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Sample records for improve cortical neuron

  1. Active engagement improves primary auditory cortical neurons' ability to discriminate temporal modulation.

    PubMed

    Niwa, Mamiko; Johnson, Jeffrey S; O'Connor, Kevin N; Sutter, Mitchell L

    2012-07-04

    The effect of attention on single neuron responses in the auditory system is unresolved. We found that when monkeys discriminated temporally amplitude modulated (AM) from unmodulated sounds, primary auditory cortical (A1) neurons better discriminated those sounds than when the monkeys were not discriminating them. This was observed for both average firing rate and vector strength (VS), a measure of how well neurons temporally follow the stimulus' temporal modulation. When data were separated by nonsynchronized and synchronized responses, the firing rate of nonsynchronized responses best distinguished AM- noise from unmodulated noise, followed by VS for synchronized responses, with firing rate for synchronized neurons providing the poorest AM discrimination. Firing rate-based AM discrimination for synchronized neurons, however, improved most with task engagement, showing that the least sensitive code in the passive condition improves the most with task engagement. Rate coding improved due to larger increases in absolute firing rate at higher modulation depths than for lower depths and unmodulated sounds. Relative to spontaneous activity (which increased with engagement), the response to unmodulated sounds decreased substantially. The temporal coding improvement--responses more precisely temporally following a stimulus when animals were required to attend to it--expands the framework of possible mechanisms of attention to include increasing temporal precision of stimulus following. These findings provide a crucial step to understanding the coding of temporal modulation and support a model in which rate and temporal coding work in parallel, permitting a multiplexed code for temporal modulation, and for a complementary representation of rate and temporal coding.

  2. Human induced pluripotent stem cell-derived cortical neurons integrate in stroke-injured cortex and improve functional recovery.

    PubMed

    Tornero, Daniel; Wattananit, Somsak; Grønning Madsen, Marita; Koch, Philipp; Wood, James; Tatarishvili, Jemal; Mine, Yutaka; Ge, Ruimin; Monni, Emanuela; Devaraju, Karthikeyan; Hevner, Robert F; Brüstle, Oliver; Lindvall, Olle; Kokaia, Zaal

    2013-12-01

    Stem cell-based approaches to restore function after stroke through replacement of dead neurons require the generation of specific neuronal subtypes. Loss of neurons in the cerebral cortex is a major cause of stroke-induced neurological deficits in adult humans. Reprogramming of adult human somatic cells to induced pluripotent stem cells is a novel approach to produce patient-specific cells for autologous transplantation. Whether such cells can be converted to functional cortical neurons that survive and give rise to behavioural recovery after transplantation in the stroke-injured cerebral cortex is not known. We have generated progenitors in vitro, expressing specific cortical markers and giving rise to functional neurons, from long-term self-renewing neuroepithelial-like stem cells, produced from adult human fibroblast-derived induced pluripotent stem cells. At 2 months after transplantation into the stroke-damaged rat cortex, the cortically fated cells showed less proliferation and more efficient conversion to mature neurons with morphological and immunohistochemical characteristics of a cortical phenotype and higher axonal projection density as compared with non-fated cells. Pyramidal morphology and localization of the cells expressing the cortex-specific marker TBR1 in a certain layered pattern provided further evidence supporting the cortical phenotype of the fated, grafted cells, and electrophysiological recordings demonstrated their functionality. Both fated and non-fated cell-transplanted groups showed bilateral recovery of the impaired function in the stepping test compared with vehicle-injected animals. The behavioural improvement at this early time point was most likely not due to neuronal replacement and reconstruction of circuitry. At 5 months after stroke in immunocompromised rats, there was no tumour formation and the grafted cells exhibited electrophysiological properties of mature neurons with evidence of integration in host circuitry. Our

  3. Training in cortical control of neuroprosthetic devices improves signal extraction from small neuronal ensembles.

    PubMed

    Helms Tillery, S I; Taylor, D M; Schwartz, A B

    2003-01-01

    We have recently developed a closed-loop environment in which we can test the ability of primates to control the motion of a virtual device using ensembles of simultaneously recorded neurons /29/. Here we use a maximum likelihood method to assess the information about task performance contained in the neuronal ensemble. We trained two animals to control the motion of a computer cursor in three dimensions. Initially the animals controlled cursor motion using arm movements, but eventually they learned to drive the cursor directly from cortical activity. Using a population vector (PV) based upon the relation between cortical activity and arm motion, the animals were able to control the cursor directly from the brain in a closed-loop environment, but with difficulty. We added a supervised learning method that modified the parameters of the PV according to task performance (adaptive PV), and found that animals were able to exert much finer control over the cursor motion from brain signals. Here we describe a maximum likelihood method (ML) to assess the information about target contained in neuronal ensemble activity. Using this method, we compared the information about target contained in the ensemble during arm control, during brain control early in the adaptive PV, and during brain control after the adaptive PV had settled and the animal could drive the cursor reliably and with fine gradations. During the arm-control task, the ML was able to determine the target of the movement in as few as 10% of the trials, and as many as 75% of the trials, with an average of 65%. This average dropped when the animals used a population vector to control motion of the cursor. On average we could determine the target in around 35% of the trials. This low percentage was also reflected in poor control of the cursor, so that the animal was unable to reach the target in a large percentage of trials. Supervised adjustment of the population vector parameters produced new weighting

  4. Skin suturing and cortical surface viral infusion improves imaging of neuronal ensemble activity with head-mounted miniature microscopes.

    PubMed

    Li, Xinjian; Cao, Vania Y; Zhang, Wenyu; Mastwal, Surjeet S; Liu, Qing; Otte, Stephani; Wang, Kuan Hong

    2017-08-19

    In vivo optical imaging of neural activity provides important insights into brain functions at the single-cell level. Cranial windows and virally delivered calcium indicators are commonly used for imaging cortical activity through two-photon microscopes in head-fixed animals. Recently, head-mounted one-photon microscopes have been developed for freely behaving animals. However, minimizing tissue damage from the virus injection procedure and maintaining window clarity for imaging can be technically challenging. We used a wide-diameter glass pipette at the cortical surface for infusing the viral calcium reporter AAV-GCaMP6 into the cortex. After infusion, the scalp skin over the implanted optical window was sutured to facilitate postoperative recovery. The sutured scalp was removed approximately two weeks later and a miniature microscope was attached above the window to image neuronal activity in freely moving mice. We found that cortical surface virus infusion efficiently labeled neurons in superficial layers, and scalp skin suturing helped to maintain the long-term clarity of optical windows. As a result, several hundred neurons could be recorded in freely moving animals. Compared to intracortical virus injection and open-scalp postoperative recovery, our methods minimized tissue damage and dura overgrowth underneath the optical window, and significantly increased the experimental success rate and the yield of identified neurons. Our improved cranial surgery technique allows for high-yield calcium imaging of cortical neurons with head-mounted microscopes in freely behaving animals. This technique may be beneficial for other optical applications such as two-photon microscopy, multi-site imaging, and optogenetic modulation. Published by Elsevier B.V.

  5. Biomechanics of Single Cortical Neurons

    PubMed Central

    Bernick, Kristin B.; Prevost, Thibault P.; Suresh, Subra; Socrate, Simona

    2011-01-01

    This study presents experimental results and computational analysis of the large strain dynamic behavior of single neurons in vitro with the objective of formulating a novel quantitative framework for the biomechanics of cortical neurons. Relying on the atomic force microscopy (AFM) technique, novel testing protocols are developed to enable the characterization of neural soma deformability over a range of indentation rates spanning three orders of magnitude – 10, 1, and 0.1 μm/s. Modified spherical AFM probes were utilized to compress the cell bodies of neonatal rat cortical neurons in load, unload, reload and relaxation conditions. The cell response showed marked hysteretic features, strong non-linearities, and substantial time/rate dependencies. The rheological data were complemented with geometrical measurements of cell body morphology, i.e. cross-diameter and height estimates. A constitutive model, validated by the present experiments, is proposed to quantify the mechanical behavior of cortical neurons. The model aimed to correlate empirical findings with measurable degrees of (hyper-) elastic resilience and viscosity at the cell level. The proposed formulation, predicated upon previous constitutive model developments undertaken at the cortical tissue level, was implemented into a three-dimensional finite element framework. The simulated cell response was calibrated to the experimental measurements under the selected test conditions, providing a novel single cell model that could form the basis for further refinements. PMID:20971217

  6. Improving Focal Photostimulation of Cortical Neurons with Pre-derived Wavefront Correction.

    PubMed

    Choy, Julian M C; Sané, Sharmila S; Lee, Woei M; Stricker, Christian; Bachor, Hans A; Daria, Vincent R

    2017-01-01

    Recent progress in neuroscience to image and investigate brain function has been made possible by impressive developments in optogenetic and opto-molecular tools. Such research requires advances in optical techniques for the delivery of light through brain tissue with high spatial resolution. The tissue causes distortions to the wavefront of the incoming light which broadens the focus and consequently reduces the intensity and degrades the resolution. Such effects are detrimental in techniques requiring focal stimulation. Adaptive wavefront correction has been demonstrated to compensate for these distortions. However, iterative derivation of the corrective wavefront introduces time constraints that limit its applicability to probe living cells. Here, we demonstrate that we can pre-determine and generalize a small set of Zernike modes to correct for aberrations of the light propagating through specific brain regions. A priori identification of a corrective wavefront is a direct and fast technique that improves the quality of the focus without the need for iterative adaptive wavefront correction. We verify our technique by measuring the efficiency of two-photon photolysis of caged neurotransmitters along the dendrites of a whole-cell patched neuron. Our results show that encoding the selected Zernike modes on the excitation light can improve light propagation through brain slices of rats as observed by the neuron's evoked excitatory post-synaptic potential in response to localized focal uncaging at the spines of the neuron's dendrites.

  7. Mapping cortical mesoscopic networks of single spiking cortical or sub-cortical neurons.

    PubMed

    Xiao, Dongsheng; Vanni, Matthieu P; Mitelut, Catalin C; Chan, Allen W; LeDue, Jeffrey M; Xie, Yicheng; Chen, Andrew Cn; Swindale, Nicholas V; Murphy, Timothy H

    2017-02-04

    Understanding the basis of brain function requires knowledge of cortical operations over wide-spatial scales, but also within the context of single neurons. In vivo, wide-field GCaMP imaging and sub-cortical/cortical cellular electrophysiology were used in mice to investigate relationships between spontaneous single neuron spiking and mesoscopic cortical activity. We make use of a rich set of cortical activity motifs that are present in spontaneous activity in anesthetized and awake animals. A mesoscale spike-triggered averaging procedure allowed the identification of motifs that are preferentially linked to individual spiking neurons by employing genetically targeted indicators of neuronal activity. Thalamic neurons predicted and reported specific cycles of wide-scale cortical inhibition/excitation. In contrast, spike-triggered maps derived from single cortical neurons yielded spatio-temporal maps expected for regional cortical consensus function. This approach can define network relationships between any point source of neuronal spiking and mesoscale cortical maps.

  8. Cholinergic Neurons Excite Cortically Projecting Basal Forebrain GABAergic Neurons

    PubMed Central

    Yang, Chun; McKenna, James T.; Zant, Janneke C.; Winston, Stuart; Basheer, Radhika

    2014-01-01

    The basal forebrain (BF) plays an important role in the control of cortical activation and attention. Understanding the modulation of BF neuronal activity is a prerequisite to treat disorders of cortical activation involving BF dysfunction, such as Alzheimer's disease. Here we reveal the interaction between cholinergic neurons and cortically projecting BF GABAergic neurons using immunohistochemistry and whole-cell recordings in vitro. In GAD67-GFP knock-in mice, BF cholinergic (choline acetyltransferase-positive) neurons were intermingled with GABAergic (GFP+) neurons. Immunohistochemistry for the vesicular acetylcholine transporter showed that cholinergic fibers apposed putative cortically projecting GABAergic neurons containing parvalbumin (PV). In coronal BF slices from GAD67-GFP knock-in or PV-tdTomato mice, pharmacological activation of cholinergic receptors with bath application of carbachol increased the firing rate of large (>20 μm diameter) BF GFP+ and PV (tdTomato+) neurons, which exhibited the intrinsic membrane properties of cortically projecting neurons. The excitatory effect of carbachol was blocked by antagonists of M1 and M3 muscarinic receptors in two subpopulations of BF GABAergic neurons [large hyperpolarization-activated cation current (Ih) and small Ih, respectively]. Ion substitution experiments and reversal potential measurements suggested that the carbachol-induced inward current was mediated mainly by sodium-permeable cation channels. Carbachol also increased the frequency of spontaneous excitatory and inhibitory synaptic currents. Furthermore, optogenetic stimulation of cholinergic neurons/fibers caused a mecamylamine- and atropine-sensitive inward current in putative GABAergic neurons. Thus, cortically projecting, BF GABAergic/PV neurons are excited by neighboring BF and/or brainstem cholinergic neurons. Loss of cholinergic neurons in Alzheimer's disease may impair cortical activation, in part, through disfacilitation of BF cortically

  9. Mapping cortical mesoscopic networks of single spiking cortical or sub-cortical neurons

    PubMed Central

    Xiao, Dongsheng; Vanni, Matthieu P; Mitelut, Catalin C; Chan, Allen W; LeDue, Jeffrey M; Xie, Yicheng; Chen, Andrew CN; Swindale, Nicholas V; Murphy, Timothy H

    2017-01-01

    Understanding the basis of brain function requires knowledge of cortical operations over wide-spatial scales, but also within the context of single neurons. In vivo, wide-field GCaMP imaging and sub-cortical/cortical cellular electrophysiology were used in mice to investigate relationships between spontaneous single neuron spiking and mesoscopic cortical activity. We make use of a rich set of cortical activity motifs that are present in spontaneous activity in anesthetized and awake animals. A mesoscale spike-triggered averaging procedure allowed the identification of motifs that are preferentially linked to individual spiking neurons by employing genetically targeted indicators of neuronal activity. Thalamic neurons predicted and reported specific cycles of wide-scale cortical inhibition/excitation. In contrast, spike-triggered maps derived from single cortical neurons yielded spatio-temporal maps expected for regional cortical consensus function. This approach can define network relationships between any point source of neuronal spiking and mesoscale cortical maps. DOI: http://dx.doi.org/10.7554/eLife.19976.001 PMID:28160463

  10. Reduced Synaptic Vesicle Recycling during Hypoxia in Cultured Cortical Neurons

    PubMed Central

    Fedorovich, Sergei; Hofmeijer, Jeannette; van Putten, Michel J. A. M.; le Feber, Joost

    2017-01-01

    Improvement of neuronal recovery in the ischemic penumbra, an area around the core of a brain infarct with some remaining perfusion, has a large potential for the development of therapy against acute ischemic stroke. However, mechanisms that lead to either recovery or secondary damage in the penumbra largely remain unclear. Recent studies in cultured networks of cortical neurons showed that failure of synaptic transmission (referred to as synaptic failure) is a critical factor in the penumbral area, but the mechanisms that lead to synaptic failure are still under investigation. Here we used a Styryl dye, FM1-43, to quantify endocytosis and exocytosis in cultures of rat cortical neurons under normoxic and hypoxic conditions. Hypoxia in cultured cortical networks rapidly depressed endocytosis and, to a lesser extent, exocytosis. These findings support electrophysiological findings that synaptic failure occurs quickly after the induction of hypoxia, and confirms that the failing processes are at least in part presynaptic. PMID:28261063

  11. Improving the Post-Stroke Therapeutic Potency of Mesenchymal Multipotent Stromal Cells by Cocultivation With Cortical Neurons: The Role of Crosstalk Between Cells.

    PubMed

    Babenko, Valentina A; Silachev, Denis N; Zorova, Ljubava D; Pevzner, Irina B; Khutornenko, Anastasia A; Plotnikov, Egor Y; Sukhikh, Gennady T; Zorov, Dmitry B

    2015-09-01

    The goal of the present study was to maximally alleviate the negative impact of stroke by increasing the therapeutic potency of injected mesenchymal multipotent stromal cells (MMSCs). To pursue this goal, the intercellular communications of MMSCs and neuronal cells were studied in vitro. As a result of cocultivation of MMSCs and rat cortical neurons, we proved the existence of intercellular contacts providing transfer of cellular contents from one cell to another. We present evidence of intercellular exchange with fluorescent probes specifically occupied by cytosol with preferential transfer from neurons toward MMSCs. In contrast, we observed a reversed transfer of mitochondria (from MMSCs to neural cells). Intravenous injection of MMSCs in a postischemic period alleviated the pathological indexes of a stroke, expressed as a lower infarct volume in the brain and partial restoration of neurological status. Also, MMSCs after cocultivation with neurons demonstrated more profound neuroprotective effects than did unprimed MMSCs. The production of the brain-derived neurotrophic factor was slightly increased in MMSCs, and the factor itself was redistributed in these cells after cocultivation. The level of Miro1 responsible for intercellular traffic of mitochondria was increased in MMSCs after cocultivation. We conclude that the exchange by cellular compartments between neural and stem cells improves MMSCs' protective abilities for better rehabilitation after stroke. This could be used as an approach to enhance the therapeutic benefits of stem cell therapy to the damaged brain. The idea of priming stem cells before practical use for clinical purposes was applied. Thus, cells were preconditioned by coculturing them with the targeted cells (i.e., neurons for the treatment of brain pathological features) before the transfusion of stem cells to the organism. Such priming improved the capacity of stem cells to treat stroke. Some additional minimal study will be required to

  12. Selective adaptation in networks of cortical neurons.

    PubMed

    Eytan, Danny; Brenner, Naama; Marom, Shimon

    2003-10-15

    A key property of neural systems is their ability to adapt selectively to stimuli with different features. Using multisite electrical recordings from networks of cortical neurons developing ex vivo, we show that neurons adapt selectively to different stimuli invading the network. We focus on selective adaptation to frequent and rare stimuli; networks were stimulated at two sites with two different stimulus frequencies. When both stimuli were presented within the same period, neurons in the network attenuated their responsiveness to the more frequent input, whereas their responsiveness to the rarely delivered stimuli showed a marked average increase. The amplification of the response to rare stimuli required the presence of the other, more frequent stimulation source. By contrast, the decreased response to the frequent stimuli occurred regardless of the presence of the rare stimuli. Analysis of the response of single units suggests that both of these effects are caused by changes in synaptic transmission. By using synaptic blockers, we find that the increased responsiveness to the rarely stimulated site depends specifically on fast GABAergic transmission. Thus, excitatory synaptic depression, the inhibitory sub-network, and their balance play an active role in generating selective gain control. The observation that selective adaptation arises naturally in a network of cortical neurons developing ex vivo indicates that this is an inherent feature of spontaneously organizing cortical networks.

  13. Serotonin modulation of cortical neurons and networks.

    PubMed

    Celada, Pau; Puig, M Victoria; Artigas, Francesc

    2013-01-01

    The serotonergic pathways originating in the dorsal and median raphe nuclei (DR and MnR, respectively) are critically involved in cortical function. Serotonin (5-HT), acting on postsynaptic and presynaptic receptors, is involved in cognition, mood, impulse control and motor functions by (1) modulating the activity of different neuronal types, and (2) varying the release of other neurotransmitters, such as glutamate, GABA, acetylcholine and dopamine. Also, 5-HT seems to play an important role in cortical development. Of all cortical regions, the frontal lobe is the area most enriched in serotonergic axons and 5-HT receptors. 5-HT and selective receptor agonists modulate the excitability of cortical neurons and their discharge rate through the activation of several receptor subtypes, of which the 5-HT1A, 5-HT1B, 5-HT2A, and 5-HT3 subtypes play a major role. Little is known, however, on the role of other excitatory receptors moderately expressed in cortical areas, such as 5-HT2C, 5-HT4, 5-HT6, and 5-HT7. In vitro and in vivo studies suggest that 5-HT1A and 5-HT2A receptors are key players and exert opposite effects on the activity of pyramidal neurons in the medial prefrontal cortex (mPFC). The activation of 5-HT1A receptors in mPFC hyperpolarizes pyramidal neurons whereas that of 5-HT2A receptors results in neuronal depolarization, reduction of the afterhyperpolarization and increase of excitatory postsynaptic currents (EPSCs) and of discharge rate. 5-HT can also stimulate excitatory (5-HT2A and 5-HT3) and inhibitory (5-HT1A) receptors in GABA interneurons to modulate synaptic GABA inputs onto pyramidal neurons. Likewise, the pharmacological manipulation of various 5-HT receptors alters oscillatory activity in PFC, suggesting that 5-HT is also involved in the control of cortical network activity. A better understanding of the actions of 5-HT in PFC may help to develop treatments for mood and cognitive disorders associated with an abnormal function of the frontal lobe.

  14. Serotonin modulation of cortical neurons and networks

    PubMed Central

    Celada, Pau; Puig, M. Victoria; Artigas, Francesc

    2013-01-01

    The serotonergic pathways originating in the dorsal and median raphe nuclei (DR and MnR, respectively) are critically involved in cortical function. Serotonin (5-HT), acting on postsynaptic and presynaptic receptors, is involved in cognition, mood, impulse control and motor functions by (1) modulating the activity of different neuronal types, and (2) varying the release of other neurotransmitters, such as glutamate, GABA, acetylcholine and dopamine. Also, 5-HT seems to play an important role in cortical development. Of all cortical regions, the frontal lobe is the area most enriched in serotonergic axons and 5-HT receptors. 5-HT and selective receptor agonists modulate the excitability of cortical neurons and their discharge rate through the activation of several receptor subtypes, of which the 5-HT1A, 5-HT1B, 5-HT2A, and 5-HT3 subtypes play a major role. Little is known, however, on the role of other excitatory receptors moderately expressed in cortical areas, such as 5-HT2C, 5-HT4, 5-HT6, and 5-HT7. In vitro and in vivo studies suggest that 5-HT1A and 5-HT2A receptors are key players and exert opposite effects on the activity of pyramidal neurons in the medial prefrontal cortex (mPFC). The activation of 5-HT1A receptors in mPFC hyperpolarizes pyramidal neurons whereas that of 5-HT2A receptors results in neuronal depolarization, reduction of the afterhyperpolarization and increase of excitatory postsynaptic currents (EPSCs) and of discharge rate. 5-HT can also stimulate excitatory (5-HT2A and 5-HT3) and inhibitory (5-HT1A) receptors in GABA interneurons to modulate synaptic GABA inputs onto pyramidal neurons. Likewise, the pharmacological manipulation of various 5-HT receptors alters oscillatory activity in PFC, suggesting that 5-HT is also involved in the control of cortical network activity. A better understanding of the actions of 5-HT in PFC may help to develop treatments for mood and cognitive disorders associated with an abnormal function of the frontal lobe

  15. High-Degree Neurons Feed Cortical Computations.

    PubMed

    Timme, Nicholas M; Ito, Shinya; Myroshnychenko, Maxym; Nigam, Sunny; Shimono, Masanori; Yeh, Fang-Chin; Hottowy, Pawel; Litke, Alan M; Beggs, John M

    2016-05-01

    Recent work has shown that functional connectivity among cortical neurons is highly varied, with a small percentage of neurons having many more connections than others. Also, recent theoretical developments now make it possible to quantify how neurons modify information from the connections they receive. Therefore, it is now possible to investigate how information modification, or computation, depends on the number of connections a neuron receives (in-degree) or sends out (out-degree). To do this, we recorded the simultaneous spiking activity of hundreds of neurons in cortico-hippocampal slice cultures using a high-density 512-electrode array. This preparation and recording method combination produced large numbers of neurons recorded at temporal and spatial resolutions that are not currently available in any in vivo recording system. We utilized transfer entropy (a well-established method for detecting linear and nonlinear interactions in time series) and the partial information decomposition (a powerful, recently developed tool for dissecting multivariate information processing into distinct parts) to quantify computation between neurons where information flows converged. We found that computations did not occur equally in all neurons throughout the networks. Surprisingly, neurons that computed large amounts of information tended to receive connections from high out-degree neurons. However, the in-degree of a neuron was not related to the amount of information it computed. To gain insight into these findings, we developed a simple feedforward network model. We found that a degree-modified Hebbian wiring rule best reproduced the pattern of computation and degree correlation results seen in the real data. Interestingly, this rule also maximized signal propagation in the presence of network-wide correlations, suggesting a mechanism by which cortex could deal with common random background input. These are the first results to show that the extent to which a neuron

  16. High-Degree Neurons Feed Cortical Computations

    PubMed Central

    Timme, Nicholas M.; Ito, Shinya; Shimono, Masanori; Yeh, Fang-Chin; Litke, Alan M.; Beggs, John M.

    2016-01-01

    Recent work has shown that functional connectivity among cortical neurons is highly varied, with a small percentage of neurons having many more connections than others. Also, recent theoretical developments now make it possible to quantify how neurons modify information from the connections they receive. Therefore, it is now possible to investigate how information modification, or computation, depends on the number of connections a neuron receives (in-degree) or sends out (out-degree). To do this, we recorded the simultaneous spiking activity of hundreds of neurons in cortico-hippocampal slice cultures using a high-density 512-electrode array. This preparation and recording method combination produced large numbers of neurons recorded at temporal and spatial resolutions that are not currently available in any in vivo recording system. We utilized transfer entropy (a well-established method for detecting linear and nonlinear interactions in time series) and the partial information decomposition (a powerful, recently developed tool for dissecting multivariate information processing into distinct parts) to quantify computation between neurons where information flows converged. We found that computations did not occur equally in all neurons throughout the networks. Surprisingly, neurons that computed large amounts of information tended to receive connections from high out-degree neurons. However, the in-degree of a neuron was not related to the amount of information it computed. To gain insight into these findings, we developed a simple feedforward network model. We found that a degree-modified Hebbian wiring rule best reproduced the pattern of computation and degree correlation results seen in the real data. Interestingly, this rule also maximized signal propagation in the presence of network-wide correlations, suggesting a mechanism by which cortex could deal with common random background input. These are the first results to show that the extent to which a neuron

  17. Properties of persistent postnatal cortical subplate neurons.

    PubMed

    Torres-Reveron, Juan; Friedlander, Michael J

    2007-09-12

    Subplate (SP) neurons are important for the proper development of thalamocortical innervation. They are necessary for formation of ocular dominance and orientation columns in visual cortex. During the perinatal period, many SP neurons die. The surviving cohort forms interstitial cells in the white matter (WM) and a band of horizontally oriented cells below layer VI (layer VIb, layer VII, or subplate cells). Although the function of embryonic SP neurons has been well established, the functional roles of WM and postnatal SP cells are not known. We used a combination of anatomical, immunohistochemical, and electrophysiological techniques to explore the dendritic morphology, neurotransmitter phenotype, intrinsic electrophysiological, and synaptic input properties of these surviving cells in the rat visual cortex. The density of SP and WM cells significantly decreases during the first month of life. Both populations express neuronal markers and have extensive dendritic arborizations within the SP, WM, and to the overlying visual cortex. Some intrinsic electrophysiological properties of SP and WM cells are similar: each generates high-frequency slowly adapting trains of action potentials in response to a sustained depolarization. However, SP cells exhibit greater frequency-dependent action potential broadening than WM neurons. Both cell types receive predominantly AMPA/kainate receptor-mediated excitatory synaptic input that undergoes paired-pulse facilitation as well as NMDA receptor and GABAergic input. Synaptic inputs to these cells can also undergo long-term synaptic plasticity. Thus, surviving SP and WM cells are functional electrogenic neurons integrated within the postnatal visual cortical circuit.

  18. Tunable Neuromimetic Integrated System for Emulating Cortical Neuron Models

    PubMed Central

    Grassia, Filippo; Buhry, Laure; Lévi, Timothée; Tomas, Jean; Destexhe, Alain; Saïghi, Sylvain

    2011-01-01

    Nowadays, many software solutions are currently available for simulating neuron models. Less conventional than software-based systems, hardware-based solutions generally combine digital and analog forms of computation. In previous work, we designed several neuromimetic chips, including the Galway chip that we used for this paper. These silicon neurons are based on the Hodgkin–Huxley formalism and they are optimized for reproducing a large variety of neuron behaviors thanks to tunable parameters. Due to process variation and device mismatch in analog chips, we use a full-custom fitting method in voltage-clamp mode to tune our neuromimetic integrated circuits. By comparing them with experimental electrophysiological data of these cells, we show that the circuits can reproduce the main firing features of cortical cell types. In this paper, we present the experimental measurements of our system which mimic the four most prominent biological cells: fast spiking, regular spiking, intrinsically bursting, and low-threshold spiking neurons into analog neuromimetic integrated circuit dedicated to cortical neuron simulations. This hardware and software platform will allow to improve the hybrid technique, also called “dynamic-clamp,” that consists of connecting artificial and biological neurons to study the function of neuronal circuits. PMID:22163213

  19. Subplate Neurons: Crucial Regulators of Cortical Development and Plasticity

    PubMed Central

    Kanold, Patrick O.

    2009-01-01

    The developing cerebral cortex contains a distinct class of cells, subplate neurons, which form one of the first functional cortical circuits. Subplate neurons reside in the cortical white matter, receive thalamic inputs and project into the developing cortical plate, mostly to layer 4. Subplate neurons are present at key time points during development. Removal of subplate neurons profoundly affects cortical development. Subplate removal in visual cortex prevents the maturation of thalamocortical synapse, the maturation of inhibition in layer 4, the development of orientation selective responses in individual cortical neurons, and the formation of ocular dominance columns. In addition, monocular deprivation during development reveals that ocular dominance plasticity is paradoxical in the absence of subplate neurons. Because subplate neurons projecting to layer 4 are glutamatergic, these diverse deficits following subplate removal were hypothesized to be due to lack of feed-forward thalamic driven cortical excitation. A computational model of the developing thalamocortical pathway incorporating feed-forward excitatory subplate projections replicates both normal development and plasticity of ocular dominance as well as the effects of subplate removal. Therefore, we postulate that feed-forward excitatory projections from subplate neurons into the developing cortical plate enhance correlated activity between thalamus and layer 4 and, in concert with Hebbian learning rules in layer 4, allow maturational and plastic processes in layer 4 to commence. Thus subplate neurons are a crucial regulator of cortical development and plasticity, and damage to these neurons might play a role in the pathology of many neurodevelopmental disorders. PMID:19738926

  20. In vivo multiphoton nanosurgery on cortical neurons.

    PubMed

    Sacconi, Leonardo; O'Connor, Rodney P; Jasaitis, Audrius; Masi, Alessio; Buffelli, Mario; Pavone, Francesco S

    2007-01-01

    Two-photon microscopy has been used to perform high spatial resolution imaging of spine plasticity in the intact neocortex of living mice. Multiphoton absorption has also been used as a tool for the selective disruption of cellular structures in living cells and simple organisms. In this work, we exploit the spatial localization of multiphoton excitation to perform selective lesions on the neuronal processes of cortical neurons in living mice expressing fluorescent proteins. Neurons are irradiated with a focused, controlled dose of femtosecond laser energy delivered through cranial optical windows. The morphological consequences are then characterized with time lapse 3-D two-photon imaging over a period of minutes to days after the procedure. This methodology is applied to dissect single dendrites with submicrometric precision without causing any visible collateral damage to the surrounding neuronal structures. The spatial precision of this method is demonstrated by ablating individual dendritic spines, while sparing the adjacent spines and the structural integrity of the dendrite. The combination of multiphoton nanosurgery and in vivo imaging in mammals represents a promising tool for neurobiology and neuropharmacology research.

  1. Cooperative nonlinearities in auditory cortical neurons.

    PubMed

    Atencio, Craig A; Sharpee, Tatyana O; Schreiner, Christoph E

    2008-06-26

    Cortical receptive fields represent the signal preferences of sensory neurons. Receptive fields are thought to provide a representation of sensory experience from which the cerebral cortex may make interpretations. While it is essential to determine a neuron's receptive field, it remains unclear which features of the acoustic environment are specifically represented by neurons in the primary auditory cortex (AI). We characterized cat AI spectrotemporal receptive fields (STRFs) by finding both the spike-triggered average (STA) and stimulus dimensions that maximized the mutual information between response and stimulus. We derived a nonlinearity relating spiking to stimulus projection onto two maximally informative dimensions (MIDs). The STA was highly correlated with the first MID. Generally, the nonlinearity for the first MID was asymmetric and often monotonic in shape, while the second MID nonlinearity was symmetric and nonmonotonic. The joint nonlinearity for both MIDs revealed that most first and second MIDs were synergistic and thus should be considered conjointly. The difference between the nonlinearities suggests different possible roles for the MIDs in auditory processing.

  2. Cooperative Nonlinearities in Auditory Cortical Neurons

    PubMed Central

    Atencio, Craig A.; Sharpee, Tatyana O.; Schreiner, Christoph E.

    2008-01-01

    SUMMARY Cortical receptive fields represent the signal preferences of sensory neurons. Receptive fields are thought to provide a representation of sensory experience from which the cerebral cortex may make interpretations. While it is essential to determine a neuron’s receptive field, it remains unclear which features of the acoustic environment are specifically represented by neurons in the primary auditory cortex (AI). We characterized cat AI spectrotemporal receptive fields (STRFs) by finding both the spike-triggered average (STA) and stimulus dimensions that maximized the mutual information between response and stimulus. We derived a nonlinearity relating spiking to stimulus projection onto two maximally informative dimensions (MIDs). The STA was highly correlated with the first MID. Generally, the nonlinearity for the first MID was asymmetric and often monotonic in shape, while the second MID nonlinearity was symmetric and non-monotonic. The joint nonlinearity for both MIDs revealed that most first and second MIDs were synergistic, and thus should be considered conjointly. The difference between the nonlinearities suggests different possible roles for the MIDs in auditory processing. PMID:18579084

  3. Liver X receptor-β improves autism symptoms via downregulation of β-amyloid expression in cortical neurons.

    PubMed

    Zhang, Ji-Xiang; Zhang, Jun; Li, Ye

    2016-05-06

    We study the effect of liver X receptor β (LXRβ) on β-amyloid (Aβ) peptide generation and autism behaviors by conducting an animal experiment. In autistic mice treated with LXRβ agonist T0901317, enzyme linked immunosorbent assay was used to measure Aβ in brain tissue homogenates. Western blot was used to detect Aβ precursors, Aβ degradation and secretase enzymes, and expression of autophagy-related proteins and Ras/Raf/Erkl/2 signaling pathway proteins in brain tissue. Changes in autism spectrum disorder syndromes of the BTBR mice were compared before and after T0901317 treatment. Compared with the control group, autistic mice treated with LXRβ agonist T0901317 showed significantly lower Aβ level in brain tissue (P < 0.05), significantly higher Aβ degradation enzyme (NEP, IDE proteins) levels (all P < 0.05), significantly lower Aβ secretase enzyme BACE1 protein level (P < 0.05), and significantly lower Ras, P-C-Raf, C-Raf, P-Mekl/2, P-Erkl/2 protein levels (all P < 0.05). BTBR mice treated with T0901317 showed improvements in repetitive stereotyped behavior, inactivity, wall-facing standing time, self-combing time and center stay time, stayed longer in platform quadrant, and crossed the platform more frequently (all P < 0.05). LXRβ could potentially reduce brain Aβ generation by inhibiting Aβ production and promoting Aβ degradation, thereby increasing the expression of autophagy-related proteins, reducing Ras/Raf/Erkl/2 signaling pathway proteins, and improving autism behaviors.

  4. Quantitative analysis of cortical pyramidal neurons after corpus callosotomy.

    PubMed

    Jacobs, Bob; Creswell, Johanna; Britt, Jonathan P; Ford, Kevin L; Bogen, Joseph E; Zaidel, Eran

    2003-07-01

    This study quantitatively explored the dendritic/spine extent of supragranular pyramidal neurons across several cortical areas in two adult male subjects who had undergone a callosotomy several decades before death. In all cortical areas, there were numerous atypical, supragranular pyramidal neurons with elongated "tap root" basilar dendrites. These atypical cells could be associated with an underlying epileptic condition and/or could represent a compensatory mechanism in response to deafferentation after callosotomy.

  5. Neuronal cell sheet of cortical motor neuron phenotype derived from human iPS cells.

    PubMed

    Suzuki, Noboru; Arimitsu, Nagisa; Shimizu, Jun; Takai, Kenji; Hirotsu, Chieko; Takada, Erika; Ueda, Yuji; Wakisaka, Sueshige; Fujiwara, Naruyoshi; Suzuki, Tomoko

    2017-03-17

    Transplantation of stem cells which differentiate into more mature neural cells brings about functional improvement in pre-clinical studies of stroke. Previous transplant approaches in diseased brain have utilized injection of the cells in a cell suspension. In addition, neural stem cells were preferentially used as graft. However, these cells had no specific relationship to the damaged tissue of stroke patients and brain injury. The injection of cells in a suspension destroyed the cell-cell interactions that are suggested to be important for promoting functional integrity as cortical motor neurons.

    In order to obtain suitable cell types for grafting patients with stroke and brain damage, we have modified a protocol for differentiating human iPS cells to cells phenotypically related to cortical motor neurons. Moreover, we applied cell sheet technology to neural cell transplantation due to the idea in which keeping cell-cell communications was regarded as important for the repair of host brain architecture.

    Accordingly, we developed neuronal cell sheets being positive for FEZ family zinc finger 2 (Fezf2), COUP-TF-interacting protein 2 (CTIP2), insulin-like growth factor-binding protein 4 (Igfbp4), cysteine-rich motor neuron 1 protein precursor (CRIM1) and forkhead box p2 (Foxp2). These markers are associated with cortical motoneuron which is appropriate for the transplant location in the lesions. The sheets allowed preservation of cell-cell interactions shown by synapsin1 staining after transplantation to damaged mouse brain. The sheet transplantation brought about structural restoration partly and improvement of motor functions in hemiplegic mice.

    Collectively, the cell sheets were transplanted to damaged motor cortex in a way of a novel neuronal cell sheet that maintained cell-cell interactions and improved motor functions of the hemiplegic model mice. The motoneuron cell sheets are possibly applicable for stroke patients and patients with

  6. Secretory function in subplate neurons during cortical development

    PubMed Central

    Kondo, Shinichi; Al-Hasani, Hannah; Hoerder-Suabedissen, Anna; Wang, Wei Zhi; Molnár, Zoltán

    2015-01-01

    Subplate cells are among the first generated neurons in the mammalian cerebral cortex and have been implicated in the establishment of cortical wiring. In rodents some subplate neurons persist into adulthood. Here we would like to highlight several converging findings which suggest a novel secretory function of subplate neurons during cortical development. Throughout the postnatal period in rodents, subplate neurons have highly developed rough endoplasmic reticulum (ER) and are under an ER stress condition. By comparing gene expression between subplate and layer 6, we found that several genes encoding secreted proteins are highly expressed in subplate neurons. One of these secreted proteins, neuroserpin, encoded by the serpini1 gene, is localized to the ER in subplate cells. We propose that subplate might influence cortical circuit formation through a transient secretory function. PMID:25859180

  7. Probabilistic Identification of Cerebellar Cortical Neurones across Species

    PubMed Central

    Van Dijck, Gert; Van Hulle, Marc M.; Heiney, Shane A.; Blazquez, Pablo M.; Meng, Hui; Angelaki, Dora E.; Arenz, Alexander; Margrie, Troy W.; Mostofi, Abteen; Edgley, Steve; Bengtsson, Fredrik; Ekerot, Carl-Fredrik; Jörntell, Henrik; Dalley, Jeffrey W.; Holtzman, Tahl

    2013-01-01

    Despite our fine-grain anatomical knowledge of the cerebellar cortex, electrophysiological studies of circuit information processing over the last fifty years have been hampered by the difficulty of reliably assigning signals to identified cell types. We approached this problem by assessing the spontaneous activity signatures of identified cerebellar cortical neurones. A range of statistics describing firing frequency and irregularity were then used, individually and in combination, to build Gaussian Process Classifiers (GPC) leading to a probabilistic classification of each neurone type and the computation of equi-probable decision boundaries between cell classes. Firing frequency statistics were useful for separating Purkinje cells from granular layer units, whilst firing irregularity measures proved most useful for distinguishing cells within granular layer cell classes. Considered as single statistics, we achieved classification accuracies of 72.5% and 92.7% for granular layer and molecular layer units respectively. Combining statistics to form twin-variate GPC models substantially improved classification accuracies with the combination of mean spike frequency and log-interval entropy offering classification accuracies of 92.7% and 99.2% for our molecular and granular layer models, respectively. A cross-species comparison was performed, using data drawn from anaesthetised mice and decerebrate cats, where our models offered 80% and 100% classification accuracy. We then used our models to assess non-identified data from awake monkeys and rabbits in order to highlight subsets of neurones with the greatest degree of similarity to identified cell classes. In this way, our GPC-based approach for tentatively identifying neurones from their spontaneous activity signatures, in the absence of an established ground-truth, nonetheless affords the experimenter a statistically robust means of grouping cells with properties matching known cell classes. Our approach therefore

  8. Hyaluronan synthesis by developing cortical neurons in vitro

    PubMed Central

    Fowke, Tania M.; Karunasinghe, Rashika N.; Bai, Ji-Zhong; Jordan, Shawn; Gunn, Alistair J.; Dean, Justin M.

    2017-01-01

    Hyaluronan is a linear glycosaminoglycan that forms the backbone of perineuronal nets around neurons in the cerebral cortex. However, it remains controversial whether neurons are capable of independent hyaluronan synthesis. Herein, we examined the expression of hyaluronan and hyaluronan synthases (HASs) throughout cortical neuron development in vitro. Enriched cultures of cortical neurons were established from E16 rats. Neurons were collected at days in vitro (DIV) 0 (4 h), 1, 3, 7, 14, and 21 for qPCR or immunocytochemistry. In the relative absence of glia, neurons exhibited HAS1–3 mRNA at all time-points. By immunocytochemistry, puncta of HAS2–3 protein and hyaluronan were located on neuronal cell bodies, neurites, and lamellipodia/growth cones from as early as 4 h in culture. As neurons matured, hyaluronan was also detected on dendrites, filopodia, and axons, and around synapses. Percentages of hyaluronan-positive neurons increased with culture time to ~93% by DIV21, while only half of neurons at DIV21 expressed the perineuronal net marker Wisteria floribunda agglutinin. These data clearly demonstrate that neurons in vitro can independently synthesise hyaluronan throughout all maturational stages, and that hyaluronan production is not limited to neurons expressing perineuronal nets. The specific structural localisation of hyaluronan suggests potential roles in neuronal development and function. PMID:28287145

  9. Pyramidal Neurons Are Not Generalizable Building Blocks of Cortical Networks

    PubMed Central

    Luebke, Jennifer I.

    2017-01-01

    A key challenge in cortical neuroscience is to gain a comprehensive understanding of how pyramidal neuron heterogeneity across different areas and species underlies the functional specialization of individual neurons, networks, and areas. Comparative studies have been important in this endeavor, providing data relevant to the question of which of the many inherent properties of individual pyramidal neurons are necessary and sufficient for species-specific network and areal function. In this mini review, the importance of pyramidal neuron structural properties for signaling are outlined, followed by a summary of our recent work comparing the structural features of mouse (C57/BL6 strain) and rhesus monkey layer 3 (L3) pyramidal neurons in primary visual and frontal association cortices and their implications for neuronal and areal function. Based on these and other published data, L3 pyramidal neurons plausibly might be considered broadly “generalizable” from one area to another in the mouse neocortex due to their many similarities, but major differences in the properties of these neurons in diverse areas in the rhesus monkey neocortex rules this out in the primate. Further, fundamental differences in the dendritic topology of mouse and rhesus monkey pyramidal neurons highlight the implausibility of straightforward scaling and/or extrapolation from mouse to primate neurons and cortical networks. PMID:28326020

  10. Effects of Morphology Constraint on Electrophysiological Properties of Cortical Neurons

    NASA Astrophysics Data System (ADS)

    Zhu, Geng; Du, Liping; Jin, Lei; Offenhäusser, Andreas

    2016-04-01

    There is growing interest in engineering nerve cells in vitro to control architecture and connectivity of cultured neuronal networks or to build neuronal networks with predictable computational function. Pattern technologies, such as micro-contact printing, have been developed to design ordered neuronal networks. However, electrophysiological characteristics of the single patterned neuron haven’t been reported. Here, micro-contact printing, using polyolefine polymer (POP) stamps with high resolution, was employed to grow cortical neurons in a designed structure. The results demonstrated that the morphology of patterned neurons was well constrained, and the number of dendrites was decreased to be about 2. Our electrophysiological results showed that alterations of dendritic morphology affected firing patterns of neurons and neural excitability. When stimulated by current, though both patterned and un-patterned neurons presented regular spiking, the dynamics and strength of the response were different. The un-patterned neurons exhibited a monotonically increasing firing frequency in response to injected current, while the patterned neurons first exhibited frequency increase and then a slow decrease. Our findings indicate that the decrease in dendritic complexity of cortical neurons will influence their electrophysiological characteristics and alter their information processing activity, which could be considered when designing neuronal circuitries.

  11. Effects of Morphology Constraint on Electrophysiological Properties of Cortical Neurons.

    PubMed

    Zhu, Geng; Du, Liping; Jin, Lei; Offenhäusser, Andreas

    2016-04-07

    There is growing interest in engineering nerve cells in vitro to control architecture and connectivity of cultured neuronal networks or to build neuronal networks with predictable computational function. Pattern technologies, such as micro-contact printing, have been developed to design ordered neuronal networks. However, electrophysiological characteristics of the single patterned neuron haven't been reported. Here, micro-contact printing, using polyolefine polymer (POP) stamps with high resolution, was employed to grow cortical neurons in a designed structure. The results demonstrated that the morphology of patterned neurons was well constrained, and the number of dendrites was decreased to be about 2. Our electrophysiological results showed that alterations of dendritic morphology affected firing patterns of neurons and neural excitability. When stimulated by current, though both patterned and un-patterned neurons presented regular spiking, the dynamics and strength of the response were different. The un-patterned neurons exhibited a monotonically increasing firing frequency in response to injected current, while the patterned neurons first exhibited frequency increase and then a slow decrease. Our findings indicate that the decrease in dendritic complexity of cortical neurons will influence their electrophysiological characteristics and alter their information processing activity, which could be considered when designing neuronal circuitries.

