MicroRNAs (miRNAs) play an important role in the regulation of protein expression and subcellular localisation. In this study, we show that three miRNAs belonging to the miR379–410 cluster regulate N-cadherin expression levels in neural stem cells and migrating neurons. The overexpression of these three miRNAs in radial glial cells repressed N-cadherin expression and increased neural stem cell different…
Phf21b imprints the spatiotemporal epigenetic switch essential for neural stem cell differentiation.
2019
Cerebral cortical development in mammals involves a highly complex and organized set of events including the transition of neural stem and progenitor cells (NSCs) from proliferative to differentiative divisions to generate neurons. Despite progress, the spatiotemporal regulation of this proliferation-differentiation switch during neurogenesis and the upstream epigenetic triggers remain poorly known. Here we report a cortex-specific PHD finger protein, Phf21b, which is highly expressed in the neurogenic phase of cortical development and gets induced as NSCs begin to differentiate. Depletion of Phf21b in vivo inhibited neuronal differentiation as cortical progenitors lacking Phf21b were retai…
Transient cortical circuits match spontaneous and sensory-driven activity during development.
2020
At the earliest developmental stages, spontaneous activity synchronizes local and large-scale cortical networks. These networks form the functional template for the establishment of global thalamocortical networks and cortical architecture. The earliest connections are established autonomously. However, activity from the sensory periphery reshapes these circuits as soon as afferents reach the cortex. The early-generated, largely transient neurons of the subplate play a key role in integrating spontaneous and sensory-driven activity. Early pathological conditions—such as hypoxia, inflammation, or exposure to pharmacological compounds—alter spontaneous activity patterns, which subsequently in…
Reawakening the sleeping beauty in the adult brain: neurogenesis from parenchymal glia
2015
Life-long neurogenesis is highly restricted to specialized niches in the adult mammalian brain and therefore the brain's capacity for spontaneous regeneration is extremely limited. However, recent work has demonstrated that under certain circumstances parenchymal astrocytes and NG2 glia can generate neuronal progeny. In the striatum, stroke or excitotoxic lesions can reawaken in astrocytes a latent neurogenic program resulting in the genesis of new neurons. By contrast, in brain areas that fail to mount a neurogenic response following injury, such as the cerebral cortex, forced expression of neurogenic reprogramming factors can lineage convert local glia into induced neurons. Yet, injury-in…
Can we understand human brain development from experimental studies in rodents?
2020
Animal models are needed to gain an understanding of the genetic, molecular, cellular, and network mechanisms of human brain development. In rodents, a large spectrum of in vitro and in vivo approaches allows detailed analyses and specific experimental manipulations for studying the sequence of developmental steps in corticogenesis. Neurogenesis, neuronal migration, cellular differentiation, programmed cell death, synaptogenesis, and myelination are surprisingly similar in the rodent cortex and the human cortex. Spontaneous EEG activity in the pre- and early postnatal human cortex resembles the activity patterns recorded with intracortical multi-electrode arrays in newborn rodents. This ear…
Electrophysiological evidence of memory-based detection of auditory regularity violations in anesthetized mice
2017
In humans, automatic change detection is reflected by an electrical brain response called mismatch negativity (MMN). Mismatch response is also elicited in mice, but it is unclear to what extent it is functionally similar to human MMN. We investigated this possible similarity by recording local field potentials from the auditory cortex of anesthetized mice. First, we tested whether the response to stimulus changes reflected the detection of regularity violations or adaptation to standard stimuli. Responses obtained from an oddball condition, where occasional changes in frequency were presented amongst of a standard sound, were compared to responses obtained from a control condition, where no…
Changes in NMDA-receptor function in the first week following laser-induced lesions in rat visual cortex.
2011
Focal brain injuries are accompanied by processes of functional reorganization that partially compensate the functional loss. In a previous study, extracellular recordings at the border of a laser-induced lesion in the visual cortex of rats showed an enhanced synaptic plasticity, which was mediated by the activity of NR2B-contaning NMDA-receptors (NMDARs) shedding light on the potential cellular mechanisms underlying this reorganization. Given the potentially important contribution of NMDARs in processes of functional reorganization, in the present study, we used the same lesion model to further investigate lesion-induced changes in function and localization of NMDARs in the vicinity of the…
Triiodothyronine-Induced Shortening of Chromatin Repeat Length in Neurons Cultured in a Chemically Denned Medium
1987
Abstract: At the time of terminal differentiation, mammalian cortical neurons undergo a dramatic change in the structural organization of their chromatin: the nucleosomal repeat length shortens from ∼200 base pairs in fetuses to a value of 165 base pairs after birth. These events occur several days after the end of neuronal proliferation. Previously, we reported that rat cortical neurons cultured in a very selective synthetic medium were not yet programmed to these events at the end of mitotic cycles. Herein, we report that addition of triiodothyronine to neuronal cultures induces a shortening of the chromatin repeat length comparable to the natural one. Copyright © 1987, Wiley Blackwell. A…
Cajal–Retzius cells: Update on structural and functional properties of these mystic neurons that bridged the 20th century
2014
Cajal-Retzius cells (CRc) represent a mostly transient neuronal cell type localized in the uppermost layer of the developing neocortex. The observation that CRc are a major source of the extracellular matrix protein reelin, which is essential for the laminar development of the cerebral cortex, attracted the interest in this unique cell type. In this review we will (i) describe the morphological and molecular properties of neocortical CRc, with a special emphasize on the question which markers can be used to identify CRc, (ii) summarize reports that identified the different developmental origins of CRc, (iii) discuss the fate of CRc, including recent evidence for apoptotic cell death and a p…
Multiple-unit responses to pitch changes in rabbits
1996
Multiple-unit activity (MUA) was recorded from the hippocampus (Hc), the visual cortex (VCx) and the cerebellar cortex (CerCx) in rabbits when pitch deviant tones were presented in a series of standard tones (oddball situation) and when standard tones were absent (deviant-alone situation). Significant MMN-like responses (deviant responses minus standard responses in the oddball situation) occurred in Hc, reflecting a MUA increase to the standards and its decrease to the deviants. In accordance with parallel ERPs reported earlier, the MMN-like responses reflected responses only to different presentation frequencies of stimuli. Non-selectivity in the pitch of such responses in VCx and a lack …