  12. Cortically projecting basal forebrain parvalbumin neurons regulate cortical gamma band oscillations.

    PubMed

    Kim, Tae; Thankachan, Stephen; McKenna, James T; McNally, James M; Yang, Chun; Choi, Jee Hyun; Chen, Lichao; Kocsis, Bernat; Deisseroth, Karl; Strecker, Robert E; Basheer, Radhika; Brown, Ritchie E; McCarley, Robert W

    2015-03-17

    Cortical gamma band oscillations (GBO, 30-80 Hz, typically ∼40 Hz) are involved in higher cognitive functions such as feature binding, attention, and working memory. GBO abnormalities are a feature of several neuropsychiatric disorders associated with dysfunction of cortical fast-spiking interneurons containing the calcium-binding protein parvalbumin (PV). GBO vary according to the state of arousal, are modulated by attention, and are correlated with conscious awareness. However, the subcortical cell types underlying the state-dependent control of GBO are not well understood. Here we tested the role of one cell type in the wakefulness-promoting basal forebrain (BF) region, cortically projecting GABAergic neurons containing PV, whose virally transduced fibers we found apposed cortical PV interneurons involved in generating GBO. Optogenetic stimulation of BF PV neurons in mice preferentially increased cortical GBO power by entraining a cortical oscillator with a resonant frequency of ∼40 Hz, as revealed by analysis of both rhythmic and nonrhythmic BF PV stimulation. Selective saporin lesions of BF cholinergic neurons did not alter the enhancement of cortical GBO power induced by BF PV stimulation. Importantly, bilateral optogenetic inhibition of BF PV neurons decreased the power of the 40-Hz auditory steady-state response, a read-out of the ability of the cortex to generate GBO used in clinical studies. Our results are surprising and novel in indicating that this presumptively inhibitory BF PV input controls cortical GBO, likely by synchronizing the activity of cortical PV interneurons. BF PV neurons may represent a previously unidentified therapeutic target to treat disorders involving abnormal GBO, such as schizophrenia.

  13. Unique features of action potential initiation in cortical neurons.

    PubMed

    Naundorf, Björn; Wolf, Fred; Volgushev, Maxim

    2006-04-20

    Neurons process and encode information by generating sequences of action potentials. For all spiking neurons, the encoding of single-neuron computations into sequences of spikes is biophysically determined by the cell's action-potential-generating mechanism. It has recently been discovered that apparently minor modifications of this mechanism can qualitatively change the nature of neuronal encoding. Here we quantitatively analyse the dynamics of action potential initiation in cortical neurons in vivo, in vitro and in computational models. Unexpectedly, key features of the initiation dynamics of cortical neuron action potentials--their rapid initiation and variable onset potential--are outside the range of behaviours described by the classical Hodgkin-Huxley theory. We propose a new model based on the cooperative activation of sodium channels that reproduces the observed dynamics of action potential initiation. This new model predicts that Hodgkin-Huxley-type dynamics of action potential initiation can be induced by artificially decreasing the effective density of sodium channels. In vitro experiments confirm this prediction, supporting the hypothesis that cooperative sodium channel activation underlies the dynamics of action potential initiation in cortical neurons.

  14. Cortical neurons gradually attain a post-mitotic state

    PubMed Central

    Anda, Froylan Calderon de; Madabhushi, Ram; Rei, Damien; Meng, Jia; Gräff, Johannes; Durak, Omer; Meletis, Konstantinos; Richter, Melanie; Schwanke, Birgit; Mungenast, Alison; Tsai, Li-Huei

    2016-01-01

    Once generated, neurons are thought to permanently exit the cell cycle and become irreversibly differentiated. However, neither the precise point at which this post-mitotic state is attained nor the extent of its irreversibility is clearly defined. Here we report that newly born neurons from the upper layers of the mouse cortex, despite initiating axon and dendrite elongation, continue to drive gene expression from the neural progenitor tubulin α1 promoter (Tα1p). These observations suggest an ambiguous post-mitotic neuronal state. Whole transcriptome analysis of sorted upper cortical neurons further revealed that neurons continue to express genes related to cell cycle progression long after mitotic exit until at least post-natal day 3 (P3). These genes are however down-regulated thereafter, associated with a concomitant up-regulation of tumor suppressors at P5. Interestingly, newly born neurons located in the cortical plate (CP) at embryonic day 18-19 (E18-E19) and P3 challenged with calcium influx are found in S/G2/M phases of the cell cycle, and still able to undergo division at E18-E19 but not at P3. At P5 however, calcium influx becomes neurotoxic and leads instead to neuronal loss. Our data delineate an unexpected flexibility of cell cycle control in early born neurons, and describe how neurons transit to a post-mitotic state. PMID:27325298

  15. Cortical neurons gradually attain a post-mitotic state.

    PubMed

    Anda, Froylan Calderon de; Madabhushi, Ram; Rei, Damien; Meng, Jia; Gräff, Johannes; Durak, Omer; Meletis, Konstantinos; Richter, Melanie; Schwanke, Birgit; Mungenast, Alison; Tsai, Li-Huei

    2016-09-01

    Once generated, neurons are thought to permanently exit the cell cycle and become irreversibly differentiated. However, neither the precise point at which this post-mitotic state is attained nor the extent of its irreversibility is clearly defined. Here we report that newly born neurons from the upper layers of the mouse cortex, despite initiating axon and dendrite elongation, continue to drive gene expression from the neural progenitor tubulin α1 promoter (Tα1p). These observations suggest an ambiguous post-mitotic neuronal state. Whole transcriptome analysis of sorted upper cortical neurons further revealed that neurons continue to express genes related to cell cycle progression long after mitotic exit until at least post-natal day 3 (P3). These genes are however down-regulated thereafter, associated with a concomitant up-regulation of tumor suppressors at P5. Interestingly, newly born neurons located in the cortical plate (CP) at embryonic day 18-19 (E18-E19) and P3 challenged with calcium influx are found in S/G2/M phases of the cell cycle, and still able to undergo division at E18-E19 but not at P3. At P5 however, calcium influx becomes neurotoxic and leads instead to neuronal loss. Our data delineate an unexpected flexibility of cell cycle control in early born neurons, and describe how neurons transit to a post-mitotic state.

  16. Targeting RPTPσ with lentiviral shRNA promotes neurites outgrowth of cortical neurons and improves functional recovery in a rat spinal cord contusion model.

    PubMed

    Zhou, Heng-Xing; Li, Xue-Ying; Li, Fu-Yuan; Liu, Chang; Liang, Zhi-Pin; Liu, Shen; Zhang, Bin; Wang, Tian-Yi; Chu, Tian-Ci; Lu, Lu; Ning, Guang-Zhi; Kong, Xiao-Hong; Feng, Shi-Qing

    2014-10-24

    After spinal cord injury (SCI), the rapidly upregulated chondroitin sulfate proteoglycans (CSPGs), the prominent chemical constituents and main repulsive factors of the glial scar, play an important role in the extremely limited ability to regenerate in adult mammals. Although many methods to overcome the inhibition have been tested, no successful method with clinical feasibility has been devised to date. It was recently discovered that receptor protein tyrosine phosphatase sigma (RPTPσ) is a functional receptor for CSPGs-mediated inhibition. In view of the potential clinical application of RNA interference (RNAi), here we investigated whether silencing RPTPσ via lentivirus-mediated RNA interference can promote axon regeneration and functional recovery after SCI. Neurites of primary rat cerebral cortical neurons with depleted RPTPσ exhibited a significant enhancement in elongation and crossing ability when they encountered CSPGs in vitro. A contusion model of spinal cord injury in Wistar rats (the New York University (NYU) impactor) was used for in vivo experiments. Local injection of lentivirus encoding RPTPσ shRNA at the lesion site promoted axon regeneration and synapse formation, but did not affect the scar formation. Meanwhile, in vivo functional recovery (motor and sensory) was also enhanced after RPTPσ depletion. Therefore, strategies directed at silencing RPTPσ by RNAi may prove to be a beneficial, efficient and valuable approach for the treatment of SCI. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Electrical Interactions Between Mammalian Cortical Neurons

    DTIC Science & Technology

    1988-09-28

    nuclei. Kynurenic acid and Dtf-glutamylglycine (broad-spectrum EAA antagonists) reduced EPSPs in supraoptic neurons, while N-methyl-D-aspartate (NMDA...antagonists had relatively little effect on EPSPs . Other studies showed that kynurenic acid had dose-dependent effects on EPSPs of at least two types of...The primary method has been to examine the effects of EAA antagonists on EPSPs of hypothalamic neurons. Finally, another objective is to ascertain

  18. Early phenotype expression of cortical neurons: Evidence that a subclass of migrating neurons have callosal axons

    SciTech Connect

    Schwartz, M.L.; Rakic, P.; Goldman-Rakic, P.S. )

    1991-02-15

    The use of ({sup 3}H)thymidine labeling in combination with various axonal transport tracers has revealed that a subset of migrating neurons in the fetal monkey cerebrum issue axons to the opposite cerebral hemisphere while still migrating to their final positions in the cortical plate. Other cortical neurons with the same birthdate (i.e., that underwent their last round of DNA synthesis on the same day) are not retrogradely labeled by tracer injections of the opposite hemisphere. These findings suggest that the cardinal distinction between projection and local circuit neurons may be specified in postmitotic neurons before they acquire their final positions in the cortex.

  19. Control of cortical neuronal migration by glutamate and GABA

    PubMed Central

    Luhmann, Heiko J.; Fukuda, A.; Kilb, W.

    2015-01-01

    Neuronal migration in the cortex is controlled by the paracrine action of the classical neurotransmitters glutamate and GABA. Glutamate controls radial migration of pyramidal neurons by acting primarily on NMDA receptors and regulates tangential migration of inhibitory interneurons by activating non-NMDA and NMDA receptors. GABA, acting on ionotropic GABAA-rho and GABAA receptors, has a dichotomic action on radially migrating neurons by acting as a GO signal in lower layers and as a STOP signal in upper cortical plate (CP), respectively. Metabotropic GABAB receptors promote radial migration into the CP and tangential migration of interneurons. Besides GABA, the endogenous GABAergic agonist taurine is a relevant agonist controlling radial migration. To a smaller extent glycine receptor activation can also influence radial and tangential migration. Activation of glutamate and GABA receptors causes increases in intracellular Ca2+ transients, which promote neuronal migration by acting on the cytoskeleton. Pharmacological or genetic manipulation of glutamate or GABA receptors during early corticogenesis induce heterotopic cell clusters in upper layers and loss of cortical lamination, i.e., neuronal migration disorders which can be associated with neurological or neuropsychiatric diseases. The pivotal role of NMDA and ionotropic GABA receptors in cortical neuronal migration is of major clinical relevance, since a number of drugs acting on these receptors (e.g., anti-epileptics, anesthetics, alcohol) may disturb the normal migration pattern when present during early corticogenesis. PMID:25688185

  20. Control of cortical neuronal migration by glutamate and GABA.

    PubMed

    Luhmann, Heiko J; Fukuda, A; Kilb, W

    2015-01-01

    Neuronal migration in the cortex is controlled by the paracrine action of the classical neurotransmitters glutamate and GABA. Glutamate controls radial migration of pyramidal neurons by acting primarily on NMDA receptors and regulates tangential migration of inhibitory interneurons by activating non-NMDA and NMDA receptors. GABA, acting on ionotropic GABAA-rho and GABAA receptors, has a dichotomic action on radially migrating neurons by acting as a GO signal in lower layers and as a STOP signal in upper cortical plate (CP), respectively. Metabotropic GABAB receptors promote radial migration into the CP and tangential migration of interneurons. Besides GABA, the endogenous GABAergic agonist taurine is a relevant agonist controlling radial migration. To a smaller extent glycine receptor activation can also influence radial and tangential migration. Activation of glutamate and GABA receptors causes increases in intracellular Ca(2+) transients, which promote neuronal migration by acting on the cytoskeleton. Pharmacological or genetic manipulation of glutamate or GABA receptors during early corticogenesis induce heterotopic cell clusters in upper layers and loss of cortical lamination, i.e., neuronal migration disorders which can be associated with neurological or neuropsychiatric diseases. The pivotal role of NMDA and ionotropic GABA receptors in cortical neuronal migration is of major clinical relevance, since a number of drugs acting on these receptors (e.g., anti-epileptics, anesthetics, alcohol) may disturb the normal migration pattern when present during early corticogenesis.

  1. Visual experience without lines: effect on developing cortical neurons.

    PubMed

    Pettigrew, J D; Freeman, R D

    1973-11-09

    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.

  2. Cortical cell and neuron density estimates in one chimpanzee hemisphere.

    PubMed

    Collins, Christine E; Turner, Emily C; Sawyer, Eva Kille; Reed, Jamie L; Young, Nicole A; Flaherty, David K; Kaas, Jon H

    2016-01-19

    The density of cells and neurons in the neocortex of many mammals varies across cortical areas and regions. This variability is, perhaps, most pronounced in primates. Nonuniformity in the composition of cortex suggests regions of the cortex have different specializations. Specifically, regions with densely packed neurons contain smaller neurons that are activated by relatively few inputs, thereby preserving information, whereas regions that are less densely packed have larger neurons that have more integrative functions. Here we present the numbers of cells and neurons for 742 discrete locations across the neocortex in a chimpanzee. Using isotropic fractionation and flow fractionation methods for cell and neuron counts, we estimate that neocortex of one hemisphere contains 9.5 billion cells and 3.7 billion neurons. Primary visual cortex occupies 35 cm(2) of surface, 10% of the total, and contains 737 million densely packed neurons, 20% of the total neurons contained within the hemisphere. Other areas of high neuron packing include secondary visual areas, somatosensory cortex, and prefrontal granular cortex. Areas of low levels of neuron packing density include motor and premotor cortex. These values reflect those obtained from more limited samples of cortex in humans and other primates.

  3. Rich-Club Organization in Effective Connectivity among Cortical Neurons

    PubMed Central

    Shimono, Masanori; Ito, Shinya; Yeh, Fang-Chin; Timme, Nicholas; Myroshnychenko, Maxym; Lapish, Christopher C.; Tosi, Zachary; Hottowy, Pawel; Smith, Wesley C.; Masmanidis, Sotiris C.; Litke, Alan M.; Sporns, Olaf; Beggs, John M.

    2016-01-01

    The performance of complex networks, like the brain, depends on how effectively their elements communicate. Despite the importance of communication, it is virtually unknown how information is transferred in local cortical networks, consisting of hundreds of closely spaced neurons. To address this, it is important to record simultaneously from hundreds of neurons at a spacing that matches typical axonal connection distances, and at a temporal resolution that matches synaptic delays. We used a 512-electrode array (60 μm spacing) to record spontaneous activity at 20 kHz from up to 500 neurons simultaneously in slice cultures of mouse somatosensory cortex for 1 h at a time. We applied a previously validated version of transfer entropy to quantify information transfer. Similar to in vivo reports, we found an approximately lognormal distribution of firing rates. Pairwise information transfer strengths also were nearly lognormally distributed, similar to reports of synaptic strengths. Some neurons transferred and received much more information than others, which is consistent with previous predictions. Neurons with the highest outgoing and incoming information transfer were more strongly connected to each other than chance, thus forming a “rich club.” We found similar results in networks recorded in vivo from rodent cortex, suggesting the generality of these findings. A rich-club structure has been found previously in large-scale human brain networks and is thought to facilitate communication between cortical regions. The discovery of a small, but information-rich, subset of neurons within cortical regions suggests that this population will play a vital role in communication, learning, and memory. SIGNIFICANCE STATEMENT Many studies have focused on communication networks between cortical brain regions. In contrast, very few studies have examined communication networks within a cortical region. This is the first study to combine such a large number of neurons (several

  4. Spatial Stream Segregation by Auditory Cortical Neurons

    PubMed Central

    Bremen, Peter

    2013-01-01

    In a complex auditory scene, a “cocktail party” for example, listeners can disentangle multiple competing sequences of sounds. A recent psychophysical study in our laboratory demonstrated a robust spatial component of stream segregation showing ∼8° acuity. Here, we recorded single- and multiple-neuron responses from the primary auditory cortex of anesthetized cats while presenting interleaved sound sequences that human listeners would experience as segregated streams. Sequences of broadband sounds alternated between pairs of locations. Neurons synchronized preferentially to sounds from one or the other location, thereby segregating competing sound sequences. Neurons favoring one source location or the other tended to aggregate within the cortex, suggestive of modular organization. The spatial acuity of stream segregation was as narrow as ∼10°, markedly sharper than the broad spatial tuning for single sources that is well known in the literature. Spatial sensitivity was sharpest among neurons having high characteristic frequencies. Neural stream segregation was predicted well by a parameter-free model that incorporated single-source spatial sensitivity and a measured forward-suppression term. We found that the forward suppression was not due to post discharge adaptation in the cortex and, therefore, must have arisen in the subcortical pathway or at the level of thalamocortical synapses. A linear-classifier analysis of single-neuron responses to rhythmic stimuli like those used in our psychophysical study yielded thresholds overlapping those of human listeners. Overall, the results indicate that the ascending auditory system does the work of segregating auditory streams, bringing them to discrete modules in the cortex for selection by top-down processes. PMID:23825404

  5. Network Receptive Field Modeling Reveals Extensive Integration and Multi-feature Selectivity in Auditory Cortical Neurons.

    PubMed

    Harper, Nicol S; Schoppe, Oliver; Willmore, Ben D B; Cui, Zhanfeng; Schnupp, Jan W H; King, Andrew J

    2016-11-01

    Cortical sensory neurons are commonly characterized using the receptive field, the linear dependence of their response on the stimulus. In primary auditory cortex neurons can be characterized by their spectrotemporal receptive fields, the spectral and temporal features of a sound that linearly drive a neuron. However, receptive fields do not capture the fact that the response of a cortical neuron results from the complex nonlinear network in which it is embedded. By fitting a nonlinear feedforward network model (a network receptive field) to cortical responses to natural sounds, we reveal that primary auditory cortical neurons are sensitive over a substantially larger spectrotemporal domain than is seen in their standard spectrotemporal receptive fields. Furthermore, the network receptive field, a parsimonious network consisting of 1-7 sub-receptive fields that interact nonlinearly, consistently better predicts neural responses to auditory stimuli than the standard receptive fields. The network receptive field reveals separate excitatory and inhibitory sub-fields with different nonlinear properties, and interaction of the sub-fields gives rise to important operations such as gain control and conjunctive feature detection. The conjunctive effects, where neurons respond only if several specific features are present together, enable increased selectivity for particular complex spectrotemporal structures, and may constitute an important stage in sound recognition. In conclusion, we demonstrate that fitting auditory cortical neural responses with feedforward network models expands on simple linear receptive field models in a manner that yields substantially improved predictive power and reveals key nonlinear aspects of cortical processing, while remaining easy to interpret in a physiological context.

  6. Network Receptive Field Modeling Reveals Extensive Integration and Multi-feature Selectivity in Auditory Cortical Neurons

    PubMed Central

    Willmore, Ben D. B.; Cui, Zhanfeng; Schnupp, Jan W. H.; King, Andrew J.

    2016-01-01

    Cortical sensory neurons are commonly characterized using the receptive field, the linear dependence of their response on the stimulus. In primary auditory cortex neurons can be characterized by their spectrotemporal receptive fields, the spectral and temporal features of a sound that linearly drive a neuron. However, receptive fields do not capture the fact that the response of a cortical neuron results from the complex nonlinear network in which it is embedded. By fitting a nonlinear feedforward network model (a network receptive field) to cortical responses to natural sounds, we reveal that primary auditory cortical neurons are sensitive over a substantially larger spectrotemporal domain than is seen in their standard spectrotemporal receptive fields. Furthermore, the network receptive field, a parsimonious network consisting of 1–7 sub-receptive fields that interact nonlinearly, consistently better predicts neural responses to auditory stimuli than the standard receptive fields. The network receptive field reveals separate excitatory and inhibitory sub-fields with different nonlinear properties, and interaction of the sub-fields gives rise to important operations such as gain control and conjunctive feature detection. The conjunctive effects, where neurons respond only if several specific features are present together, enable increased selectivity for particular complex spectrotemporal structures, and may constitute an important stage in sound recognition. In conclusion, we demonstrate that fitting auditory cortical neural responses with feedforward network models expands on simple linear receptive field models in a manner that yields substantially improved predictive power and reveals key nonlinear aspects of cortical processing, while remaining easy to interpret in a physiological context. PMID:27835647

  7. Morphology and ontogeny of rat perirhinal cortical neurons.

    PubMed

    Furtak, Sharon Christine; Moyer, James Russell; Brown, Thomas Huntington

    2007-12-10

    Golgi-impregnated neurons from rat perirhinal cortex (PR) were classified into one of 15 distinct morphological categories (N = 6,891). The frequency of neurons in each cell class was determined as a function of the layer of PR and the age of the animal, which ranged from postnatal day 0 (P0) to young adulthood (P45). The developmental appearance of Golgi-impregnated neurons conformed to the expected "inside-out" pattern of development, meaning that cells populated in deep before superficial layers of PR. The relative frequencies of different cell types changed during the first 2 weeks of postnatal development. The largest cells, which were pyramidal and spiny multipolar neurons, appeared earliest. Aspiny stellate neurons were the last to appear. The total number of Golgi-impregnated neurons peaked at P10-12, corresponding to the time of eye-opening. This early increase in the number of impregnated neurons parallels observations in other cortical areas. The relative frequency of the 15 cell types remained constant between P14 to P45. The proportion of pyramidal neurons in PR ( approximately 50%) was much smaller than is typical of neocortex ( approximately 70%). A correspondingly larger proportion of PR neurons were nonpyramidal cells that are less common in neocortex. The relative frequency distribution of cell types creates an overall impression of considerable morphological diversity, which is arguably related to the particular manner in which this periallocortical brain region processes and stores information.

  8. Coordinated scaling of cortical and cerebellar numbers of neurons.

    PubMed

    Herculano-Houzel, Suzana

    2010-01-01

    While larger brains possess concertedly larger cerebral cortices and cerebella, the relative size of the cerebral cortex increases with brain size, but relative cerebellar size does not. In the absence of data on numbers of neurons in these structures, this discrepancy has been used to dispute the hypothesis that the cerebral cortex and cerebellum function and have evolved in concert and to support a trend towards neocorticalization in evolution. However, the rationale for interpreting changes in absolute and relative size of the cerebral cortex and cerebellum relies on the assumption that they reflect absolute and relative numbers of neurons in these structures across all species - an assumption that our recent studies have shown to be flawed. Here I show for the first time that the numbers of neurons in the cerebral cortex and cerebellum are directly correlated across 19 mammalian species of four different orders, including humans, and increase concertedly in a similar fashion both within and across the orders Eulipotyphla (Insectivora), Rodentia, Scandentia and Primata, such that on average a ratio of 3.6 neurons in the cerebellum to every neuron in the cerebral cortex is maintained across species. This coordinated scaling of cortical and cerebellar numbers of neurons provides direct evidence in favor of concerted function, scaling and evolution of these brain structures, and suggests that the common notion that equates cognitive advancement with neocortical expansion should be revisited to consider in its stead the coordinated scaling of neocortex and cerebellum as a functional ensemble.

  9. Coordinated Scaling of Cortical and Cerebellar Numbers of Neurons

    PubMed Central

    Herculano-Houzel, Suzana

    2010-01-01

    While larger brains possess concertedly larger cerebral cortices and cerebella, the relative size of the cerebral cortex increases with brain size, but relative cerebellar size does not. In the absence of data on numbers of neurons in these structures, this discrepancy has been used to dispute the hypothesis that the cerebral cortex and cerebellum function and have evolved in concert and to support a trend towards neocorticalization in evolution. However, the rationale for interpreting changes in absolute and relative size of the cerebral cortex and cerebellum relies on the assumption that they reflect absolute and relative numbers of neurons in these structures across all species – an assumption that our recent studies have shown to be flawed. Here I show for the first time that the numbers of neurons in the cerebral cortex and cerebellum are directly correlated across 19 mammalian species of four different orders, including humans, and increase concertedly in a similar fashion both within and across the orders Eulipotyphla (Insectivora), Rodentia, Scandentia and Primata, such that on average a ratio of 3.6 neurons in the cerebellum to every neuron in the cerebral cortex is maintained across species. This coordinated scaling of cortical and cerebellar numbers of neurons provides direct evidence in favor of concerted function, scaling and evolution of these brain structures, and suggests that the common notion that equates cognitive advancement with neocortical expansion should be revisited to consider in its stead the coordinated scaling of neocortex and cerebellum as a functional ensemble. PMID:20300467

  10. Spontaneous cortical activity in awake monkeys composed of neuronal avalanches.

    PubMed

    Petermann, Thomas; Thiagarajan, Tara C; Lebedev, Mikhail A; Nicolelis, Miguel A L; Chialvo, Dante R; Plenz, Dietmar

    2009-09-15

    Spontaneous neuronal activity is an important property of the cerebral cortex but its spatiotemporal organization and dynamical framework remain poorly understood. Studies in reduced systems--tissue cultures, acute slices, and anesthetized rats--show that spontaneous activity forms characteristic clusters in space and time, called neuronal avalanches. Modeling studies suggest that networks with this property are poised at a critical state that optimizes input processing, information storage, and transfer, but the relevance of avalanches for fully functional cerebral systems has been controversial. Here we show that ongoing cortical synchronization in awake rhesus monkeys carries the signature of neuronal avalanches. Negative LFP deflections (nLFPs) correlate with neuronal spiking and increase in amplitude with increases in local population spike rate and synchrony. These nLFPs form neuronal avalanches that are scale-invariant in space and time and with respect to the threshold of nLFP detection. This dimension, threshold invariance, describes a fractal organization: smaller nLFPs are embedded in clusters of larger ones without destroying the spatial and temporal scale-invariance of the dynamics. These findings suggest an organization of ongoing cortical synchronization that is scale-invariant in its three fundamental dimensions--time, space, and local neuronal group size. Such scale-invariance has ontogenetic and phylogenetic implications because it allows large increases in network capacity without a fundamental reorganization of the system.

  11. Spontaneous cortical activity in awake monkeys composed of neuronal avalanches

    PubMed Central

    Petermann, Thomas; Thiagarajan, Tara C.; Lebedev, Mikhail A.; Nicolelis, Miguel A. L.; Chialvo, Dante R.; Plenz, Dietmar

    2009-01-01

    Spontaneous neuronal activity is an important property of the cerebral cortex but its spatiotemporal organization and dynamical framework remain poorly understood. Studies in reduced systems—tissue cultures, acute slices, and anesthetized rats—show that spontaneous activity forms characteristic clusters in space and time, called neuronal avalanches. Modeling studies suggest that networks with this property are poised at a critical state that optimizes input processing, information storage, and transfer, but the relevance of avalanches for fully functional cerebral systems has been controversial. Here we show that ongoing cortical synchronization in awake rhesus monkeys carries the signature of neuronal avalanches. Negative LFP deflections (nLFPs) correlate with neuronal spiking and increase in amplitude with increases in local population spike rate and synchrony. These nLFPs form neuronal avalanches that are scale-invariant in space and time and with respect to the threshold of nLFP detection. This dimension, threshold invariance, describes a fractal organization: smaller nLFPs are embedded in clusters of larger ones without destroying the spatial and temporal scale-invariance of the dynamics. These findings suggest an organization of ongoing cortical synchronization that is scale-invariant in its three fundamental dimensions—time, space, and local neuronal group size. Such scale-invariance has ontogenetic and phylogenetic implications because it allows large increases in network capacity without a fundamental reorganization of the system. PMID:19717463

  12. Signal transfer within a cultured asymmetric cortical neuron circuit

    NASA Astrophysics Data System (ADS)

    Isomura, Takuya; Shimba, Kenta; Takayama, Yuzo; Takeuchi, Akimasa; Kotani, Kiyoshi; Jimbo, Yasuhiko

    2015-12-01

    Objective. Simplified neuronal circuits are required for investigating information representation in nervous systems and for validating theoretical neural network models. Here, we developed patterned neuronal circuits using micro fabricated devices, comprising a micro-well array bonded to a microelectrode-array substrate. Approach. The micro-well array consisted of micrometre-scale wells connected by tunnels, all contained within a silicone slab called a micro-chamber. The design of the micro-chamber confined somata to the wells and allowed axons to grow through the tunnels bidirectionally but with a designed, unidirectional bias. We guided axons into the point of the arrow structure where one of the two tunnel entrances is located, making that the preferred direction. Main results. When rat cortical neurons were cultured in the wells, their axons grew through the tunnels and connected to neurons in adjoining wells. Unidirectional burst transfers and other asymmetric signal-propagation phenomena were observed via the substrate-embedded electrodes. Seventy-nine percent of burst transfers were in the forward direction. We also observed rapid propagation of activity from sites of local electrical stimulation, and significant effects of inhibitory synapse blockade on bursting activity. Significance. These results suggest that this simple, substrate-controlled neuronal circuit can be applied to develop in vitro models of the function of cortical microcircuits or deep neural networks, better to elucidate the laws governing the dynamics of neuronal networks.

  13. Synchronized dynamics of cortical neurons with time-delay feedback.

    PubMed

    Landsman, Alexandra S; Schwartz, Ira B

    2007-07-05

    The dynamics of three mutually coupled cortical neurons with time delays in the coupling are explored numerically and analytically. The neurons are coupled in a line, with the middle neuron sending a somewhat stronger projection to the outer neurons than the feedback it receives, to model for instance the relay of a signal from primary to higher cortical areas. For a given coupling architecture, the delays introduce correlations in the time series at the time-scale of the delay. It was found that the middle neuron leads the outer ones by the delay time, while the outer neurons are synchronized with zero lag times. Synchronization is found to be highly dependent on the synaptic time constant, with faster synapses increasing both the degree of synchronization and the firing rate. Analysis shows that pre-synaptic input during the inter-spike interval stabilizes the synchronous state, even for arbitrarily weak coupling, and independent of the initial phase. The finding may be of significance to synchronization of large groups of cells in the cortex that are spatially distanced from each other.

  14. Synchronized dynamics of cortical neurons with time-delay feedback

    PubMed Central

    Landsman, Alexandra S; Schwartz, Ira B

    2007-01-01

    The dynamics of three mutually coupled cortical neurons with time delays in the coupling are explored numerically and analytically. The neurons are coupled in a line, with the middle neuron sending a somewhat stronger projection to the outer neurons than the feedback it receives, to model for instance the relay of a signal from primary to higher cortical areas. For a given coupling architecture, the delays introduce correlations in the time series at the time-scale of the delay. It was found that the middle neuron leads the outer ones by the delay time, while the outer neurons are synchronized with zero lag times. Synchronization is found to be highly dependent on the synaptic time constant, with faster synapses increasing both the degree of synchronization and the firing rate. Analysis shows that pre-synaptic input during the inter-spike interval stabilizes the synchronous state, even for arbitrarily weak coupling, and independent of the initial phase. The finding may be of significance to synchronization of large groups of cells in the cortex that are spatially distanced from each other. PMID:17908335

  15. Direct control of paralysed muscles by cortical neurons.

    PubMed

    Moritz, Chet T; Perlmutter, Steve I; Fetz, Eberhard E

    2008-12-04

    A potential treatment for paralysis resulting from spinal cord injury is to route control signals from the brain around the injury by artificial connections. Such signals could then control electrical stimulation of muscles, thereby restoring volitional movement to paralysed limbs. In previously separate experiments, activity of motor cortex neurons related to actual or imagined movements has been used to control computer cursors and robotic arms, and paralysed muscles have been activated by functional electrical stimulation. Here we show that Macaca nemestrina monkeys can directly control stimulation of muscles using the activity of neurons in the motor cortex, thereby restoring goal-directed movements to a transiently paralysed arm. Moreover, neurons could control functional stimulation equally well regardless of any previous association to movement, a finding that considerably expands the source of control signals for brain-machine interfaces. Monkeys learned to use these artificial connections from cortical cells to muscles to generate bidirectional wrist torques, and controlled multiple neuron-muscle pairs simultaneously. Such direct transforms from cortical activity to muscle stimulation could be implemented by autonomous electronic circuitry, creating a relatively natural neuroprosthesis. These results are the first demonstration that direct artificial connections between cortical cells and muscles can compensate for interrupted physiological pathways and restore volitional control of movement to paralysed limbs.

  16. Direct control of paralyzed muscles by cortical neurons

    PubMed Central

    Moritz, Chet T.; Perlmutter, Steve I.; Fetz, Eberhard E.

    2011-01-01

    A potential treatment for paralysis resulting from spinal cord injury is to route control signals from the brain around the injury via artificial connections. Such signals could then control electrical stimulation of muscles, thereby restoring volitional movement to paralyzed limbs1–3. In previously separate experiments, activity of motor cortex neurons related to actual or imagined movements has been used to control computer cursors and robotic arms4–10, and paralyzed muscles have been activated by functional electrical stimulation (FES)11–13. Here we show that monkeys can directly control stimulation of muscles using the activity of neurons in motor cortex, thereby restoring goal-directed movements to a transiently paralyzed arm. Moreover, neurons could control functional stimulation equally well regardless of any prior association to movement, a finding that significantly expands the source of control signals for brain-machine interfaces. Monkeys learned to utilize these artificial connections from cortical cells to muscles to generate bidirectional wrist torques, and controlled multiple neuron-muscle pairs simultaneously. Such direct transforms from cortical activity to muscle stimulation could be implemented by autonomous electronic circuitry, creating a relatively natural neuroprosthesis. These results are the first demonstration that direct artificial connections between cortical cells and muscles can compensate for interrupted physiological pathways and restore volitional control of movement to paralyzed limbs. PMID:18923392

  17. Capsaicin protects cortical neurons against ischemia/reperfusion injury via down-regulating NMDA receptors.

    PubMed

    Huang, Ming; Cheng, Gen; Tan, Han; Qin, Rui; Zou, Yimin; Wang, Yun; Zhang, Ying

    2017-09-01

    Capsaicin, the ingredient responsible for the pungent taste of hot chili peppers, is widely used in the study and management of pain. Recently, its neuroprotective effect has been described in multiple studies. Herein, we investigated the underlying mechanisms for the neuroprotective effect of capsaicin. Direct injection of capsaicin (1 or 3nmol) into the peri-infarct area reduced the infarct volume and improved neurological behavioral scoring and motor coordination function in the middle cerebral artery occlusion (MCAO)/reperfusion model in rats. The time window of the protective effect of capsaicin was within 1h after reperfusion, when excitotoxicity is the main reason of cell death. In cultured cortical neurons, administration of capsaicin attenuated glutamate-induced excitotoxic injury. With respect to the mechanisms of the neuroprotective effect of capsaicin, reduced calcium influx after glutamate stimulation was observed following capsaicin pretreatment in cortical neurons. Trpv1 knock-out abolished the inhibitory effect of capsaicin on glutamate-induced calcium influx and subsequent neuronal death. Reduced expression of GluN1 and GluN2B, subunits of NMDA receptor, was examined after capsaicin treatment in cortical neurons. In summary, our studies reveal that the neuroprotective effect of capsaicin in cortical neurons is TRPV1-dependent and down-regulation of the expression and function of NMDA receptors contributes to the protection afforded by capsaicin. Copyright © 2017. Published by Elsevier Inc.

  18. Inferring pathological states in cortical neuron microcircuits.

    PubMed

    Rydzewski, Jakub; Nowak, Wieslaw; Nicosia, Giuseppe

    2015-12-07

    The brain activity is to a large extent determined by states of neural cortex microcircuits. Unfortunately, accuracy of results from neural circuits׳ mathematical models is often biased by the presence of uncertainties in underlying experimental data. Moreover, due to problems with uncertainties identification in a multidimensional parameters space, it is almost impossible to classify states of the neural cortex, which correspond to a particular set of the parameters. Here, we develop a complete methodology for determining uncertainties and the novel protocol for classifying all states in any neuroinformatic model. Further, we test this protocol on the mathematical, nonlinear model of such a microcircuit developed by Giugliano et al. (2008) and applied in the experimental data analysis of Huntington׳s disease. Up to now, the link between parameter domains in the mathematical model of Huntington׳s disease and the pathological states in cortical microcircuits has remained unclear. In this paper we precisely identify all the uncertainties, the most crucial input parameters and domains that drive the system into an unhealthy state. The scheme proposed here is general and can be easily applied to other mathematical models of biological phenomena. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Neuronal gap junctions play a role in the secondary neuronal death following controlled cortical impact.

    PubMed

    Belousov, Andrei B; Wang, Yongfu; Song, Ji-Hoon; Denisova, Janna V; Berman, Nancy E; Fontes, Joseph D

    2012-08-22

    In the mammalian CNS, excessive release of glutamate and overactivation of glutamate receptors are responsible for the secondary (delayed) neuronal death following neuronal injury, including ischemia, traumatic brain injury (TBI) and epilepsy. Recent studies in mice showed a critical role for neuronal gap junctions in NMDA receptor-mediated excitotoxicity and ischemia-mediated neuronal death. Here, using controlled cortical impact (CCI) in adult mice, as a model of TBI, and Fluoro-Jade B staining for analysis of neuronal death, we set to determine whether neuronal gap junctions play a role in the CCI-mediated secondary neuronal death. We report that 24h post-CCI, substantial neuronal death is detected in a number of brain regions outside the injury core, including the striatum. The striatal neuronal death is reduced both in wild-type mice by systemic administration of mefloquine (a relatively selective blocker of neuronal gap junctions) and in knockout mice lacking connexin 36 (neuronal gap junction protein). It is also reduced by inactivation of group II metabotropic glutamate receptors (with LY341495) which, as reported previously, control the rapid increase in neuronal gap junction coupling following different types of neuronal injury. The results suggest that neuronal gap junctions play a critical role in the CCI-induced secondary neuronal death. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  20. Cortical neurons exposed to glutamate rapidly leak preloaded chromium 51

    SciTech Connect

    Maulucci-Gedde, M.; Choi, D.W.

    1987-05-01

    The acute toxic effects of excess glutamate exposure on cortical neurons in culture was followed using a novel adaptation of the /sup 51/Cr efflux assay. Although the acute, sodium-dependent phase of glutamate neurotoxicity may contribute to several acute disease settings, including sustained seizures and stroke, functional aspects of the phenomenon have not been previously studied. We report here that the earliest morphologic sign of glutamate neurotoxicity, neuronal swelling, is accompanied by a large efflux of complexed /sup 51/Cr from preloaded neurons in the first hour after exposure, and that this efflux is detectable as early as 15 min after the onset of glutamate exposure. We suggest that this pathological burst of /sup 51/Cr may result from glutamate-induced leakiness of neuronal cell membranes.

  1. Rich club neurons dominate Information Transfer in local cortical networks

    NASA Astrophysics Data System (ADS)

    Nigam, Sunny; Shimono, Masanori; Sporns, Olaf; Beggs, John

    2015-03-01

    The performance of complex networks depends on how they route their traffic. It is unknown how information is transferred in local cortical networks of hundreds of closely-spaced neurons. To address this, it is necessary to record simultaneously from hundreds of neurons at a spacing that matches typical axonal connection distances, and at a temporal resolution that matches synaptic delays. We used a 512 electrode array (60 μm spacing) to record spontaneous activity at 20 kHz, simultaneously from up to 700 neurons in slice cultures of mouse somatosensory cortex for 1 hr at a time. We used transfer entropy to quantify directed information transfer (IT) between pairs of neurons. We found an approximately lognormal distribution of firing rates as reported in in-vivo. Pairwise information transfer strengths also were nearly lognormally distributed, similar to synaptic strengths. 20% of the neurons accounted for 70% of the total IT coming into, and going out of the network and were defined as rich nodes. These rich nodes were more densely and strongly connected to each other expected by chance, forming a rich club. This highly uneven distribution of IT has implications for the efficiency and robustness of local cortical networks, and gives clues to the plastic processes that shape them. JSPS.

  2. Potentiated necrosis of cultured cortical neurons by neurotrophins.

    PubMed

    Koh, J Y; Gwag, B J; Lobner, D; Choi, D W

    1995-04-28

    The effects of neurotrophins on several forms of neuronal degeneration in murine cortical cell cultures were examined. Consistent with other studies, brain-derived neurotrophic factor, neurotrophin-3, and neurotrophin-4/5 all attenuated the apoptotic death induced by serum deprivation or exposure to the calcium channel antagonist nimodipine. Unexpectedly, however, 24-hour pretreatment with these same neurotrophins markedly potentiated the necrotic death induced by exposure to oxygen-glucose deprivation or N-methyl-D-aspartate. Thus, certain neurotrophins may have opposing effects on different types of death in the same neurons.

  3. Optogenetic stimulation of GABA neurons can decrease local neuronal activity while increasing cortical blood flow

    PubMed Central

    Anenberg, Eitan; Chan, Allen W; Xie, Yicheng; LeDue, Jeffrey M; Murphy, Timothy H

    2015-01-01

    We investigated the link between direct activation of inhibitory neurons, local neuronal activity, and hemodynamics. Direct optogenetic cortical stimulation in the sensorimotor cortex of transgenic mice expressing Channelrhodopsin-2 in GABAergic neurons (VGAT-ChR2) greatly attenuated spontaneous cortical spikes, but was sufficient to increase blood flow as measured with laser speckle contrast imaging. To determine whether the observed optogenetically evoked gamma aminobutyric acid (GABA)-neuron hemodynamic responses were dependent on ionotropic glutamatergic or GABAergic synaptic mechanisms, we paired optogenetic stimulation with application of antagonists to the cortex. Incubation of glutamatergic antagonists directly on the cortex (NBQX and MK-801) blocked cortical sensory evoked responses (as measured with electroencephalography and intrinsic optical signal imaging), but did not significantly attenuate optogenetically evoked hemodynamic responses. Significant light-evoked hemodynamic responses were still present after the addition of picrotoxin (GABA-A receptor antagonist) in the presence of the glutamatergic synaptic blockade. This activation of cortical inhibitory interneurons can mediate large changes in blood flow in a manner that is by and large not dependent on ionotropic glutamatergic or GABAergic synaptic transmission. This supports the hypothesis that activation of inhibitory neurons can increase local cerebral blood flow in a manner that is not entirely dependent on levels of net ongoing neuronal activity. PMID:26082013

  4. Cortical neuronal mechanisms of sleep homeostasis.

    PubMed

    Vyazovskiy, Vladyslav V

    2013-01-01

    The longer we are awake, the deeper is our subsequent sleep. On the other hand, the shorter and more fragmented is our sleep, the more difficult it is for us to maintain wakefulness and stable cognitive performance the next day. This relationship between wakefulness and subsequent sleep becomes especially apparent after sleep deprivation or during chronic sleep restriction, which is experienced by millions of people in our society, as well as in multiple neurological, respiratory and other chronic diseases. Invariably, poor sleep leads to fatigue, sleepiness, marked cognitive deficits and impaired mood. The crucial question is what happens to the brain after a period of being awake or asleep, and where in the brain and why do these changes occur. This review summarizes information about neurophysiological substrates of sleep homeostatic processes at the cellular and network levels. It is suggested that sensory, behavioral and cognitive deficits after sleep deprivation resulting from the imbalance between local and global neuronal interactions can be reversed only by physiological sleep.

  5. Ginkgolides protect primary cortical neurons from potassium cyanide-induced hypoxic injury.

    PubMed

    Zhu, Li; Xu, You Jia; Du, Fang; Qian, Zhong Ming

    2007-06-01

    In this study, we investigated the effects of ginkgolides (Gins A, B, C and J), the main constituent of the non-flavone fraction of EGb 761, on hypoxic injury induced by potassium cyanide (KCN) in primary cortical neurons. The neurons were pretreated with or without ginkgolides for 24 h before incubation with KCN for 4 h. Cell viability was then determined by a MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyletrazolium bromide] assay and lactate dehydrogenase (LDH) release from neurons into the medium was measured. The morphological changes of neurons were observed under inverse microscopy and electron microscopy. The results demonstrated that KCN (0.05 mmol/l) significantly decreased cell viability and increased LDH release (P < 0.05 versus the control). The characteristic changes of neuronal morphology induced by KCN were observed. However, pretreatment of neurons with 37.5 microg/ml of ginkgolides (ginkgolides + KCN group) led to a significant increase in cell viability, a decrease in LDH release (P < 0.05 versus the KCN group) and a remarkable improvement in cellular morphology in hypoxic neurons compared with the KCN group. The data suggested that ginkgolides have a significant role to protect the primary cortical neurons from hypoxic injury induced by KCN.

  6. Cortical neuronal activity does not regulate sleep homeostasis.

    PubMed

    Qiu, M-H; Chen, M C; Lu, J

    2015-06-25

    The neural substrate of sleep homeostasis is unclear, but both cortical and subcortical structures are thought to be involved in sleep regulation. To test whether prior neuronal activity in the cortex or in subcortical regions drives sleep rebound, we systemically administered atropine (100mg/kg) to rats, producing a dissociated state with slow-wave cortical electroencephalogram (EEG) but waking behavior (e.g. locomotion). Atropine injections during the light period produced 6h of slow-wave cortical EEG but also subcortical arousal. Afterward, rats showed a significant increase in non-rapid eye movement (NREM) sleep, compared to the same period on a baseline day. Consistent with the behavioral and cortical EEG state produced by systemic atropine, c-Fos expression was low in the cortex but high in multiple subcortical arousal systems. These data suggest that subcortical arousal and behavior are sufficient to drive sleep homeostasis, while a sleep-like pattern of cortical activity is not sufficient to satisfy sleep homeostasis.

  7. Sensory experience regulates cortical inhibition by inducing IGF1 in VIP neurons.

    PubMed

    Mardinly, A R; Spiegel, I; Patrizi, A; Centofante, E; Bazinet, J E; Tzeng, C P; Mandel-Brehm, C; Harmin, D A; Adesnik, H; Fagiolini, M; Greenberg, M E

    2016-03-17

    Inhibitory neurons regulate the adaptation of neural circuits to sensory experience, but the molecular mechanisms by which experience controls the connectivity between different types of inhibitory neuron to regulate cortical plasticity are largely unknown. Here we show that exposure of dark-housed mice to light induces a gene program in cortical vasoactive intestinal peptide (VIP)-expressing neurons that is markedly distinct from that induced in excitatory neurons and other subtypes of inhibitory neuron. We identify Igf1 as one of several activity-regulated genes that are specific to VIP neurons, and demonstrate that IGF1 functions cell-autonomously in VIP neurons to increase inhibitory synaptic input onto these neurons. Our findings further suggest that in cortical VIP neurons, experience-dependent gene transcription regulates visual acuity by activating the expression of IGF1, thus promoting the inhibition of disinhibitory neurons and affecting inhibition onto cortical pyramidal neurons.

  8. Extracting Kinematic Parameters for Monkey Bipedal Walking from Cortical Neuronal Ensemble Activity

    PubMed Central

    Fitzsimmons, Nathan A.; Lebedev, Mikhail A.; Peikon, Ian D.; Nicolelis, Miguel A. L.

    2009-01-01

    The ability to walk may be critically impacted as the result of neurological injury or disease. While recent advances in brain–machine interfaces (BMIs) have demonstrated the feasibility of upper-limb neuroprostheses, BMIs have not been evaluated as a means to restore walking. Here, we demonstrate that chronic recordings from ensembles of cortical neurons can be used to predict the kinematics of bipedal walking in rhesus macaques – both offline and in real time. Linear decoders extracted 3D coordinates of leg joints and leg muscle electromyograms from the activity of hundreds of cortical neurons. As more complex patterns of walking were produced by varying the gait speed and direction, larger neuronal populations were needed to accurately extract walking patterns. Extraction was further improved using a switching decoder which designated a submodel for each walking paradigm. We propose that BMIs may one day allow severely paralyzed patients to walk again. PMID:19404411

  9. Sonic Hedgehog Promotes Neurite Outgrowth of Primary Cortical Neurons Through Up-Regulating BDNF Expression.

    PubMed

    He, Weiliang; Cui, Lili; Zhang, Cong; Zhang, Xiangjian; He, Junna; Xie, Yanzhao

    2016-04-01

    Sonic hedgehog (Shh), a secreted glycoprotein factor, can activate the Shh pathway, which has been implicated in neuronal polarization involving neurite outgrowth. However, little evidence is available about the effect of Shh on neurite outgrowth in primary cortical neurons and its potential mechanism. Here, we revealed that Shh increased neurite outgrowth in primary cortical neurons, while the Shh pathway inhibitor (cyclopamine, CPM) partially suppressed Shh-induced neurite outgrowth. Similar results were found for the expressions of Shh and Patched genes in Shh-induced primary cortical neurons. Moreover, Shh increased the levels of brain-derived neurotrophic factor (BDNF) not only in lysates and in culture medium but also in the longest neurites of primary cortical neurons, which was partially blocked by CPM. In addition, blocking of BDNF action suppressed Shh-mediated neurite elongation in primary cortical neurons. In conclusion, these findings suggest that Shh promotes neurite outgrowth in primary cortical neurons at least partially through modulating BDNF expression.

  10. Short-term memory in networks of dissociated cortical neurons.

    PubMed

    Dranias, Mark R; Ju, Han; Rajaram, Ezhilarasan; VanDongen, Antonius M J

    2013-01-30

    Short-term memory refers to the ability to store small amounts of stimulus-specific information for a short period of time. It is supported by both fading and hidden memory processes. Fading memory relies on recurrent activity patterns in a neuronal network, whereas hidden memory is encoded using synaptic mechanisms, such as facilitation, which persist even when neurons fall silent. We have used a novel computational and optogenetic approach to investigate whether these same memory processes hypothesized to support pattern recognition and short-term memory in vivo, exist in vitro. Electrophysiological activity was recorded from primary cultures of dissociated rat cortical neurons plated on multielectrode arrays. Cultures were transfected with ChannelRhodopsin-2 and optically stimulated using random dot stimuli. The pattern of neuronal activity resulting from this stimulation was analyzed using classification algorithms that enabled the identification of stimulus-specific memories. Fading memories for different stimuli, encoded in ongoing neural activity, persisted and could be distinguished from each other for as long as 1 s after stimulation was terminated. Hidden memories were detected by altered responses of neurons to additional stimulation, and this effect persisted longer than 1 s. Interestingly, network bursts seem to eliminate hidden memories. These results are similar to those that have been reported from similar experiments in vivo and demonstrate that mechanisms of information processing and short-term memory can be studied using cultured neuronal networks, thereby setting the stage for therapeutic applications using this platform.

  11. Mutual information and redundancy in spontaneous communication between cortical neurons.

    PubMed

    Szczepanski, J; Arnold, M; Wajnryb, E; Amigó, J M; Sanchez-Vives, M V

    2011-03-01

    An important question in neural information processing is how neurons cooperate to transmit information. To study this question, we resort to the concept of redundancy in the information transmitted by a group of neurons and, at the same time, we introduce a novel concept for measuring cooperation between pairs of neurons called relative mutual information (RMI). Specifically, we studied these two parameters for spike trains generated by neighboring neurons from the primary visual cortex in the awake, freely moving rat. The spike trains studied here were spontaneously generated in the cortical network, in the absence of visual stimulation. Under these conditions, our analysis revealed that while the value of RMI oscillated slightly around an average value, the redundancy exhibited a behavior characterized by a higher variability. We conjecture that this combination of approximately constant RMI and greater variable redundancy makes information transmission more resistant to noise disturbances. Furthermore, the redundancy values suggest that neurons can cooperate in a flexible way during information transmission. This mostly occurs via a leading neuron with higher transmission rate or, less frequently, through the information rate of the whole group being higher than the sum of the individual information rates-in other words in a synergetic manner. The proposed method applies not only to the stationary, but also to locally stationary neural signals.

  12. Locus coeruleus stimulation recruits a broad cortical neuronal network and increases cortical perfusion.

    PubMed

    Toussay, Xavier; Basu, Kaustuv; Lacoste, Baptiste; Hamel, Edith

    2013-02-20

    The locus coeruleus (LC), the main source of brain noradrenalin (NA), modulates cortical activity, cerebral blood flow (CBF), glucose metabolism, and blood-brain barrier permeability. However, the role of the LC-NA system in the regulation of cortical CBF has remained elusive. This rat study shows that similar proportions (∼20%) of cortical pyramidal cells and GABA interneurons are contacted by LC-NA afferents on their cell soma or proximal dendrites. LC stimulation induced ipsilateral activation (c-Fos upregulation) of pyramidal cells and of a larger proportion (>36%) of interneurons that colocalize parvalbumin, somatostatin, or nitric oxide synthase compared with pyramidal cells expressing cyclooxygenase-2 (22%, p < 0.05) or vasoactive intestinal polypeptide-containing interneurons (16%, p < 0.01). Concurrently, LC stimulation elicited larger ipsilateral compared with contralateral increases in cortical CBF (52 vs 31%, p < 0.01). These CBF responses were almost abolished (-70%, p < 0.001) by cortical NA denervation with DSP-4 [N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride] and were significantly reduced by α- and β-adrenoceptor antagonists (-40%, p < 0.001 and -30%, p < 0.05, respectively). Blockade of glutamatergic or GABAergic neurotransmission with NMDA or GABA(A) receptor antagonists potently reduced the LC-induced hyperemic response (-56%, p < 0.001 or -47%, p < 0.05). Moreover, inhibition of astroglial metabolism (-35%, p < 0.01), vasoactive epoxyeicosatrienoic acids (EETs; -60%, p < 0.001) synthesis, large-conductance, calcium-operated (BK, -52%, p < 0.05), and inward-rectifier (Kir, -40%, p < 0.05) K+ channels primarily impaired the hyperemic response. The data demonstrate that LC stimulation recruits a broad network of cortical excitatory and inhibitory neurons resulting in increased cortical activity and that K+ fluxes and EET signaling mediate a large part of the hemodynamic response.

  13. Spiking neural networks for cortical neuronal spike train decoding.

    PubMed

    Fang, Huijuan; Wang, Yongji; He, Jiping

    2010-04-01

    Recent investigation of cortical coding and computation indicates that temporal coding is probably a more biologically plausible scheme used by neurons than the rate coding used commonly in most published work. We propose and demonstrate in this letter that spiking neural networks (SNN), consisting of spiking neurons that propagate information by the timing of spikes, are a better alternative to the coding scheme based on spike frequency (histogram) alone. The SNN model analyzes cortical neural spike trains directly without losing temporal information for generating more reliable motor command for cortically controlled prosthetics. In this letter, we compared the temporal pattern classification result from the SNN approach with results generated from firing-rate-based approaches: conventional artificial neural networks, support vector machines, and linear regression. The results show that the SNN algorithm can achieve higher classification accuracy and identify the spiking activity related to movement control earlier than the other methods. Both are desirable characteristics for fast neural information processing and reliable control command pattern recognition for neuroprosthetic applications.

  14. Dense Neuron Clustering Explains Connectivity Statistics in Cortical Microcircuits

    PubMed Central

    Klinshov, Vladimir V.; Teramae, Jun-nosuke; Nekorkin, Vladimir I.; Fukai, Tomoki

    2014-01-01

    Local cortical circuits appear highly non-random, but the underlying connectivity rule remains elusive. Here, we analyze experimental data observed in layer 5 of rat neocortex and suggest a model for connectivity from which emerge essential observed non-random features of both wiring and weighting. These features include lognormal distributions of synaptic connection strength, anatomical clustering, and strong correlations between clustering and connection strength. Our model predicts that cortical microcircuits contain large groups of densely connected neurons which we call clusters. We show that such a cluster contains about one fifth of all excitatory neurons of a circuit which are very densely connected with stronger than average synapses. We demonstrate that such clustering plays an important role in the network dynamics, namely, it creates bistable neural spiking in small cortical circuits. Furthermore, introducing local clustering in large-scale networks leads to the emergence of various patterns of persistent local activity in an ongoing network activity. Thus, our results may bridge a gap between anatomical structure and persistent activity observed during working memory and other cognitive processes. PMID:24732632

  15. Computational Study of Subdural Cortical Stimulation: Effects of Simulating Anisotropic Conductivity on Activation of Cortical Neurons

    PubMed Central

    Seo, Hyeon; Kim, Donghyeon; Jun, Sung Chan

    2015-01-01

    Subdural cortical stimulation (SuCS) is an appealing method in the treatment of neurological disorders, and computational modeling studies of SuCS have been applied to determine the optimal design for electrotherapy. To achieve a better understanding of computational modeling on the stimulation effects of SuCS, the influence of anisotropic white matter conductivity on the activation of cortical neurons was investigated in a realistic head model. In this paper, we constructed pyramidal neuronal models (layers 3 and 5) that showed primary excitation of the corticospinal tract, and an anatomically realistic head model reflecting complex brain geometry. The anisotropic information was acquired from diffusion tensor magnetic resonance imaging (DT-MRI) and then applied to the white matter at various ratios of anisotropic conductivity. First, we compared the isotropic and anisotropic models; compared to the isotropic model, the anisotropic model showed that neurons were activated in the deeper bank during cathodal stimulation and in the wider crown during anodal stimulation. Second, several popular anisotropic principles were adapted to investigate the effects of variations in anisotropic information. We observed that excitation thresholds varied with anisotropic principles, especially with anodal stimulation. Overall, incorporating anisotropic conductivity into the anatomically realistic head model is critical for accurate estimation of neuronal responses; however, caution should be used in the selection of anisotropic information. PMID:26057524

  16. Self-organization and neuronal avalanches in networks of dissociated cortical neurons.

    PubMed

    Pasquale, V; Massobrio, P; Bologna, L L; Chiappalone, M; Martinoia, S

    2008-06-02

    Dissociated cortical neurons from rat embryos cultured onto micro-electrode arrays exhibit characteristic patterns of electrophysiological activity, ranging from isolated spikes in the first days of development to highly synchronized bursts after 3-4 weeks in vitro. In this work we analyzed these features by considering the approach proposed by the self-organized criticality theory: we found that networks of dissociated cortical neurons also generate spontaneous events of spreading activity, previously observed in cortical slices, in the form of neuronal avalanches. Choosing an appropriate time scale of observation to detect such neuronal avalanches, we studied the dynamics by considering the spontaneous activity during acute recordings in mature cultures and following the development of the network. We observed different behaviors, i.e. sub-critical, critical or super-critical distributions of avalanche sizes and durations, depending on both the age and the development of cultures. In order to clarify this variability, neuronal avalanches were correlated with other statistical parameters describing the global activity of the network. Criticality was found in correspondence to medium synchronization among bursts and high ratio between bursting and spiking activity. Then, the action of specific drugs affecting global bursting dynamics (i.e. acetylcholine and bicuculline) was investigated to confirm the correlation between criticality and regulated balance between synchronization and variability in the bursting activity. Finally, a computational model of neuronal network was developed in order to interpret the experimental results and understand which parameters (e.g. connectivity, excitability) influence the distribution of avalanches. In summary, cortical neurons preserve their capability to self-organize in an effective network even when dissociated and cultured in vitro. The distribution of avalanche features seems to be critical in those cultures displaying

  17. Neurotoxicity of heroin-cocaine combinations in rat cortical neurons.

    PubMed

    Cunha-Oliveira, Teresa; Rego, A Cristina; Garrido, Jorge; Borges, Fernanda; Macedo, Tice; Oliveira, Catarina R

    2010-09-30

    Cocaine and heroin are frequently co-abused by humans, in a combination known as speedball. Recently, chemical interactions between heroin (Her) or its metabolite morphine (Mor) and cocaine (Coc) were described, resulting in the formation of strong adducts. In this work, we evaluated whether combinations of Coc and Her affect the neurotoxicity of these drugs, using rat cortical neurons incubated with Coc, Her, Her followed by Coc (Her+Coc) and Her plus Coc (Her:Coc, 1:1). Neurons exposed to Her, Her+Coc and Her:Coc exhibited a decrease in cell viability, which was more pronounced in neurons exposed to Her and Her+Coc, in comparison with neurons exposed to the mixture (Her:Coc). Cells exposed to the mixture showed increased intracellular calcium and mitochondrial dysfunction, as determined by a decrease in intracellular ATP levels and in mitochondrial membrane potential, displaying both apoptotic and necrotic characteristics. Conversely, a major increase in cytochrome c release, caspase 3-dependent apoptosis, and decreased metabolic neuronal viability were observed upon sequential exposure to Her and Coc. The data show that drug combinations potentiate cortical neurotoxicity and that the mode of co-exposure changes cellular death pathways activated by the drugs, strongly suggesting that chemical interactions occurring in Her:Coc, such as adduct formation, shift cell death mechanisms towards necrosis. Since impairment of the prefrontal cortex is involved in the loss of impulse control observed in drug addicts, the data presented here may contribute to explain the increase in treatment failure observed in speedball abusers.

  18. Human Temporal Cortical Single Neuron Activity during Language: A Review

    PubMed Central

    Ojemann, George A.

    2013-01-01

    Findings from recordings of human temporal cortical single neuron activity during several measures of language, including object naming and word reading are reviewed and related to changes in activity in the same neurons during recent verbal memory and verbal associative learning measures, in studies conducted during awake neurosurgery for the treatment of epilepsy. The proportion of neurons changing activity with language tasks was similar in either hemisphere. Dominant hemisphere activity was characterized by relative inhibition, some of which occurred during overt speech, possibly to block perception of one’s own voice. However, the majority seems to represent a dynamic network becoming active with verbal memory encoding and especially verbal learning, but inhibited during performance of overlearned language tasks. Individual neurons are involved in different networks for different aspects of language, including naming or reading and naming in different languages. The majority of the changes in activity were tonic sustained shifts in firing. Patterned phasic activity for specific language items was very infrequently recorded. Human single neuron recordings provide a unique perspective on the biologic substrate for language, for these findings are in contrast to many of the findings from other techniques for investigating this. PMID:24961418

  19. Leading role of thalamic over cortical neurons during postinhibitory rebound excitation

    PubMed Central

    Grenier, F.; Timofeev, I.; Steriade, M.

    1998-01-01

    The postinhibitory rebound excitation is an intrinsic property of thalamic and cortical neurons that is implicated in a variety of normal and abnormal operations of neuronal networks, such as slow or fast brain rhythms during different states of vigilance as well as seizures. We used dual simultaneous intracellular recordings of thalamocortical neurons from the ventrolateral nucleus and neurons from the motor cortex, together with thalamic and cortical field potentials, to investigate the temporal relations between thalamic and cortical events during the rebound excitation that follows prolonged periods of stimulus-induced inhibition. Invariably, the rebound spike-bursts in thalamocortical cells occurred before the rebound depolarization in cortical neurons and preceded the peak of the depth-negative, rebound field potential in cortical areas. Also, the inhibitory-rebound sequences were more pronounced and prolonged in cortical neurons when elicited by thalamic stimuli, compared with cortical stimuli. The role of thalamocortical loops in the rebound excitation of cortical neurons was shown further by the absence of rebound activity in isolated cortical slabs. However, whereas thalamocortical neurons remained hyperpolarized after rebound excitation, because of the prolonged spike-bursts in inhibitory thalamic reticular neurons, the rebound depolarization in cortical neurons was prolonged, suggesting the role of intracortical excitatory circuits in this sustained activity. The role of intrathalamic events in triggering rebound cortical activity should be taken into consideration when analyzing information processes at the cortical level; at each step, corticothalamic volleys can set into action thalamic inhibitory neurons, leading to rebound spike-bursts that are transferred back to the cortex, thus modifying cortical activities. PMID:9811903

  20. Multilaminar networks of cortical neurons integrate common inputs from sensory thalamus.

    PubMed

    Morgenstern, Nicolás A; Bourg, Jacques; Petreanu, Leopoldo

    2016-08-01

    Neurons in the thalamorecipient layers of sensory cortices integrate thalamic and recurrent cortical input. Cortical neurons form fine-scale, functionally cotuned networks, but whether interconnected cortical neurons within a column process common thalamocortical inputs is unknown. We tested how local and thalamocortical connectivity relate to each other by analyzing cofluctuations of evoked responses in cortical neurons after photostimulation of thalamocortical axons. We found that connected pairs of pyramidal neurons in layer (L) 4 of mouse visual cortex share more inputs from the dorsal lateral geniculate nucleus than nonconnected pairs. Vertically aligned connected pairs of L4 and L2/3 neurons were also preferentially contacted by the same thalamocortical axons. Our results provide a circuit mechanism for the observed amplification of sensory responses by L4 circuits. They also show that sensory information is concurrently processed in L4 and L2/3 by columnar networks of interconnected neurons contacted by the same thalamocortical axons.

  1. [Collective behavior of cortical neurons upon long-term reinforcement].

    PubMed

    Zhadin, M N

    1995-01-01

    The differential equation describing behaviour of a large ensemble of cortical cells under the extended action of positive or negative reinforcement is derived. The equation is based on the concept that the reinforcement changes synaptic effectiveness in the learning process and a sign of this change depends on an average pulse frequency of a presynaptic neuron and a reinforcement sign. This equation turns out to be identical to the equation which was derived by us earlier based on the ideas that the reinforcement influences on a threshold of neuronal excitation. The comparison of the equation solution with our experimental data lends support for the solution and enables to believe that the serotoninergic system of the brain is a terminal link of the positive reinforcement system and that the noradrenalinergic one is a terminal link of the negative reinforcement.

  2. Axon guidance of rat cortical neurons by microcontact printed gradients.

    PubMed

    Fricke, Rita; Zentis, Peter D; Rajappa, Lionel T; Hofmann, Boris; Banzet, Marko; Offenhäusser, Andreas; Meffert, Simone H

    2011-03-01

    Substrate-bound gradients expressed in numerous spatio-temporal patterns play a crucial role during the development of complex neural circuits. A deeper understanding of the axon guidance mechanism is provided by studying the effect of a defined substrate-bound cue on a confined neural network. In this study, we constructed a discontinuous substrate-bound gradient to control neuronal cell position, the path of neurite growth, and axon directionality. A variety of gradient patterns, with slight changes in slope, width, and length were designed and fabricated by microcontact printing using laminin/poly-l-lysine (PLL) or PLL alone. The gradients were tested for neurite growth and their impact on axon guidance of embryonic rat cortical neurons. The neurite length was determined and the axon was evaluated by Tau-1 immunostaining. We found that the microgradients of laminin/PLL and PLL directed neurons' adhesion, differentially controlled the neurite growth, and guided up to 84% of the axons. The effect of the protein micropattern on axon guidance and neurite growth depended on the protein and geometric parameters used. Our approach proved to be very successful in guiding axons of single multipolar neurons with very high efficiency. It could thereby be useful to engineer defined neural networks for analyzing signal processing of functional circuits, as well as to unravel fundamental questions of the axon guidance mechanism.

  3. Transcranial electric stimulation entrains cortical neuronal populations in rats

    PubMed Central

    Ozen, Simal; Sirota, Anton; Belluscio, Mariano A.; Anastassiou, Costas A.; Stark, Eran; Koch, Christof; Buzsáki, György

    2010-01-01

    Low intensity electric fields have been suggested to affect the ongoing neuronal activity in vitro and in human studies. However, the physiological mechanism of how weak electrical fields affect and interact with intact brain activity is not well understood. We performed in vivo extracellular and intracellular recordings from the neocortex and hippocampus of anaesthetized rats and extracellular recordings in behaving rats. Electric fields were generated by sinusoid patterns at slow frequency (0.8, 1.25 or 1.7 Hz) via electrodes placed on the surface of the skull or the dura. Transcranial electric stimulation (TES) reliably entrained neurons in widespread cortical areas, including the hippocampus. The percentage of TES phase-locked neurons increased with stimulus intensity and depended on the behavioral state of the animal. TES-induced voltage gradient, as low as 1 mV/mm at the recording sites, was sufficient to phase-bias neuronal spiking. Intracellular recordings showed that both spiking and subthreshold activity were under the combined influence of TES forced fields and network activity. We suggest that TES in chronic preparations may be used for experimental and therapeutic control of brain activity. PMID:20739569

  4. Order-Based Representation in Random Networks of Cortical Neurons

    PubMed Central

    Kermany, Einat; Lyakhov, Vladimir; Zrenner, Christoph; Marom, Shimon

    2008-01-01

    The wide range of time scales involved in neural excitability and synaptic transmission might lead to ongoing change in the temporal structure of responses to recurring stimulus presentations on a trial-to-trial basis. This is probably the most severe biophysical constraint on putative time-based primitives of stimulus representation in neuronal networks. Here we show that in spontaneously developing large-scale random networks of cortical neurons in vitro the order in which neurons are recruited following each stimulus is a naturally emerging representation primitive that is invariant to significant temporal changes in spike times. With a relatively small number of randomly sampled neurons, the information about stimulus position is fully retrievable from the recruitment order. The effective connectivity that makes order-based representation invariant to time warping is characterized by the existence of stations through which activity is required to pass in order to propagate further into the network. This study uncovers a simple invariant in a noisy biological network in vitro; its applicability under in vivo constraints remains to be seen. PMID:19023409

  5. Engineering cortical neuron polarity with nanomagnets on a chip.

    PubMed

    Kunze, Anja; Tseng, Peter; Godzich, Chanya; Murray, Coleman; Caputo, Anna; Schweizer, Felix E; Di Carlo, Dino

    2015-01-01

    Intra- and extracellular signaling play critical roles in cell polarity, ultimately leading to the development of functional cell-cell connections, tissues, and organs. In the brain, pathologically oriented neurons are often the cause for disordered circuits, severely impacting motor function, perception, and memory. Aside from control through gene expression and signaling pathways, it is known that nervous system development can be manipulated by mechanical stimuli (e.g., outgrowth of axons through externally applied forces). The inverse is true as well: intracellular molecular signals can be converted into forces to yield axonal outgrowth. The complete role played by mechanical signals in mediating single-cell polarity, however, remains currently unclear. Here we employ highly parallelized nanomagnets on a chip to exert local mechanical stimuli on cortical neurons, independently of the amount of superparamagnetic nanoparticles taken up by the cells. The chip-based approach was utilized to quantify the effect of nanoparticle-mediated forces on the intracellular cytoskeleton as visualized by the distribution of the microtubule-associated protein tau. While single cortical neurons prefer to assemble tau proteins following poly-L-lysine surface cues, an optimal force range of 4.5-70 pN by the nanomagnets initiated a tau distribution opposed to the pattern cue. In larger cell clusters (groups comprising six or more cells), nanoparticle-mediated forces induced tau repositioning in an observed range of 190-270 pN, and initiation of magnetic field-directed cell displacement was observed at forces above 300 pN. Our findings lay the groundwork for high-resolution mechanical encoding of neural networks in vitro, mechanically driven cell polarization in brain tissues, and neurotherapeutic approaches using functionalized superparamagnetic nanoparticles to potentially restore disordered neural circuits.

  6. Active cortical innervation protects striatal neurons from slow degeneration in culture.

    PubMed

    Fishbein, Ianai; Segal, Menahem

    2011-03-01

    Spiny striatal GABAergic neurons receive most of their excitatory input from the neocortex. In culture, striatal neurons form inhibitory connections, but the lack of intrinsic excitatory afferents prevents the development of spontaneous network activity. Addition of cortical neurons to the striatal culture provides the necessary excitatory input to the striatal neurons, and in the presence of these neurons, striatal cultures do express spontaneous network activity. We have confirmed that cortical neurons provide excitatory drive to striatal neurons in culture using paired recording from cortical and striatal neurons. In the presence of tetrodotoxin (TTX), which blocks action potential discharges, the connections between cortical and striatal neurons are still formed, and in fact synaptic currents generated between them when TTX is removed are far larger than in control, undrugged cultures. Interestingly, the continuous presence of TTX in the co-culture caused striatal cell death. These observations indicate that the mere presence of cortical neurons is not sufficient to preserve striatal neurons in culture, but their synchronous activity, triggered by cortical excitatory synapses, is critical for the maintenance of viability of striatal neurons. These results have important implications for understanding the role of activity in neurodegenerative diseases of the striatum.

  7. Growth and follow-up of primary cortical neuron cells on nonfunctionalized graphene nanosheet film.

    PubMed

    Meng, Shiyun; Peng, Rong

    2016-04-06

    Conductive biomaterials are an ideal biosubstrate for modifying cellular behaviors by conducting either internal or external electrical signals. In this study, based on a simple-preparation graphite exfoliation method in organic reagent, a nonfunctionalized graphene nanosheet film (NGNF) with high conductivity and large size was simply fabricated through spraying coating. The biocompatibility of the NGNF was carefully tested with primary cortical neuron cells, and its biocompatibility properties were compared with a chemical vapor deposition (CVD) graphene film. Nonfunctionalized graphene nanosheet (NGN) was first exfoliated from graphite with a flat-tip ultrasonicator probe, and then spray-coated onto glass slide substrate to form the film. The morphology of NGNF was observed with light microscopy and SEM. The morphology and neuronal network formation of primary cortical neuron cells onto NGNF, as shown by DAPI and Alexa Fluor® 488 staining, were observed with fluorescent microscopy. Cell viability and proliferation were measured with MTT. NGNF had better cell biocompatibility than CVD graphene film. MTT test showed that NGNF exhibited no cytotoxicity. According to neuronal network formation at 7 days of cell culture, primary neuron cells aggregated into 50-μm "nuclei"; the average neurite number and length were 3 and 100 μm, respectively. However, these values were almost doubled after 14 days of cell culture. These results may improve the use of NGNF as a conductive scaffold for nerve regeneration.

  8. Cytokine immunoreactivity in cortical and subcortical neurons in periventricular leukomalacia: are cytokines implicated in neuronal dysfunction in cerebral palsy?

    PubMed

    Kadhim, Hazim; Tabarki, Brahim; De Prez, Carine; Sébire, Guillaume

    2003-03-01

    The major neuropathological substrate associated with cerebral palsy (CP) is a form of white matter (WM) injury known as periventricular leukomalacia (PVL). Proinflammatory cytokines were recently shown to be implicated in PVL pathogenesis. Many PVL patients develop cortical and deep gray neuronal dysfunctions such as epilepsy, cognitive deficits and extrapyramidal disorders. The precise nature of the relationship between the WM lesion and the subsequent neuronal disorders is unclear. Cytokines were shown to exert neurotoxicity in experimental models. This raises the need to investigate a possible noxious effect by cytokines on neuronal cortical development. In situ immunohistochemical methods were applied on 22 brains from infants both with PVL (study group) and without PVL (control group) to detect any immunoreactivity for cytokines (TNF-alpha, IL-1beta, IL-6) in cortical and gray matter neurons. While cortical and other neuronal structures in PVL brains did not display noticeable pathological anomalies, strong cytokine immunoreactivity was detected in many neurons in the neocortex, hippocampus, basal ganglia and thalamus. There were, however, regional differences in cytokine labeling. In addition, there was more TNF-alpha staining than IL-1beta; IL-6 was negative. In contrast, neuronal cytokine labeling in the "control" brains was negligible. In conclusion, we report and characterize, for the first time, the in situ immunoreactivity for proinflammatory cytokines in cortical and deep gray neurons in PVL. These findings might provide insights into the neuro-anatomical correlate for the intellectual deficits and the other cortical and deep gray neuronal dysfunctions associated with PVL.

  9. 14,15-EET promotes mitochondrial biogenesis and protects cortical neurons against oxygen/glucose deprivation-induced apoptosis

    SciTech Connect

    Wang, Lai; Chen, Man; Yuan, Lin; Xiang, Yuting; Zheng, Ruimao; Zhu, Shigong

    2014-07-18

    Highlights: • 14,15-EET inhibits OGD-induced apoptosis in cortical neurons. • Mitochondrial biogenesis of cortical neurons is promoted by 14,15-EET. • 14,15-EET preserves mitochondrial function of cortical neurons under OGD. • CREB mediates effect of 14,15-EET on mitochondrial biogenesis and function. - Abstract: 14,15-Epoxyeicosatrienoic acid (14,15-EET), a metabolite of arachidonic acid, is enriched in the brain cortex and exerts protective effect against neuronal apoptosis induced by ischemia/reperfusion. Although apoptosis has been well recognized to be closely associated with mitochondrial biogenesis and function, it is still unclear whether the neuroprotective effect of 14,15-EET is mediated by promotion of mitochondrial biogenesis and function in cortical neurons under the condition of oxygen–glucose deprivation (OGD). In this study, we found that 14,15-EET improved cell viability and inhibited apoptosis of cortical neurons. 14,15-EET significantly increased the mitochondrial mass and the ratio of mitochondrial DNA to nuclear DNA. Key makers of mitochondrial biogenesis, peroxisome proliferator activator receptor gamma-coactivator 1 alpha (PGC-1α), nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM), were elevated at both mRNA and protein levels in the cortical neurons treated with 14,15-EET. Moreover, 14,15-EET markedly attenuated the decline of mitochondrial membrane potential, reduced ROS, while increased ATP synthesis. Knockdown of cAMP-response element binding protein (CREB) by siRNA blunted the up-regulation of PGC-1α and NRF-1 stimulated by 14,15-EET, and consequently abolished the neuroprotective effect of 14,15-EET. Our results indicate that 14,15-EET protects neurons from OGD-induced apoptosis by promoting mitochondrial biogenesis and function through CREB mediated activation of PGC-1α and NRF-1.

  10. Using melanopsin to study G protein signaling in cortical neurons.

    PubMed

    McGregor, K M; Bécamel, C; Marin, P; Andrade, R

    2016-09-01

    Our understanding of G protein-coupled receptors (GPCRs) in the central nervous system (CNS) has been hampered by the limited availability of tools allowing for the study of their signaling with precise temporal control. To overcome this, we tested the utility of the bistable mammalian opsin melanopsin to examine G protein signaling in CNS neurons. Specifically, we used biolistic (gene gun) approaches to transfect melanopsin into cortical pyramidal cells maintained in organotypic slice culture. Whole cell recordings from transfected neurons indicated that application of blue light effectively activated the transfected melanopsin to elicit the canonical biphasic modulation of membrane excitability previously associated with the activation of GPCRs coupling to Gαq-11 Remarkably, full mimicry of exogenous agonist concentration could be obtained with pulses as short as a few milliseconds, suggesting that their triggering required a single melanopsin activation-deactivation cycle. The resulting temporal control over melanopsin activation allowed us to compare the activation kinetics of different components of the electrophysiological response. We also replaced the intracellular loops of melanopsin with those of the 5-HT2A receptor to create a light-activated GPCR capable of interacting with the 5-HT2A receptor interacting proteins. The resulting chimera expressed weak activity but validated the potential usefulness of melanopsin as a tool for the study of G protein signaling in CNS neurons. Copyright © 2016 the American Physiological Society.

  11. Spontaneous, synchronous electrical activity in neonatal mouse cortical neurones

    PubMed Central

    Corlew, Rebekah; Bosma, Martha M; Moody, William J

    2004-01-01

    Spontaneous [Ca2+]i transients were measured in the mouse neocortex from embryonic day 16 (E16) to postnatal day 6 (P6). On the day of birth (P0), cortical neurones generated widespread, highly synchronous [Ca2+]i transients over large areas. On average, 52% of neurones participated in these transients, and in 20% of slices, an average of 80% participated. These transients were blocked by TTX and nifedipine, indicating that they resulted from Ca2+ influx during electrical activity, and occurred at a mean frequency of 0.91 min−1. The occurrence of this activity was highly centred at P0: at E16 and P2 an average of only 15% and 24% of neurones, respectively, participated in synchronous transients, and they occurred at much lower frequencies at both E16 and P2 than at P0. The overall frequency of [Ca2+]i transients in individual cells did not change between E16 and P2, just the degree of their synchronicity. The onset of this spontaneous, synchronous activity correlated with a large increase in Na+ current density that occurred just before P0, and its cessation with a large decrease in resting resistance that occurred just after P2. This widespread, synchronous activity may serve a variety of functions in the neonatal nervous system. PMID:15297578

  12. Effects of 810 nm laser on mouse primary cortical neurons

    NASA Astrophysics Data System (ADS)

    Kharkwal, Gitika B.; Sharma, Sulbha K.; Huang, Ying-Ying; De Taboada, Luis; McCarthy, Thomas; Hamblin, Michael R.

    2011-03-01

    In the past four decades numerous studies have reported the efficacy of low level light (laser) therapy (LLLT) as a treatment for diverse diseases and injuries. Recent studies have shown that LLLT can biomodulate processes in the central nervous system and has been extensively studied as a stroke treatment. However there is still a lack of knowledge on the effects of LLLT at the cellular level in neurons. The present study aimed to study the effect of 810 nm laser on several cellular processes in primary cortical neurons cultured from mouse embryonic brains. Neurons were irradiated with light dose of 0.03, 0.3, 3, 10 and 30 J/cm2 and intracellular levels of reactive oxygen species, nitric oxide and calcium were measured. The changes in mitochondrial function in response to light were studied in terms of adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP). Light induced a significant increase in calcium, ATP and MMP at lower fluences and a decrease at higher fluence. ROS was induced significantly by light at all light doses. Nitric oxide levels also showed an increase on treatment with light. The results of the present study suggest that LLLT at lower fluences is capable of inducing mediators of cell signaling process which in turn may be responsible for the biomodulatory effects of the low level laser. At higher fluences beneficial mediators are reduced but potentially harmful mediators are increased thus offering an explanation for the biphasic dose response.

  13. Three-dimensional localization of neurons in cortical tetrode recordings

    PubMed Central

    Victor, Jonathan D.; Ohiorhenuan, Ifije; Schmid, Anita M.; Hu, Qin

    2011-01-01

    The recording radius and spatial selectivity of an extracellular probe are important for interpreting neurophysiological recordings but are rarely measured. Moreover, an analysis of the recording biophysics of multisite probes (e.g., tetrodes) can provide for source characterization and localization of spiking single units, but this capability has remained largely unexploited. Here we address both issues quantitatively. Advancing a tetrode (≈40-μm contact separation, tetrahedral geometry) in 5- to 10-μm steps, we repeatedly recorded extracellular action potentials (EAPs) of single neurons in the visual cortex. Using measured spatial variation of EAPs, the tetrodes' measured geometry, and a volume conductor model of the cortical tissue, we solved the inverse problem of estimating the location and the size of the equivalent dipole model of the spike generator associated with each neuron. Half of the 61 visual neurons were localized within a radius of ≈100 μm and 95% within ≈130 μm around the tetrode tip (i.e., a large fraction was much further than previously thought). Because of the combined angular sensitivity of the tetrode's leads, location uncertainty was less than one-half the cell's distance. We quantified the spatial dependence of the probability of cell isolation, the isolated fraction, and the dependence of the recording radius on probe size and equivalent dipole size. We also reconstructed the spatial configuration of sets of simultaneously recorded neurons to demonstrate the potential use of 3D dipole localization for functional anatomy. Finally, we found that the dipole moment vector, surprisingly, tended to point toward the probe, leading to the interpretation that the equivalent dipole represents a “local lobe” of the dendritic arbor. PMID:21613581

  14. Ketamine-induced apoptosis in cultured rat cortical neurons

    SciTech Connect

    Takadera, Tsuneo . E-mail: t-takadera@hokuriku-u.ac.jp; Ishida, Akira; Ohyashiki, Takao

    2006-01-15

    Recent data suggest that anesthetic drugs cause neurodegeneration during development. Ketamine is frequently used in infants and toddlers for elective surgeries. The purpose of this study is to determine whether glycogen synthase kinase-3 (GSK-3) is involved in ketamine-induced apoptosis. Ketamine increased apoptotic cell death with morphological changes which were characterized by cell shrinkage, nuclear condensation or fragmentation. In addition, insulin growth factor-1 completely blocked the ketamine-induced apoptotic cell death. Ketamine decreased Akt phosphorylation. GSK-3 is known as a downstream target of Akt. The selective inhibitors of GSK-3 prevented the ketamine-induced apoptosis. Moreover, caspase-3 activation was accompanied by the ketamine-induced cell death and inhibited by the GSK-3 inhibitors. These results suggest that activation of GSK-3 is involved in ketamine-induced apoptosis in rat cortical neurons.

  15. Early neurone loss in Alzheimer's disease: cortical or subcortical?

    PubMed

    Arendt, Thomas; Brückner, Martina K; Morawski, Markus; Jäger, Carsten; Gertz, Hermann-Josef

    2015-02-10

    Alzheimer's disease (AD) is a degenerative disorder where the distribution of pathology throughout the brain is not random but follows a predictive pattern used for pathological staging. While the involvement of defined functional systems is fairly well established for more advanced stages, the initial sites of degeneration are still ill defined. The prevailing concept suggests an origin within the transentorhinal and entorhinal cortex (EC) from where pathology spreads to other areas. Still, this concept has been challenged recently suggesting a potential origin of degeneration in nonthalamic subcortical nuclei giving rise to cortical innervation such as locus coeruleus (LC) and nucleus basalis of Meynert (NbM). To contribute to the identification of the early site of degeneration, here, we address the question whether cortical or subcortical degeneration occurs more early and develops more quickly during progression of AD. To this end, we stereologically assessed neurone counts in the NbM, LC and EC layer-II in the same AD patients ranging from preclinical stages to severe dementia. In all three areas, neurone loss becomes detectable already at preclinical stages and is clearly manifest at prodromal AD/MCI. At more advanced AD, cell loss is most pronounced in the NbM > LC > layer-II EC. During early AD, however, the extent of cell loss is fairly balanced between all three areas without clear indications for a preference of one area. We can thus not rule out that there is more than one way of spreading from its site of origin or that degeneration even occurs independently at several sites in parallel.

  16. Neuronal branching patterns and the economy of cortical wiring.

    PubMed

    Mitchison, G

    1991-08-22

    Keeping the volume of connections in the cortex as low as possible may be an important evolutionary constraint on the design of the brain. Much as an engineer tries to arrange the components of a computer in such a way as to give efficient wiring, so the brain may have evolved a layout of neuronal types which gives an economical use of axonal 'wiring'. One key difference between computer and brain is that connections in the brain take the form of elaborate branching structures. It is argued here that certain features of cortical mapping, such as the stripes and patches seen within cortical areas, may be adaptations which allow efficient wiring by such structures. Some simple calculations are given to support this, using as models for axonal arbors certain branching patterns which give a low volume of wiring. In particular, it is shown that a pattern of stripes can give economical wiring when axon diameters follow a law dp = dp1 + dp2 with p greater than 4, where d1 and d2 are the diameters of the daughter branches and d that of the parent.

  17. Loss of MeCP2 From Forebrain Excitatory Neurons Leads to Cortical Hyperexcitation and Seizures

    PubMed Central

    Zhang, Wen; Peterson, Matthew; Beyer, Barbara; Frankel, Wayne N.

    2014-01-01

    Mutations of MECP2 cause Rett syndrome (RTT), a neurodevelopmental disorder leading to loss of motor and cognitive functions, impaired social interactions, and seizure at young ages. Defects of neuronal circuit development and function are thought to be responsible for the symptoms of RTT. The majority of RTT patients show recurrent seizures, indicating that neuronal hyperexcitation is a common feature of RTT. However, mechanisms underlying hyperexcitation in RTT are poorly understood. Here we show that deletion of Mecp2 from cortical excitatory neurons but not forebrain inhibitory neurons in the mouse leads to spontaneous seizures. Selective deletion of Mecp2 from excitatory but not inhibitory neurons in the forebrain reduces GABAergic transmission in layer 5 pyramidal neurons in the prefrontal and somatosensory cortices. Loss of MeCP2 from cortical excitatory neurons reduces the number of GABAergic synapses in the cortex, and enhances the excitability of layer 5 pyramidal neurons. Using single-cell deletion of Mecp2 in layer 2/3 pyramidal neurons, we show that GABAergic transmission is reduced in neurons without MeCP2, but is normal in neighboring neurons with MeCP2. Together, these results suggest that MeCP2 in cortical excitatory neurons plays a critical role in the regulation of GABAergic transmission and cortical excitability. PMID:24523563

  18. Human temporal cortical single neuron activity during working memory maintenance.

    PubMed

    Zamora, Leona; Corina, David; Ojemann, George

    2016-06-01

    The Working Memory model of human memory, first introduced by Baddeley and Hitch (1974), has been one of the most influential psychological constructs in cognitive psychology and human neuroscience. However the neuronal correlates of core components of this model have yet to be fully elucidated. Here we present data from two studies where human temporal cortical single neuron activity was recorded during tasks differentially affecting the maintenance component of verbal working memory. In Study One we vary the presence or absence of distracting items for the entire period of memory storage. In Study Two we vary the duration of storage so that distractors filled all, or only one-third of the time the memory was stored. Extracellular single neuron recordings were obtained from 36 subjects undergoing awake temporal lobe resections for epilepsy, 25 in Study one, 11 in Study two. Recordings were obtained from a total of 166 lateral temporal cortex neurons during performance of one of these two tasks, 86 study one, 80 study two. Significant changes in activity with distractor manipulation were present in 74 of these neurons (45%), 38 Study one, 36 Study two. In 48 (65%) of those there was increased activity during the period when distracting items were absent, 26 Study One, 22 Study Two. The magnitude of this increase was greater for Study One, 47.6%, than Study Two, 8.1%, paralleling the reduction in memory errors in the absence of distracters, for Study One of 70.3%, Study Two 26.3% These findings establish that human lateral temporal cortex is part of the neural system for working memory, with activity during maintenance of that memory that parallels performance, suggesting it represents active rehearsal. In 31 of these neurons (65%) this activity was an extension of that during working memory encoding that differed significantly from the neural processes recorded during overt and silent language tasks without a recent memory component, 17 Study one, 14 Study two

  19. Exogenous Reelin modifies the migratory behavior of neurons depending on cortical location.

    PubMed

    Britto, Joanne M; Tait, Karen J; Lee, Ean Phing; Gamble, Robin S; Hattori, Mitsuharu; Tan, Seong-Seng

    2014-11-01

    Malformations of cortical development can arise when projection neurons generated in the germinal zones fail to migrate properly into the cortical plate. This process is critically dependent on the Reelin glycoprotein, which when absent leads to an inversion of cortical layers and blurring of borders. Reelin has other functions including supporting neuron migration and maintaining their trajectories; however, the precise role on glial fiber-dependent or -independent migration of neurons remains controversial. In this study, we wish to test the hypothesis that migrating cortical neurons at different levels of the cortical wall have differential responses to Reelin. We exposed neurons migrating across the cortical wall to exogenous Reelin and monitored their migratory behavior using time-lapse imaging. Our results show that, in the germinal zones, exogenous Reelin retarded neuron migration and altered their trajectories. This behavior is in contrast to the response of neurons located in the intermediate zone (IZ), possibly because Reelin receptors are not expressed in this zone. In the reeler cortex, Reelin receptors are expressed in the IZ and exposure to exogenous Reelin was able to rescue the migratory defect. These studies demonstrate that migrating neurons have nonequivalent responses to Reelin depending on their location within the cortical wall.

  20. Neurodegenerative, with expression ATF-2 by p38 in cortical neurons.

    PubMed

    Hosseini, M; Ostad, N; Parivar, K; Ghahremani, M H

    2010-03-01

    DNA damage, as an important initiator of neuronal cell death, has been implicated in numerous neurodegenerative conditions. We previously delineated several pathways that control embryonic cortical neuronal cell death evoked by the DNA-damaging agent, camptothecin. The topisomerase-1 inhibitor, camptothecin, has been shown to induce cortical neuronal cell death in a reproducible and synchronistic manner. Primary embryonic neuronal cell culture cortical neurons were prepared. In the study, the survival % of neurons in camptothecin P38 group, after 6 hours (85%), 24 hours (64%) and 48 hours (50%), compared to camptothecin ATF-2 and P38 group after 4 hours (97 and 95%), have been significantly lower, and the expression % of neurons in camptothecin P38 group , after 6 hours (20%), 24 hours (40%) and 48 hours (55%), compared to camptothecin ATF-2 and P38 group after 4 hours (5 and 3%) have been significant lower (p<0.05). The expression % of neurons in camptothecin P38 group, after 24 hours (40%), compared to camptothecin ATF-2 group after 24hours (30%), have been significant lower (p<0.05). This study revealed that camptothecin induces P38 expression and P38 in embryonic cortical neurons to determine the importance of the P38 pathway in neuronal death following DNA damage, and P38 is induce phosphorylation of ATF-2 in embryonic cortical neurons following DNA damage.

  1. Alterations in cortical thickness and neuronal density in the frontal cortex of Albert Einstein.

    PubMed

    Anderson, B; Harvey, T

    1996-06-07

    Neuronal density, neuron size, and the number of neurons under 1 mm2 of cerebral cortical surface area were measured in the right pre-frontal cortex of Albert Einstein and five elderly control subjects. Measurement of neuronal density used the optical dissector technique on celloidin-embedded cresyl violet-stained sections. The neurons counted provided a systematic random sample for the measurement of cell body cross-sectional area. Einstein's cortex did not differ from the control subjects in the number of neurons under 1 mm2 of cerebral cortex or in mean neuronal size. Because Einstein's cortex was thinner than the controls he had a greater neuronal density.

  2. Cortical neuron loss in post-traumatic higher brain dysfunction using (123)I-iomazenil SPECT.

    PubMed

    Nakagawara, Jyoji; Kamiyama, Kenji; Takahashi, Masaaki; Nakamura, Hirohiko

    2013-01-01

    In patients with higher brain dysfunction (HBD) after mild traumatic brain injury (MTBI), diagnostic imaging of cortical neuron loss in the frontal lobes was studied using SPECT with (123)I-iomazenil (IMZ), as a radioligand for central benzodiazepine receptor (BZR). Statistical imaging analysis using three-dimensional stereotactic surface projections (3D-SSP) for (123)I-IMZ SPECT was performed in 17 patients. In all patients with HBD defined by neuropsychological tests, cortical neuron loss was indicated in the bilateral medial frontal lobes in 14 patients (83 %). A comparison between the group of 17 patients and the normal database demonstrated common areas of cortical neuron loss in the bilateral medial frontal lobes involving the medial frontal gyrus (MFG) and the anterior cingulate gyrus (ACG). In an assessment of cortical neuron loss in the frontal medial cortex using the stereotactic extraction estimation (SEE) method (level 3), significant cortical neuron loss was observed within bilateral MFG in 9 patients and unilateral MFG in 4, and bilateral ACG in 12 and unilateral ACG in 3. Fourteen patients showed significant cortical neuron loss in bilateral MFG or ACG. In patients with MTBI, HBD seemed to correlate with selective cortical neuron loss within the bilateral MFG or ACG where the responsible lesion could be. 3D-SSP and SEE level 3 analysis for (123)I-IMZ SPECT could be valuable for diagnostic imaging of HBD after MTBI.

  3. IgLON Cell Adhesion Molecules Are Shed from the Cell Surface of Cortical Neurons to Promote Neuronal Growth*

    PubMed Central

    Sanz, Ricardo; Ferraro, Gino B.; Fournier, Alyson E.

    2015-01-01

    Matrix metalloproteinases and a disintegrin and metalloproteinases are members of the zinc endopeptidases, which cleave components of the extracellular matrix as well as cell surface proteins resulting in degradation or release of biologically active fragments. Surface ectodomain shedding affects numerous biological processes, including survival, axon outgrowth, axon guidance, and synaptogenesis. In this study, we evaluated the role of metalloproteinases in regulating cortical neurite growth. We found that treatment of mature cortical neurons with pan-metalloproteinase inhibitors or with tissue inhibitors of metalloproteinase-3 reduced neurite outgrowth. Through mass spectrometry, we characterized the metalloproteinase-sensitive cell surface proteome of mature cortical neurons. Members of the IgLON family of glycosylphosphatidylinositol-anchored neural cell adhesion molecules were identified and validated as proteins that were shed from the surface of mature cortical neurons in a metalloproteinase-dependent manner. Introduction of two members of the IgLON family, neurotrimin and NEGR1, in early embryonic neurons was sufficient to confer sensitivity to metalloproteinase inhibitors in neurite outgrowth assays. Outgrowth experiments on immobilized IgLON proteins revealed a role for all IgLON family members in promoting neurite extension from cortical neurons. Together, our findings support a role for metalloproteinase-dependent shedding of IgLON family members in regulating neurite outgrowth from mature cortical neurons. PMID:25538237

  4. IgLON cell adhesion molecules are shed from the cell surface of cortical neurons to promote neuronal growth.

    PubMed

    Sanz, Ricardo; Ferraro, Gino B; Fournier, Alyson E

    2015-02-13

    Matrix metalloproteinases and a disintegrin and metalloproteinases are members of the zinc endopeptidases, which cleave components of the extracellular matrix as well as cell surface proteins resulting in degradation or release of biologically active fragments. Surface ectodomain shedding affects numerous biological processes, including survival, axon outgrowth, axon guidance, and synaptogenesis. In this study, we evaluated the role of metalloproteinases in regulating cortical neurite growth. We found that treatment of mature cortical neurons with pan-metalloproteinase inhibitors or with tissue inhibitors of metalloproteinase-3 reduced neurite outgrowth. Through mass spectrometry, we characterized the metalloproteinase-sensitive cell surface proteome of mature cortical neurons. Members of the IgLON family of glycosylphosphatidylinositol-anchored neural cell adhesion molecules were identified and validated as proteins that were shed from the surface of mature cortical neurons in a metalloproteinase-dependent manner. Introduction of two members of the IgLON family, neurotrimin and NEGR1, in early embryonic neurons was sufficient to confer sensitivity to metalloproteinase inhibitors in neurite outgrowth assays. Outgrowth experiments on immobilized IgLON proteins revealed a role for all IgLON family members in promoting neurite extension from cortical neurons. Together, our findings support a role for metalloproteinase-dependent shedding of IgLON family members in regulating neurite outgrowth from mature cortical neurons.

  5. Optogenetic stimulation of cholinergic brainstem neurons during focal limbic seizures: Effects on cortical physiology.

    PubMed

    Furman, Moran; Zhan, Qiong; McCafferty, Cian; Lerner, Benjamin A; Motelow, Joshua E; Meng, Jin; Ma, Chanthia; Buchanan, Gordon F; Witten, Ilana B; Deisseroth, Karl; Cardin, Jessica A; Blumenfeld, Hal

    2015-12-01

    Focal temporal lobe seizures often cause impaired cortical function and loss of consciousness. Recent work suggests that the mechanism for depressed cortical function during focal seizures may depend on decreased subcortical cholinergic arousal, which leads to a sleep-like state of cortical slow-wave activity. To test this hypothesis, we sought to directly activate subcortical cholinergic neurons during focal limbic seizures to determine the effects on cortical function. Here we used an optogenetic approach to selectively stimulate cholinergic brainstem neurons in the pedunculopontine tegmental nucleus during focal limbic seizures induced in a lightly anesthetized rat model. We found an increase in cortical gamma activity and a decrease in delta activity in response to cholinergic stimulation. These findings support the mechanistic role of reduced subcortical cholinergic arousal in causing cortical dysfunction during seizures. Through further work, electrical or optogenetic stimulation of subcortical arousal networks may ultimately lead to new treatments aimed at preventing cortical dysfunction during seizures.

  6. Development and Maturation of Embryonic Cortical Neurons Grafted into the Damaged Adult Motor Cortex

    PubMed Central

    Ballout, Nissrine; Frappé, Isabelle; Péron, Sophie; Jaber, Mohamed; Zibara, Kazem; Gaillard, Afsaneh

    2016-01-01

    Injury to the human central nervous system can lead to devastating consequences due to its poor ability to self-repair. Neural transplantation aimed at replacing lost neurons and restore functional circuitry has proven to be a promising therapeutical avenue. We previously reported in adult rodent animal models with cortical lesions that grafted fetal cortical neurons could effectively re-establish specific patterns of projections and synapses. The current study was designed to provide a detailed characterization of the spatio-temporal in vivo development of fetal cortical transplanted cells within the lesioned adult motor cortex and their corresponding axonal projections. We show here that as early as 2 weeks after grafting, cortical neuroblasts transplanted into damaged adult motor cortex developed appropriate projections to cortical and subcortical targets. Grafted cells initially exhibited characteristics of immature neurons, which then differentiated into mature neurons with appropriate cortical phenotypes where most were glutamatergic and few were GABAergic. All cortical subtypes identified with the specific markers CTIP2, Cux1, FOXP2, and Tbr1 were generated after grafting as evidenced with BrdU co-labeling. The set of data provided here is of interest as it sets biological standards for future studies aimed at replacing fetal cells with embryonic stem cells as a source of cortical neurons. PMID:27536221

  7. Cytotoxicity and cytoprotective activity of naphthalenediols in rat cortical neurons.

    PubMed

    Flueraru, Mihaela; So, Remmick; Willmore, William G; Poulter, Michael O; Durst, Tony; Charron, Martin; Wright, James S

    2006-09-01

    Some members of the naphthalenediol family have been shown in previous work on PC-12 cells to act as effective antioxidants while being relatively nontoxic. In the present work, we extend that study to examine the effect of naphthalenediols on rat primary cortical neurons exposed to AAPH (2,2'-azobis (2-amidinopropane) hydrochloride), a source of peroxyl radicals. Compounds tested included the acetylated forms of 1,2-naphthalenediol, that is, 1,2-ND, as well as 1,4-ND, 2,3-ND, 1,8-ND, and the known highly potent antioxidant (-)-epigallocatechin gallate (EGCG). In cytoxicity studies, cells were exposed to the compounds for 24 h, leading to observed toxicity in the order of 1,4-ND > 1,2 ND > 2,3-ND approximately EGCG > 1,8-ND. In cytoprotection studies, the desired compounds were incubated with neurons prior to AAPH exposure, and live cell counts were determined by trypan blue and/or MTT assays. Excellent protection, superior to EGCG, was provided by 2,3-ND and 1,8-ND. Additional studies using glutamate as a stressor showed that 1,8-ND had a significant protective effect at concentrations as low as 500 nM. The results can be understood on the basis of the tendency (or lack thereof) to form the corresponding quinone, which in turn depends on whether or not there is a loss of aromaticity in the ring adjacent to the quinone moiety. Thus, certain members of the family of naphthalenediols are quite cytotoxic, whereas others show promise as neuroprotective antioxidants.

  8. Enriched Endogenous Omega-3 Polyunsaturated Fatty Acids Protect Cortical Neurons from Experimental Ischemic Injury.

    PubMed

    Shi, Zhe; Ren, Huixia; Luo, Chuanming; Yao, Xiaoli; Li, Peng; He, Chengwei; Kang, Jing-X; Wan, Jian-Bo; Yuan, Ti-Fei; Su, Huanxing

    2016-11-01

    Omega-3 polyunsaturated fatty acids (n-3 PUFAs) exert therapeutic potential in a variety of neurological disorders, including ischemic stroke. However, the underlying mechanisms still lack investigation. Here, we report that cultured cortical neurons isolated from fat-1 mice with high endogenous n-3 PUFAs were tolerant to oxygen-glucose deprivation/reperfusion (OGD/R) injury. Fat-1 neurons exhibited significantly attenuated reactive oxygen species (ROS) activation induced by OGD/R injury, upregulated antiapoptotic proteins Bcl-2 and Bcl-xL, and reduced cleaved caspase-3. Exogenous administration of docosahexaenoic acid (DHA), a major component of the n-3 PUFA family, resulted in similar protective effects on cultured cortex neurons. We further verified the protective effects of n-3 PUFAs in vivo, using a mini ischemic model with a reproducible cortical infarct and manifest function deficits by occlusion of the distal branch of the middle cerebral artery with focused femtosecond laser pulses. The Fat-1 animals showed decreased ROS expression and higher level of glutathione in the injured brain, associated with improved functional recovery. We therefore provide evidence that n-3 PUFAs exert their protective effects against ischemic injury both in vitro and in vivo, partly through inhibiting ROS activation.

  9. Neuropeptide Y protects cerebral cortical neurons by regulating microglial immune function

    PubMed Central

    Li, Qijun; Dong, Changzheng; Li, Wenling; Bu, Wei; Wu, Jiang; Zhao, Wenqing

    2014-01-01

    Neuropeptide Y has been shown to inhibit the immunological activity of reactive microglia in the rat cerebral cortex, to reduce N-methyl-D-aspartate current (INMDA) in cortical neurons, and protect neurons. In this study, after primary cultured microglia from the cerebral cortex of rats were treated with lipopolysaccharide, interleukin-1β and tumor necrosis factor-α levels in the cell culture medium increased, and mRNA expression of these cytokines also increased. After primary cultured cortical neurons were incubated with the lipopolysaccharide-treated microglial conditioned medium, peak INMDA in neurons increased. These effects of lipopolysaccharide were suppressed by neuropeptide Y. After addition of the neuropeptide Y Y1 receptor antagonist BIBP3226, the effects of neuropeptide Y completely disappeared. These results suggest that neuropeptide Y prevents excessive production of interleukin-1β and tumor necrosis factor-α by inhibiting microglial reactivity. This reduces INMDA in rat cortical neurons, preventing excitotoxicity, thereby protecting neurons. PMID:25206918

  10. Euchromatin histone methyltransferase 1 regulates cortical neuronal network development

    PubMed Central

    Bart Martens, Marijn; Frega, Monica; Classen, Jessica; Epping, Lisa; Bijvank, Elske; Benevento, Marco; van Bokhoven, Hans; Tiesinga, Paul; Schubert, Dirk; Nadif Kasri, Nael

    2016-01-01

    Heterozygous mutations or deletions in the human Euchromatin histone methyltransferase 1 (EHMT1) gene cause Kleefstra syndrome, a neurodevelopmental disorder that is characterized by autistic-like features and severe intellectual disability (ID). Neurodevelopmental disorders including ID and autism may be related to deficits in activity-dependent wiring of brain circuits during development. Although Kleefstra syndrome has been associated with dendritic and synaptic defects in mice and Drosophila, little is known about the role of EHMT1 in the development of cortical neuronal networks. Here we used micro-electrode arrays and whole-cell patch-clamp recordings to investigate the impact of EHMT1 deficiency at the network and single cell level. We show that EHMT1 deficiency impaired neural network activity during the transition from uncorrelated background action potential firing to synchronized network bursting. Spontaneous bursting and excitatory synaptic currents were transiently reduced, whereas miniature excitatory postsynaptic currents were not affected. Finally, we show that loss of function of EHMT1 ultimately resulted in less regular network bursting patterns later in development. These data suggest that the developmental impairments observed in EHMT1-deficient networks may result in a temporal misalignment between activity-dependent developmental processes thereby contributing to the pathophysiology of Kleefstra syndrome. PMID:27767173

  11. Reward-timing-dependent bidirectional modulation of cortical microcircuits during optical single-neuron operant conditioning.

    PubMed

    Hira, Riichiro; Ohkubo, Fuki; Masamizu, Yoshito; Ohkura, Masamichi; Nakai, Junichi; Okada, Takashi; Matsuzaki, Masanori

    2014-11-24

    Animals rapidly adapt to environmental change. To reveal how cortical microcircuits are rapidly reorganized when an animal recognizes novel reward contingency, we conduct two-photon calcium imaging of layer 2/3 motor cortex neurons in mice and simultaneously reinforce the activity of a single cortical neuron with water delivery. Here we show that when the target neuron is not relevant to a pre-trained forelimb movement, the mouse increases the target neuron activity and the number of rewards delivered during 15-min operant conditioning without changing forelimb movement behaviour. The reinforcement bidirectionally modulates the activity of subsets of non-target neurons, independent of distance from the target neuron. The bidirectional modulation depends on the relative timing between the reward delivery and the neuronal activity, and is recreated by pairing reward delivery and photoactivation of a subset of neurons. Reward-timing-dependent bidirectional modulation may be one of the fundamental processes in microcircuit reorganization for rapid adaptation.

  12. The age and genomic integrity of neurons after cortical stroke in humans.

    PubMed

    Huttner, Hagen B; Bergmann, Olaf; Salehpour, Mehran; Rácz, Attila; Tatarishvili, Jemal; Lindgren, Emma; Csonka, Tamás; Csiba, László; Hortobágyi, Tibor; Méhes, Gábor; Englund, Elisabet; Solnestam, Beata Werne; Zdunek, Sofia; Scharenberg, Christian; Ström, Lena; Ståhl, Patrik; Sigurgeirsson, Benjamin; Dahl, Andreas; Schwab, Stefan; Possnert, Göran; Bernard, Samuel; Kokaia, Zaal; Lindvall, Olle; Lundeberg, Joakim; Frisén, Jonas

    2014-06-01

    It has been unclear whether ischemic stroke induces neurogenesis or neuronal DNA rearrangements in the human neocortex. Using immunohistochemistry; transcriptome, genome and ploidy analyses; and determination of nuclear bomb test-derived (14)C concentration in neuronal DNA, we found neither to be the case. A large proportion of cortical neurons displayed DNA fragmentation and DNA repair a short time after stroke, whereas neurons at chronic stages after stroke showed DNA integrity, demonstrating the relevance of an intact genome for survival.

  13. Variations in Acetylcholinesterase Activity within Human Cortical Pyramidal Neurons Across Age and Cognitive Trajectories.

    PubMed

    Janeczek, Monica; Gefen, Tamar; Samimi, Mehrnoosh; Kim, Garam; Weintraub, Sandra; Bigio, Eileen; Rogalski, Emily; Mesulam, M-Marsel; Geula, Changiz

    2017-03-01

    We described an extensive network of cortical pyramidal neurons in the human brain with abundant acetylcholinesterase (AChE) activity. Emergence of these neurons during childhood/adolescence, attainment of highest density in early adulthood, and virtual absence in other species led us to hypothesize involvement of AChE within these neurons in higher cortical functions. The current study quantified the density and staining intensity of these neurons using histochemical procedures. Few faintly stained AChE-positive cortical pyramidal neurons were observed in children/adolescents. These neurons attained their highest density and staining intensity in young adulthood. Compared with the young adult group, brains of cognitively normal elderly displayed no significant change in numerical density but a significant decrease in staining intensity of AChE-positive cortical pyramidal neurons. Brains of elderly above age 80 with unusually preserved memory performance (SuperAgers) showed significantly lower staining intensity and density of these neurons when compared with same-age peers. Conceivably, low levels of AChE activity could enhance the impact of acetylcholine on pyramidal neurons to counterbalance other involutional factors that mediate the decline of memory capacity during average aging. We cannot yet tell if elderly with superior memory capacity have constitutively low neuronal AChE levels or if this feature reflects adaptive neuroplasticity.

  14. Expression of gonadotropin-releasing hormone receptor in cerebral cortical neurons of embryos and adult rats.

    PubMed

    Quintanar, J Luis; Salinas, Eva; González, Rodolfo

    2007-01-03

    Mammalian gonadotropin-releasing hormone (GnRH) was initially isolated from hypothalamus and its receptor from anterior pituitary, although extrapituitary GnRH receptors have been reported. The aim of the present study was to investigate whether GnRH receptor and its mRNA are expressed in cerebral cortical neurons of rat embryos and adult rats using immunohistochemical and reverse transcriptase polymerase chain reaction (RT-PCR) techniques. The immunohistochemistry and RT-PCR analysis showed expression of GnRH receptor and presence of its mRNA, in both cerebral cortical neurons of rat embryos and cerebral cortical tissues of adult rats. Additional experiments showed a decrease in the receptor mRNA expression when cultured neurons of rat embryos were treated with GnRH. It is possible that the presence of GnRH receptors in cortical neurons of rat may be involved in other physiological roles such as neurohormone or neuromodulator.

  15. Pulse activity of populations of cortical neurons under microwave exposures of different intensity.

    PubMed

    Chizhenkova, R A

    2004-06-01

    In rabbit pulse flows of populations of cortical neurons were investigated prior to, during, and after 1-min microwave irradiation (wavelength 37.5 cm, power density 0.2-40 mW/cm2). It was found that the microwave irradiation produced shifts in mean values of interspike intervals and in the number of spike bursts. Peculiarities of rearrangements of pulse flows of cortical neurons were conditioned by an intensity of exposures.

  16. Distribution of neurons in functional areas of the mouse cerebral cortex reveals quantitatively different cortical zones.

    PubMed

    Herculano-Houzel, Suzana; Watson, Charles; Paxinos, George

    2013-01-01

    How are neurons distributed along the cortical surface and across functional areas? Here we use the isotropic fractionator (Herculano-Houzel and Lent, 2005) to analyze the distribution of neurons across the entire isocortex of the mouse, divided into 18 functional areas defined anatomically. We find that the number of neurons underneath a surface area (the N/A ratio) varies 4.5-fold across functional areas and neuronal density varies 3.2-fold. The face area of S1 contains the most neurons, followed by motor cortex and the primary visual cortex. Remarkably, while the distribution of neurons across functional areas does not accompany the distribution of surface area, it mirrors closely the distribution of cortical volumes-with the exception of the visual areas, which hold more neurons than expected for their volume. Across the non-visual cortex, the volume of individual functional areas is a shared linear function of their number of neurons, while in the visual areas, neuronal densities are much higher than in all other areas. In contrast, the 18 functional areas cluster into three different zones according to the relationship between the N/A ratio and cortical thickness and neuronal density: these three clusters can be called visual, sensory, and, possibly, associative. These findings are remarkably similar to those in the human cerebral cortex (Ribeiro et al., 2013) and suggest that, like the human cerebral cortex, the mouse cerebral cortex comprises two zones that differ in how neurons form the cortical volume, and three zones that differ in how neurons are distributed underneath the cortical surface, possibly in relation to local differences in connectivity through the white matter. Our results suggest that beyond the developmental divide into visual and non-visual cortex, functional areas initially share a common distribution of neurons along the parenchyma that become delimited into functional areas according to the pattern of connectivity established later.

  17. Real-time Recordings of Migrating Cortical Neurons from GFP and Cre Recombinase Expressing Mice.

    PubMed

    Tielens, Sylvia; Godin, Juliette D; Nguyen, Laurent

    2016-01-04

    The cerebral cortex is one of the most intricate regions of the brain that requires elaborate cell migration patterns for its development. Experimental observations show that projection neurons migrate radially within the cortical wall, whereas interneurons migrate along multiple tangential paths to reach the developing cortex. Tight regulation of the cell migration processes ensures proper positioning and functional integration of neurons to specific cerebral cortical circuits. Disruption of neuronal migration often leads to cortical dysfunction and/or malformation associated with neurological disorders. Unveiling the molecular control of neuron migration is thus fundamental to understanding the physiological or pathological development of the cerebral cortex. In this unit, protocols allowing detailed analysis of patterns of migration of both interneurons and projection neurons under different experimental conditions (i.e., loss or gain of function) are presented.

  18. Acidosis-Induced Dysfunction of Cortical GABAergic Neurons through Astrocyte-Related Excitotoxicity

    PubMed Central

    Guan, Sudong; Zhu, Yan; Wang, Jin-Hui

    2015-01-01

    Background Acidosis impairs cognitions and behaviors presumably by acidification-induced changes in neuronal metabolism. Cortical GABAergic neurons are vulnerable to pathological factors and their injury leads to brain dysfunction. How acidosis induces GABAergic neuron injury remains elusive. As the glia cells and neurons interact each other, we intend to examine the role of the astrocytes in acidosis-induced GABAergic neuron injury. Results Experiments were done at GABAergic cells and astrocytes in mouse cortical slices. To identify astrocytic involvement in acidosis-induced impairment, we induced the acidification in single GABAergic neuron by infusing proton intracellularly or in both neurons and astrocytes by using proton extracellularly. Compared the effects of intracellular acidification and extracellular acidification on GABAergic neurons, we found that their active intrinsic properties and synaptic outputs appeared more severely impaired in extracellular acidosis than intracellular acidosis. Meanwhile, extracellular acidosis deteriorated glutamate transporter currents on the astrocytes and upregulated excitatory synaptic transmission on the GABAergic neurons. Moreover, the antagonists of glutamate NMDA-/AMPA-receptors partially reverse extracellular acidosis-induced injury in the GABAergic neurons. Conclusion Our studies suggest that acidosis leads to the dysfunction of cortical GABAergic neurons by astrocyte-mediated excitotoxicity, in addition to their metabolic changes as indicated previously. PMID:26474076

  19. Acidosis-Induced Dysfunction of Cortical GABAergic Neurons through Astrocyte-Related Excitotoxicity.

    PubMed

    Huang, Li; Zhao, Shidi; Lu, Wei; Guan, Sudong; Zhu, Yan; Wang, Jin-Hui

    2015-01-01

    Acidosis impairs cognitions and behaviors presumably by acidification-induced changes in neuronal metabolism. Cortical GABAergic neurons are vulnerable to pathological factors and their injury leads to brain dysfunction. How acidosis induces GABAergic neuron injury remains elusive. As the glia cells and neurons interact each other, we intend to examine the role of the astrocytes in acidosis-induced GABAergic neuron injury. Experiments were done at GABAergic cells and astrocytes in mouse cortical slices. To identify astrocytic involvement in acidosis-induced impairment, we induced the acidification in single GABAergic neuron by infusing proton intracellularly or in both neurons and astrocytes by using proton extracellularly. Compared the effects of intracellular acidification and extracellular acidification on GABAergic neurons, we found that their active intrinsic properties and synaptic outputs appeared more severely impaired in extracellular acidosis than intracellular acidosis. Meanwhile, extracellular acidosis deteriorated glutamate transporter currents on the astrocytes and upregulated excitatory synaptic transmission on the GABAergic neurons. Moreover, the antagonists of glutamate NMDA-/AMPA-receptors partially reverse extracellular acidosis-induced injury in the GABAergic neurons. Our studies suggest that acidosis leads to the dysfunction of cortical GABAergic neurons by astrocyte-mediated excitotoxicity, in addition to their metabolic changes as indicated previously.

  20. Tangentially migrating transient glutamatergic neurons control neurogenesis and maintenance of cerebral cortical progenitor pools.

    PubMed

    Teissier, A; Waclaw, R R; Griveau, A; Campbell, K; Pierani, A

    2012-02-01

    The relative contribution of intrinsic and extrinsic cues in the regulation of cortical neurogenesis remains a crucial challenge in developmental neurobiology. We previously reported that a transient population of glutamatergic neurons, the cortical plate (CP) transient neurons, migrates from the ventral pallium (VP) over long distances and participate in neocortical development. Here, we show that the genetic ablation of this population leads to a reduction in the number of cortical neurons especially fated to superficial layers. These defects result from precocious neurogenesis followed by a depletion of the progenitor pools. Notably, these changes progress from caudolateral to rostrodorsal pallial territories between E12.5 and E14.5 along the expected trajectory of the ablated cells. Conversely, we describe enhanced proliferation resulting in an increase in the number of cortical neurons in the Gsx2 mutants which present an expansion of the VP and a higher number of CP transient neurons migrating into the pallium. Our findings indicate that these neurons act to maintain the proliferative state of neocortical progenitors and delay differentiation during their migration from extraneocortical regions and, thus, participate in the extrinsic control of cortical neuronal numbers.

  1. Neuregulin-1 Regulates Cortical Inhibitory Neuron Dendrite and Synapse Growth through DISC1

    PubMed Central

    Kwan, Vickie

    2016-01-01

    Cortical inhibitory neurons play crucial roles in regulating excitatory synaptic networks and cognitive function and aberrant development of these cells have been linked to neurodevelopmental disorders. The secreted neurotrophic factor Neuregulin-1 (NRG1) and its receptor ErbB4 are established regulators of inhibitory neuron connectivity, but the developmental signalling mechanisms regulating this process remain poorly understood. Here, we provide evidence that NRG1-ErbB4 signalling functions through the multifunctional scaffold protein, Disrupted in Schizophrenia 1 (DISC1), to regulate the development of cortical inhibitory interneuron dendrite and synaptic growth. We found that NRG1 increases inhibitory neuron dendrite complexity and glutamatergic synapse formation onto inhibitory neurons and that this effect is blocked by expression of a dominant negative DISC1 mutant, or DISC1 knockdown. We also discovered that NRG1 treatment increases DISC1 expression and its localization to glutamatergic synapses being made onto cortical inhibitory neurons. Mechanistically, we determined that DISC1 binds ErbB4 within cortical inhibitory neurons. Collectively, these data suggest that a NRG1-ErbB4-DISC1 signalling pathway regulates the development of cortical inhibitory neuron dendrite and synaptic growth. Given that NRG1, ErbB4, and DISC1 are schizophrenia-linked genes, these findings shed light on how independent risk factors may signal in a common developmental pathway that contributes to neural connectivity defects and disease pathogenesis. PMID:27847649

  2. Why Cortical Neurons Cannot Divide, and Why Do They Usually Die in the Attempt?

    PubMed

    Aranda-Anzaldo, Armando; Dent, Myrna A R

    2017-04-01

    Cortical neurons are prime examples of terminally differentiated, postmitotic cells. However, under experimental or pathological conditions, they can re-enter the cell cycle and replicate DNA but are unable to divide, dying by apoptosis or becoming either polyploid or aneuploid. Any cellular state that depends on the action of genes and their products can be reverted or bypassed by spontaneous or induced mutations, yet there are currently no reports of dividing cortical neurons. Thus, it seems unlikely that the remarkably stable postmitotic condition of cortical neurons depends on specific gene functions. This Review summarizes evidence that the postmitotic state of cortical neurons depends on the high stability of its underlying nuclear structure that results from an entropy-driven process aimed at dissipating the intrinsic structural stress present in chromosomal DNA in such a way that the structural stability of the neuronal nucleus becomes an insurmountable energy barrier for karyokinesis and mitosis. From this perspective, the integral properties of the nuclear higher order structure in neurons provide an explanation not only for why cortical neurons cannot divide but also for why they usually die if they happen to replicate their DNA. © 2016 Wiley Periodicals, Inc.

  3. Rab, Arf, and Arl-Regulated Membrane Traffic in Cortical Neuron Migration.

    PubMed

    Tang, Bor Luen

    2016-07-01

    The migration of projection neurons from its birthplace in the subventricular zone to their final destination in the cortical plate is a complex process that requires a series of highly coordinated cellular events. Amongst the key factors involved in the processes are modulators of cytoskeletal dynamics, as well as cellular membrane traffic. Members of the small GTPases family responsible for the latter process, the Rabs and Arfs, have been recently implicated in cortical neuron migration. Rab5 and Rab11, which are key modulators of endocytosis and endocytic recycling respectively, ensure proper surface expression and distribution of N-cadherin, a key adhesion protein that tethers migrating neurons to the radial glia fiber tracts during pia-directed migration. Rab7, which is associated with lysosomal biogenesis and function, is important for the final step of terminal translocation when N-cadherin is downregulated by lysosomal degradation. Arf6 activity, which is known to be important in neuronal processes outgrowth, may negatively impact the multipolar-bipolar transition of cortical neurons undergoing radial migration, but the downstream effector of Arf6 in this regard is not yet known. In addition to the above, members of the Arl family which have been recently shown to be important in radial glia scaffold formation, would also be important for cortical neuron migration. In this short review, we discuss recent advances in our understanding of the importance of membrane traffic regulated by the Rab, Arf, and Arl family members in cortical neuron migration.

  4. Bilaminar Co-culture of Primary Rat Cortical Neurons and Glia

    PubMed Central

    Meucci, Olimpia

    2011-01-01

    This video will guide you through the process of culturing rat cortical neurons in the presence of a glial feeder layer, a system known as a bilaminar or co-culture model. This system is suitable for a variety of experimental needs requiring either a glass or plastic growth substrate and can also be used for culture of other types of neurons. Rat cortical neurons obtained from the late embryonic stage (E17) are plated on glass coverslips or tissue culture dishes facing a feeder layer of glia grown on dishes or plastic coverslips (known as Thermanox), respectively. The choice between the two configurations depends on the specific experimental technique used, which may require, or not, that neurons are grown on glass (e.g. calcium imaging versus Western blot). The glial feeder layer, an astroglia-enriched secondary culture of mixed glia, is separately prepared from the cortices of newborn rat pups (P2-4) prior to the neuronal dissection. A major advantage of this culture system as compared to a culture of neurons only is the support of neuronal growth, survival, and differentiation provided by trophic factors secreted from the glial feeder layer, which more accurately resembles the brain environment in vivo. Furthermore, the co-culture can be used to study neuronal-glial interactions1. At the same time, glia contamination in the neuronal layer is prevented by different means (low density culture, addition of mitotic inhibitors, lack of serum and use of optimized culture medium) leading to a virtually pure neuronal layer, comparable to other established methods1-3. Neurons can be easily separated from the glial layer at any time during culture and used for different experimental applications ranging from electrophysiology4, cellular and molecular biology5-8, biochemistry5, imaging and microscopy4,6,7,9,10. The primary neurons extend axons and dendrites to form functional synapses11, a process which is not observed in neuronal cell lines, although some cell lines do

  5. Discontinuous Galerkin finite element method for solving population density functions of cortical pyramidal and thalamic neuronal populations.

    PubMed

    Huang, Chih-Hsu; Lin, Chou-Ching K; Ju, Ming-Shaung

    2015-02-01

    Compared with the Monte Carlo method, the population density method is efficient for modeling collective dynamics of neuronal populations in human brain. In this method, a population density function describes the probabilistic distribution of states of all neurons in the population and it is governed by a hyperbolic partial differential equation. In the past, the problem was mainly solved by using the finite difference method. In a previous study, a continuous Galerkin finite element method was found better than the finite difference method for solving the hyperbolic partial differential equation; however, the population density function often has discontinuity and both methods suffer from a numerical stability problem. The goal of this study is to improve the numerical stability of the solution using discontinuous Galerkin finite element method. To test the performance of the new approach, interaction of a population of cortical pyramidal neurons and a population of thalamic neurons was simulated. The numerical results showed good agreement between results of discontinuous Galerkin finite element and Monte Carlo methods. The convergence and accuracy of the solutions are excellent. The numerical stability problem could be resolved using the discontinuous Galerkin finite element method which has total-variation-diminishing property. The efficient approach will be employed to simulate the electroencephalogram or dynamics of thalamocortical network which involves three populations, namely, thalamic reticular neurons, thalamocortical neurons and cortical pyramidal neurons.

  6. Cortical Overexpression of Neuronal Calcium Sensor-1 Induces Functional Plasticity in Spinal Cord Following Unilateral Pyramidal Tract Injury in Rat

    PubMed Central

    Yip, Ping K.; Wong, Liang-Fong; Sears, Thomas A.; Yáñez-Muñoz, Rafael J.; McMahon, Stephen B.

    2010-01-01

    Following trauma of the adult brain or spinal cord the injured axons of central neurons fail to regenerate or if intact display only limited anatomical plasticity through sprouting. Adult cortical neurons forming the corticospinal tract (CST) normally have low levels of the neuronal calcium sensor-1 (NCS1) protein. In primary cultured adult cortical neurons, the lentivector-induced overexpression of NCS1 induces neurite sprouting associated with increased phospho-Akt levels. When the PI3K/Akt signalling pathway was pharmacologically inhibited the NCS1-induced neurite sprouting was abolished. The overexpression of NCS1 in uninjured corticospinal neurons exhibited axonal sprouting across the midline into the CST-denervated side of the spinal cord following unilateral pyramidotomy. Improved forelimb function was demonstrated behaviourally and electrophysiologically. In injured corticospinal neurons, overexpression of NCS1 induced axonal sprouting and regeneration and also neuroprotection. These findings demonstrate that increasing the levels of intracellular NCS1 in injured and uninjured central neurons enhances their intrinsic anatomical plasticity within the injured adult central nervous system. PMID:20585375

  7. Cortical discrimination of complex natural stimuli: can single neurons match behavior?

    PubMed

    Wang, Le; Narayan, Rajiv; Graña, Gilberto; Shamir, Maoz; Sen, Kamal

    2007-01-17

    A central finding in many cortical areas is that single neurons can match behavioral performance in the discrimination of sensory stimuli. However, whether this is true for natural behaviors involving complex natural stimuli remains unknown. Here we use the model system of songbirds to address this problem. Specifically, we investigate whether neurons in field L, the homolog of primary auditory cortex, can match behavioral performance in the discrimination of conspecific songs. We use a classification framework based on the (dis)similarity between single spike trains to quantify neural discrimination. We use this framework to investigate the discriminability of single spike trains in field L in response to conspecific songs, testing different candidate neural codes underlying discrimination. We find that performance based on spike timing is significantly higher than performance based on spike rate and interspike intervals. We then assess the impact of temporal correlations in spike trains on discrimination. In contrast to widely discussed effects of correlations in limiting the accuracy of a population code, temporal correlations appear to improve the performance of single neurons in the majority of cases. Finally, we compare neural performance with behavioral performance. We find a diverse range of performance levels in field L, with neural performance matching behavioral accuracy only for the best neurons using a spike-timing-based code.

  8. Sleep active cortical neurons expressing neuronal nitric oxide synthase are active after both acute sleep deprivation and chronic sleep restriction.

    PubMed

    Zielinski, M R; Kim, Y; Karpova, S A; Winston, S; McCarley, R W; Strecker, R E; Gerashchenko, D

    2013-09-05

    Non-rapid eye movement (NREM) sleep electroencephalographic (EEG) delta power (~0.5-4 Hz), also known as slow wave activity (SWA), is typically enhanced after acute sleep deprivation (SD) but not after chronic sleep restriction (CSR). Recently, sleep-active cortical neurons expressing neuronal nitric oxide synthase (nNOS) were identified and associated with enhanced SWA after short acute bouts of SD (i.e., 6h). However, the relationship between cortical nNOS neuronal activity and SWA during CSR is unknown. We compared the activity of cortical neurons expressing nNOS (via c-Fos and nNOS immuno-reactivity, respectively) and sleep in rats in three conditions: (1) after 18-h of acute SD; (2) after five consecutive days of sleep restriction (SR) (18-h SD per day with 6h ad libitum sleep opportunity per day); (3) and time-of-day matched ad libitum sleep controls. Cortical nNOS neuronal activity was enhanced during sleep after both 18-h SD and 5 days of SR treatments compared to control treatments. SWA and NREM sleep delta energy (the product of NREM sleep duration and SWA) were positively correlated with enhanced cortical nNOS neuronal activity after 18-h SD but not 5days of SR. That neurons expressing nNOS were active after longer amounts of acute SD (18h vs. 6h reported in the literature) and were correlated with SWA further suggest that these cells might regulate SWA. However, since these neurons were active after CSR when SWA was not enhanced, these findings suggest that mechanisms downstream of their activation are altered during CSR.

  9. Lycopene Prevents Amyloid [Beta]-Induced Mitochondrial Oxidative Stress and Dysfunctions in Cultured Rat Cortical Neurons.

    PubMed

    Qu, Mingyue; Jiang, Zheng; Liao, Yuanxiang; Song, Zhenyao; Nan, Xinzhong

    2016-06-01

    Brains affected by Alzheimer's disease (AD) show a large spectrum of mitochondrial alterations at both morphological and genetic level. The causal link between β-amyloid (Aβ) and mitochondrial dysfunction has been established in cellular models of AD. We observed previously that lycopene, a member of the carotenoid family of phytochemicals, could counteract neuronal apoptosis and cell damage induced by Aβ and other neurotoxic substances, and that this neuroprotective action somehow involved the mitochondria. The present study aims to investigate the effects of lycopene on mitochondria in cultured rat cortical neurons exposed to Aβ. It was found that lycopene attenuated Aβ-induced oxidative stress, as evidenced by the decreased intracellular reactive oxygen species generation and mitochondria-derived superoxide production. Additionally, lycopene ameliorated Aβ-induced mitochondrial morphological alteration, opening of the mitochondrial permeability transition pores and the consequent cytochrome c release. Lycopene also improved mitochondrial complex activities and restored ATP levels in Aβ-treated neuron. Furthermore, lycopene prevented mitochondrial DNA damages and improved the protein level of mitochondrial transcription factor A in mitochondria. Those results indicate that lycopene protects mitochondria against Aβ-induced damages, at least in part by inhibiting mitochondrial oxidative stress and improving mitochondrial function. These beneficial effects of lycopene may account for its protection against Aβ-induced neurotoxicity.

  10. GABA and glycine are protective to mature but toxic to immature rat cortical neurons under hypoxia.

    PubMed

    Zhao, Peng; Qian, Hong; Xia, Ying

    2005-07-01

    Although recent studies suggest that gamma-aminobutyric acid (GABA) and glycine may be 'inhibitory' to mature neurons, but 'excitatory' to immature neurons under normoxia, it is unknown whether inhibitory neurotransmitters are differentially involved in neuronal response to hypoxia in immature and mature neurons. In the present study, we exposed rat cortical neurons to hypoxia (1% O2) and examined the effects of three major inhibitory neurotransmitters (GABA, glycine and taurine) on the hypoxic neurons at different neuronal ages [days in vitro (DIV)4-20]. Our data showed that the cortical neurons expressed both GABA(A) and glycine receptors with differential developmental profiles. GABA (10-2000 microm) was neuroprotective to hypoxic neurons of DIV20, but enhanced hypoxic injury in neurons of neurons, and was slightly toxic to neurons>DIV4. In comparison with delta-opioid receptor (DOR)-induced protection in DIV20 neurons exposed to 72 h of hypoxia, glycine-induced protection was weaker than that of DOR but stronger than that of GABA and taurine. These data suggest that the effects of the inhibitory neurotransmitters on hypoxic cortical neurons are age-dependent, with GABA and glycine being neurotoxic to immature neurons and neuroprotective to mature neurons.

  11. Three Types of Cortical Layer 5 Neurons That Differ in Brain-wide Connectivity and Function.

    PubMed

    Kim, Euiseok J; Juavinett, Ashley L; Kyubwa, Espoir M; Jacobs, Matthew W; Callaway, Edward M

    2015-12-16

    Cortical layer 5 (L5) pyramidal neurons integrate inputs from many sources and distribute outputs to cortical and subcortical structures. Previous studies demonstrate two L5 pyramid types: cortico-cortical (CC) and cortico-subcortical (CS). We characterize connectivity and function of these cell types in mouse primary visual cortex and reveal a new subtype. Unlike previously described L5 CC and CS neurons, this new subtype does not project to striatum [cortico-cortical, non-striatal (CC-NS)] and has distinct morphology, physiology, and visual responses. Monosynaptic rabies tracing reveals that CC neurons preferentially receive input from higher visual areas, while CS neurons receive more input from structures implicated in top-down modulation of brain states. CS neurons are also more direction-selective and prefer faster stimuli than CC neurons. These differences suggest distinct roles as specialized output channels, with CS neurons integrating information and generating responses more relevant to movement control and CC neurons being more important in visual perception.

  12. Spatiotemporal memory is an intrinsic property of networks of dissociated cortical neurons.

    PubMed

    Ju, Han; Dranias, Mark R; Banumurthy, Gokulakrishna; VanDongen, Antonius M J

    2015-03-04

    The ability to process complex spatiotemporal information is a fundamental process underlying the behavior of all higher organisms. However, how the brain processes information in the temporal domain remains incompletely understood. We have explored the spatiotemporal information-processing capability of networks formed from dissociated rat E18 cortical neurons growing in culture. By combining optogenetics with microelectrode array recording, we show that these randomly organized cortical microcircuits are able to process complex spatiotemporal information, allowing the identification of a large number of temporal sequences and classification of musical styles. These experiments uncovered spatiotemporal memory processes lasting several seconds. Neural network simulations indicated that both short-term synaptic plasticity and recurrent connections are required for the emergence of this capability. Interestingly, NMDA receptor function is not a requisite for these short-term spatiotemporal memory processes. Indeed, blocking the NMDA receptor with the antagonist APV significantly improved the temporal processing ability of the networks, by reducing spontaneously occurring network bursts. These highly synchronized events have disastrous effects on spatiotemporal information processing, by transiently erasing short-term memory. These results show that the ability to process and integrate complex spatiotemporal information is an intrinsic property of generic cortical networks that does not require specifically designed circuits. Copyright © 2015 the authors 0270-6474/15/354040-12$15.00/0.

  13. Effect of nano-hydroxyapatite on the axonal guidance growth of rat cortical neurons

    NASA Astrophysics Data System (ADS)

    Liu, Meili; Zhou, Gang; Song, Wei; Li, Ping; Liu, Haifeng; Niu, Xufeng; Fan, Yubo

    2012-05-01

    Nanomaterials such as carbon nanotubes (CNT) can improve axonal connecting in a target direction during regeneration, however, it is limited by the neurotoxicity of CNT. Here we investigate the possible protective effect of nano-hydroxyapatite (n-HA) against nerve injury, as well as CNT in cultured rat cortical neurons. In this study the nanomaterials were characterized by X-Ray diffractometry (XRD) and atomic force microscopy (AFM) analysis. Our results showed that axonal migration and extension were increased significantly after n-HA treatment by immunocytochemistry assay. The patch clamp assay results showed that n-HA acts protectively after nerve injury, which inhibited the average amplitude and frequency of excitatory postsynaptic currents (EPSCs). n-HA is not neurotoxic for the electrophysiology activity of cells. To find the effect of n-HA on axonal guidance growth in the cultured cortical neurons, Netrin 1, one of the axonal guidance cues, was determined by RT-PCR and western blot assay. Compared to the control group, n-HA down-regulated the mRNA level of netrin 1, and moreover, the expression of netrin 1 decreased significantly in the cells. n-HA caused the axonal guidance growth to be mediated by netrin 1 during nerve regeneration. Therefore, the data from the present study provided a new approach for the therapy or prevention of nerve injury.

  14. Amyloid precursor protein expression and processing are differentially regulated during cortical neuron differentiation.

    PubMed

    Bergström, Petra; Agholme, Lotta; Nazir, Faisal Hayat; Satir, Tugce Munise; Toombs, Jamie; Wellington, Henrietta; Strandberg, Joakim; Bontell, Thomas Olsson; Kvartsberg, Hlin; Holmström, Maria; Boreström, Cecilia; Simonsson, Stina; Kunath, Tilo; Lindahl, Anders; Blennow, Kaj; Hanse, Eric; Portelius, Erik; Wray, Selina; Zetterberg, Henrik

    2016-07-07

    Amyloid precursor protein (APP) and its cleavage product amyloid β (Aβ) have been thoroughly studied in Alzheimer's disease. However, APP also appears to be important for neuronal development. Differentiation of induced pluripotent stem cells (iPSCs) towards cortical neurons enables in vitro mechanistic studies on human neuronal development. Here, we investigated expression and proteolytic processing of APP during differentiation of human iPSCs towards cortical neurons over a 100-day period. APP expression remained stable during neuronal differentiation, whereas APP processing changed. α-Cleaved soluble APP (sAPPα) was secreted early during differentiation, from neuronal progenitors, while β-cleaved soluble APP (sAPPβ) was first secreted after deep-layer neurons had formed. Short Aβ peptides, including Aβ1-15/16, peaked during the progenitor stage, while processing shifted towards longer peptides, such as Aβ1-40/42, when post-mitotic neurons appeared. This indicates that APP processing is regulated throughout differentiation of cortical neurons and that amyloidogenic APP processing, as reflected by Aβ1-40/42, is associated with mature neuronal phenotypes.

  15. Amyloid precursor protein expression and processing are differentially regulated during cortical neuron differentiation

    PubMed Central

    Bergström, Petra; Agholme, Lotta; Nazir, Faisal Hayat; Satir, Tugce Munise; Toombs, Jamie; Wellington, Henrietta; Strandberg, Joakim; Bontell, Thomas Olsson; Kvartsberg, Hlin; Holmström, Maria; Boreström, Cecilia; Simonsson, Stina; Kunath, Tilo; Lindahl, Anders; Blennow, Kaj; Hanse, Eric; Portelius, Erik; Wray, Selina; Zetterberg, Henrik

    2016-01-01

    Amyloid precursor protein (APP) and its cleavage product amyloid β (Aβ) have been thoroughly studied in Alzheimer’s disease. However, APP also appears to be important for neuronal development. Differentiation of induced pluripotent stem cells (iPSCs) towards cortical neurons enables in vitro mechanistic studies on human neuronal development. Here, we investigated expression and proteolytic processing of APP during differentiation of human iPSCs towards cortical neurons over a 100-day period. APP expression remained stable during neuronal differentiation, whereas APP processing changed. α-Cleaved soluble APP (sAPPα) was secreted early during differentiation, from neuronal progenitors, while β-cleaved soluble APP (sAPPβ) was first secreted after deep-layer neurons had formed. Short Aβ peptides, including Aβ1-15/16, peaked during the progenitor stage, while processing shifted towards longer peptides, such as Aβ1-40/42, when post-mitotic neurons appeared. This indicates that APP processing is regulated throughout differentiation of cortical neurons and that amyloidogenic APP processing, as reflected by Aβ1-40/42, is associated with mature neuronal phenotypes. PMID:27383650

  16. Reelin and cofilin cooperate during the migration of cortical neurons: a quantitative morphological analysis.

    PubMed

    Chai, Xuejun; Zhao, Shanting; Fan, Li; Zhang, Wei; Lu, Xi; Shao, Hong; Wang, Shaobo; Song, Lingzhen; Failla, Antonio Virgilio; Zobiak, Bernd; Mannherz, Hans G; Frotscher, Michael

    2016-03-15

    In reeler mutant mice, which are deficient in reelin (Reln), the lamination of the cerebral cortex is disrupted. Reelin signaling induces phosphorylation of LIM kinase 1, which phosphorylates the actin-depolymerizing protein cofilin in migrating neurons. Conditional cofilin mutants show neuronal migration defects. Thus, both reelin and cofilin are indispensable during cortical development. To analyze the effects of cofilin phosphorylation on neuronal migration we used in utero electroporation to transfect E14.5 wild-type cortical neurons with pCAG-EGFP plasmids encoding either a nonphosphorylatable form of cofilin 1 (cofilin(S3A)), a pseudophosphorylated form (cofilin(S3E)) or wild-type cofilin 1 (cofilin(WT)). Wild-type controls and reeler neurons were transfected with pCAG-EGFP. Real-time microscopy and histological analyses revealed that overexpression of cofilin(WT) and both phosphomutants induced migration defects and morphological abnormalities of cortical neurons. Of note, reeler neurons and cofilin(S3A)- and cofilin(S3E)-transfected neurons showed aberrant backward migration towards the ventricular zone. Overexpression of cofilin(S3E), the pseudophosphorylated form, partially rescued the migration defect of reeler neurons, as did overexpression of Limk1. Collectively, the results indicate that reelin and cofilin cooperate in controlling cytoskeletal dynamics during neuronal migration.

  17. Primates exposed to cocaine in utero display reduced density and number of cerebral cortical neurons.

    PubMed

    Lidow, M S; Song, Z M

    2001-07-02

    This study examined the effects of cocaine use during the second trimester of pregnancy on cerebral neocortical volume and density, and total number of neocortical neurons and glia in offspring. We also evaluated the extent of postnatal recovery of cytoarchitectural abnormalities previously observed in the neocortex of two-month-old primates born from cocaine-treated mothers (Lidow [1995] Synapse 21:332-334). Pregnant monkeys received cocaine orally (20 mg/kg/day) from the 40th to 102nd days of pregnancy (embryonic day [E]40-E102). On E64 and E65, the animals were injected with [(3)H]thymidine. Cerebral hemispheres of the offspring were examined at three years of age. We found a reduction in the neocortical volume and density and total number of neocortical neurons. The observed reduction in neuronal number within the neocortex was not accounted for by the increase in the number of neurons in the white matter of cocaine-exposed animals, because the number of these "extra" neurons was equal to only half that of missing neurons. We detected no significant changes in the number of neocortical glia. The cytoarchitectural abnormalities in the neocortex of prenatally cocaine-exposed three-year-old monkeys closely resembled previously described neocortical abnormalities in similarly exposed two-month-old animals: the neocortex lacked a discernible lamination; the majority of the cells labeled by [(3)H]thymidine injected during neocortical neurogenesis did not reach their proper position within the cortical plate. Therefore, postnatal maturation is not associated with significant improvement in neocortical organization in primates prenatally exposed to cocaine. There was, however, a postnatal recovery of low glial fibrillary acidic protein (GFAP) immunoreactivity previously observed in 2-month-old cocaine-exposed animals.

  18. Secreted factors from ventral telencephalon induce the differentiation of GABAergic neurons in cortical cultures.

    PubMed

    Trinh, H-h; Reid, J; Shin, E; Liapi, A; Parnavelas, J G; Nadarajah, B

    2006-12-01

    It is widely believed that the pyramidal cells and interneurons of the cerebral cortex are distinct in their origin, lineage and genetic make up. In view of these findings, the current thesis is that the phenotype determination of cortical neurons is primarily directed by genetic mechanisms. Using in vitro assays, the present study demonstrates that secreted factors from ganglionic eminence (GE) of the ventral telencephalon have the potency to induce the differentiation of a subset of cortical neurons towards gamma-aminobutyric acid (GABA)ergic lineage. Characterization of cortical cultures that were exposed to medium derived from GE illustrated a significant increase in the number of GABA-, calretinin- and calbindin-positive neurons. Calcium imaging together with pharmacological studies showed that the application of exogenous medium significantly elevated the intracellular calcium transients in cortical neurons through the activation of ionotropic glutamate receptors. The increase in GABA+ neurons appeared to be associated with the elevated calcium activity; treatment with blockers specific for glutamate receptors abolished both the synchronized transients and reduced the differentiation of GABAergic neurons. Such studies demonstrate that although intrinsic mechanisms determine the fate of cortical interneurons, extrinsic factors have the potency to influence their neurochemical differentiation and contribute towards their molecular diversity.

  19. MEC-17 deficiency leads to reduced α-tubulin acetylation and impaired migration of cortical neurons.

    PubMed

    Li, Lei; Wei, Dan; Wang, Qiong; Pan, Jing; Liu, Rong; Zhang, Xu; Bao, Lan

    2012-09-12

    Neuronal migration is a fundamental process during the development of the cerebral cortex and is regulated by cytoskeletal components. Microtubule dynamics can be modulated by posttranslational modifications to tubulin subunits. Acetylation of α-tubulin at lysine 40 is important in regulating microtubule properties, and this process is controlled by acetyltransferase and deacetylase. MEC-17 is a newly discovered α-tubulin acetyltransferase that has been found to play a major role in the acetylation of α-tubulin in different species in vivo. However, the physiological function of MEC-17 during neural development is largely unknown. Here, we report that MEC-17 is critical for the migration of cortical neurons in the rat. MEC-17 was strongly expressed in the cerebral cortex during development. MEC-17 deficiency caused migratory defects in the cortical projection neurons and interneurons, and perturbed the transition of projection neurons from the multipolar stage to the unipolar/bipolar stage in the intermediate zone of the cortex. Furthermore, knockdown of α-tubulin deacetylase HDAC6 or overexpression of tubulin(K40Q) to mimic acetylated α-tubulin could reduce the migratory and morphological defects caused by MEC-17 deficiency in cortical projection neurons. Thus, MEC-17, which regulates the acetylation of α-tubulin, appears to control the migration and morphological transition of cortical neurons. This finding reveals the importance of MEC-17 and α-tubulin acetylation in cortical development.

  20. Low level laser therapy reduces oxidative stress in cortical neurons in vitro

    NASA Astrophysics Data System (ADS)

    Huang, Ying-Ying; Tedford, Clark E.; McCarthy, Thomas; Hamblin, Michael R.

    2012-03-01

    It is accepted that the mechanisms of low level laser therapy (LLLT) involves photons that are absorbed in the mitochondria of cells and lead to increase of mitochondrial metabolism resulting in more electron transport, increase of mitochondrial membrane potential, and more ATP production. Intracellular calcium changes are seen that correlate with mitochondrial stimulation. The situation with two other intermediates is more complex however: reactive oxygen species (ROS) and nitric oxide (NO). Evidence exists that low levels of ROS are produced by LLLT in normal cells that can be beneficial by (for instance) activating NF-kB. However high fluences of light can produce large amounts of ROS that can damage the cells. In oxidatively stressed cells the situation may be different. We exposed primary cultured cortical neurons to hydrogen peroxide (H2O2) or cobalt chloride (CoCl2) oxidative insults in the presence or absence of LLLT (810-nm laser at 0.3 or 3 J/cm2). Cell viability of cortical neurons was determined by lactate dehydrogenase assay. ROS in neurons was detected using an ROS probe, MitoRox with confocal microscopy. Results showed that LLLT dose-dependently reversed ROS production and protected cortical neurons against H2O2 or CoCl2 induced oxidative injury in cultured cortical neurons. Conclusion: LLLT can protect cortical neurons against oxidative stress by reversing the levels of ROS.

  1. Excitatory cortical neurons with multipolar shape establish neuronal polarity by forming a tangentially oriented axon in the intermediate zone.

    PubMed

    Hatanaka, Yumiko; Yamauchi, Kenta

    2013-01-01

    The formation of axon-dendrite polarity is crucial for neuron to make the proper information flow within the brain. Although the processes of neuronal polarity formation have been extensively studied using neurons in dissociated culture, the corresponding developmental processes in vivo are still unclear. Here, we illuminate the initial steps of morphological polarization of excitatory cortical neurons in situ, by sparsely labeling their neuroepithelial progenitors using in utero electroporation and then examining their neuronal progeny in brain sections and in slice cultures. Morphological analysis showed that an axon-like long tangential process formed in progeny cells in the intermediate zone (IZ). Time-lapse imaging analysis using slice culture revealed that progeny cells with multipolar shape, after alternately extending and retracting their short processes for several hours, suddenly elongated a long process tangentially. These cells then transformed into a bipolar shape, extending a pia-directed leading process, and migrated radially leaving the tangential process behind, which gave rise to an "L-shaped" axon. Our findings suggest that neuronal polarity in these cells is established de novo from a nonpolarized stage in vivo and indicate that excitatory cortical neurons with multipolar shape in the IZ initiate axon outgrowth before radial migration into the cortical plate.

  2. Assessing similarity to primary tissue and cortical layer identity in induced pluripotent stem cell-derived cortical neurons through single-cell transcriptomics

    PubMed Central

    Handel, Adam E.; Chintawar, Satyan; Lalic, Tatjana; Whiteley, Emma; Vowles, Jane; Giustacchini, Alice; Argoud, Karene; Sopp, Paul; Nakanishi, Mahito; Bowden, Rory; Cowley, Sally; Newey, Sarah; Akerman, Colin; Ponting, Chris P.; Cader, M. Zameel

    2016-01-01

    Induced pluripotent stem cell (iPSC)-derived cortical neurons potentially present a powerful new model to understand corticogenesis and neurological disease. Previous work has established that differentiation protocols can produce cortical neurons, but little has been done to characterize these at cellular resolution. In particular, it is unclear to what extent in vitro two-dimensional, relatively disordered culture conditions recapitulate the development of in vivo cortical layer identity. Single-cell multiplex reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) was used to interrogate the expression of genes previously implicated in cortical layer or phenotypic identity in individual cells. Totally, 93.6% of single cells derived from iPSCs expressed genes indicative of neuronal identity. High proportions of single neurons derived from iPSCs expressed glutamatergic receptors and synaptic genes. And, 68.4% of iPSC-derived neurons expressing at least one layer marker could be assigned to a laminar identity using canonical cortical layer marker genes. We compared single-cell RNA-seq of our iPSC-derived neurons to available single-cell RNA-seq data from human fetal and adult brain and found that iPSC-derived cortical neurons closely resembled primary fetal brain cells. Unexpectedly, a subpopulation of iPSC-derived neurons co-expressed canonical fetal deep and upper cortical layer markers. However, this appeared to be concordant with data from primary cells. Our results therefore provide reassurance that iPSC-derived cortical neurons are highly similar to primary cortical neurons at the level of single cells but suggest that current layer markers, although effective, may not be able to disambiguate cortical layer identity in all cells. PMID:26740550

  3. Assessing similarity to primary tissue and cortical layer identity in induced pluripotent stem cell-derived cortical neurons through single-cell transcriptomics.

    PubMed

    Handel, Adam E; Chintawar, Satyan; Lalic, Tatjana; Whiteley, Emma; Vowles, Jane; Giustacchini, Alice; Argoud, Karene; Sopp, Paul; Nakanishi, Mahito; Bowden, Rory; Cowley, Sally; Newey, Sarah; Akerman, Colin; Ponting, Chris P; Cader, M Zameel

    2016-03-01

    Induced pluripotent stem cell (iPSC)-derived cortical neurons potentially present a powerful new model to understand corticogenesis and neurological disease. Previous work has established that differentiation protocols can produce cortical neurons, but little has been done to characterize these at cellular resolution. In particular, it is unclear to what extent in vitro two-dimensional, relatively disordered culture conditions recapitulate the development of in vivo cortical layer identity. Single-cell multiplex reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) was used to interrogate the expression of genes previously implicated in cortical layer or phenotypic identity in individual cells. Totally, 93.6% of single cells derived from iPSCs expressed genes indicative of neuronal identity. High proportions of single neurons derived from iPSCs expressed glutamatergic receptors and synaptic genes. And, 68.4% of iPSC-derived neurons expressing at least one layer marker could be assigned to a laminar identity using canonical cortical layer marker genes. We compared single-cell RNA-seq of our iPSC-derived neurons to available single-cell RNA-seq data from human fetal and adult brain and found that iPSC-derived cortical neurons closely resembled primary fetal brain cells. Unexpectedly, a subpopulation of iPSC-derived neurons co-expressed canonical fetal deep and upper cortical layer markers. However, this appeared to be concordant with data from primary cells. Our results therefore provide reassurance that iPSC-derived cortical neurons are highly similar to primary cortical neurons at the level of single cells but suggest that current layer markers, although effective, may not be able to disambiguate cortical layer identity in all cells.

  4. [Patterns of action potential firing in cortical neurons of neonatal mice and their electrophysiological property].

    PubMed

    Furong, Liu; Shengtian, L I

    2016-05-25

    To investigate patterns of action potential firing in cortical heurons of neonatal mice and their electrophysiological properties. The passive and active membrane properties of cortical neurons from 3-d neonatal mice were observed by whole-cell patch clamp with different voltage and current mode. Three patterns of action potential firing were identified in response to depolarized current injection. The effects of action potential firing patterns on voltage-dependent inward and outward current were found. Neurons with three different firing patterns had different thresholds of depolarized current. In the morphology analysis of action potential, the three type neurons were different in rise time, duration, amplitude and threshold of the first action potential evoked by 80 pA current injection. The passive properties were similar in three patterns of action potential firing. These results indicate that newborn cortical neurons exhibit different patterns of action potential firing with different action potential parameters such as shape and threshold.

  5. The excitation and depression of mammalian cortical neurones by amino acids

    PubMed Central

    Crawford, J. M.; Curtis, D. R.

    1964-01-01

    Amino acids related to L-glutamic and γ-amino-n-butyric acid have been administered electrophoretically, and by pressure ejection, into the extraneuronal environment of single neurones in the pericruciate cortex of cats anaesthetized with allobarbitone or allobarbitone-urethane. Acidic amino acids related to glutamic acid, particularly N-methyl-D-aspartic acid, excited cortical neurones. Neutral amino acids related to γ-amino-n-butyric acid, particularly 3-amino-1-propanesulphonic acid, depressed cortical neurones. Some of the depressants blocked the antidromic invasion of Betz cells by pyramidal volleys. There are no essential differences between the sensitivities of cortical and spinal neurones towards locally administered amino acids. A transmitter function of such amino acids within the mammalian central nervous system is considered unlikely. PMID:14228133

  6. Bidirectional Regulation of Innate and Learned Behaviors That Rely on Frequency Discrimination by Cortical Inhibitory Neurons.

    PubMed

    Aizenberg, Mark; Mwilambwe-Tshilobo, Laetitia; Briguglio, John J; Natan, Ryan G; Geffen, Maria N

    2015-12-01

    The ability to discriminate tones of different frequencies is fundamentally important for everyday hearing. While neurons in the primary auditory cortex (AC) respond differentially to tones of different frequencies, whether and how AC regulates auditory behaviors that rely on frequency discrimination remains poorly understood. Here, we find that the level of activity of inhibitory neurons in AC controls frequency specificity in innate and learned auditory behaviors that rely on frequency discrimination. Photoactivation of parvalbumin-positive interneurons (PVs) improved the ability of the mouse to detect a shift in tone frequency, whereas photosuppression of PVs impaired the performance. Furthermore, photosuppression of PVs during discriminative auditory fear conditioning increased generalization of conditioned response across tone frequencies, whereas PV photoactivation preserved normal specificity of learning. The observed changes in behavioral performance were correlated with bidirectional changes in the magnitude of tone-evoked responses, consistent with predictions of a model of a coupled excitatory-inhibitory cortical network. Direct photoactivation of excitatory neurons, which did not change tone-evoked response magnitude, did not affect behavioral performance in either task. Our results identify a new function for inhibition in the auditory cortex, demonstrating that it can improve or impair acuity of innate and learned auditory behaviors that rely on frequency discrimination.

  7. Response of cat cortical neurons to position and movement of the femur.

    PubMed

    Aloisi, A M; Decchi, B; Fontani, G; Rossi, A; Carli, G

    1996-01-01

    The contribution of joint afferents to the response of cortical neurons in area 3a to mechanical stimulation of the contralateral hindlimb was evaluated in cats anesthetized with sodium pentobarbital and paralyzed with pancuronium bromide. The hindlimb projection to the pericruciate cortex was established by recording the evoked potentials to electrical stimulation of the sciatic nerve and some of its branches, the bicepssemitendinosus and the quadratus femoris. Out of 169 neurons, 63 responded exclusively to cutaneous stimuli (superficial), whereas the others could be activated by local pressure of hindlimb muscles and/or by joint rotation (deep). Deep neurons were classified as slowly adapting (SA) or rapidly adapting (RA) units. In the neurons responding exclusively to joint rotation, the site of the receptive field could not be identified with certainty. In 13 deep neurons, their firing was affected by rotation of multiple joints of the contralateral hindlimb. In an attempt to identify the source of activation of cortical neurons, partial denervations and muscle disconnections were performed in five animals to isolate and stimulate the hip capsule. In these preparations, in 14 of 15 cortical neurons the source of activation was localized in the periarticular muscles, with no response to mechanical stimulation of the joint capsule. Only one neuron (SA) could be selectively excited by punctate pressure on the hip capsule. Our results suggest that in neurons of area 3a of the cat, the information about the position of the femur relies mainly on muscle afferents.

  8. Canonical Organization of Layer 1 Neuron-Led Cortical Inhibitory and Disinhibitory Interneuronal Circuits

    PubMed Central

    Lee, Alice J.; Wang, Guangfu; Jiang, Xiaolong; Johnson, Seraphina M.; Hoang, Elizabeth T.; Lanté, Fabien; Stornetta, Ruth L.; Beenhakker, Mark P.; Shen, Ying; Julius Zhu, J.

    2015-01-01

    Interneurons play a key role in cortical function and dysfunction, yet organization of cortical interneuronal circuitry remains poorly understood. Cortical Layer 1 (L1) contains 2 general GABAergic interneuron groups, namely single bouquet cells (SBCs) and elongated neurogliaform cells (ENGCs). SBCs predominantly make unidirectional inhibitory connections (SBC→) with L2/3 interneurons, whereas ENGCs frequently form reciprocal inhibitory and electric connections (ENGC↔) with L2/3 interneurons. Here, we describe a systematic investigation of the pyramidal neuron targets of L1 neuron-led interneuronal circuits in the rat barrel cortex with simultaneous octuple whole-cell recordings and report a simple organizational scheme of the interneuronal circuits. Both SBCs→ and ENGC ↔ L2/3 interneuronal circuits connect to L2/3 and L5, but not L6, pyramidal neurons. SBC → L2/3 interneuronal circuits primarily inhibit the entire dendritic–somato–axonal axis of a few L2/3 and L5 pyramidal neurons located within the same column. In contrast, ENGC ↔ L2/3 interneuronal circuits generally inhibit the distal apical dendrite of many L2/3 and L5 pyramidal neurons across multiple columns. Finally, L1 interneuron-led circuits target distinct subcellular compartments of L2/3 and L5 pyramidal neurons in a L2/3 interneuron type-dependent manner. These results suggest that L1 neurons form canonical interneuronal circuits to control information processes in both supra- and infragranular cortical layers. PMID:24554728

  9. Recombinant Probes Reveal Dynamic Localization of CaMKIIα within Somata of Cortical Neurons

    PubMed Central

    Mora, Rudy J.; Roberts, Richard W.

    2013-01-01

    In response to NMDA receptor stimulation, CaMKIIα moves rapidly from a diffuse distribution within the shafts of neuronal dendrites to a clustered postsynaptic distribution. However, less is known about CaMKIIα localization and trafficking within neuronal somata. Here we use a novel recombinant probe capable of labeling endogenous CaMKIIα in living rat neurons to examine its localization and trafficking within the somata of cortical neurons. This probe, which was generated using an mRNA display selection, binds to endogenous CaMKIIα at high affinity and specificity following expression in rat cortical neurons in culture. In ∼45% of quiescent cortical neurons, labeled clusters of CaMKIIα 1–4 μm in diameter were present. Upon exposure to glutamate and glycine, CaMKIIα clusters disappeared in a Ca2+-dependent manner within seconds. Moreover, minutes after the removal of glutamate and glycine, the clusters returned to their original configuration. The clusters, which also appear in cortical neurons in sections taken from mouse brains, contain actin and disperse upon exposure to cytochalasin D, an actin depolymerizer. In conclusion, within the soma, CaMKII localizes and traffics in a manner that is distinct from its localization and trafficking within the dendrites. PMID:24005308

  10. Cultured networks of excitatory projection neurons and inhibitory interneurons for studying human cortical neurotoxicity.

    PubMed

    Xu, Jin-Chong; Fan, Jing; Wang, Xueqing; Eacker, Stephen M; Kam, Tae-In; Chen, Li; Yin, Xiling; Zhu, Juehua; Chi, Zhikai; Jiang, Haisong; Chen, Rong; Dawson, Ted M; Dawson, Valina L

    2016-04-06

    Translating neuroprotective treatments from discovery in cell and animal models to the clinic has proven challenging. To reduce the gap between basic studies of neurotoxicity and neuroprotection and clinically relevant therapies, we developed a human cortical neuron culture system from human embryonic stem cells or human inducible pluripotent stem cells that generated both excitatory and inhibitory neuronal networks resembling the composition of the human cortex. This methodology used timed administration of retinoic acid to FOXG1(+) neural precursor cells leading to differentiation of neuronal populations representative of the six cortical layers with both excitatory and inhibitory neuronal networks that were functional and homeostatically stable. In human cortical neuronal cultures, excitotoxicity or ischemia due to oxygen and glucose deprivation led to cell death that was dependent on N-methyl-D-aspartate (NMDA) receptors, nitric oxide (NO), and poly(ADP-ribose) polymerase (PARP) (a cell death pathway called parthanatos that is distinct from apoptosis, necroptosis, and other forms of cell death). Neuronal cell death was attenuated by PARP inhibitors that are currently in clinical trials for cancer treatment. This culture system provides a new platform for the study of human cortical neurotoxicity and suggests that PARP inhibitors may be useful for ameliorating excitotoxic and ischemic cell death in human neurons.

  11. Canonical Organization of Layer 1 Neuron-Led Cortical Inhibitory and Disinhibitory Interneuronal Circuits.

    PubMed

    Lee, Alice J; Wang, Guangfu; Jiang, Xiaolong; Johnson, Seraphina M; Hoang, Elizabeth T; Lanté, Fabien; Stornetta, Ruth L; Beenhakker, Mark P; Shen, Ying; Julius Zhu, J

    2015-08-01

    Interneurons play a key role in cortical function and dysfunction, yet organization of cortical interneuronal circuitry remains poorly understood. Cortical Layer 1 (L1) contains 2 general GABAergic interneuron groups, namely single bouquet cells (SBCs) and elongated neurogliaform cells (ENGCs). SBCs predominantly make unidirectional inhibitory connections (SBC→) with L2/3 interneurons, whereas ENGCs frequently form reciprocal inhibitory and electric connections (ENGC↔) with L2/3 interneurons. Here, we describe a systematic investigation of the pyramidal neuron targets of L1 neuron-led interneuronal circuits in the rat barrel cortex with simultaneous octuple whole-cell recordings and report a simple organizational scheme of the interneuronal circuits. Both SBCs→ and ENGC ↔ L2/3 interneuronal circuits connect to L2/3 and L5, but not L6, pyramidal neurons. SBC → L2/3 interneuronal circuits primarily inhibit the entire dendritic-somato-axonal axis of a few L2/3 and L5 pyramidal neurons located within the same column. In contrast, ENGC ↔ L2/3 interneuronal circuits generally inhibit the distal apical dendrite of many L2/3 and L5 pyramidal neurons across multiple columns. Finally, L1 interneuron-led circuits target distinct subcellular compartments of L2/3 and L5 pyramidal neurons in a L2/3 interneuron type-dependent manner. These results suggest that L1 neurons form canonical interneuronal circuits to control information processes in both supra- and infragranular cortical layers.

  12. α-Tocopherol at Nanomolar Concentration Protects Cortical Neurons against Oxidative Stress

    PubMed Central

    Zakharova, Irina O.; Sokolova, Tatiana V.; Vlasova, Yulia A.; Bayunova, Liubov V.; Rychkova, Maria P.; Avrova, Natalia F.

    2017-01-01

    The aim of the present work is to study the mechanism of the α-tocopherol (α-T) protective action at nanomolar and micromolar concentrations against H2O2-induced brain cortical neuron death. The mechanism of α-T action on neurons at its nanomolar concentrations characteristic for brain extracellular space has not been practically studied yet. Preincubation with nanomolar and micromolar α-T for 18 h was found to increase the viability of cortical neurons exposed to H2O2; α-T effect was concentration-dependent in the nanomolar range. However, preincubation with nanomolar α-T for 30 min was not effective. Nanomolar and micromolar α-T decreased the reactive oxygen species accumulation induced in cortical neurons by the prooxidant. Using immunoblotting it was shown that preincubation with α-T at nanomolar and micromolar concentrations for 18 h prevented Akt inactivation and decreased PKCδ activation induced in cortical neurons by H2O2. α-T prevented the ERK1/2 sustained activation during 24 h caused by H2O2. α-T at nanomolar and micromolar concentrations prevented a great increase of the proapoptotic to antiapoptotic proteins (Bax/Bcl-2) ratio, elicited by neuron exposure to H2O2. The similar neuron protection mechanism by nanomolar and micromolar α-T suggests that a “more is better” approach to patients’ supplementation with vitamin E or α-T is not reasonable. PMID:28117722

  13. Neuron numbers in sensory cortices of five delphinids compared to a physeterid, the pygmy sperm whale.

    PubMed

    Poth, C; Fung, C; Güntürkün, O; Ridgway, S H; Oelschläger, H H A

    2005-09-15

    With its large mass and enormous gyrification, the neocortex of whales and dolphins has always been a challenge to neurobiologists. Here we analyse the relationship between neuron number per cortical unit in three different sensory areas and brain mass in six different toothed whale species, five delphinids and one physeterid. Cortex samples, including primary cortical areas of the auditory, visual, and somatosensory systems were taken from both hemispheres of brains fixed in 10% buffered formalin. The samples were embedded in paraffin, sectioned at 25 microm thickness and stained with cresyl violet. Because cortical thickness varies among toothed whale species, cell counts were done in cortical units measuring 150mum in width, 25 microm in thickness, and extending from the pial surface to the white matter. By arranging the delphinid brains according to their total mass, 834-6052 g, we found decreasing neuron numbers in the investigated areas with increasing brain mass. The pigmy sperm whale (Kogia breviceps), a physeterid with an adult brain weight of 1000 g had a distinctly lower neuron number per cortical unit. As had been expected, an increase in adult brain weight in delphinid cetaceans (family Delphinidae) is not correlated with an increase in neuron number per cortical unit.

  14. Cortical Divergent Projections in Mice Originate from Two Sequentially Generated, Distinct Populations of Excitatory Cortical Neurons with Different Initial Axonal Outgrowth Characteristics.

    PubMed

    Hatanaka, Yumiko; Namikawa, Tomohiro; Yamauchi, Kenta; Kawaguchi, Yasuo

    2016-05-01

    Excitatory cortical neurons project to various subcortical and intracortical regions, and exhibit diversity in their axonal connections. Although this diversity may develop from primary axons, how many types of axons initially occur remains unknown. Using a sparse-labeling in utero electroporation method, we investigated the axonal outgrowth of these neurons in mice and correlated the data with axonal projections in adults. Examination of lateral cortex neurons labeled during the main period of cortical neurogenesis (E11.5-E15.5) indicated that axonal outgrowth commonly occurs in the intermediate zone. Conversely, the axonal direction varied; neurons labeled before E12.5 and the earliest cortical plate neurons labeled at E12.5 projected laterally, whereas neurons labeled thereafter projected medially. The expression of Ctip2 and Satb2 and the layer destinations of these neurons support the view that lateral and medial projection neurons are groups of prospective subcortical and callosal projection neurons, respectively. Consistently, birthdating experiments demonstrated that presumptive lateral projection neurons were generated earlier than medial projection neurons, even within the same layer. These results suggest that the divergent axonal connections of excitatory cortical neurons begin from two types of primary axons, which originate from two sequentially generated distinct subpopulations: early-born lateral (subcortical) and later-born medial (callosal) projection neuron groups.

  15. Caloric restriction stimulates autophagy in rat cortical neurons through neuropeptide Y and ghrelin receptors activation

    PubMed Central

    Carmo-Silva, Sara; Botelho, Mariana; de Almeida, Luís Pereira; Cavadas, Cláudia

    2016-01-01

    Caloric restriction is an anti-aging intervention known to extend lifespan in several experimental models, at least in part, by stimulating autophagy. Caloric restriction increases neuropeptide Y (NPY) in the hypothalamus and plasma ghrelin, a peripheral gut hormone that acts in hypothalamus to modulate energy homeostasis. NPY and ghrelin have been shown to be neuroprotective in different brain areas and to induce several physiological modifications similar to those induced by caloric restriction. However, the effect of NPY and ghrelin in autophagy in cortical neurons is currently not known. Using a cell culture of rat cortical neurons we investigate the involvement of NPY and ghrelin in caloric restriction-induced autophagy. We observed that a caloric restriction mimetic cell culture medium stimulates autophagy in rat cortical neurons and NPY or ghrelin receptor antagonists blocked this effect. On the other hand, exogenous NPY or ghrelin stimulate autophagy in rat cortical neurons. Moreover, NPY mediates the stimulatory effect of ghrelin on autophagy in rat cortical neurons. Since autophagy impairment occurs in aging and age-related neurodegenerative diseases, NPY and ghrelin synergistic effect on autophagy stimulation may suggest a new strategy to delay aging process. PMID:27441412

  16. Hydrogen peroxide mediated the neurotoxicity of an antibody against plasmalemmal neuronspecific enolase in primary cortical neurons.

    PubMed

    Yamamoto, Yasuhiro; Koma, Hiromi; Yagami, Tatsurou

    2015-07-01

    Neuron-specific enolase (NSE) is not only a glycolytic enzyme in the cytosol, but also localized in the synaptic plasma membrane. The plasmalemmal NSE is one of autoantigen targets in post-streptococcal autoimmune central nervous system disease. Although anti-neuronal antibodies in patients bind to a restricted group of NSE in cerebral cortex, it has not yet been clarified how the anti-NSE antibody have negative impacts on cortical neurons. Here, we found that NSE was also localized at neuronal cell bodies and neuritis on the neuronal cell surface in the primary culture of rat cortical neurons. The anti-NSE antibody induced neuronal cell death in a concentration-dependent manner. The neuronal cell death required a lag time and was not accompanied with caspase-3 activation and chromatin condensation. The anti-NSE antibody elevated a level of intracellular H2O2 prior to neuronal cell death. Catalase protected neurons from the anti-NSE antibody-induced H2O2 generation and cell death. The post-treatment of neurons with catalase after the application of the anti-NSE antibody exhibited neuroprotective effects as well as the co-treatment. The cascade of mitogen-activated protein kinase (MAPK) is one of signal transductions of H2O2. Among MAPK, a c-Jun N-terminal kinase partially contributed to the neurotoxicity of anti-NSE antibody. Thus, the anti-NSE antibody acted at the plasmalemmal NSE, produced H2O2, and caused neuronal cell death via non-apoptotic pathway in the cortical neurons. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Genetic evidence for p75NTR-dependent tetraploidy in cortical projection neurons from adult mice.

    PubMed

    López-Sánchez, Noelia; Frade, José M

    2013-04-24

    A subpopulation of chick retinal projection neurons becomes tetraploid during development, an event prevented by blocking antibodies against p75 neurotrophin receptor (p75(NTR)). We have used an optimized flow cytometric assay, based on the analysis of unfixed brain cell nuclei, to study whether p75(NTR)-dependent neuronal tetraploidization takes place in the cerebral cortex, giving rise to projection neurons as well. We show that 3% of neurons in both murine neocortex and chick telencephalic derivatives are tetraploid, and that in the mouse ~85% of these neurons express the immediate early genes Erg-1 and c-Fos, indicating that they are functionally active. Tetraploid cortical neurons (65-80%) express CTIP2, a transcription factor specific for subcortical projection neurons in the mouse neocortex. During the period in which these neurons are born, p75(NTR) is detected in differentiating neurons undergoing DNA replication. Accordingly, p75(NTR)-deficient mice contain a reduced proportion of both NeuN and CTIP2-positive neocortical tetraploid neurons, thus providing genetic evidence for the participation of p75(NTR) in the induction of neuronal tetraploidy in the mouse neocortex. In the striatum tetraploidy is mainly associated with long-range projection neurons as well since ~80% of tetraploid neurons in this structure express calbindin, a marker of neostriatal-matrix spiny neurons, known to establish long-range projections to the substantia nigra and globus pallidus. In contrast, only 20% of tetraploid cortical neurons express calbindin, which is mainly expressed in layers II-III, where CTIP2 is absent. We conclude that tetraploidy mainly affects long-range projection neurons, being facilitated by p75(NTR) in the neocortex.

  18. Necroptosis contributes to methamphetamine-induced cytotoxicity in rat cortical neurons.

    PubMed

    Xiong, Kun; Liao, Huidan; Long, Lingling; Ding, Yanjun; Huang, Jufang; Yan, Jie

    2016-09-01

    Necroptosis, a programmed necrosis, is involved in various types of neurodegenerative diseases. In this study, we investigated whether necroptosis contributed to neuronal damage in a methamphetamine injury model. Primary cultures of embryonic cortical neurons from Sprague-Dawley rats were subjected to different doses of methamphetamine with/without pre-treatment with a specific necroptosis inhibitor, Necrostatin-1. Necrosis was assessed by determining lactate dehydrogenase release and by Annexin V/propidium iodide double staining, while the neuronal ultra-structure was examined by electron microscopy. Tumor necrosis factor-α protein levels were determined by enzyme-linked immunosorbent assay. At early stages (12h) of post-treatment with methamphetamine, significant necrosis occurred and the viability of neurons decreased in a dose- and time-dependent manner in this model of acute neuronal injury. Pretreatment with Necrostatin-1 led to significant neuronal preservation compared with the methamphetamine-treated groups. Furthermore, tumor necrosis factor-α expression increased in a dose-dependent manner following methamphetamine exposure. Methamphetamine induced necrosis in rat cortical neurons in vitro, both time and dose dependently, and necroptosis may be an important newly identified mode of cortical neuronal death caused by single high-dose methamphetamine administration. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. The Impact of CXCR4 Blockade on the Survival of Rat Brain Cortical Neurons

    PubMed Central

    Merino, José Joaquín; Garcimartín, Alba; López-Oliva, María Elvira; Benedí, Juana; González, María Pilar

    2016-01-01

    Background: Chemokine receptor type 4 (CXCR4) plays a role in neuronal survival/cell repair and also contributes to the progression of cancer and neurodegenerative diseases. Chemokine ligand 12 (CXCL12) binds to CXCR4. In this study, we have investigated whether CXCR4 blockade by AMD3100 (a CXCR4 antagonist, member of bicyclam family) may affect neuronal survival in the absence of insult. Thus, we have measured the mitochondrial membrane potential (MMP), Bax and Bcl-2 protein translocation, and cytochrome c release in AMD3100-treated brain cortical neurons at 7 DIV (days in vitro). Methods: For this aim, AMD3100 (200 nM) was added to cortical neurons for 24 h, and several biomarkers like cell viability, reactive oxygen species (ROS) generation, lactate dehydrogenase (LDH) release, caspase-3/9 activity, proteins Bax and Bcl-2 translocation, and cytochrome c release were analyzed by immunoblot. Results: CXCR4 blockade by AMD3100 (200 nM, 24 h) induces mitochondrial hyperpolarization and increases caspase-3/9 hyperpolarization without affecting LDH release as compared to untreated controls. AMD3100 also increases cytochrome c release and promotes Bax translocation to the mitochondria, whereas it raises cytosolic Bcl-2 levels in brain cortical neurons. Conclusion: CXCR4 blockade induces cellular death via intrinsic apoptosis in rat brain cortical neurons in absence of insult. PMID:27916896

  20. The Impact of CXCR4 Blockade on the Survival of Rat Brain Cortical Neurons.

    PubMed

    Merino, José Joaquín; Garcimartín, Alba; López-Oliva, María Elvira; Benedí, Juana; González, María Pilar

    2016-11-30

    Chemokine receptor type 4 (CXCR4) plays a role in neuronal survival/cell repair and also contributes to the progression of cancer and neurodegenerative diseases. Chemokine ligand 12 (CXCL12) binds to CXCR4. In this study, we have investigated whether CXCR4 blockade by AMD3100 (a CXCR4 antagonist, member of bicyclam family) may affect neuronal survival in the absence of insult. Thus, we have measured the mitochondrial membrane potential (MMP), Bax and Bcl-2 protein translocation, and cytochrome c release in AMD3100-treated brain cortical neurons at 7 DIV (days in vitro). For this aim, AMD3100 (200 nM) was added to cortical neurons for 24 h, and several biomarkers like cell viability, reactive oxygen species (ROS) generation, lactate dehydrogenase (LDH) release, caspase-3/9 activity, proteins Bax and Bcl-2 translocation, and cytochrome c release were analyzed by immunoblot. CXCR4 blockade by AMD3100 (200 nM, 24 h) induces mitochondrial hyperpolarization and increases caspase-3/9 hyperpolarization without affecting LDH release as compared to untreated controls. AMD3100 also increases cytochrome c release and promotes Bax translocation to the mitochondria, whereas it raises cytosolic Bcl-2 levels in brain cortical neurons. CXCR4 blockade induces cellular death via intrinsic apoptosis in rat brain cortical neurons in absence of insult.

  1. Morphological Changes of Cortical and Hippocampal Neurons after Treatment with VEGF and Bevacizumab.

    PubMed

    Latzer, Pauline; Schlegel, Uwe; Theiss, Carsten

    2016-06-01

    Vascular endothelial growth factor (VEGF) is a hallmark of glioblastoma multiforme (GBM) and plays an important role in brain development and function. Recently, it has been reported that treatment of GBM patients with bevacizumab, an anti-VEGF antibody, may cause a decline in neurocognitive function and compromise quality of life. Therefore, we investigated the effects of VEGF and bevacizumab on the morphology and on survival of neurons and glial cells. Dissociated cortical and hippocampal cell cultures of juvenile rats were treated with VEGF, bevacizumab, and VEGF + bevacizumab. Neuronal and glial cell viability was analyzed, and the morphology of neurons was objectified by morphometric analysis. In cortical cultures, bevacizumab significantly decreased the number of neurons after 20 days and the number of glial cells subsequent 30 days. Additionally, an increase in the dendritic length of cortical neurons was obvious after 10 days of incubation with bevacizumab, but returned to control level after 30 days. In hippocampal cultures, cell viability was not affected by bevacizumab; however, dendritic length increased at day 10, but decreased after long-term treatment. Therefore, bevacizumab obviously has a cytotoxic effect in cortical cultures and decreases the dendritic length in hippocampal neurons after long-term treatment. © 2016 The Authors. CNS Neuroscience & Therapeutics Published by John Wiley & Sons Ltd.

  2. Sulfite triggers sustained calcium overload in cultured cortical neurons via a redox-dependent mechanism.

    PubMed

    Wang, Xiao; Cao, Hui; Guan, Xin-Lei; Long, Li-Hong; Hu, Zhuang-Li; Ni, Lan; Wang, Fang; Chen, Jian-Guo; Wu, Peng-Fei

    2016-09-06

    Sulfite is a compound commonly used as preservative in foods and pharmaceuticals. Many studies have examined the neurotoxicity of sulfite, but its effect on neuronal calcium homeostasis has not yet been reported. Here, we observed the effect of sulfite on the cytosolic free calcium concentration ([Ca(2+)]i) in cultured cortical neurons using Fura-2/AM based calcium imaging technique. Sulfite (250-1000μM) caused a sustained increase in [Ca(2+)]i in the neurons via a dose-dependent manner. In Ca(2+)-free solution, sulfite failed to increase [Ca(2+)]i. After the depletion of the intracellular calcium store, the effect of sulfite on the [Ca(2+)]i was largely abolished. Pharmacological inhibition of phospholipase C (PLC)-inositol 1,4,5-triphosphate (IP3) signaling pathway blocked sulfite-induced increase of [Ca(2+)]i. Interestingly, antioxidants such as trolox and dithiothreitol, abolished the increase of [Ca(2+)]i induced by sulfite. Exposure to sulfite triggered generation of sulfur- and oxygen-centered free radicals in neurons and increased oxidative stress both in the cultured cortical neurons and the prefrontal cortex of rats. Furthemore, sulfite decreased cell viability in cultured cortical neurons via a calcium-dependent manner. Thus, our current study suggests that the redox-dependent calcium overload triggered by sulfite in cortical neuronsmay be involved in its neurotoxicity.

  3. Mice lacking p35, a neuronal specific activator of Cdk5, display cortical lamination defects, seizures, and adult lethality.

    PubMed

    Chae, T; Kwon, Y T; Bronson, R; Dikkes, P; Li, E; Tsai, L H

    1997-01-01

    The adult mammalian cortex is characterized by a distinct laminar structure generated through a well-defined pattern of neuronal migration. Successively generated neurons are layered in an "inside-out" manner to produce six cortical laminae. We demonstrate here that p35, the neuronal-specific activator of cyclin-dependent kinase 5, plays a key role in proper neuronal migration. Mice lacking p35, and thus p35/cdk5 kinase activity, display severe cortical lamination defects and suffer from sporadic adult lethality and seizures. Histological examination reveals that the mutant mice lack the characteristic laminated structure of the cortex. Neuronal birth-dating experiments indicate a reversed packing order of cortical neurons such that earlier born neurons reside in superficial layers and later generated neurons occupy deep layers. The phenotype of p35 mutant mice thus demonstrates that the formation of cortical laminar structure depends on the action of the p35/cdk5 kinase.

  4. Potentiation of the depression by adenosine of rat cerebral cortical neurones by progestational agents.

    PubMed Central

    Phillis, J. W.

    1986-01-01

    The effects of four progestational agents pregnenolone sulphate, cyproterone acetate, norethindrone acetate and progesterone, on adenosine-evoked depression of the firing of rat cerebral cortical neurones have been studied. When applied iontophoretically, pregnenolone sulphate, cyproterone, and norethindrone enhanced the actions of iontophoretically applied adenosine and failed to potentiate the depressant effects of adenosine 5'-N-ethylcarboxamide and gamma-aminobutyric acid. Cyproterone acetate (50 micrograms kg-1) and progesterone (200 micrograms kg-1) administered intravenously enhanced the depressant actions of iontophoretically applied adenosine. When applied by large currents, cyproterone, and less frequently norethindrone, depressed the firing of cerebral cortical neurones. The depressant effects of cyproterone were antagonized by caffeine. Pregnenolone sulphate tended to excite cortical neurones but neither this action, nor its potentiation of adenosine were reproduced by application of sulphate ions. It is hypothesized that some of the psychotropic actions of progestational agents may involve an enhancement of 'purinergic' tone in the central nervous system. PMID:3814905

  5. In utero Electroporation followed by Primary Neuronal Culture for Studying Gene Function in Subset of Cortical Neurons

    PubMed Central

    Rice, Heather; Suth, Seiyam; Cavanaugh, William; Bai, Jilin; Young-Pearse, Tracy L.

    2010-01-01

    In vitro study of primary neuronal cultures allows for quantitative analyses of neurite outgrowth. In order to study how genetic alterations affect neuronal process outgrowth, shRNA or cDNA constructs can be introduced into primary neurons via chemical transfection or viral transduction. However, with primary cortical cells, a heterogeneous pool of cell types (glutamatergic neurons from different layers, inhibitory neurons, glial cells) are transfected using these methods. The use of in utero electroporation to introduce DNA constructs in the embryonic rodent cortex allows for certain subsets of cells to be targeted: while electroporation of early embryonic cortex targets deep layers of the cortex, electroporation at late embryonic timepoints targets more superficial layers. Further, differential placement of electrodes across the heads of individual embryos results in the targeting of dorsal-medial versus ventral-lateral regions of the cortex. Following electroporation, transfected cells can be dissected out, dissociated, and plated in vitro for quantitative analysis of neurite outgrowth. Here, we provide a step-by-step method to quantitatively measure neuronal process outgrowth in subsets of cortical cells. The basic protocol for in utero electroporation has been described in detail in two other JoVE articles from the Kriegstein lab 1, 2. We will provide an overview of our protocol for in utero electroporation, focusing on the most important details, followed by a description of our protocol that applies in utero electroporation to the study of gene function in neuronal process outgrowth. PMID:20972409

  6. Transplantation of reprogrammed neurons for improved recovery after stroke.

    PubMed

    Kokaia, Zaal; Tornero, Daniel; Lindvall, Olle

    2017-01-01

    Somatic cells such as fibroblasts, reprogrammed to induced pluripotent stem cells, can be used to generate neural stem/progenitor cells or neuroblasts for transplantation. In this review, we summarize recent studies demonstrating that when grafted intracerebrally in animal models of stroke, reprogrammed neurons improve function, probably by several different mechanisms, e.g., trophic actions, modulation of inflammation, promotion of angiogenesis, cellular and synaptic plasticity, and neuroprotection. In our own work, we have shown that human skin-derived reprogrammed neurons, fated to cortical progeny, integrate in stroke-injured neuronal network and form functional afferent synapses with host neurons, responding to peripheral sensory stimulation. However, whether neuronal replacement plays a role for the improvement of sensory, motor, and cognitive deficits after transplantation of reprogrammed neurons is still unclear. We conclude that further preclinical studies are needed to understand the therapeutic potential of grafted reprogrammed neurons and to define a road map for their clinical translation in stroke. © 2017 Elsevier B.V. All rights reserved.

  7. GVS-111 prevents oxidative damage and apoptosis in normal and Down's syndrome human cortical neurons.

    PubMed

    Pelsman, Alejandra; Hoyo-Vadillo, Carlos; Gudasheva, Tatiana A; Seredenin, Sergei B; Ostrovskaya, Rita U; Busciglio, Jorge

    2003-05-01

    The neuroprotective activity of a novel N-acylprolyl-containing dipeptide analog of the nootropic 2-oxo-1-pyrrolidine acetamide (Piracetam) designated as GVS-111 (DVD-111/Noopept) was tested in two in vitro models of neuronal degeneration mediated by oxidative stress: normal human cortical neurons treated with H(2)O(2), and Down's syndrome (DS) cortical neurons. Incubation of normal cortical neurons with 50 microM H(2)O(2) for 1h resulted in morphological and structural changes consistent with neuronal apoptosis and in the degeneration of more than 60% of the neurons present in the culture. GVS-111 significantly increased neuronal survival after H(2)O(2)-treatment displaying a dose-dependent neuroprotective activity from 10nM to 100 microM, and an IC(50) value of 1.21+/-0.07 microM. GVS-111 inhibited the accumulation of intracellular free radicals and lipid peroxidation damage in neurons treated with H(2)O(2) or FeSO(4), suggesting an antioxidant mechanism of action. GVS-111 exhibited significantly higher neuroprotection compared to the standard cognition enhancer Piracetam, or to the antioxidants Vitamin E, propyl gallate and N-tert-butyl-2-sulpho-phenylnitrone (s-PBN). In DS cortical cultures, chronic treatment with GVS-111 significantly reduced the appearance of degenerative changes and enhanced neuronal survival. The results suggest that the neuroprotective effect of GVS-111 against oxidative damage and its potential nootropic activity may present a valuable therapeutic combination for the treatment of mental retardation and chronic neurodegenerative disorders.

  8. Coordinated Plasticity between Barrel Cortical Glutamatergic and GABAergic Neurons during Associative Memory

    PubMed Central

    Yan, Fenxia; Gao, Zilong; Chen, Pin; Huang, Li; Wang, Dangui; Chen, Na; Wu, Ruixiang; Feng, Jing; Cui, Shan; Lu, Wei

    2016-01-01

    Neural plasticity is associated with memory formation. The coordinated refinement and interaction between cortical glutamatergic and GABAergic neurons remain elusive in associative memory, which we examine in a mouse model of associative learning. In the mice that show odorant-induced whisker motion after pairing whisker and odor stimulations, the barrel cortical glutamatergic and GABAergic neurons are recruited to encode the newly learnt odor signal alongside the innate whisker signal. These glutamatergic neurons are functionally upregulated, and GABAergic neurons are refined in a homeostatic manner. The mutual innervations between these glutamatergic and GABAergic neurons are upregulated. The analyses by high throughput sequencing show that certain microRNAs related to regulating synapses and neurons are involved in this cross-modal reflex. Thus, the coactivation of the sensory cortices through epigenetic processes recruits their glutamatergic and GABAergic neurons to be the associative memory cells as well as drive their coordinated refinements toward the optimal state for the storage of the associated signals. PMID:28070425

  9. Neuronal cell loss in the CA3 subfield of the hippocampus following cortical contusion utilizing the optical disector method for cell counting.

    PubMed

    Baldwin, S A; Gibson, T; Callihan, C T; Sullivan, P G; Palmer, E; Scheff, S W

    1997-06-01

    Unilateral cortical contusion in the rat results in cell loss in both the cortex and hippocampus. Pharmacological intervention with growth factors or excitatory neurotransmitter antagonists may reduce cell loss and improve neurological outcome. The window of opportunity for such intervention remains unclear because a detailed temporal analysis of neuronal loss has not been performed in the rodent cortical contusion model. To elucidate the time course of hippocampal CA3 neuronal death ensuing cortical contusion, we employed the optical disector method for assessing the total number of CA3 neurons at 1 and 6 hours, 1, 2, 10, and 30 days following injury. This stereological technique allows reporting of total cell numbers within a given region and is unaffected by change in the volume of the structure or cell size. A rapid and significant reduction in neurons/mm3 in the ipsilateral CA3 field was observed by 1 h following trauma. However, a significant increase in neurons/mm3 was seen at 30 days postinjury. This surprising finding is a result of CA3 volume shrinkage and redistribution of CA3 neurons. Utilization of the optical disector reveals that regardless of an increase in neurons/mm3 at 30 days following injury, CA3 cell loss reaches 41% of control animals by 1 day posttrauma and remains near that level at all subsequent time points examined. It is estimated that there are about 156,000 neurons in the CA3 region in control animals. By 1 h following cortical contusion the cell population decreases to 93,000 neurons indicating a very rapid cell loss. This suggests a window of less than 24 h for pharmacological intervention in order to save CA3 neurons following cortical contusion.

  10. Extraction and analysis of neuron firing signals from deep cortical video microscopy

    SciTech Connect

    Kerekes, Ryan A; Blundon, Jay

    2014-01-01

    We introduce a method for extracting and analyzing neuronal activity time signals from video of the cortex of a live animal. The signals correspond to the firing activity of individual cortical neurons. Activity signals are based on the changing fluorescence of calcium indicators in the cells over time. We propose a cell segmentation method that relies on a user-specified center point, from which the signal extraction method proceeds. A stabilization approach is used to reduce tissue motion in the video. The extracted signal is then processed to flatten the baseline and detect action potentials. We show results from applying the method to a cortical video of a live mouse.

  11. Integrative properties and transfer function of cortical neurons initiating absence seizures in a rat genetic model.

    PubMed

    Williams, Mark S; Altwegg-Boussac, Tristan; Chavez, Mario; Lecas, Sarah; Mahon, Séverine; Charpier, Stéphane

    2016-11-15

    Absence seizures are accompanied by spike-and-wave discharges in cortical electroencephalograms. These complex paroxysmal activities, affecting the thalamocortical networks, profoundly alter cognitive performances and preclude conscious perception. Here, using a well-recognized genetic model of absence epilepsy, we investigated in vivo how information processing was impaired in the ictogenic neurons, i.e. the population of cortical neurons responsible for seizure initiation. In between seizures, ictogenic neurons were more prone to generate bursting activity and their firing response to weak depolarizing events was considerably facilitated compared to control neurons. In the course of seizures, information processing became unstable in ictogenic cells, alternating between an increased and a decreased responsiveness to excitatory inputs, depending on the spike and wave patterns. The state-dependent modulation in the excitability of ictogenic neurons affects their inter-seizure transfer function and their time-to-time responsiveness to incoming inputs during absences. Epileptic seizures result from aberrant cellular and/or synaptic properties that can alter the capacity of neurons to integrate and relay information. During absence seizures, spike-and-wave discharges (SWDs) interfere with incoming sensory inputs and preclude conscious experience. The Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a well-established animal model of absence epilepsy, allows exploration of the cellular basis of this impaired information processing. Here, by combining in vivo electrocorticographic and intracellular recordings from GAERS and control animals, we investigated how the pro-ictogenic properties of seizure-initiating cortical neurons modify their integrative properties and input-output operation during inter-ictal periods and during the spike (S-) and wave (W-) cortical patterns alternating during seizures. In addition to a sustained depolarization and an excessive

  12. Deciphering Neuron-Glia Compartmentalization in Cortical Energy Metabolism

    PubMed Central

    Jolivet, Renaud; Magistretti, Pierre J.; Weber, Bruno

    2009-01-01

    Energy demand is an important constraint on neural signaling. Several methods have been proposed to assess the energy budget of the brain based on a bottom-up approach in which the energy demand of individual biophysical processes are first estimated independently and then summed up to compute the brain's total energy budget. Here, we address this question using a novel approach that makes use of published datasets that reported average cerebral glucose and oxygen utilization in humans and rodents during different activation states. Our approach allows us (1) to decipher neuron-glia compartmentalization in energy metabolism and (2) to compute a precise state-dependent energy budget for the brain. Under the assumption that the fraction of energy used for signaling is proportional to the cycling of neurotransmitters, we find that in the activated state, most of the energy (∼80%) is oxidatively produced and consumed by neurons to support neuron-to-neuron signaling. Glial cells, while only contributing for a small fraction to energy production (∼6%), actually take up a significant fraction of glucose (50% or more) from the blood and provide neurons with glucose-derived energy substrates. Our results suggest that glycolysis occurs for a significant part in astrocytes whereas most of the oxygen is utilized in neurons. As a consequence, a transfer of glucose-derived metabolites from glial cells to neurons has to take place. Furthermore, we find that the amplitude of this transfer is correlated to (1) the activity level of the brain; the larger the activity, the more metabolites are shuttled from glia to neurons and (2) the oxidative activity in astrocytes; with higher glial pyruvate metabolism, less metabolites are shuttled from glia to neurons. While some of the details of a bottom-up biophysical approach have to be simplified, our method allows for a straightforward assessment of the brain's energy budget from macroscopic measurements with minimal underlying

  13. Visual Receptive Field Heterogeneity and Functional Connectivity of Adjacent Neurons in Primate Frontoparietal Association Cortices.

    PubMed

    Viswanathan, Pooja; Nieder, Andreas

    2017-09-13

    The basic organization principles of the primary visual cortex (V1) are commonly assumed to also hold in the association cortex such that neurons within a cortical column share functional connectivity patterns and represent the same region of the visual field. We mapped the visual receptive fields (RFs) of neurons recorded at the same electrode in the ventral intraparietal area (VIP) and the lateral prefrontal cortex (PFC) of rhesus monkeys. We report that the spatial characteristics of visual RFs between adjacent neurons differed considerably, with increasing heterogeneity from VIP to PFC. In addition to RF incongruences, we found differential functional connectivity between putative inhibitory interneurons and pyramidal cells in PFC and VIP. These findings suggest that local RF topography vanishes with hierarchical distance from visual cortical input and argue for increasingly modified functional microcircuits in noncanonical association cortices that contrast V1.SIGNIFICANCE STATEMENT Our visual field is thought to be represented faithfully by the early visual brain areas; all the information from a certain region of the visual field is conveyed to neurons situated close together within a functionally defined cortical column. We examined this principle in the association areas, PFC, and ventral intraparietal area of rhesus monkeys and found that adjacent neurons represent markedly different areas of the visual field. This is the first demonstration of such noncanonical organization of these brain areas. Copyright © 2017 the authors 0270-6474/17/378919-10$15.00/0.

  14. Function and regulation of Rnd proteins in cortical projection neuron migration

    PubMed Central

    Azzarelli, Roberta; Guillemot, François; Pacary, Emilie

    2015-01-01

    The mammalian cerebral cortex contains a high variety of neuronal subtypes that acquire precise spatial locations and form long or short-range connections to establish functional neuronal circuits. During embryonic development, cortical projection neurons are generated in the areas lining the lateral ventricles and they subsequently undergo radial migration to reach the position of their final maturation within the cortical plate. The control of the neuroblast migratory behavior and the coordination of the migration process with other neurogenic events such as cell cycle exit, differentiation and final maturation are crucial to normal brain development. Among the key regulators of cortical neuron migration, the small GTP binding proteins of the Rho family and the atypical Rnd members play important roles in integrating intracellular signaling pathways into changes in cytoskeletal dynamics and motility behavior. Here we review the role of Rnd proteins during cortical neuronal migration and we discuss both the upstream mechanisms that regulate Rnd protein activity and the downstream molecular pathways that mediate Rnd effects on cell cytoskeleton. PMID:25705175

  15. Metformin attenuate PTZ-induced apoptotic neurodegeneration in human cortical neuronal cells.

    PubMed

    Bibi, Fehmida; Ullah, Ikram; Kim, Myeong Ok; Naseer, Muhammad Imran

    2017-01-01

    Seizures are one of the neurodegenerative disorders of human being. Metformin has antioxidant properties and commonly used as an oral antidiabetic drug. The current study was aimed to observe the neuroprotective effect of metformin against PTZ-induced apoptotic neurodegeneration in human cortical neuronal cell culture. To observe that exposure of pentylenetetrazol (PTZ) at the dose of (30mM) for 30 minutes induced neuronal cell death by activation of caspase-3 in human cortical neuronal 2 (HCN-2) cell line. While the metformin at the dose of (20mM) along with PTZ for 30 minutes showed neuroprotection against PTZ-induced neuronal cell loss by MTT assay and Western blot analysis. The results of this study showed that PTZ-induced neuronal cell death by activation of pro apoptotic proteins caspase-3 and 9 whereas the exposure of metformin showed its protective effect against neuronal loss in HCN-2 cell line. Finally, our results showed that exposure of metformin can prevent the harmful effect induced by PTZ in neuronal cells cultures. Our finding suggest that metformin exposure attenuates PTZ-induced neuronal cell death may act as a safe therapeutics and neuroprotective agent for the treatment of neuronal loss as result of seizure.

  16. Transcranial Direct Current Stimulation Modulates Cortical Neuronal Activity in Alzheimer's Disease.

    PubMed

    Marceglia, Sara; Mrakic-Sposta, Simona; Rosa, Manuela; Ferrucci, Roberta; Mameli, Francesca; Vergari, Maurizio; Arlotti, Mattia; Ruggiero, Fabiana; Scarpini, Elio; Galimberti, Daniela; Barbieri, Sergio; Priori, Alberto

    2016-01-01

    Quantitative electroencephalography (qEEG) showed that Alzheimer's disease (AD) is characterized by increased theta power, decreased alpha and beta power, and decreased coherence in the alpha and theta band in posterior regions. These abnormalities are thought to be associated with functional disconnections among cortical areas, death of cortical neurons, axonal pathology, and cholinergic deficits. Since transcranial Direct Current Stimulation (tDCS) over the temporo-parietal area is thought to have beneficial effects in patients with AD, in this study we aimed to investigate whether tDCS benefits are related to tDCS-induced changes in cortical activity, as represented by qEEG. A weak anodal current (1.5 mA, 15 min) was delivered bilaterally over the temporal-parietal lobe to seven subjects with probable AD (Mini-Mental State Examination, MMSE score >20). EEG (21 electrodes, 10-20 international system) was recorded for 5 min with eyes closed before (baseline, t0) and 30 min after anodal and cathodal tDCS ended (t1). At the same time points, patients performed a Word Recognition Task (WRT) to assess working memory functions. The spectral power and the inter- and intra-hemispheric EEG coherence in different frequency bands (e.g., low frequencies, including delta and theta; high frequencies, including alpha and beta) were calculated for each subject at t0 and t1. tDCS-induced changes in EEG neurophysiological markers were correlated with the performance of patients at the WRT. At baseline, qEEG features in AD patients confirmed that the decreased high frequency power was correlated with lower MMSE. After anodal tDCS, we observed an increase in the high-frequency power in the temporo-parietal area and an increase in the temporo-parieto-occipital coherence that correlated with the improvement at the WRT. In addition, cathodal tDCS produced a non-specific effect of decreased theta power all over the scalp that was not correlated with the clinical observation at the WRT

  17. Transcranial Direct Current Stimulation Modulates Cortical Neuronal Activity in Alzheimer's Disease

    PubMed Central

    Marceglia, Sara; Mrakic-Sposta, Simona; Rosa, Manuela; Ferrucci, Roberta; Mameli, Francesca; Vergari, Maurizio; Arlotti, Mattia; Ruggiero, Fabiana; Scarpini, Elio; Galimberti, Daniela; Barbieri, Sergio; Priori, Alberto

    2016-01-01

    Quantitative electroencephalography (qEEG) showed that Alzheimer's disease (AD) is characterized by increased theta power, decreased alpha and beta power, and decreased coherence in the alpha and theta band in posterior regions. These abnormalities are thought to be associated with functional disconnections among cortical areas, death of cortical neurons, axonal pathology, and cholinergic deficits. Since transcranial Direct Current Stimulation (tDCS) over the temporo-parietal area is thought to have beneficial effects in patients with AD, in this study we aimed to investigate whether tDCS benefits are related to tDCS-induced changes in cortical activity, as represented by qEEG. A weak anodal current (1.5 mA, 15 min) was delivered bilaterally over the temporal-parietal lobe to seven subjects with probable AD (Mini-Mental State Examination, MMSE score >20). EEG (21 electrodes, 10–20 international system) was recorded for 5 min with eyes closed before (baseline, t0) and 30 min after anodal and cathodal tDCS ended (t1). At the same time points, patients performed a Word Recognition Task (WRT) to assess working memory functions. The spectral power and the inter- and intra-hemispheric EEG coherence in different frequency bands (e.g., low frequencies, including delta and theta; high frequencies, including alpha and beta) were calculated for each subject at t0 and t1. tDCS-induced changes in EEG neurophysiological markers were correlated with the performance of patients at the WRT. At baseline, qEEG features in AD patients confirmed that the decreased high frequency power was correlated with lower MMSE. After anodal tDCS, we observed an increase in the high-frequency power in the temporo-parietal area and an increase in the temporo-parieto-occipital coherence that correlated with the improvement at the WRT. In addition, cathodal tDCS produced a non-specific effect of decreased theta power all over the scalp that was not correlated with the clinical observation at the WRT

  18. Synaptic responses of neurons in heterotopic gray matter in an animal model of cortical dysgenesis.

    PubMed

    Smith, B N; Dudek, F E; Roper, S N

    1999-11-01

    Neuronal heterotopia is a malformation of cortical development that is closely associated with epilepsy in humans. Despite emerging interest in the structure and function of the heterotopic cortex, little is known about the membrane properties and synaptic connections of these displaced neurons. We used whole-cell patch-clamp and extracellular field potential recordings from heterotopic neurons in slices from young adult rats with experimentally induced cortical dysgenesis to determine if local synaptic connections were present in nodular heterotopia. Complex synaptic responses were observed after electrical stimulation of adjacent white matter. The results suggest that neurons in nodular heterotopic gray matter can form local excitatory and inhibitory synaptic connections and may participate in epileptiform events.

  19. Chronic haloperidol increases voltage-gated Na+ currents in mouse cortical neurons.

    PubMed

    Chen, Weiqiang; Zhu, Fangfang; Guo, Jingfang; Sheng, Jiangtao; Li, Wenli; Zhao, Xiangfeng; Wang, Gefei; Li, Kangsheng

    2014-07-18

    Typical antipsychotics are characterized by extrapyramidal syndrome (EPS). Previous studies demonstrated that typical antipsychotics could inhibit neuronal voltage-gated sodium channel (VGSC). However, EPS typically emerge only upon prolonged exposure. As a result, we examined effects of haloperidol, a prototype typical antipsychotic, on neuronal VGSC upon incubation for varying duration. Briefly, VGSC currents were activated and recorded using a whole-cell patch-clamp technique in primary culture of mouse cortical neurons. VGSC activity was inhibited by acute haloperidol exposure (for minutes), but enhanced in a time- and concentration-dependent manner by chronic haloperidol exposure (for hours). The effects of chronic haloperidol were associated with increased expression of VGSC subunits as well as corresponding electrophysiological channel properties. In summary, we found enhanced VGSC currents upon chronic haloperidol exposure in cortical neurons in contrast to inhibition by acute haloperidol exposure. Such a results may contribute to EPS of typical antipsychotics.

  20. NEUROD2 Regulates Stim1 Expression and Store-Operated Calcium Entry in Cortical Neurons

    PubMed Central

    Akkaya, Cansu; Bayam, Efil

    2017-01-01

    Abstract Calcium signaling controls many key processes in neurons, including gene expression, axon guidance, and synaptic plasticity. In contrast to calcium influx through voltage- or neurotransmitter-gated channels, regulatory pathways that control store-operated calcium entry (SOCE) in neurons are poorly understood. Here, we report a transcriptional control of Stim1 (stromal interaction molecule 1) gene, which is a major sensor of endoplasmic reticulum (ER) calcium levels and a regulator of SOCE. By using a genome-wide chromatin immunoprecipitation and sequencing approach in mice, we find that NEUROD2, a neurogenic transcription factor, binds to an intronic element within the Stim1 gene. We show that NEUROD2 limits Stim1 expression in cortical neurons and consequently fine-tunes the SOCE response upon depletion of ER calcium. Our findings reveal a novel mechanism that regulates neuronal calcium homeostasis during cortical development. PMID:28303257

  1. Magnetic Tunnel Junction Mimics Stochastic Cortical Spiking Neurons

    NASA Astrophysics Data System (ADS)

    Sengupta, Abhronil; Panda, Priyadarshini; Wijesinghe, Parami; Kim, Yusung; Roy, Kaushik

    2016-07-01

    Brain-inspired computing architectures attempt to mimic the computations performed in the neurons and the synapses in the human brain in order to achieve its efficiency in learning and cognitive tasks. In this work, we demonstrate the mapping of the probabilistic spiking nature of pyramidal neurons in the cortex to the stochastic switching behavior of a Magnetic Tunnel Junction in presence of thermal noise. We present results to illustrate the efficiency of neuromorphic systems based on such probabilistic neurons for pattern recognition tasks in presence of lateral inhibition and homeostasis. Such stochastic MTJ neurons can also potentially provide a direct mapping to the probabilistic computing elements in Belief Networks for performing regenerative tasks.

  2. TETRAMETHRIN AND DDT INHIBIT SPONTANEOUS FIRING IN CORTICAL NEURONAL NETWORKS

    EPA Science Inventory

    The insecticidal and neurotoxic effects of pyrethroids result from prolonged sodium channel inactivation, which causes alterations in neuronal firing and communication. Previously, we determined the relative potencies of 11 type I and type II pyrethroid insecticides using microel...

  3. TETRAMETHRIN AND DDT INHIBIT SPONTANEOUS FIRING IN CORTICAL NEURONAL NETWORKS

    EPA Science Inventory

    The insecticidal and neurotoxic effects of pyrethroids result from prolonged sodium channel inactivation, which causes alterations in neuronal firing and communication. Previously, we determined the relative potencies of 11 type I and type II pyrethroid insecticides using microel...

  4. Magnetic Tunnel Junction Mimics Stochastic Cortical Spiking Neurons

    PubMed Central

    Sengupta, Abhronil; Panda, Priyadarshini; Wijesinghe, Parami; Kim, Yusung; Roy, Kaushik

    2016-01-01

    Brain-inspired computing architectures attempt to mimic the computations performed in the neurons and the synapses in the human brain in order to achieve its efficiency in learning and cognitive tasks. In this work, we demonstrate the mapping of the probabilistic spiking nature of pyramidal neurons in the cortex to the stochastic switching behavior of a Magnetic Tunnel Junction in presence of thermal noise. We present results to illustrate the efficiency of neuromorphic systems based on such probabilistic neurons for pattern recognition tasks in presence of lateral inhibition and homeostasis. Such stochastic MTJ neurons can also potentially provide a direct mapping to the probabilistic computing elements in Belief Networks for performing regenerative tasks. PMID:27443913

  5. [Behavioral specialization of cortical and hypothalamic neurons in the rabbit].

    PubMed

    Shevchenko, D G

    1987-01-01

    Behavioural specialization was analyzed of hypothalamic and limbic neurones, with their activity recorded in rabbits during food-acquisition behaviour. The neurones with activity changed during staying of the animal in a definite place of the cage or during behavioural acts, characteristic of a specific behaviour in the cage, are considered as specialized in relation to the most "new" systems, acquired by the rabbit directly during learning of the given behaviour. Neurones with the activity changed with rabbit's turns, i.e. connected with behavioural acts, which the rabbit has not specially learnt, are considered specialized in relation to more "old" inborn systems. Neurones, in which no constant connection with any part of the studied behaviour was observed, are related to the most "ancient" systems. Comparison of the number of hypothalamic and limbic neurones of different groups showed that in the cortex there were some more neurones specialized in relation to behavioural acts, which were formed directly during learning of the rabbit in the experimental cage.

  6. Interleukin-18 directly protects cortical neurons by activating PI3K/AKT/NF-κB/CREB pathways.

    PubMed

    Zhou, Jia; Ping, Feng-feng; Lv, Wen-ting; Feng, Jun-yi; Shang, Jing

    2014-09-01

    Interleukin-18 (IL-18), a member of the IL-1 family of cytokines, was initially identified as an interferon (IFN)-γ-inducing factor. IL-18 is expressed in both immune and non-immune cells and participates in the adjustment of multitude cellular functions. Nonetheless, the effects of IL-18 on cortical neurons have not been explored. The present study was conducted to investigate the influence of IL-18 on rat primary cortical neurons and elucidate the underlying mechanisms. We proved that rrIL-18 increased the brain-derived neurotrophic factor (BDNF) expression in a time-dependent manner. Treatment with rrIL-18 (50 ng/ml) deactivated phosphatase and tensin homolog deleted on chromosome 10 (PTEN) by facilitating its phosphorylation, enhanced the expression of Phosphoinositide 3-OH kinase (PI3K) and p-Akt, standing for the activation of the PI3K/Akt pathway. As its pivotal downstream pathways, nuclear factor-kappa B (NF-κB), cAMP-responsive element binding protein (CREB)/Bcl-2 and glycogen synthase kinase-3β (GSK-3β) were examined in further steps. Our data revealed that rrIL-18 stimulated NF-κB activation, improved p-CREB and anti-apoptotic Bcl-2 expression levels. But rrIL-18 had little or no effect on GSK-3β pathway. Besides, rrIL-18 increased levels of BDNF and Bcl-2/Bax ratio and decreased cleaved caspase-3 expression to protect cortical neurons from damage induced by oxygen-glucose deprivation (OGD). These results in vitro showed the protection of IL-18 on cortical neurons. And this direct neuroprotective effect of IL-18 is crippled by PI3K inhibitor wortmannin.

  7. Anthocyanins extracted from black soybean seed coat protect primary cortical neurons against in vitro ischemia.

    PubMed

    Bhuiyan, Mohammad Iqbal Hossain; Kim, Joo Youn; Ha, Tae Joung; Kim, Seong Yun; Cho, Kyung-Ok

    2012-01-01

    The present study investigated the neuroprotective effects of anthocyanins extracted from black soybean (cv. Cheongja 3, Glycine max (L.) MERR.) seed coat against oxygen-glucose deprivation (OGD) and glutamate-induced cell death in rat primary cortical neurons. Lactate dehydrogenase (LDH) release and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assays were employed to assess cell membrane damage and viability of primary neurons, respectively. OGD-induced cell death in 7 d in vitro primary cortical neurons was found to be OGD duration-dependent, and approximately 3.5 h of OGD resulted in ≈60% cell death. Treatment with black soybean anthocyanins dose-dependently prevented membrane damage and increased the viability of primary neurons that were exposed to OGD. Glutamate-induced neuronal cell death was dependent on the glutamate concentration at relatively low concentrations and the number of days the cells remained in culture. Interestingly, black soybean anthocyanins did not protect against glutamate-induced neuronal cell death. They did, however, inhibit the excessive generation of reactive oxygen species (ROS) and preserve mitochondrial membrane potential (MMP) in primary neurons exposed to OGD. In agreement with the neuroprotective effect of crude black soybean anthocyanins, purified cyanidin-3-glucoside (C3G), the major component of anthocyanins, also offered dose-dependent neuroprotection against OGD-induced neuronal cell death. Moreover, black soybean C3G markedly prevented excessive generation of ROS and preserved MMP in primary neurons that were exposed to OGD. Collectively, these results suggest that the neuroprotection of primary rat cortical neurons by anthocyanins that were extracted from black soybean seed coat might be mediated through oxidative stress inhibition and MMP preservation but not through glutamate-induced excitotoxicity attenuation.

  8. Live-Cell, Label-Free Identification of GABAergic and Non-GABAergic Neurons in Primary Cortical Cultures Using Micropatterned Surface

    PubMed Central

    Kono, Sho; Kushida, Takatoshi; Hirano-Iwata, Ayumi; Niwano, Michio; Tanii, Takashi

    2016-01-01

    Excitatory and inhibitory neurons have distinct roles in cortical dynamics. Here we present a novel method for identifying inhibitory GABAergic neurons from non-GABAergic neurons, which are mostly excitatory glutamatergic neurons, in primary cortical cultures. This was achieved using an asymmetrically designed micropattern that directs an axonal process to the longest pathway. In the current work, we first modified the micropattern geometry to improve cell viability and then studied the axon length from 2 to 7 days in vitro (DIV). The cell types of neurons were evaluated retrospectively based on immunoreactivity against GAD67, a marker for inhibitory GABAergic neurons. We found that axons of non-GABAergic neurons grow significantly longer than those of GABAergic neurons in the early stages of development. The optimal threshold for identifying GABAergic and non-GABAergic neurons was evaluated to be 110 μm at 6 DIV. The method does not require any fluorescence labelling and can be carried out on live cells. The accuracy of identification was 98.2%. We confirmed that the high accuracy was due to the use of a micropattern, which standardized the development of cultured neurons. The method promises to be beneficial both for engineering neuronal networks in vitro and for basic cellular neuroscience research. PMID:27513933

  9. Procedure for recording the simultaneous activity of single neurons distributed across cortical areas during sensory discrimination

    PubMed Central

    Hernández, Adrián; Nácher, Verónica; Luna, Rogelio; Alvarez, Manuel; Zainos, Antonio; Cordero, Silvia; Camarillo, Liliana; Vázquez, Yuriria; Lemus, Luis; Romo, Ranulfo

    2008-01-01

    We report a procedure for recording the simultaneous activity of single neurons distributed across five cortical areas in behaving monkeys. The procedure consists of a commercially available microdrive adapted to a commercially available neural data collection system. The critical advantage of this procedure is that, in each cortical area, a configuration of seven microelectrodes spaced 250–500 μm can be inserted transdurally and each can be moved independently in the z axis. For each microelectrode, the data collection system can record the activity of up to five neurons together with the local field potential (LFP). With this procedure, we normally monitor the simultaneous activity of 70–100 neurons while trained monkeys discriminate the difference in frequency between two vibrotactile stimuli. Approximately 20–60 of these neurons have response properties previously reported in this task. The neuronal recordings show good signal-to-noise ratio, are remarkably stable along a 1-day session, and allow testing several protocols. Microelectrodes are removed from the brain after a 1-day recording session, but are reinserted again the next day by using the same or different x-y microelectrode array configurations. The fact that microelectrodes can be moved in the z axis during the recording session and that the x-y configuration can be changed from day to day maximizes the probability of studying simultaneous interactions, both local and across distant cortical areas, between neurons associated with the different components of this task. PMID:18946031

  10. Influenza Virus Induces Inflammatory Response in Mouse Primary Cortical Neurons with Limited Viral Replication.

    PubMed

    Wang, Gefei; Li, Rui; Jiang, Zhiwu; Gu, Liming; Chen, Yanxia; Dai, Jianping; Li, Kangsheng

    2016-01-01

    Unlike stereotypical neurotropic viruses, influenza A viruses have been detected in the brain tissues of human and animal models. To investigate the interaction between neurons and influenza A viruses, mouse cortical neurons were isolated, infected with human H1N1 influenza virus, and then examined for the production of various inflammatory molecules involved in immune response. We found that replication of the influenza virus in neurons was limited, although early viral transcription was not affected. Virus-induced neuron viability decreased at 6 h postinfection (p.i.) but increased at 24 h p.i. depending upon the viral strain. Virus-induced apoptosis and cytopathy in primary cortical neurons were not apparent at 24 h p.i. The mRNA levels of inflammatory cytokines, chemokines, and type I interferons were upregulated at 6 h and 24 h p.i. These results indicate that the influenza virus induces inflammatory response in mouse primary cortical neurons with limited viral replication. The cytokines released in viral infection-induced neuroinflammation might play critical roles in influenza encephalopathy, rather than in viral replication-induced cytopathy.

  11. Alterations in Cortical Network Oscillations and Parvalbumin Neurons in Schizophrenia

    PubMed Central

    Gonzalez-Burgos, Guillermo; Cho, Raymond Y; Lewis, David A

    2015-01-01

    Cognitive deficits are a core clinical feature of schizophrenia but respond poorly to available medications. Thus, understanding the neural basis of these deficits is crucial for the development of new therapeutic interventions. The types of cognitive processes affected in schizophrenia are thought to depend on the precisely timed transmission of information in cortical regions via synchronous oscillations at gamma band frequency. Here, we review 1) data from clinical studies suggesting that induction of frontal cortex gamma oscillations during tasks that engage cognitive or complex perceptual functions is attenuated in schizophrenia, 2) findings from basic neuroscience studies highlighting the features of parvalbumin-positive (PV) interneurons that are critical for gamma oscillation production and 3) results from recent postmortem human brain studies providing additional molecular bases for PV interneuron alterations in prefrontal cortical circuitry in schizophrenia. PMID:25863358

  12. Alterations in cortical network oscillations and parvalbumin neurons in schizophrenia.

    PubMed

    Gonzalez-Burgos, Guillermo; Cho, Raymond Y; Lewis, David A

    2015-06-15

    Cognitive deficits are a core clinical feature of schizophrenia but respond poorly to available medications. Thus, understanding the neural basis of these deficits is crucial for the development of new therapeutic interventions. The types of cognitive processes affected in schizophrenia are thought to depend on the precisely timed transmission of information in cortical regions via synchronous oscillations at gamma band frequency. Here, we review 1) data from clinical studies suggesting that induction of frontal cortex gamma oscillations during tasks that engage cognitive or complex perceptual functions is attenuated in schizophrenia; 2) findings from basic neuroscience studies highlighting the features of parvalbumin-positive interneurons that are critical for gamma oscillation production; and 3) results from recent postmortem human brain studies providing additional molecular bases for parvalbumin-positive interneuron alterations in prefrontal cortical circuitry in schizophrenia. Copyright © 2015 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  13. Dependence of Cortical Plasticity on Correlated Activity of Single Neurons and on Behavioral Context

    NASA Astrophysics Data System (ADS)

    Ahissar, Ehud; Vaadia, Eilon; Ahissar, Merav; Bergman, Hagai; Arieli, Amos; Abeles, Moshe

    1992-09-01

    It has not been possible to analyze the cellular mechanisms underlying learning in behaving mammals because of the difficulties in recording intracellularly from awake animals. Therefore, in the present study of neuronal plasticity in behaving monkeys, the net effect of a single neuron on another neuron (the "functional connection") was evaluated by cross-correlating the times of firing of the two neurons. When two neurons were induced to fire together within a short time window, the functional connection between them was potentiated, and when simultaneous firing was prevented, the connection was depressed. These modifications were strongly dependent on the behavioral context of the stimuli that induced them. The results indicate that changes in the temporal contingency between neurons are often necessary, but not sufficient, for cortical plasticity in the adult monkey: behavioral relevance is required.

  14. Cortical neuronal cytoskeletal changes associated with FIV infection

    NASA Technical Reports Server (NTRS)

    Jacobson, S.; Henriksen, S. J.; Prospero-Garcia, O.; Phillips, T. R.; Elder, J. H.; Young, W. G.; Bloom, F. E.; Fox, H. S.

    1997-01-01

    HIV-1 infection is often complicated by central nervous system (CNS) dysfunction. Degenerative neuronal changes as well as neuronal loss have been documented in individuals with AIDS. Feline immunodeficiency virus (FIV) infection of cats provides a model for both the immune and the central nervous system manifestations of HIV infection of humans. In this study we have examined neurons in the frontal cortex of feline immunodeficiency virus-infected cats and controls for immunoreactivity with SMI 32, an antibody recognizing a non-phosphorylated epitope on neurofilaments. We noted a significant increase in the number of immunoreactive pyramidal cells in infected animals compared to controls. The changes seen in the neuronal cytoskeleton as a consequence of the inoculation with FIV were similar to those seen in humans undergoing the normal aging process as well as those suffering from neurological diseases, including Alzheimer's and dementia pugilistica. The changes we noted in the feline brain were also similar to that reported in animals with traumatic injuries or with spontaneously occurring or induced motor neuron diseases, suggesting that the increase in reactivity represents a deleterious effect of FIV on the central nervous system.

  15. Cortical neuronal cytoskeletal changes associated with FIV infection

    NASA Technical Reports Server (NTRS)

    Jacobson, S.; Henriksen, S. J.; Prospero-Garcia, O.; Phillips, T. R.; Elder, J. H.; Young, W. G.; Bloom, F. E.; Fox, H. S.

    1997-01-01

    HIV-1 infection is often complicated by central nervous system (CNS) dysfunction. Degenerative neuronal changes as well as neuronal loss have been documented in individuals with AIDS. Feline immunodeficiency virus (FIV) infection of cats provides a model for both the immune and the central nervous system manifestations of HIV infection of humans. In this study we have examined neurons in the frontal cortex of feline immunodeficiency virus-infected cats and controls for immunoreactivity with SMI 32, an antibody recognizing a non-phosphorylated epitope on neurofilaments. We noted a significant increase in the number of immunoreactive pyramidal cells in infected animals compared to controls. The changes seen in the neuronal cytoskeleton as a consequence of the inoculation with FIV were similar to those seen in humans undergoing the normal aging process as well as those suffering from neurological diseases, including Alzheimer's and dementia pugilistica. The changes we noted in the feline brain were also similar to that reported in animals with traumatic injuries or with spontaneously occurring or induced motor neuron diseases, suggesting that the increase in reactivity represents a deleterious effect of FIV on the central nervous system.

  16. Real-time prediction of hand trajectory by ensembles of cortical neurons in primates

    NASA Astrophysics Data System (ADS)

    Wessberg, Johan; Stambaugh, Christopher R.; Kralik, Jerald D.; Beck, Pamela D.; Laubach, Mark; Chapin, John K.; Kim, Jung; Biggs, S. James; Srinivasan, Mandayam A.; Nicolelis, Miguel A. L.

    2000-11-01

    Signals derived from the rat motor cortex can be used for controlling one-dimensional movements of a robot arm. It remains unknown, however, whether real-time processing of cortical signals can be employed to reproduce, in a robotic device, the kind of complex arm movements used by primates to reach objects in space. Here we recorded the simultaneous activity of large populations of neurons, distributed in the premotor, primary motor and posterior parietal cortical areas, as non-human primates performed two distinct motor tasks. Accurate real-time predictions of one- and three-dimensional arm movement trajectories were obtained by applying both linear and nonlinear algorithms to cortical neuronal ensemble activity recorded from each animal. In addition, cortically derived signals were successfully used for real-time control of robotic devices, both locally and through the Internet. These results suggest that long-term control of complex prosthetic robot arm movements can be achieved by simple real-time transformations of neuronal population signals derived from multiple cortical areas in primates.

  17. Desynchronization of the Rat Cortical Network and Excitation of White Matter Neurons by Neurotensin.

    PubMed

    Case, Lovisa; Lyons, David J; Broberger, Christian

    2017-04-01

    Cortical network activity correlates with vigilance state: Deep sleep is characterized by slow, synchronized oscillations, whereas desynchronized, stochastic discharge is typical of the waking state. Neuropeptides, such as orexin and substance P but also neurotensin (NT), promote arousal. Relatively little is known about if NT can directly affect the cortical network, and if so, through which mechanisms and cellular targets. Here, we addressed these issues using rat in vitro cortex preparations. Following NT application specifically to deeper layers, slow oscillation activity was attenuated with a significant reduction in UP state frequency. The cortical response to thalamic stimulation exhibited enhanced temporal precision in the presence of NT, consistent with the transition in vivo from sleep to wakefulness. These changes were associated with a relative shift toward inhibition in the excitation/inhibition balance. Whole-cell recordings from layer 6 revealed presynaptically driven NT-induced inhibition of pyramidal neurons and excitation of fast-spiking interneurons. Deeper in the cortex, neurons within the white matter (WM) were strongly depolarized by NT application. The colocalization of NT and tyrosine hydroxylase immunoreactivities in deep layer fibers throughout the cortical mantle indicates mediation via dopaminergic systems. These data suggest a cortical mechanism for NT-induced wakefulness and support a role for WM neurons in state control. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  18. Regulation of Cerebral Cortical Size and Neuron Number by Fibroblast Growth Factors: Implications for Autism

    ERIC Educational Resources Information Center

    Vaccarino, Flora M.; Grigorenko, Elena L.; Smith, Karen Muller; Stevens, Hanna E.

    2009-01-01

    Increased brain size is common in children with autism spectrum disorders. Here we propose that an increased number of cortical excitatory neurons may underlie the increased brain volume, minicolumn pathology and excessive network excitability, leading to sensory hyper-reactivity and seizures, which are often found in autism. We suggest that…

  19. Simultaneous measurement of neuronal activity and cortical hemodynamics by unshielded magnetoencephalography and near-infrared spectroscopy.

    PubMed

    Seki, Yusuke; Miyashita, Tsuyoshi; Kandori, Akihiko; Maki, Atsushi; Koizumi, Hideaki

    2012-10-01

    The correlation between neuronal activity and cortical hemodynamics, namely, neurovascular coupling (NVC), is important to shed light on the mechanism of a variety of brain functions or neuronal diseases. NVC can be studied by simultaneously measuring neuronal activity and cortical hemodynamics. Consequently, noninvasive measurements of the NVC have been widely studied using both electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). However, electromagnetic interference between EEG and fMRI is still a major problem. On the other hand, near-infrared spectroscopy (NIRS) is another promising tool for detecting cortical hemodynamics because it can be combined with EEG or magnetoencephalography (MEG) without any electromagnetic interference. Accordingly, in the present study, a simultaneous measurement system-combining an unshielded MEG using a two-dimensional gradiometer based on a low-Tc superconducting quantum interference device (SQUID) and an NIRS using nonmagnetic thin probes-was developed. This combined system was used to simultaneously measure both an auditory-evoked magnetic field and blood flow change in the auditory cortex. It was experimentally demonstrated that the combined unshielded MEG/NIRS system can simultaneously measure neuronal activity and cortical hemodynamics.

  20. Tangential migration of glutamatergic neurons and cortical patterning during development: Lessons from Cajal-Retzius cells.

    PubMed

    Barber, Melissa; Pierani, Alessandra

    2016-08-01

    Tangential migration is a mode of cell movement, which in the developing cerebral cortex, is defined by displacement parallel to the ventricular surface and orthogonal to the radial glial fibers. This mode of long-range migration is a strategy by which distinct neuronal classes generated from spatially and molecularly distinct origins can integrate to form appropriate neural circuits within the cortical plate. While it was previously believed that only GABAergic cortical interneurons migrate tangentially from their origins in the subpallial ganglionic eminences to integrate in the cortical plate, it is now known that transient populations of glutamatergic neurons also adopt this mode of migration. These include Cajal-Retzius cells (CRs), subplate neurons (SPs), and cortical plate transient neurons (CPTs), which have crucial roles in orchestrating the radial and tangential development of the embryonic cerebral cortex in a noncell-autonomous manner. While CRs have been extensively studied, it is only in the last decade that the molecular mechanisms governing their tangential migration have begun to be elucidated. To date, the mechanisms of SPs and CPTs tangential migration remain unknown. We therefore review the known signaling pathways, which regulate parameters of CRs migration including their motility, contact-redistribution and adhesion to the pial surface, and discuss this in the context of how CR migration may regulate their signaling activity in a spatial and temporal manner. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 847-881, 2016.

  1. Simultaneous measurement of neuronal activity and cortical hemodynamics by unshielded magnetoencephalography and near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Seki, Yusuke; Miyashita, Tsuyoshi; Kandori, Akihiko; Maki, Atsushi; Koizumi, Hideaki

    2012-10-01

    The correlation between neuronal activity and cortical hemodynamics, namely, neurovascular coupling (NVC), is important to shed light on the mechanism of a variety of brain functions or neuronal diseases. NVC can be studied by simultaneously measuring neuronal activity and cortical hemodynamics. Consequently, noninvasive measurements of the NVC have been widely studied using both electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). However, electromagnetic interference between EEG and fMRI is still a major problem. On the other hand, near-infrared spectroscopy (NIRS) is another promising tool for detecting cortical hemodynamics because it can be combined with EEG or magnetoencephalography (MEG) without any electromagnetic interference. Accordingly, in the present study, a simultaneous measurement system-combining an unshielded MEG using a two-dimensional gradiometer based on a low-T superconducting quantum interference device (SQUID) and an NIRS using nonmagnetic thin probes-was developed. This combined system was used to simultaneously measure both an auditory-evoked magnetic field and blood flow change in the auditory cortex. It was experimentally demonstrated that the combined unshielded MEG/NIRS system can simultaneously measure neuronal activity and cortical hemodynamics.

  2. Linear integration of spine Ca2+ signals in layer 4 cortical neurons in vivo

    PubMed Central

    Jia, Hongbo; Varga, Zsuzsanna; Sakmann, Bert; Konnerth, Arthur

    2014-01-01

    Sensory information reaches the cortex through synchronously active thalamic axons, which provide a strong drive to layer 4 (L4) cortical neurons. Because of technical limitations, the dendritic signaling processes underlying the rapid and efficient activation of L4 neurons in vivo remained unknown. Here we introduce an approach that allows the direct monitoring of single dendritic spine Ca2+ signals in L4 spiny stellate cells of the vibrissal mouse cortex in vivo. Our results demonstrate that activation of N-methyl-D-aspartate (NMDA) receptors is required for sensory-evoked action potential (AP) generation in these neurons. By analyzing NMDA receptor-mediated Ca2+ signaling, we identify whisker stimulation-evoked large responses in a subset of dendritic spines. These sensory-stimulation–activated spines, representing predominantly thalamo-cortical input sites, were denser at proximal dendritic regions. The amplitude of sensory-evoked spine Ca2+ signals was independent of the activity of neighboring spines, without evidence for cooperativity. Furthermore, we found that spine Ca2+ signals evoked by back-propagating APs sum linearly with sensory-evoked synaptic Ca2+ signals. Thus, our results identify in sensory information-receiving L4 cortical neurons a linear mode of dendritic integration that underlies the rapid and reliable transfer of peripheral signals to the cortical network. PMID:24927564

  3. Flicker adaptation of low-level cortical visual neurons contributes to temporal dilation

    PubMed Central

    Ortega, Laura; Guzman-Martinez, Emmanuel; Grabowecky, Marcia; Suzuki, Satoru

    2013-01-01

    Several seconds of adaptation to a flickered stimulus causes a subsequent brief static stimulus to appear longer in duration. Non-sensory factors such as increased arousal and attention have been thought to mediate this flicker-based temporal-dilation aftereffect. Here we provide evidence that adaptation of low-level cortical visual neurons contributes to this aftereffect. The aftereffect was significantly reduced by a 45° change in Gabor orientation between adaptation and test. Because orientation-tuning bandwidths are smaller in lower-level cortical visual areas and are approximately 45° in human V1, the result suggests that flicker adaptation of orientation-tuned V1 neurons contributes to the temporal-dilation aftereffect. The aftereffect was abolished when the adaptor and test stimuli were presented to different eyes. Because eye preferences are strong in V1 but diminish in higher-level visual areas, the eye specificity of the aftereffect corroborates the involvement of low-level cortical visual neurons. Our results thus suggest that flicker adaptation of low-level cortical visual neurons contributes to expanding visual duration. Furthermore, this temporal-dilation aftereffect dissociates from the previously reported temporal-constriction aftereffect on the basis of the differences in their orientation and flicker-frequency selectivity, suggesting that the visual system possesses at least two distinct and potentially complementary mechanisms for adaptively coding perceived duration. PMID:22866761

  4. Regulation of Cerebral Cortical Size and Neuron Number by Fibroblast Growth Factors: Implications for Autism

    ERIC Educational Resources Information Center

    Vaccarino, Flora M.; Grigorenko, Elena L.; Smith, Karen Muller; Stevens, Hanna E.

    2009-01-01

    Increased brain size is common in children with autism spectrum disorders. Here we propose that an increased number of cortical excitatory neurons may underlie the increased brain volume, minicolumn pathology and excessive network excitability, leading to sensory hyper-reactivity and seizures, which are often found in autism. We suggest that…

  5. Mitigation of ROS Insults by Streptomyces Secondary Metabolites in Primary Cortical Neurons

    PubMed Central

    2013-01-01

    Oxidative stress is a common point in neurodegenerative diseases, widely connected with mitochondrial dysfunction. In this study, we screened seven natural products from Streptomyces sources against hydrogen peroxide insult in primary cortical neurons, an oxidative stress in vitro model. We showed the ability of these compounds to inhibit neuronal cytotoxicity and to reduce ROS release after 12 h treatment. Among the tested compounds, the quinone anhydroexfoliamycin and the red pyrrole-type pigment undecylprodigiosin stand out. These two compounds displayed the most complete protection against oxidative stress with mitochondrial function improvement, ROS production inhibition, and increase of antioxidant enzyme levels, glutathione and catalase. Further investigations confirmed that anhydroexfoliamycin acts over the Nrf2-ARE pathway, as a Nrf2 nuclear translocation inductor, and is able to strongly inhibit the effect of the mitochondrial uncoupler FCCP over cytosolic Ca2+, pointing to mitochondria as a cellular target for this molecule. In addition, both compounds were able to reduce caspase-3 activity induced by the apoptotic enhancer staurosporine, but undecylprodigiosin failed to inhibit FCCP effects and it did not act over the Nrf2 pathway as was the case for anhydroexfoliamycin. These results show that Streptomyces metabolites could be useful for the development of new drugs for prevention of neurodegenerative disorders such as Parkinson’s and Alzheimer’s diseases and cerebral ischemia. PMID:24219236

  6. 14,15-EET promotes mitochondrial biogenesis and protects cortical neurons against oxygen/glucose deprivation-induced apoptosis.

    PubMed

    Wang, Lai; Chen, Man; Yuan, Lin; Xiang, Yuting; Zheng, Ruimao; Zhu, Shigong

    2014-07-18

    14,15-Epoxyeicosatrienoic acid (14,15-EET), a metabolite of arachidonic acid, is enriched in the brain cortex and exerts protective effect against neuronal apoptosis induced by ischemia/reperfusion. Although apoptosis has been well recognized to be closely associated with mitochondrial biogenesis and function, it is still unclear whether the neuroprotective effect of 14,15-EET is mediated by promotion of mitochondrial biogenesis and function in cortical neurons under the condition of oxygen-glucose deprivation (OGD). In this study, we found that 14,15-EET improved cell viability and inhibited apoptosis of cortical neurons. 14,15-EET significantly increased the mitochondrial mass and the ratio of mitochondrial DNA to nuclear DNA. Key makers of mitochondrial biogenesis, peroxisome proliferator activator receptor gamma-coactivator 1 alpha (PGC-1α), nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM), were elevated at both mRNA and protein levels in the cortical neurons treated with 14,15-EET. Moreover, 14,15-EET markedly attenuated the decline of mitochondrial membrane potential, reduced ROS, while increased ATP synthesis. Knockdown of cAMP-response element binding protein (CREB) by siRNA blunted the up-regulation of PGC-1α and NRF-1 stimulated by 14,15-EET, and consequently abolished the neuroprotective effect of 14,15-EET. Our results indicate that 14,15-EET protects neurons from OGD-induced apoptosis by promoting mitochondrial biogenesis and function through CREB mediated activation of PGC-1α and NRF-1.

  7. The efferent projections of neurons in the white matter of different cortical areas of the adult rat.

    PubMed

    Meyer, G; Gonzalez-Hernandez, T; Galindo-Mireles, D; Castañeyra-Perdomo, A; Ferres-Torres, R

    1991-01-01

    Injection of Fast Blue into different cortical areas (frontal, parietal, anterior and posterior cingulate cortex) revealed that neurons in the white matter (interstitial neurons) give rise to association fibers which project mostly to the gray matter of the overlying cytoarchitectonic area, but which may extend also over different cytoarchitectonic areas. The rostrocaudal extent of the projecting axons was up to 1 mm in the frontal and parietal cortex, and up to 3.5 mm in the cingulate cortex. Concurrent processing for dihydronicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry showed that 70% of cortically projecting interstitial neurons were NADPH-d-positive. An analysis of neuronal morphology suggests that the FasT-Blue-labeled, NADPH-d-negative neurons may represent displaced pyramidal neurons of layer VIb; the Fast-Blue-labeled and NADPH-d-positive neurons have bipolar or multipolar dendritic trees, constituting a population of nonpyramidal interstitial neurons that project into the cortical gray matter.

  8. Cortical Stimulation Concurrent With Skilled Motor Training Improves Forelimb Function and Enhances Motor Cortical Reorganization Following Controlled Cortical Impact.

    PubMed

    Jefferson, Stephanie C; Clayton, Elyse Renee; Donlan, Nicole A; Kozlowski, Dorothy Annette; Jones, Theresa A; Adkins, DeAnna Lynn

    2016-02-01

    Electrical and magnetic brain stimulation can improve motor function following stroke in humans, rats, and nonhuman primates, especially when paired with rehabilitative training (RT). Previously, we found in rodent stroke models that epidural electrical cortical stimulation (CS) of the ipsilesional motor cortex (MC) combined with motor RT enhances motor function and motor cortical plasticity. It was unknown whether CS following experimental traumatic brain injury (TBI) would have similar effects. To test the effects of CS combined with motor training after moderate/severe TBI on behavioral outcome and motor cortical organization. Following unilateral controlled cortical impact (CCI) over the caudal forelimb area of the MC in adult male rats, forelimb reach training was administered daily for 9 weeks concurrently with subthreshold, 100-Hz monopolar CS or no-stimulation control procedures. The rate and magnitude of behavioral improvements and changes in forelimb movement representations in the injured MC as revealed by intracortical microstimulation were measured. CCI resulted in severe motor impairments persisting throughout the 9 weeks of training in both groups, but CS-treated animals had significantly greater behavioral improvements. CS also increased wrist motor cortical representation, one of the main movements used in the training task, when compared with RT alone. However, the overall recovery level was modest, leaving animals still extremely impaired. These data suggest that CS may be useful for improving rehabilitation efficacy after TBI but also raise the possibility that the CS parameters that are highly effective following stroke are suboptimal after moderate/severe TBI. © The Author(s) 2015.

  9. Coconut oil attenuates the effects of amyloid-β on cortical neurons in vitro.

    PubMed

    Nafar, Firoozeh; Mearow, Karen M

    2014-01-01

    Dietary supplementation has been studied as an approach to ameliorating deficits associated with aging and neurodegeneration. We undertook this pilot study to investigate the effects of coconut oil supplementation directly on cortical neurons treated with amyloid-β (Aβ) peptide in vitro. Our results indicate that neuron survival in cultures co-treated with coconut oil and Aβ is rescued compared to cultures exposed only to Aβ. Coconut oil co-treatment also attenuates Aβ-induced mitochondrial alterations. The results of this pilot study provide a basis for further investigation of the effects of coconut oil, or its constituents, on neuronal survival focusing on mechanisms that may be involved.

  10. Elemental gesture dynamics are encoded by song premotor cortical neurons.

    PubMed

    Amador, Ana; Perl, Yonatan Sanz; Mindlin, Gabriel B; Margoliash, Daniel

    2013-03-07

    Quantitative biomechanical models can identify control parameters that are used during movements, and movement parameters that are encoded by premotor neurons. We fit a mathematical dynamical systems model including subsyringeal pressure, syringeal biomechanics and upper-vocal-tract filtering to the songs of zebra finches. This reduces the dimensionality of singing dynamics, described as trajectories (motor 'gestures') in a space of syringeal pressure and tension. Here we assess model performance by characterizing the auditory response 'replay' of song premotor HVC neurons to the presentation of song variants in sleeping birds, and by examining HVC activity in singing birds. HVC projection neurons were excited and interneurons were suppressed within a few milliseconds of the extreme time points of the gesture trajectories. Thus, the HVC precisely encodes vocal motor output through activity at the times of extreme points of movement trajectories. We propose that the sequential activity of HVC neurons is used as a 'forward' model, representing the sequence of gestures in song to make predictions on expected behaviour and evaluate feedback.

  11. Survival of Adhering Cortical Neurons on Polyethylenimine Micropatterns

    DTIC Science & Technology

    2001-10-25

    survive in a physiological surrounding over prolonged periods of time. The development of a cultured neuron probe [1] is considered to be an...J. Biomed. Microdev., vol. 1:1, pp. 49-64, 1998. [11] C.A. Thomas, P.A. Springer, G.E. Loeb, Y. Berwald- Netter , and L.M. Okun, “A miniature

  12. Neuronal heterotopia with capillary penetration of neurons and cortical dysplasia in a patient with complex partial seizures. Case report.

    PubMed

    Jay, V; Becker, L E; Otsubo, H; Hwang, P; Hoffman, H J; Armstrong, D C

    1993-04-01

    Unusual pathological findings were encountered in a temporal lobectomy specimen from a 9-year-old boy with intractable complex partial seizures. Magnetic resonance imaging revealed an enlarged left temporal lobe, with diffuse high signal intensity over the cortex and poor gray-white differentiation on T2-weighted imaging; single-photon emission computerized tomography showed decreased blood flow. Active epileptiform discharges were identified in the left temporal lobe with focal slow waves and generalized epileptiform paroxysms. Pathologically, the cortex revealed changes of focal cortical dysplasia with extensive disorganization of neuronal morphology, layering, and orientation as well as focal polymicrogyria. The cortical-white matter junction was indistinct with extensive neuronal heterotopias in the white matter. Large pale balloon cells akin to those seen in tuberous sclerosis were found scattered within the cortex and white matter. The most striking finding was that of a heterotopic nodule in the white matter, which revealed abnormal neurons with penetration of cell bodies by capillaries. Ultrastructurally, there were no degenerative changes in these neurons, and this unusual phenomenon is attributed to a developmental disturbance affecting neuronal, glial, and vascular elements.

  13. Autaptic self-inhibition of cortical GABAergic neurons: synaptic narcissism or useful introspection?

    PubMed

    Deleuze, Charlotte; Pazienti, Antonio; Bacci, Alberto

    2014-06-01

    Fast synaptic inhibition sculpts all forms of cortical activity by means of a specialized connectivity pattern between highly heterogeneous inhibitory interneurons and principal excitatory cells. Importantly, inhibitory neurons connect also to each other extensively, following a detailed blueprint, and, indeed, specific forms of disinhibition affect important behavioral functions. Here we discuss a peculiar form of cortical disinhibition: the massive autaptic self-inhibition of parvalbumin-(PV) positive basket cells. Despite being described long ago, autaptic inhibition onto PV basket cells is rarely included in cortical circuit diagrams, perhaps because of its still elusive function. We propose here a potential dual role of autaptic feedback inhibition in temporally coordinating PV basket cells during cortical network activity.

  14. Dipeptide Piracetam Analogue Noopept Improves Viability of Hippocampal HT-22 Neurons in the Glutamate Toxicity Model.

    PubMed

    Antipova, T A; Nikolaev, S V; Ostrovskaya, P U; Gudasheva, T A; Seredenin, S B

    2016-05-01

    Effect of noopept (N-phenylacetyl-prolylglycine ethyl ester) on viability of neurons exposed to neurotoxic action of glutamic acid (5 mM) was studied in vitro in immortalized mouse hippocampal HT-22 neurons. Noopept added to the medium before or after glutamic acid improved neuronal survival in a concentration range of 10-11-10-5 M. Comparison of the effective noopept concentrations determined in previous studies on cultured cortical and cerebellar neurons showed that hippocampal neurons are more sensitive to the protective effect of noopept.

  15. Genistein Partly Eases Aging and Estropause-Induced Primary Cortical Neuronal Changes in Rats

    PubMed Central

    Wang, Tsyr-Jiuan; Chen, Jeng-Rung; Wang, Wen-Jay; Wang, Yueh-Jan; Tseng, Guo-Fang

    2014-01-01

    Gonadal hormones can modulate brain morphology and behavior. Recent studies have shown that hypogonadism could result in cortical function deficits. To this end, hormone therapy has been used to ease associated symptoms but the risk may outweigh the benefits. Here we explored whether genistein, a phytoestrogen, is effective in restoring the cognitive and central neuronal changes in late middle age and surgically estropause female rats. Both animal groups showed poorer spatial learning than young adults. The dendritic arbors and spines of the somatosensory cortical and CA1 hippocampal pyramidal neurons were revealed with intracellular dye injection and analyzed. The results showed that dendritic spines on these neurons were significantly decreased. Remarkably, genistein treatment rescued spatial learning deficits and restored the spine density on all neurons in the surgically estropause young females. In late middle age females, genistein was as effective as estradiol in restoring spines; however, the recovery was less thorough than on young OHE rats. Neither genistein nor estradiol rectified the shortened dendritic arbors of the aging cortical pyramidal neurons suggesting that dendritic arbors and spines are differently modulated. Thus, genistein could work at central level to restore excitatory connectivity and appears to be potent alternative to estradiol for easing aging and menopausal syndromes. PMID:24587060

  16. Cortical GABAergic neurons are more severely impaired by alkalosis than acidosis

    PubMed Central

    2013-01-01

    Background Acid–base imbalance in various metabolic disturbances leads to human brain dysfunction. Compared with acidosis, the patients suffered from alkalosis demonstrate more severe neurological signs that are difficultly corrected. We hypothesize a causative process that the nerve cells in the brain are more vulnerable to alkalosis than acidosis. Methods The vulnerability of GABAergic neurons to alkalosis versus acidosis was compared by analyzing their functional changes in response to the extracellular high pH and low pH. The neuronal and synaptic functions were recorded by whole-cell recordings in the cortical slices. Results The elevation or attenuation of extracellular pH impaired these GABAergic neurons in terms of their capability to produce spikes, their responsiveness to excitatory synaptic inputs and their outputs via inhibitory synapses. Importantly, the dysfunction of these active properties appeared severer in alkalosis than acidosis. Conclusions The severer impairment of cortical GABAergic neurons in alkalosis patients leads to more critical neural excitotoxicity, so that alkalosis-induced brain dysfunction is difficultly corrected, compared to acidosis. The vulnerability of cortical GABAergic neurons to high pH is likely a basis of severe clinical outcomes in alkalosis versus acidosis. PMID:24314112

  17. Genistein partly eases aging and estropause-induced primary cortical neuronal changes in rats.

    PubMed

    Wang, Tsyr-Jiuan; Chen, Jeng-Rung; Wang, Wen-Jay; Wang, Yueh-Jan; Tseng, Guo-Fang

    2014-01-01

    Gonadal hormones can modulate brain morphology and behavior. Recent studies have shown that hypogonadism could result in cortical function deficits. To this end, hormone therapy has been used to ease associated symptoms but the risk may outweigh the benefits. Here we explored whether genistein, a phytoestrogen, is effective in restoring the cognitive and central neuronal changes in late middle age and surgically estropause female rats. Both animal groups showed poorer spatial learning than young adults. The dendritic arbors and spines of the somatosensory cortical and CA1 hippocampal pyramidal neurons were revealed with intracellular dye injection and analyzed. The results showed that dendritic spines on these neurons were significantly decreased. Remarkably, genistein treatment rescued spatial learning deficits and restored the spine density on all neurons in the surgically estropause young females. In late middle age females, genistein was as effective as estradiol in restoring spines; however, the recovery was less thorough than on young OHE rats. Neither genistein nor estradiol rectified the shortened dendritic arbors of the aging cortical pyramidal neurons suggesting that dendritic arbors and spines are differently modulated. Thus, genistein could work at central level to restore excitatory connectivity and appears to be potent alternative to estradiol for easing aging and menopausal syndromes.

  18. Influence of Ionic Conductances on Spike Timing Reliability of Cortical Neurons for Suprathreshold Rhythmic Inputs

    PubMed Central

    Schreiber, Susanne; Fellous, Jean-Marc; Tiesinga, Paul; Sejnowski, Terrence J.

    2010-01-01

    Spike timing reliability of neuronal responses depends on the frequency content of the input. We investigate how intrinsic properties of cortical neurons affect spike timing reliability in response to rhythmic inputs of suprathreshold mean. Analyzing reliability of conductance-based cortical model neurons on the basis of a correlation measure, we show two aspects of how ionic conductances influence spike timing reliability. First, they set the preferred frequency for spike timing reliability, which in accordance with the resonance effect of spike timing reliability is well approximated by the firing rate of a neuron in response to the DC component in the input. We demonstrate that a slow potassium current can modulate the spike timing frequency preference over a broad range of frequencies. This result is confirmed experimentally by dynamic-clamp recordings from rat prefrontal cortical neurons in vitro. Second, we provide evidence that ionic conductances also influence spike timing beyond changes in preferred frequency. Cells with the same DC firing rate exhibit more reliable spike timing at the preferred frequency and its harmonics if the slow potassium current is larger and its kinetics are faster, whereas a larger persistent sodium current impairs reliability. We predict that potassium channels are an efficient target for neuromodulators that can tune spike timing reliability to a given rhythmic input. PMID:14507985

  19. Salidroside protects cortical neurons against glutamate-induced cytotoxicity by inhibiting autophagy.

    PubMed

    Yin, Wei-Yong; Ye, Qiang; Huang, Huan-Jie; Xia, Nian-Ge; Chen, Yan-Yan; Zhang, Yi; Qu, Qiu-Min

    2016-08-01

    Recent evidence suggests that glutamate-induced cytotoxicity contributes to autophagic neuron death and is partially mediated by increased oxidative stress. Salidroside has been demonstrated to have neuroprotective effects in glutamate-induced neuronal damage. The precise mechanism of its regulatory role in neuronal autophagy is, however, poorly understood. This study aimed to probe the effects and mechanisms of salidroside in glutamate-induced autophagy activation in cultured rat cortical neurons. Cell viability assay, Western blotting, coimmunoprecipitation, and small interfering RNA were performed to analyze autophagy activities during glutamate-evoked oxidative injury. We found that salidroside protected neonatal neurons from glutamate-induced apoptotic cell death. Salidroside significantly attenuated the LC3-II/LC3-I ratio and expression of Beclin-1, but increased (SQSTM1)/p62 expression under glutamate exposure. Pretreatment with 3-methyladenine (3-MA), an autophagy inhibitor, decreased LC3-II/LC3-I ratio, attenuated glutamate-induced cell injury, and mimicked some of the protective effects of salidroside against glutamate-induced cell injury. Molecular analysis demonstrated that salidroside inhibited cortical neuron autophagy in response to glutamate exposure through p53 signaling by increasing the accumulation of cytoplasmic p53. Salidroside inhibited the glutamate-induced dissociation of the Bcl-2-Beclin-1 complex with minor affects on the PI3K/Akt/mTOR signaling pathways. These data demonstrate that the inhibition of autophagy could be responsible for the neuroprotective effects of salidroside on glutamate-induced neuronal injury.

  20. Towards a theory of cortical columns: From spiking neurons to interacting neural populations of finite size

    PubMed Central

    Gerstner, Wulfram

    2017-01-01

    Neural population equations such as neural mass or field models are widely used to study brain activity on a large scale. However, the relation of these models to the properties of single neurons is unclear. Here we derive an equation for several interacting populations at the mesoscopic scale starting from a microscopic model of randomly connected generalized integrate-and-fire neuron models. Each population consists of 50–2000 neurons of the same type but different populations account for different neuron types. The stochastic population equations that we find reveal how spike-history effects in single-neuron dynamics such as refractoriness and adaptation interact with finite-size fluctuations on the population level. Efficient integration of the stochastic mesoscopic equations reproduces the statistical behavior of the population activities obtained from microscopic simulations of a full spiking neural network model. The theory describes nonlinear emergent dynamics such as finite-size-induced stochastic transitions in multistable networks and synchronization in balanced networks of excitatory and inhibitory neurons. The mesoscopic equations are employed to rapidly integrate a model of a cortical microcircuit consisting of eight neuron types, which allows us to predict spontaneous population activities as well as evoked responses to thalamic input. Our theory establishes a general framework for modeling finite-size neural population dynamics based on single cell and synapse parameters and offers an efficient approach to analyzing cortical circuits and computations. PMID:28422957

  1. Tech: a RhoA GEF selectively expressed in hippocampal and cortical neurons.

    PubMed

    Marx, Ruth; Henderson, Jennifer; Wang, James; Baraban, Jay M

    2005-02-01

    Recent studies implicating the Rho family of small G proteins in the regulation of neuronal morphology have focused attention on identifying key components of Rho signaling pathways in neurons. To this end, we have conducted studies aimed at defining the localization and function of Tech, a Rho guanine nucleotide exchange factor (GEF) family member that is highly enriched in brain. We have found that Tech is selectively expressed in cortical and hippocampal neurons with prominent Tech immunostaining apparent in the cell bodies and dendrites of these cells. In vitro studies with prototypical members of the major Rho subfamilies, RhoA, Rac1 and Cdc42, indicate that Tech binds selectively to and activates RhoA. To assess whether Tech may be involved in the regulation of neuronal morphology, we examined the effects of Tech constructs on the morphology of cortical neurons grown in primary culture. We found that a constitutively active Tech construct, Tech 245DeltaC, decreases the number of dendritic processes present on these neurons. This reduction appears to be mediated by activation of RhoA as it is blocked by insertion of a point mutation into the DH domain of Tech which blocks its ability to activate RhoA or coexpression of a dominant negative RhoA construct. As Tech protein levels increase during post-natal development and remain at peak levels into adulthood, these results indicate that Tech regulates RhoA signaling pathways in developing and mature forebrain neurons.

  2. Towards a theory of cortical columns: From spiking neurons to interacting neural populations of finite size.

    PubMed

    Schwalger, Tilo; Deger, Moritz; Gerstner, Wulfram

    2017-04-01

    Neural population equations such as neural mass or field models are widely used to study brain activity on a large scale. However, the relation of these models to the properties of single neurons is unclear. Here we derive an equation for several interacting populations at the mesoscopic scale starting from a microscopic model of randomly connected generalized integrate-and-fire neuron models. Each population consists of 50-2000 neurons of the same type but different populations account for different neuron types. The stochastic population equations that we find reveal how spike-history effects in single-neuron dynamics such as refractoriness and adaptation interact with finite-size fluctuations on the population level. Efficient integration of the stochastic mesoscopic equations reproduces the statistical behavior of the population activities obtained from microscopic simulations of a full spiking neural network model. The theory describes nonlinear emergent dynamics such as finite-size-induced stochastic transitions in multistable networks and synchronization in balanced networks of excitatory and inhibitory neurons. The mesoscopic equations are employed to rapidly integrate a model of a cortical microcircuit consisting of eight neuron types, which allows us to predict spontaneous population activities as well as evoked responses to thalamic input. Our theory establishes a general framework for modeling finite-size neural population dynamics based on single cell and synapse parameters and offers an efficient approach to analyzing cortical circuits and computations.

  3. Thalamus-derived molecules promote survival and dendritic growth of developing cortical neurons.

    PubMed

    Sato, Haruka; Fukutani, Yuma; Yamamoto, Yuji; Tatara, Eiichi; Takemoto, Makoto; Shimamura, Kenji; Yamamoto, Nobuhiko

    2012-10-31

    The mammalian neocortex is composed of various types of neurons that reflect its laminar and area structures. It has been suggested that not only intrinsic but also afferent-derived extrinsic factors are involved in neuronal differentiation during development. However, the role and molecular mechanism of such extrinsic factors are almost unknown. Here, we attempted to identify molecules that are expressed in the thalamus and affect cortical cell development. First, thalamus-specific molecules were sought by comparing gene expression profiles of the developing rat thalamus and cortex using microarrays, and by constructing a thalamus-enriched subtraction cDNA library. A systematic screening by in situ hybridization showed that several genes encoding extracellular molecules were strongly expressed in sensory thalamic nuclei. Exogenous and endogenous protein localization further demonstrated that two extracellular molecules, Neuritin-1 (NRN1) and VGF, were transported to thalamic axon terminals. Application of NRN1 and VGF to dissociated cell culture promoted the dendritic growth. An organotypic slice culture experiment further showed that the number of primary dendrites in multipolar stellate neurons increased in response to NRN1 and VGF, whereas dendritic growth of pyramidal neurons was not promoted. These molecules also increased neuronal survival of multipolar neurons. Taken together, these results suggest that the thalamus-specific molecules NRN1 and VGF play an important role in the dendritic growth and survival of cortical neurons in a cell type-specific manner.

  4. MicroRNA targeting of CoREST controls polarization of migrating cortical neurons.

    PubMed

    Volvert, Marie-Laure; Prévot, Pierre-Paul; Close, Pierre; Laguesse, Sophie; Pirotte, Sophie; Hemphill, James; Rogister, Florence; Kruzy, Nathalie; Sacheli, Rosalie; Moonen, Gustave; Deiters, Alexander; Merkenschlager, Matthias; Chariot, Alain; Malgrange, Brigitte; Godin, Juliette D; Nguyen, Laurent

    2014-05-22

    The migration of cortical projection neurons is a multistep process characterized by dynamic cell shape remodeling. The molecular basis of these changes remains elusive, and the present work describes how microRNAs (miRNAs) control neuronal polarization during radial migration. We show that miR-22 and miR-124 are expressed in the cortical wall where they target components of the CoREST/REST transcriptional repressor complex, thereby regulating doublecortin transcription in migrating neurons. This molecular pathway underlies radial migration by promoting dynamic multipolar-bipolar cell conversion at early phases of migration, and later stabilization of cell polarity to support locomotion on radial glia fibers. Thus, our work emphasizes key roles of some miRNAs that control radial migration during cerebral corticogenesis.

  5. Characterization of neurons in the cortical white matter in human temporal lobe epilepsy.

    PubMed

    Richter, Zsófia; Janszky, József; Sétáló, György; Horváth, Réka; Horváth, Zsolt; Dóczi, Tamás; Seress, László; Ábrahám, Hajnalka

    2016-10-01

    The aim of the present work was to characterize neurons in the archi- and neocortical white matter, and to investigate their distribution in mesial temporal sclerosis. Immunohistochemistry and quantification of neurons were performed on surgically resected tissue sections of patients with therapy-resistant temporal lobe epilepsy. Temporal lobe tissues of patients with tumor but without epilepsy and that from autopsy were used as controls. Neurons were identified with immunohistochemistry using antibodies against NeuN, calcium-binding proteins, transcription factor Tbr1 and neurofilaments. We found significantly higher density of neurons in the archi- and neocortical white matter of patients with temporal lobe epilepsy than in that of controls. Based on their morphology and neurochemical content, both excitatory and inhibitory cells were present among these neurons. A subset of neurons in the white matter was Tbr-1-immunoreactive and these neurons coexpressed NeuN and neurofilament marker SMI311R. No colocalization of Tbr1 was observed with the inhibitory neuronal markers, calcium-binding proteins. We suggest that a large population of white matter neurons comprises remnants of the subplate. Furthermore, we propose that a subset of white matter neurons was arrested during migration, highlighting the role of cortical maldevelopment in epilepsy associated with mesial temporal sclerosis. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  6. Exacerbation of Apoptosis of Cortical Neurons Following Traumatic Brain Injury in Par-4 Transgenic Mice

    PubMed Central

    Payette, Daniel J; Xie, Jun; Shirwany, Najeeb; Guo, Qing

    2008-01-01

    Traumatic brain injury (TBI) is a significant clinical problem, yet few effective strategies for treating it have emerged. People that sustain and survive a TBI are left with significant cognitive, behavioral, and communicative disabilities. Apoptotic neuronal death occurs following TBI. Prostate apoptosis response-4 (Par-4) is a death domain-containing protein initially characterized as a critical regulator of apoptosis in prostate cancer cells. We have recently generated and characterized Par-4 transgenic mice in which the expression of the par-4 transgene was limited to cells of neuronal lineage. We now provide evidence that, in cortical neurons from these mice, Par-4 drastically increases apoptotic neuronal death in both in vitro and in vivo models of TBI. In vitro experiments were performed in 7-day-old primary cultures of cortical neurons using a previously published, scratch-induced mechanical trauma model. Neurons that overexpress Par-4 showed not only a significant decrease in overall neuron survival after TBI compared to wild-type cells, but also exhibited a sharper decrease in mitochondrial transmembrane potential, a higher degree of free radical accumulation, and earlier activation of caspase-3 than wild-type cells did. In vivo experiments were performed utilizing a weight drop TBI model. A significantly increased volume of cortical injury and exacerbated activation of caspase-3 were observed in Par-4 transgenic mice when compared to those in wild-type mice. These data suggests that aberrant Par-4 expression exacerbates neuronal cell death following TBI by altering mitochondrial function, enhancing oxidative damage, and execution of apoptosis via caspase activation. PMID:18784822

  7. Methamphetamine induces heme oxygenase-1 expression in cortical neurons and glia to prevent its toxicity.

    PubMed

    Huang, Ya-Ni; Wu, Ching-Hsiang; Lin, Tzu-Chao; Wang, Jia-Yi

    2009-11-01

    The impairment of cognitive and motor functions in humans and animals caused by methamphetamine (METH) administration underscores the importance of METH toxicity in cortical neurons. The heme oxygenase-1 (HO-1) exerts a cytoprotective effect against various neuronal injures; however, it remains unclear whether HO-1 is involved in METH-induced toxicity. We used primary cortical neuron/glia cocultures to explore the role of HO-1 in METH-induced toxicity. Exposure of cultured cells to various concentrations of METH (0.1, 0.5, 1, 3, 5, and 10 mM) led to cytotoxicity in a concentration-dependent manner. A METH concentration of 5 mM, which caused 50% of neuronal death and glial activation, was chosen for subsequent experiments. RT-PCR and Western blot analysis revealed that METH significantly induced HO-1 mRNA and protein expression, both preceded cell death. Double and triple immunofluorescence staining further identified HO-1-positive cells as activated astrocytes, microglia, and viable neurons, but not dying neurons. Inhibition of the p38 mitogen-activated protein kinase pathway significantly blocked HO-1 induction by METH and aggravated METH neurotoxicity. Inhibition of HO activity using tin protoporphyrine IX significantly reduced HO activity and exacerbated METH neurotoxicity. However, prior induction of HO-1 using cobalt protoporphyrine IX partially protected neurons from METH toxicity. Taken together, our results suggest that induction of HO-1 by METH via the p38 signaling pathway may be protective, albeit insufficient to completely protect cortical neurons from METH toxicity.

  8. Methamphetamine induces heme oxygenase-1 expression in cortical neurons and glia to prevent its toxicity

    SciTech Connect

    Huang, Y.-N.; Wu, C.-H.; Lin, T.-C.; Wang, J.-Y.

    2009-11-01

    The impairment of cognitive and motor functions in humans and animals caused by methamphetamine (METH) administration underscores the importance of METH toxicity in cortical neurons. The heme oxygenase-1 (HO-1) exerts a cytoprotective effect against various neuronal injures; however, it remains unclear whether HO-1 is involved in METH-induced toxicity. We used primary cortical neuron/glia cocultures to explore the role of HO-1 in METH-induced toxicity. Exposure of cultured cells to various concentrations of METH (0.1, 0.5, 1, 3, 5, and 10 mM) led to cytotoxicity in a concentration-dependent manner. A METH concentration of 5 mM, which caused 50% of neuronal death and glial activation, was chosen for subsequent experiments. RT-PCR and Western blot analysis revealed that METH significantly induced HO-1 mRNA and protein expression, both preceded cell death. Double and triple immunofluorescence staining further identified HO-1-positive cells as activated astrocytes, microglia, and viable neurons, but not dying neurons. Inhibition of the p38 mitogen-activated protein kinase pathway significantly blocked HO-1 induction by METH and aggravated METH neurotoxicity. Inhibition of HO activity using tin protoporphyrine IX significantly reduced HO activity and exacerbated METH neurotoxicity. However, prior induction of HO-1 using cobalt protoporphyrine IX partially protected neurons from METH toxicity. Taken together, our results suggest that induction of HO-1 by METH via the p38 signaling pathway may be protective, albeit insufficient to completely protect cortical neurons from METH toxicity.

  9. Functional properties of in vitro excitatory cortical neurons derived from human pluripotent stem cells

    PubMed Central

    Magnani, Dario; Hardingham, Giles E.; Chandran, Siddharthan

    2015-01-01

    Abstract The in vitro derivation of regionally defined human neuron types from patient‐derived stem cells is now established as a resource to investigate human development and disease. Characterization of such neurons initially focused on the expression of developmentally regulated transcription factors and neural markers, in conjunction with the development of protocols to direct and chart the fate of differentiated neurons. However, crucial to the understanding and exploitation of this technology is to determine the degree to which neurons recapitulate the key functional features exhibited by their native counterparts, essential for determining their usefulness in modelling human physiology and disease in vitro. Here, we review the emerging data concerning functional properties of human pluripotent stem cell‐derived excitatory cortical neurons, in the context of both maturation and regional specificity. PMID:26608229

  10. Huntingtin-Mediated Multipolar-Bipolar Transition of Newborn Cortical Neurons Is Critical for Their Postnatal Neuronal Morphology.

    PubMed

    Barnat, Monia; Le Friec, Julien; Benstaali, Caroline; Humbert, Sandrine

    2017-01-04

    In the developing cortex, projection neurons undergo multipolar-bipolar transition, radial-directed migration, and maturation. The contribution of these developmental steps to the structure of the adult cortex is not completely understood. Here, we report that huntingtin (HTT), the protein mutated in Huntington's disease, is enriched in polarizing projection neurons. The depletion of HTT in postmitotic projection neurons leads to the mislocalization of layer-specific neuronal populations in the mouse neocortex. HTT is required for the multipolar-bipolar transition of projection neurons and for the maintenance of their bipolar shape during their radial migration. HTT mediates these effects in vivo through the regulation of RAB11-dependent N-Cadherin trafficking. Importantly, HD pathological HTT alters RAB11-dependent neuronal migration. Finally, we show that the cortical defects resulting from the postmitotic loss of HTT specifically during embryonic development affect neuronal morphology at adulthood. Our data reveal a new HTT-RAB11-N-Cadherin pathway regulating multipolar-bipolar transition with direct implications for mature brain. VIDEO ABSTRACT.

  11. Cortical Hypoexcitation Defines Neuronal Responses in the Immediate Aftermath of Traumatic Brain Injury

    PubMed Central

    Johnstone, Victoria Philippa Anne; Yan, Edwin Bingbing; Alwis, Dasuni Sathsara; Rajan, Ramesh

    2013-01-01

    Traumatic brain injury (TBI) from a blow to the head is often associated with complex patterns of brain abnormalities that accompany deficits in cognitive and motor function. Previously we reported that a long-term consequence of TBI, induced with a closed-head injury method modelling human car and sporting accidents, is neuronal hyper-excitation in the rat sensory barrel cortex that receives tactile input from the face whiskers. Hyper-excitation occurred only in supra-granular layers and was stronger to complex than simple stimuli. We now examine changes in the immediate aftermath of TBI induced with same injury method. At 24 hours post-trauma significant sensorimotor deficits were observed and characterisation of the cortical population neuronal responses at that time revealed a depth-dependent suppression of neuronal responses, with reduced responses from supragranular layers through to input layer IV, but not in infragranular layers. In addition, increased spontaneous firing rate was recorded in cortical layers IV and V. We postulate that this early post-injury suppression of cortical processing of sensory input accounts for immediate post-trauma sensory morbidity and sets into train events that resolve into long-term cortical hyper-excitability in upper sensory cortex layers that may account for long-term sensory hyper-sensitivity in humans with TBI. PMID:23667624

  12. Alterations of cortical pyramidal neurons in mice lacking high-affinity nicotinic receptors

    PubMed Central

    Ballesteros-Yáñez, Inmaculada; Benavides-Piccione, Ruth; Bourgeois, Jean-Pierre; Changeux, Jean-Pierre; DeFelipe, Javier

    2010-01-01

    The neuronal nicotinic acetylcholine receptors (nAChRs) are allosteric membrane proteins involved in multiple cognitive processes, including attention, learning, and memory. The most abundant form of heterooligomeric nAChRs in the brain contains the β2- and α4- subunits and binds nicotinic agonists with high affinity. In the present study, we investigated in the mouse the consequences of the deletion of one of the nAChR components: the β2-subunit (β2−/−) on the microanatomy of cortical pyramidal cells. Using an intracellular injection method, complete basal dendritic arbors of 650 layer III pyramidal neurons were sampled from seven cortical fields, including primary sensory, motor, and associational areas, in both β2−/− and WT animals. We observed that the pyramidal cell phenotype shows significant quantitative differences among different cortical areas in mutant and WT mice. In WT mice, the density of dendritic spines was rather similar in all cortical fields, except in the prelimbic/infralimbic cortex, where it was significantly higher. In the absence of the β2-subunit, the most significant reduction in the density of spines took place in this high-order associational field. Our data suggest that the β2-subunit is involved in the dendritic morphogenesis of pyramidal neurons and, in particular, in the circuits that contribute to the high-order functional connectivity of the cerebral cortex. PMID:20534523

  13. Development of coherent neuronal activity patterns in mammalian cortical networks: common principles and local hetereogeneity.

    PubMed

    Egorov, Alexei V; Draguhn, Andreas

    2013-01-01

    Many mammals are born in a very immature state and develop their rich repertoire of behavioral and cognitive functions postnatally. This development goes in parallel with changes in the anatomical and functional organization of cortical structures which are involved in most complex activities. The emerging spatiotemporal activity patterns in multi-neuronal cortical networks may indeed form a direct neuronal correlate of systemic functions like perception, sensorimotor integration, decision making or memory formation. During recent years, several studies--mostly in rodents--have shed light on the ontogenesis of such highly organized patterns of network activity. While each local network has its own peculiar properties, some general rules can be derived. We therefore review and compare data from the developing hippocampus, neocortex and--as an intermediate region--entorhinal cortex. All cortices seem to follow a characteristic sequence starting with uncorrelated activity in uncoupled single neurons where transient activity seems to have mostly trophic effects. In rodents, before and shortly after birth, cortical networks develop weakly coordinated multineuronal discharges which have been termed synchronous plateau assemblies (SPAs). While these patterns rely mostly on electrical coupling by gap junctions, the subsequent increase in number and maturation of chemical synapses leads to the generation of large-scale coherent discharges. These patterns have been termed giant depolarizing potentials (GDPs) for predominantly GABA-induced events or early network oscillations (ENOs) for mostly glutamatergic bursts, respectively. During the third to fourth postnatal week, cortical areas reach their final activity patterns with distinct network oscillations and highly specific neuronal discharge sequences which support adult behavior. While some of the mechanisms underlying maturation of network activity have been elucidated much work remains to be done in order to fully

  14. Correlated activity of cortical neurons survives extensive removal of feedforward sensory input

    PubMed Central

    Shapcott, Katharine A.; Schmiedt, Joscha T.; Saunders, Richard C.; Maier, Alexander; Leopold, David A.; Schmid, Michael C.

    2016-01-01

    A fundamental property of brain function is that the spiking activity of cortical neurons is variable and that some of this variability is correlated between neurons. Correlated activity not due to the stimulus arises from shared input but the neuronal circuit mechanisms that result in these noise correlations are not fully understood. Here we tested in the visual system if correlated variability in mid-level area V4 of visual cortex is altered following extensive lesions of primary visual cortex (V1). To this end we recorded longitudinally the neuronal correlations in area V4 of two behaving macaque monkeys before and after a V1 lesion while the monkeys fixated a grey screen. We found that the correlations of neuronal activity survived the lesions in both monkeys. In one monkey, the correlation of multi-unit spiking signals was strongly increased in the first week post-lesion, while in the second monkey, correlated activity was slightly increased, but not greater than some week-by-week fluctuations observed. The typical drop-off of inter-neuronal correlations with cortical distance was preserved after the lesion. Therefore, as V4 noise correlations remain without feedforward input from V1, these results suggest instead that local and/or feedback input seem to be necessary for correlated activity. PMID:27721468

  15. Brain-derived neurotrophic factor stimulates energy metabolism in developing cortical neurons.

    PubMed

    Burkhalter, Julia; Fiumelli, Hubert; Allaman, Igor; Chatton, Jean-Yves; Martin, Jean-Luc

    2003-09-10

    Brain-derived neurotrophic factor (BDNF) promotes the biochemical and morphological differentiation of selective populations of neurons during development. In this study we examined the energy requirements associated with the effects of BDNF on neuronal differentiation. Because glucose is the preferred energy substrate in the brain, the effect of BDNF on glucose utilization was investigated in developing cortical neurons via biochemical and imaging studies. Results revealed that BDNF increases glucose utilization and the expression of the neuronal glucose transporter GLUT3. Stimulation of glucose utilization by BDNF was shown to result from the activation of Na+/K+-ATPase via an increase in Na+ influx that is mediated, at least in part, by the stimulation of Na+-dependent amino acid transport. The increased Na+-dependent amino acid uptake by BDNF is followed by an enhancement of overall protein synthesis associated with the differentiation of cortical neurons. Together, these data demonstrate the ability of BDNF to stimulate glucose utilization in response to an enhanced energy demand resulting from increases in amino acid uptake and protein synthesis associated with the promotion of neuronal differentiation by BDNF.

  16. The Effect of Noscapine on Oxygen-Glucose Deprivation on Primary Murine Cortical Neurons in High Glucose Condition.

    PubMed

    Vahabzadeh, Gelareh; Ebrahimi, Soltan-Ahmed; Rahbar-Roshandel, Nahid; Mahmoudian, Massoud

    2016-01-01

    In the present work we set out to investigate the neuroprotective effects of noscapine (0.5-2 µM) in presence of D-glucose on primary murine foetal cortical neurons after oxygen-glucose deprivation/24 h. recovery. Cell viability, nitric oxide production and intracellular calcium ((ca(2+))i) levels were evaluated by MTT assay, the modified Griess method and Fura-2 respectively. 25 and 100 mM D-glucose could, in a concentration dependent manner, improve cell viability and decrease NO production and (ca(2+))i level in neuronal cells after ischemic insult. Moreover, pre-incubation of cells with noscapine, noticeably enhanced protective effects of 25 and 100 mM D-glucose compared to similar conditions without noscapine pre-treatment. In fact, noscapine attenuated NO production in a dose-dependent fashion, after 30 minutes (min) OGD, during high-glucose (HG) condition in cortical neurons. Pretreatment with 2 μM noscapine and 25 or 100 mM D-glucose, was shown to decrease the rise in (ca(2+))i induced by Sodium azide/glucose deprivation (chemical OGD) model. These effects were more pronounced than that of 25 or 100 mM D-glucose alone. The present study demonstrated that the neuroprotective effects of HG before an ischemic insult were augmented by pre-treatment with noscapine. Our results also suggested that the neuroprotection offered by both HG and noscapine involve attenuation of NO production and (ca(2+))i levels stimulated by the experimental ischemia in cortical neurons.

  17. The Effect of Noscapine on Oxygen-Glucose Deprivation on Primary Murine Cortical Neurons in High Glucose Condition

    PubMed Central

    Vahabzadeh, Gelareh; Ebrahimi, Soltan-Ahmed; Rahbar-Roshandel, Nahid; Mahmoudian, Massoud

    2016-01-01

    In the present work we set out to investigate the neuroprotective effects of noscapine (0.5-2 µM) in presence of D-glucose on primary murine foetal cortical neurons after oxygen–glucose deprivation/24 h. recovery. Cell viability, nitric oxide production and intracellular calcium ((ca2+)i) levels were evaluated by MTT assay, the modified Griess method and Fura-2 respectively. 25 and 100 mM D-glucose could, in a concentration dependent manner, improve cell viability and decrease NO production and (ca2+)i level in neuronal cells after ischemic insult. Moreover, pre-incubation of cells with noscapine, noticeably enhanced protective effects of 25 and 100 mM D-glucose compared to similar conditions without noscapine pre-treatment. In fact, noscapine attenuated NO production in a dose-dependent fashion, after 30 minutes (min) OGD, during high-glucose (HG) condition in cortical neurons. Pretreatment with 2 μM noscapine and 25 or 100 mM D-glucose, was shown to decrease the rise in (ca2+)i induced by Sodium azide/glucose deprivation (chemical OGD) model. These effects were more pronounced than that of 25 or 100 mM D-glucose alone. The present study demonstrated that the neuroprotective effects of HG before an ischemic insult were augmented by pre-treatment with noscapine. Our results also suggested that the neuroprotection offered by both HG and noscapine involve attenuation of NO production and (ca2+)i levels stimulated by the experimental ischemia in cortical neurons. PMID:27642321

  18. Cortical regulation of striatal projection neurons and interneurons in a Parkinson's disease rat model

    PubMed Central

    Wu, Jia-jia; Chen, Si; Ouyang, Li-si; Jia, Yu; Liu, Bing-bing; Mu, Shu-hua; Ma, Yu-xin; Wang, Wei-ping; Wei, Jia-you; Li, You-lan; Chen, Zhi; Lei, Wan-long

    2016-01-01

    Striatal neurons can be either projection neurons or interneurons, with each type exhibiting distinct susceptibility to various types of brain damage. In this study, 6-hydroxydopamine was injected into the right medial forebrain bundle to induce dopamine depletion, and/or ibotenic acid was injected into the M1 cortex to induce motor cortex lesions. Immunohistochemistry and western blot assay showed that dopaminergic depletion results in significant loss of striatal projection neurons marked by dopamine- and cyclic adenosine monophosphate-regulated phosphoprotein, molecular weight 32 kDa, calbindin, and μ-opioid receptor, while cortical lesions reversed these pathological changes. After dopaminergic deletion, the number of neuropeptide Y-positive striatal interneurons markedly increased, which was also inhibited by cortical lesioning. No noticeable change in the number of parvalbumin-positive interneurons was found in 6-hydroxydopamine-treated rats. Striatal projection neurons and interneurons show different susceptibility to dopaminergic depletion. Further, cortical lesions inhibit striatal dysfunction and damage induced by 6-hydroxydopamine, which provides a new possibility for clinical treatment of Parkinson's disease. PMID:28197194

  19. Dynamics of Cortical Neuronal Ensembles Transit from Decision Making to Storage for Later Report

    PubMed Central

    Ponce-Alvarez, Adrián; Nácher, Verónica; Luna, Rogelio; Riehle, Alexa

    2012-01-01

    Decisions based on sensory evaluation during single trials may depend on the collective activity of neurons distributed across brain circuits. Previous studies have deepened our understanding of how the activity of individual neurons relates to the formation of a decision and its storage for later report. However, little is known about how decision-making and decision maintenance processes evolve in single trials. We addressed this problem by studying the activity of simultaneously recorded neurons from different somatosensory and frontal lobe cortices of monkeys performing a vibrotactile discrimination task. We used the hidden Markov model to describe the spatiotemporal pattern of activity in single trials as a sequence of firing rate states. We show that the animal's decision was reliably maintained in frontal lobe activity through a selective state sequence, initiated by an abrupt state transition, during which many neurons changed their activity in a concomitant way, and for which both latency and variability depended on task difficulty. Indeed, transitions were more delayed and more variable for difficult trials compared with easy trials. In contrast, state sequences in somatosensory cortices were weakly decision related, had less variable transitions, and were not affected by the difficulty of the task. In summary, our results suggest that the decision process and its subsequent maintenance are dynamically linked by a cascade of transient events in frontal lobe cortices. PMID:22933781

  20. Enhancement of synaptic transmission induced by BDNF in cultured cortical neurons

    NASA Astrophysics Data System (ADS)

    He, Jun; Gong, Hui; Zeng, Shaoqun; Li, Yanling; Luo, Qingming

    2005-03-01

    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 were 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+]c). This effect was partially dependent on [Ca2+]o; The BDNF-induced increase in [Ca2+]c can not be completely blocked by Ca2+-free solution. It was completely blocked by K252a and partially blocked by Cd2+ and TTX. The results demonstrate that BDNF can enhances synaptic transmission and that this effect is accompanied by a rise in [Ca2+]c that requires two route: the release of Ca2+ from intracellular calcium stores and influx of extracellular Ca2+ through voltage-dependent Ca2+ channels in cultured cortical neurons.

  1. Dynamics of cortical neuronal ensembles transit from decision making to storage for later report.

    PubMed

    Ponce-Alvarez, Adrián; Nácher, Verónica; Luna, Rogelio; Riehle, Alexa; Romo, Ranulfo

    2012-08-29

    Decisions based on sensory evaluation during single trials may depend on the collective activity of neurons distributed across brain circuits. Previous studies have deepened our understanding of how the activity of individual neurons relates to the formation of a decision and its storage for later report. However, little is known about how decision-making and decision maintenance processes evolve in single trials. We addressed this problem by studying the activity of simultaneously recorded neurons from different somatosensory and frontal lobe cortices of monkeys performing a vibrotactile discrimination task. We used the hidden Markov model to describe the spatiotemporal pattern of activity in single trials as a sequence of firing rate states. We show that the animal's decision was reliably maintained in frontal lobe activity through a selective state sequence, initiated by an abrupt state transition, during which many neurons changed their activity in a concomitant way, and for which both latency and variability depended on task difficulty. Indeed, transitions were more delayed and more variable for difficult trials compared with easy trials. In contrast, state sequences in somatosensory cortices were weakly decision related, had less variable transitions, and were not affected by the difficulty of the task. In summary, our results suggest that the decision process and its subsequent maintenance are dynamically linked by a cascade of transient events in frontal lobe cortices.

  2. Extending Transfer Entropy Improves Identification of Effective Connectivity in a Spiking Cortical Network Model

    PubMed Central

    Ito, Shinya; Hansen, Michael E.; Heiland, Randy; Lumsdaine, Andrew; Litke, Alan M.; Beggs, John M.

    2011-01-01

    Transfer entropy (TE) is an information-theoretic measure which has received recent attention in neuroscience for its potential to identify effective connectivity between neurons. Calculating TE for large ensembles of spiking neurons is computationally intensive, and has caused most investigators to probe neural interactions at only a single time delay and at a message length of only a single time bin. This is problematic, as synaptic delays between cortical neurons, for example, range from one to tens of milliseconds. In addition, neurons produce bursts of spikes spanning multiple time bins. To address these issues, here we introduce a free software package that allows TE to be measured at multiple delays and message lengths. To assess performance, we applied these extensions of TE to a spiking cortical network model (Izhikevich, 2006) with known connectivity and a range of synaptic delays. For comparison, we also investigated single-delay TE, at a message length of one bin (D1TE), and cross-correlation (CC) methods. We found that D1TE could identify 36% of true connections when evaluated at a false positive rate of 1%. For extended versions of TE, this dramatically improved to 73% of true connections. In addition, the connections correctly identified by extended versions of TE accounted for 85% of the total synaptic weight in the network. Cross correlation methods generally performed more poorly than extended TE, but were useful when data length was short. A computational performance analysis demonstrated that the algorithm for extended TE, when used on currently available desktop computers, could extract effective connectivity from 1 hr recordings containing 200 neurons in ∼5 min. We conclude that extending TE to multiple delays and message lengths improves its ability to assess effective connectivity between spiking neurons. These extensions to TE soon could become practical tools for experimentalists who record hundreds of spiking neurons. PMID:22102894

  3. Bioreactor Transient Exposure Activates Specific Neurotrophic Pathway in Cortical Neurons

    NASA Astrophysics Data System (ADS)

    Zimmitti, V.; Benedetti, E.; Caracciolo, V.; Sebastiani, P.; Di Loreto, S.

    2010-02-01

    Altered gravity forces might influence neuroplasticity and can provoke changes in biochemical mechanisms. In this contest, neurotrophins have a pivotal role, particularly nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF). A suspension of dissociated cortical cells from rat embryos was exposed to 24 h of microgravity before plating in normal adherent culture system. Expression and transductional signalling pathways of NGF and BDNF were assessed at the end of maturational process (8-10 days in vitro). Rotating wall vessel bioreactor (RWV) pre-exposition did not induce changes in NGF expression and its high affinity receptor TrkA. On the contrary both BDNF expression and its high affinity receptor TrkB were strongly up-regulated, inducing Erk-5, but not Erk-1/2 activation and, in turn, MEF2C over-expression and activation. According to our previous and present results, we postulate that relatively short microgravitational stimuli, applied to neural cells during the developmental stage, exert a long time activation of specific neurotrophic pathways.

  4. EPSPs Measured in Proximal Dendritic Spines of Cortical Pyramidal Neurons.

    PubMed

    Acker, Corey D; Hoyos, Erika; Loew, Leslie M

    2016-01-01

    EPSPs occur when the neurotransmitter glutamate binds to postsynaptic receptors located on small pleomorphic membrane protrusions called dendritic spines. To transmit the synaptic signal, these potentials must travel through the spine neck and the dendritic tree to reach the soma. Due to their small size, the electrical behavior of spines and their ability to compartmentalize electrical signals has been very difficult to assess experimentally. In this study, we developed a method to perform simultaneous two-photon voltage-sensitive dye recording with two-photon glutamate uncaging in order to measure the characteristics (amplitude and duration) of uncaging-evoked EPSPs in single spines on the basal dendrites of L5 pyramidal neurons in acute brain slices from CD1 control mice. We were able to record uncaging-evoked spine potentials that resembled miniature EPSPs at the soma from a wide range of spine morphologies. In proximal spines, these potentials averaged 13.0 mV (range, 6.5-30.8 mV; N = 20) for an average somatic EPSP of 0.59 mV, whereas the mean attenuation ratio (spine/soma) was found to be 25.3. Durations of spine EPSP waveforms were found to be 11.7 ms on average. Modeling studies demonstrate the important role that spine neck resistance (Rneck) plays in spine EPSP amplitudes. Simulations used to estimate Rneck by fits to voltage-sensitive dye measurements produced a mean of 179 MΩ (range, 23-420 MΩ; N = 19). Independent measurements based on fluorescence recovery after photobleaching of a cytosolic dye from spines of the same population of neurons produced a mean R eck estimate of 204 MΩ (range, 52-521 MΩ; N = 34).

  5. Minimum neuron density for synchronized bursts in a rat cortical culture on multi-electrode arrays.

    PubMed

    Ito, D; Tamate, H; Nagayama, M; Uchida, T; Kudoh, S N; Gohara, K

    2010-11-24

    To investigate the minimum neuron and neurite densities required for synchronized bursts, we cultured rat cortical neurons on planar multi-electrode arrays (MEAs) at five plating densities (2500, 1000, 500, 250, and 100 cells/mm(2)) using two culture media: Neuron Culture Medium and Dulbecco's Modified Eagle Medium supplemented with serum (DMEM/serum). Long-term recording of spontaneous electrical activity clarified that the cultures exhibiting synchronized bursts required an initial plating density of at least 250 cells/mm(2) for Neuron Culture Medium and 500 cells/mm(2) for DMEM/serum. Immediately after electrical recording, immunocytochemistry of microtubule-associated protein 2 (MAP2) and Neurofilament 200 kD (NF200) was performed directly on MEAs to investigate the actual densities of neurons and neurites forming the networks. Immunofluorescence observation revealed that the construction of complicated neuronal networks required the same initial plating density as for synchronized bursts, and that overly sparse cultures showed significant decreases of neurons and neurites. We also found that the final densities of surviving neurons at 1 month decreased greatly compared with the initial plating densities and became saturated in denser cultures. In addition, the area of neurites and the number of nuclei were saturated in denser cultures. By comparing both the results of electrophysiological recording and immunocytochemical observation, we revealed that there is a minimum threshold of neuron densities that must be met for the exhibition of synchronized bursts. Interestingly, these minimum densities of MAP2-positive final neurons did not differ between the two culture media; the density was approximately 50 neurons/mm(2). This value was obtained in the cultures with the initial plating densities of 250 cells/mm(2) for Neuron Culture Medium and 500 cells/mm(2) for DMEM/serum.

  6. FMRP regulates multipolar to bipolar transition affecting neuronal migration and cortical circuitry.

    PubMed

    La Fata, Giorgio; Gärtner, Annette; Domínguez-Iturza, Nuria; Dresselaers, Tom; Dawitz, Julia; Poorthuis, Rogier B; Averna, Michele; Himmelreich, Uwe; Meredith, Rhiannon M; Achsel, Tilmann; Dotti, Carlos G; Bagni, Claudia

    2014-12-01

    Deficiencies in fragile X mental retardation protein (FMRP) are the most common cause of inherited intellectual disability, fragile X syndrome (FXS), with symptoms manifesting during infancy and early childhood. Using a mouse model for FXS, we found that Fmrp regulates the positioning of neurons in the cortical plate during embryonic development, affecting their multipolar-to-bipolar transition (MBT). We identified N-cadherin, which is crucial for MBT, as an Fmrp-regulated target in embryonic brain. Furthermore, spontaneous network activity and high-resolution brain imaging revealed defects in the establishment of neuronal networks at very early developmental stages, further confirmed by an unbalanced excitatory and inhibitory network. Finally, reintroduction of Fmrp or N-cadherin in the embryo normalized early postnatal neuron activity. Our findings highlight the critical role of Fmrp in the developing cerebral cortex and might explain some of the clinical features observed in patients with FXS, such as alterations in synaptic communication and neuronal network connectivity.

  7. Poloxamer-188 and citicoline provide neuronal membrane integrity and protect membrane stability in cortical spreading depression.

    PubMed

    Yıldırım, Timur; Eylen, Alpaslan; Lule, Sevda; Erdener, Sefik Evren; Vural, Atay; Karatas, Hulya; Ozveren, Mehmet Faik; Dalkara, Turgay; Gursoy-Ozdemir, Yasemin

    2015-01-01

    Under pathological conditions such as brain trauma, subarachnoid hemorrhage and stroke, cortical spreading depression (CSD) or peri-infarct depolarizations contribute to brain damage in animal models of neurological disorders as well as in human neurological diseases. CSD causes transient megachannel opening on the neuronal membrane, which may compromise neuronal survival under pathological conditions. Poloxamer-188 (P-188) and citicoline are neuroprotectants with membrane sealing properties. The aim of this study is to investigate the effect of P-188 and citicoline on the neuronal megachannel opening induced by CSD in the mouse brain. We have monitored megachannel opening with propidium iodide, a membrane impermeable fluorescent dye and, demonstrate that P-188 and citicoline strikingly decreased CSD-induced neuronal PI influx in cortex and hippocampal dentate gyrus. Therefore, these agents may be providing neuroprotection by blocking megachannel opening, which may be related to their membrane sealing action and warrant further investigation for treatment of traumatic brain injury and ischemic stroke.

  8. Ultramicroscopy Reveals Axonal Transport Impairments in Cortical Motor Neurons at Prion Disease

    PubMed Central

    Ermolayev, Vladimir; Friedrich, Mike; Nozadze, Revaz; Cathomen, Toni; Klein, Michael A.; Harms, Gregory S.; Flechsig, Eckhard

    2009-01-01

    Abstract The functional imaging of neuronal circuits of the central nervous system is crucial for phenotype screenings or investigations of defects in neurodegenerative disorders. Current techniques yield either low penetration depth, yield poor resolution, or are restricted by the age of the animals. Here, we present a novel ultramicroscopy protocol for fluorescence imaging and three-dimensional reconstruction in the central nervous system of adult mice. In combination with tracing as a functional assay for axonal transport, retrogradely labeled descending motor neurons were visualized with >4 mm penetration depth. The analysis of the motor cortex shortly before the onset of clinical prion disease revealed that >80% neurons have functional impairments in axonal transport. Our study provides evidence that prion disease is associated with severe axonal transport defects in the cortical motor neurons and suggests a novel mechanism for prion-mediated neurodegeneration. PMID:19383482

  9. Inhibition of microRNA 128 promotes excitability of cultured cortical neuronal networks

    PubMed Central

    McSweeney, K. Melodi; Gussow, Ayal B.; Bradrick, Shelton S.; Dugger, Sarah A.; Gelfman, Sahar; Wang, Quanli; Petrovski, Slavé; Frankel, Wayne N.; Boland, Michael J.; Goldstein, David B.

    2016-01-01

    Cultured neuronal networks monitored with microelectrode arrays (MEAs) have been used widely to evaluate pharmaceutical compounds for potential neurotoxic effects. A newer application of MEAs has been in the development of in vitro models of neurological disease. Here, we directly evaluated the utility of MEAs to recapitulate in vivo phenotypes of mature microRNA-128 (miR-128) deficiency, which causes fatal seizures in mice. We show that inhibition of miR-128 results in significantly increased neuronal activity in cultured neuronal networks derived from primary mouse cortical neurons. These results support the utility of MEAs in developing in vitro models of neuroexcitability disorders, such as epilepsy, and further suggest that MEAs provide an effective tool for the rapid identification of microRNAs that promote seizures when dysregulated. PMID:27516621

  10. Differential distribution of voltage-gated ion channels in cortical neurons: implications for epilepsy.

    PubMed

    Child, Nicholas D; Benarroch, Eduardo E

    2014-03-18

    Neurons contain different functional somatodendritic and axonal domains, each with a characteristic distribution of voltage-gated ion channels, synaptic inputs, and function. The dendritic tree of a cortical pyramidal neuron has 2 distinct domains, the basal and the apical dendrites, both containing dendritic spines; the different domains of the axon are the axonal initial segment (AIS), axon proper (which in myelinated axons includes the node of Ranvier, paranodes, juxtaparanodes, and internodes), and the axon terminals. In the cerebral cortex, the dendritic spines of the pyramidal neurons receive most of the excitatory synapses; distinct populations of γ-aminobutyric acid (GABA)ergic interneurons target specific cellular domains and thus exert different influences on pyramidal neurons. The multiple synaptic inputs reaching the somatodendritic region and generating excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) sum and elicit changes in membrane potential at the AIS, the site of initiation of the action potential.

  11. Inhibition of microRNA 128 promotes excitability of cultured cortical neuronal networks.

    PubMed

    McSweeney, K Melodi; Gussow, Ayal B; Bradrick, Shelton S; Dugger, Sarah A; Gelfman, Sahar; Wang, Quanli; Petrovski, Slavé; Frankel, Wayne N; Boland, Michael J; Goldstein, David B

    2016-10-01

    Cultured neuronal networks monitored with microelectrode arrays (MEAs) have been used widely to evaluate pharmaceutical compounds for potential neurotoxic effects. A newer application of MEAs has been in the development of in vitro models of neurological disease. Here, we directly evaluated the utility of MEAs to recapitulate in vivo phenotypes of mature microRNA-128 (miR-128) deficiency, which causes fatal seizures in mice. We show that inhibition of miR-128 results in significantly increased neuronal activity in cultured neuronal networks derived from primary mouse cortical neurons. These results support the utility of MEAs in developing in vitro models of neuroexcitability disorders, such as epilepsy, and further suggest that MEAs provide an effective tool for the rapid identification of microRNAs that promote seizures when dysregulated.

  12. Foxp1 Regulates Cortical Radial Migration and Neuronal Morphogenesis in Developing Cerebral Cortex

    PubMed Central

    Li, Xue; Xiao, Jian; Fröhlich, Henning; Tu, Xiaomeng; Li, Lianlian; Xu, Yue; Cao, Huateng; Qu, Jia; Rappold, Gudrun A.; Chen, Jie-Guang

    2015-01-01

    FOXP1 is a member of FOXP subfamily transcription factors. Mutations in FOXP1 gene have been found in various development-related cognitive disorders. However, little is known about the etiology of these symptoms, and specifically the function of FOXP1 in neuronal development. Here, we report that suppression of Foxp1 expression in mouse cerebral cortex led to a neuronal migration defect, which was rescued by overexpression of Foxp1. Mice with Foxp1 knockdown exhibited ectopic neurons in deep layers of the cortex postnatally. The neuronal differentiation of Foxp1-downregulated cells was normal. However, morphological analysis showed that the neurons with Foxp1 deficiency had an inhibited axonal growth in vitro and a weakened transition from multipolar to bipolar in vivo. Moreover, we found that the expression of Foxp1 modulated the dendritic maturation of neurons at a late postnatal date. Our results demonstrate critical roles of Foxp1 in the radial migration and morphogenesis of cortical neurons during development. This study may shed light on the complex relationship between neuronal development and the related cognitive disorders. PMID:26010426

  13. The glutamate transporters EAAT2 and EAAT3 mediate cysteine uptake in cortical neuron cultures.

    PubMed

    Chen, Yongmei; Swanson, Raymond A

    2003-03-01

    Cysteine availability is normally the rate-limiting factor in glutathione synthesis. How neurons obtain cysteine from extracellular space is not well established. Here we used mouse cortical neuron cultures to examine the role of the excitatory amino acid transporters (EAATs) in neuronal cysteine uptake. The cultured neurons expressed both EAAT2 and EAAT3. Cysteine uptake was predominantly (> 85%) Na+-dependent, with an apparent Km of 37 microm. Cysteine uptake was reduced by the EAAT substrates l-glutamate and l-aspartate and by synthetic EAAT inhibitors. The non-selective EAAT inhibitor threo-beta-hydroxyaspartate had a significantly greater maximal inhibitory effect than did the EAAT2-selective inhibitor, dihydrokainate, indicating uptake by both EAAT2 and EAAT3. Serine, a substrate of ASC uptake system, had negligible effects on cysteine uptake at 10-fold excess concentrations. To assess the functional importance of EAAT-mediated cysteine uptake in neuronal glutathione synthesis, cultures were treated with diethylmaleate to deplete glutathione, then incubated with cysteine in the presence or absence of EAAT inhibitors. Threo-beta-benzyloxyaspartate and the non-transportable inhibitor threo-beta-hydroxyaspartate both inhibited the cysteine-dependent glutathione synthesis. The findings suggest that neuronal EAAT activity can be a rate-limiting step for neuronal glutathione synthesis and that the primary function of EAATs expressed by neurons in vivo may be to transport cysteine.

  14. Astrocyte Mediated Protection of Fetal Cerebral Cortical Neurons from Rotenone and Paraquat

    PubMed Central

    Rathinam, Mary Latha; Watts, Lora Talley; Narasimhan, Madhusudhanan; Riar, Amanjot Kaur; Mahimainathan, Lenin; Henderson, George.I.

    2012-01-01

    Primary cultures of fetal rat cortical neurons and astrocytes were used to test the hypothesis that astrocyte-mediated control of neuronal glutathione (GSH) is a potent factor in neuroprotection against rotenone and paraquat. In neurons, rotenone (0.025 to 1μM) for 4 and 24 h decreased viability as did paraquat (2 to 100μM). Rotenone (30nM) decreased neuronal viability and GSH by 24% and 30%, while ROS were increased by 56%. Paraquat (30μM) decreased neuronal viability and GSH by 36% and 70%, while ROS were increased by 23%. When neurons were co-cultured with astrocytes, their GSH increased 1.5 fold and 5 fold at 12 and 24 h. Co-culturing with astrocytes blocked neuronal death and damage by rotenone and paraquat. Astrocyte-mediated neuroprotection was dependent on the activity of components of the γ-glutamyl cycle. These studies illustrate the importance of astrocyte-mediated glutathione homeostasis for protection of neurons from rotenone and paraquat and the role of the γ-glutamyl cycle in this neuroprotection PMID:22301167

  15. Axonal shearing in mature cortical neurons induces attempted regeneration and the reestablishment of neurite polarity.

    PubMed

    Blizzard, Catherine A; King, Anna E; Haas, Matilda A; O'Toole, David A; Vickers, James C; Dickson, Tracey C

    2009-12-01

    While functional recovery after injury is limited, it has become evident that the mature central nervous system does retain some ability to regenerate. This study investigated the intrinsic capacity of relatively mature cortical neurons (21 days in vitro) to respond to axonal loss. Neurons, growing as clusters on poly-L-lysine, were completely sheared of axons through chemical and mechanical disruption and transferred to either an intact astrocyte monolayer or a substrate of poly-L-lysine. Injured neurons exhibited a regenerative sprouting response that was independent of neuronal cell division or neural progenitors, as demonstrated by negative bromodeoxyuridine (BrdU) and the neuronal precursor intermediate filament nestin, labeling. At 24 h after injury, neurons had extended appropriately polarized neurites, demonstrated by compartmentalized microtubule-associated proteins MAP2 and tau immunolabeling. Newly sprouting axons were tipped by growth cones; however, growth cones on the tips of sprouting axons (mean area, 26.32 +/- 2.20 microm) were significantly (p<0.05) smaller than their developmental counterparts (mean area, 48.64 +/- 5.9 microm), independent of substrate. Furthermore, live imaging indicated that regenerating neurons exhibited distinct axonal dynamics, with a significant (p<0.05) reduction (70%) in pausing, considered vital for interstitial branching and pathfinding, relative to developmental growth cones. This study indicates that mature cultured cortical pyramidal and interneurons have the intrinsic potential to survive, extend processes, and reestablish neurite polarity following significant physical damage. These results may aid in defining the cellular basis of neuronal structural plasticity and defining the role of astrocyte reactivity in the response to trauma.

  16. [Electrical excitability of the apical dendrites of mammalian cortical pyramidal neurons].

    PubMed

    Fan, Shih-Fang

    2012-12-25

    The electrical excitability of the dendrites of the cortical neurons was first studied on the apical dendrites of the pyramidal neurons. Professor ZHANG Xiang-Tong (H-T Chang) made important contributions in the fifties of last century on this topic. Through numerous studies later on, it has been established that the electrical excitability of dendrites of different types of neurons, even different dendrites in the same neuron is different. For the apical dendrites of the cortical pyramidal neurons, neither a single nor a train of repetitive action potentials with constant frequency can reach its terminal portion. However, some of the burst repetitive responses with non-constant frequency of the apical dendrite elicited by direct current injected into the soma may reach the terminal portion. This may be due to: (1) the calcium ion concentration in the apical dendrite is increased by the burst activities, which, in turn, increases the electrical excitability of the apical dendrite and /or (2) some retrograde collaterals of axon of the activated soma reach the apical dendrite and release neurotransmitter glutamate, which changes the properties of the voltage-gated ion channels in the apical dendrite. Low electrical excitability of the apical dendrites seems to be essential for the processing of numerous income signals to the terminal portion of the apical dendrites.

  17. Quantification of Filamentous Actin (F-actin) Puncta in Rat Cortical Neurons

    PubMed Central

    Bertrand, Sarah J.; Mactutus, Charles F.; Booze, Rosemarie

    2016-01-01

    Filamentous actin protein (F-actin) plays a major role in spinogenesis, synaptic plasticity, and synaptic stability. Changes in dendritic F-actin rich structures suggest alterations in synaptic integrity and connectivity. Here we provide a detailed protocol for culturing primary rat cortical neurons, Phalloidin staining for F-actin puncta, and subsequent quantification techniques. First, the frontal cortex of E18 rat embryos are dissociated into low-density cell culture, then the neurons grown in vitro for at least 12-14 days. Following experimental treatment, the cortical neurons are stained with AlexaFluor 488 Phalloidin (to label the dendritic F-actin puncta) and microtubule-associated protein 2 (MAP2; to validate the neuronal cells and dendritic integrity). Finally, specialized software is used to analyze and quantify randomly selected neuronal dendrites. F-actin rich structures are identified on second order dendritic branches (length range 25-75 µm) with continuous MAP2 immunofluorescence. The protocol presented here will be a useful method for investigating changes in dendritic synapse structures subsequent to experimental treatments. PMID:26889716

  18. The presence of calbindin in rat cortical neurons protects in vitro from oxydative stress.

    PubMed

    Hugon, J; Hugon, F; Esclaire, F; Lesort, M; Diop, A G

    1996-01-29

    Free radicals are highly reactive chemicals containing an unpaired electron and are normally produced by the cellular metabolism. The oxydative stress is defined as a lack of balance between the production of free radicals and the activity of antioxydant metabolites. It induces cellular damages to lipids, proteins and membranes. Abnormal calcium metabolism can be a consequence of oxydative stress leading to increased intracellular concentrations. Calbindin D28K is a calcium binding protein which could have a neuroprotective action against various cellular insults. In this study rat cortical cell cultures were exposed during various times and at different concentrations to the couple Xanthine/Xanthine oxydase (XA/XO), which produces the superoxyde radical O2-.. Neuronal survival revealed that XA/XO is toxic for cortical cell cultures. The Calbindin D28K immunocytochemical study shows that the percentages of Calbindin positive cells are greater in surviving neurons following the XA/XO exposure compared to controls. There is a time-dependent and a dose-dependent relation between the number of surviving neurons and the percentage of Calbindin positive neurons. These results suggest that the presence of cytosolic neuronal Calbindin D28k is associated with a greater resistance to oxydative stress.

  19. Spectrotemporal processing differences between auditory cortical fast-spiking and regular-spiking neurons

    PubMed Central

    Atencio, Craig A.; Schreiner, Christoph E.

    2008-01-01

    Excitatory pyramidal neurons and inhibitory interneurons constitute the main elements of cortical circuitry and have distinctive morphologic and electrophysiological properties. Here, we differentiate them by analyzing the time course of their action potentials (APs) and characterizing their receptive field properties in auditory cortex. Pyramidal neurons have longer APs and discharge as Regular-Spiking Units (RSUs), while basket and chandelier cells, which are inhibitory interneurons, have shorter APs and are Fast-Spiking Units (FSUs). To compare these neuronal classes we stimulated cat primary auditory cortex neurons with a dynamic moving ripple stimulus and constructed single-unit spectrotemporal receptive fields (STRFs) and their associated nonlinearities. FSUs had shorter latencies, broader spectral tuning, greater stimulus specificity, and higher temporal precision than RSUs. The STRF structure of FSUs was more separable, suggesting more independence between spectral and temporal processing regimes. The nonlinearities associated with the two cell classes was indicative of higher feature selectivity for FSUs. These global functional differences between RSUs and FSUs suggest fundamental distinctions between putative excitatory and inhibitory neurons that shape auditory cortical processing. PMID:18400888

  20. Quantification of Filamentous Actin (F-actin) Puncta in Rat Cortical Neurons.

    PubMed

    Li, Hailong; Aksenova, Marina; Bertrand, Sarah J; Mactutus, Charles F; Booze, Rosemarie

    2016-02-10

    Filamentous actin protein (F-actin) plays a major role in spinogenesis, synaptic plasticity, and synaptic stability. Changes in dendritic F-actin rich structures suggest alterations in synaptic integrity and connectivity. Here we provide a detailed protocol for culturing primary rat cortical neurons, Phalloidin staining for F-actin puncta, and subsequent quantification techniques. First, the frontal cortex of E18 rat embryos are dissociated into low-density cell culture, then the neurons grown in vitro for at least 12-14 days. Following experimental treatment, the cortical neurons are stained with AlexaFluor 488 Phalloidin (to label the dendritic F-actin puncta) and microtubule-associated protein 2 (MAP2; to validate the neuronal cells and dendritic integrity). Finally, specialized software is used to analyze and quantify randomly selected neuronal dendrites. F-actin rich structures are identified on second order dendritic branches (length range 25-75 µm) with continuous MAP2 immunofluorescence. The protocol presented here will be a useful method for investigating changes in dendritic synapse structures subsequent to experimental treatments.

  1. Changes in long-range connectivity and neuronal reorganization in partial cortical deafferentation model of epileptogenesis

    PubMed Central

    Kuśmierczak, Magda; Lajeunesse, Francis; Grand, Laszlo; Timofeev, Igor

    2014-01-01

    Severe brain injuries can trigger epileptogenesis, a latent period that eventually leads to epilepsy. Previous studies have demonstrated that changes in local connectivity between cortical neurons are a part of the epileptogenic processes. In the present study we aimed to investigate whether changes in long-range connectivity are also involved in epileptogenesis. We performed a large unilateral transection (undercut) of the white matter below the suprasylvian gyrus in cats. After about 2 months, we either injected retrograde tracer (choleratoxin, sub-unit B, CTB) or performed Golgi staining. We analyzed distribution of retrogradely labeled neurons, counted dendritic spines in the neocortex (Golgi staining), and analyzed dendritic orientation in control conditions and after the injury. We found a significant increase in the number of detected cells at the frontal parts of the injured hemisphere, which suggests that the process of axonal sprouting occurs in the deafferented area. The increase in the number of retrogradely stained neurons was accompanied with a significant decrease in neocortical spine density in the undercut area, a reduction in vertical and an increase in horizontal orientation of neuronal processes. The present study shows global morphological changes underlying epileptogenesis. An increased connectivity in the injured cortical regions accompanied with a decrease in spine density suggests that excitatory synapses might be formed on dendritic shafts, which probably contributes to the altered neuronal excitability that was described in previous studies on epileptogenesis. PMID:25304932

  2. Changes in long-range connectivity and neuronal reorganization in partial cortical deafferentation model of epileptogenesis.

    PubMed

    Kuśmierczak, M; Lajeunesse, F; Grand, L; Timofeev, I

    2015-01-22

    Severe brain injuries can trigger epileptogenesis, a latent period that eventually leads to epilepsy. Previous studies have demonstrated that changes in local connectivity between cortical neurons are a part of the epileptogenic processes. In the present study we aimed to investigate whether changes in long-range connectivity are also involved in epileptogenesis. We performed a large unilateral transection (undercut) of the white matter below the suprasylvian gyrus in cats. After about 2 months, we either injected retrograde tracer (cholera toxin, sub-unit B, CTB) or performed Golgi staining. We analyzed distribution of retrogradely labeled neurons, counted dendritic spines in the neocortex (Golgi staining), and analyzed dendritic orientation in control conditions and after the injury. We found a significant increase in the number of detected cells at the frontal parts of the injured hemisphere, which suggests that the process of axonal sprouting occurs in the deafferented area. The increase in the number of retrogradely stained neurons was accompanied with a significant decrease in neocortical spine density in the undercut area, a reduction in vertical and an increase in horizontal orientation of neuronal processes. The present study shows global morphological changes underlying epileptogenesis. An increased connectivity in the injured cortical regions accompanied with a decrease in spine density suggests that excitatory synapses might be formed on dendritic shafts, which probably contributes to the altered neuronal excitability that was described in previous studies on epileptogenesis.

  3. PERK regulates Gq protein-coupled intracellular Ca(2+) dynamics in primary cortical neurons.

    PubMed

    Zhu, Siying; McGrath, Barbara C; Bai, Yuting; Tang, Xin; Cavener, Douglas R

    2016-10-01

    PERK (EIF2AK3) is an ER-resident eIF2α kinase required for behavioral flexibility and metabotropic glutamate receptor-dependent long-term depression via its translational control. Motivated by the recent discoveries that PERK regulates Ca(2+) dynamics in insulin-secreting β-cells underlying glucose-stimulated insulin secretion, and modulates Ca(2+) signals-dependent working memory, we explored the role of PERK in regulating Gq protein-coupled Ca(2+) dynamics in pyramidal neurons. We found that acute PERK inhibition by the use of a highly specific PERK inhibitor reduced the intracellular Ca(2+) rise stimulated by the activation of acetylcholine, metabotropic glutamate and bradykinin-2 receptors in primary cortical neurons. More specifically, acute PERK inhibition increased IP3 receptor mediated ER Ca(2+) release, but decreased receptor-operated extracellular Ca(2+) influx. Impaired Gq protein-coupled intracellular Ca(2+) rise was also observed in genetic Perk knockout neurons. Taken together, our findings reveal a novel role of PERK in neurons, which is eIF2α-independent, and suggest that the impaired working memory in forebrain-specific Perk knockout mice may stem from altered Gq protein-coupled intracellular Ca(2+) dynamics in cortical pyramidal neurons.

  4. Differential organization of cortical inputs to striatal projection neurons of the matrix compartment in rats

    PubMed Central

    Deng, Yunping; Lanciego, Jose; Goff, Lydia Kerkerian-Le; Coulon, Patrice; Salin, Pascal; Kachidian, Philippe; Lei, Wanlong; Del Mar, Nobel; Reiner, Anton

    2015-01-01

    In prior studies, we described the differential organization of corticostriatal and thalamostriatal inputs to the spines of direct pathway (dSPNs) and indirect pathway striatal projection neurons (iSPNs) of the matrix compartment. In the present electron microscopic (EM) analysis, we have refined understanding of the relative amounts of cortical axospinous vs. axodendritic input to the two types of SPNs. Of note, we found that individual dSPNs receive about twice as many axospinous synaptic terminals from IT-type (intratelencephalically projecting) cortical neurons as they do from PT-type (pyramidal tract projecting) cortical neurons. We also found that PT-type axospinous synaptic terminals were about 1.5 times as common on individual iSPNs as IT-type axospinous synaptic terminals. Overall, a higher percentage of IT-type terminals contacted dSPN than iSPN spines, while a higher percentage of PT-type terminals contacted iSPN than dSPN spines. Notably, IT-type axospinous synaptic terminals were significantly larger on iSPN spines than on dSPN spines. By contrast to axospinous input, the axodendritic PT-type input to dSPNs was more substantial than that to iSPNs, and the axodendritic IT-type input appeared to be meager and comparable for both SPN types. The prominent axodendritic PT-type input to dSPNs may accentuate their PT-type responsiveness, and the large size of axospinous IT-type terminals on iSPNs may accentuate their IT-type responsiveness. Using transneuronal labeling with rabies virus to selectively label the cortical neurons with direct input to the dSPNs projecting to the substantia nigra pars reticulata, we found that the input predominantly arose from neurons in the upper layers of motor cortices, in which IT-type perikarya predominate. The differential cortical input to SPNs is likely to play key roles in motor control and motor learning. PMID:25926776

  5. Histamine release in the basal forebrain mediates cortical activation through cholinergic neurons.

    PubMed

    Zant, Janneke C; Rozov, Stanislav; Wigren, Henna-Kaisa; Panula, Pertti; Porkka-Heiskanen, Tarja

    2012-09-19

    The basal forebrain (BF) is a key structure in regulating both cortical activity and sleep homeostasis. It receives input from all ascending arousal systems and is particularly highly innervated by histaminergic neurons. Previous studies clearly point to a role for histamine as a wake-promoting substance in the BF. We used in vivo microdialysis and pharmacological treatments in rats to study which electroencephalogram (EEG) spectral properties are associated with histamine-induced wakefulness and whether this wakefulness is followed by increased sleep and increased EEG delta power during sleep. We also investigated which BF neurons mediate histamine-induced cortical activation. Extracellular BF histamine levels rose immediately and remained constant throughout a 6 h period of sleep deprivation, returning to baseline levels immediately afterward. During the spontaneous sleep-wake cycle, we observed a strong correlation between wakefulness and extracellular histamine concentrations in the BF, which was unaffected by the time of day. The perfusion of histamine into the BF increased wakefulness and cortical activity without inducing recovery sleep. The perfusion of a histamine receptor 1 antagonist into the BF decreased both wakefulness and cortical activity. Lesioning the BF cholinergic neurons abolished these effects. Together, these results show that activation of the cholinergic BF by histamine is important in sustaining a high level of cortical activation, and that a lack of activation of the cholinergic BF by histamine may be important in initiating and maintaining nonrapid eye movement sleep. The level of histamine release is tightly connected to behavioral state, but conveys no information about sleep pressure.

  6. Abnormalities of cortical inhibitory neurons in amyotrophic lateral sclerosis.

    PubMed

    Enterzari-Taher, M; Eisen, A; Stewart, H; Nakajima, M

    1997-01-01

    We have used peristimulus time histograms to study how paired, transcranial magnetic stimulation alters the firing of single motor units and the magnitude of unitary excitatory postsynaptic potentials (EPSPs) recorded from the extensor digitorum communis muscle. With stimulus intensity at threshold and an interstimulus interval of 30 ms, normal subjects (n = 20) demonstrated marked inhibition with a mean test/conditioning EPSP ratio of 13.8% (range 0-51%) and in 7 subjects the ratio was 0 (100% inhibition). In amyotrophic lateral sclerosis (ALS) the ratio was 133% (range 64-267%), P < 0.001. Fifty percent of patients had a test/conditioning EPSP ratio greater than 100% (0 inhibition). The abnormalities were independent of disease severity, bulbar versus spinal ALS, more prominent upper versus lower motor neuron findings, and disease duration. Normal inhibition occurred in 3 individuals, 1 each with multiple sclerosis, Kennedy's syndrome, and monomelic amyotrophy. We speculate that the marked loss of inhibition seen in all patients with ALS, which may be unique to this disorder, reflects loss of inhibitory modulation of the corticomotoneuron and could result in their chronic excitatory drive and eventual demise.

  7. Calcium imaging of cortical neurons using Fura-2 AM.

    PubMed

    Barreto-Chang, Odmara L; Dolmetsch, Ricardo E

    2009-01-19

    Calcium imaging is a common technique that is useful for measuring calcium signals in cultured cells. Calcium imaging techniques take advantage of calcium indicator dyes, which are BAPTA-based organic molecules that change their spectral properties in response to the binding of Ca2+ ions. Calcium indicator dyes fall into two categories, ratio-metric dyes like Fura-2 and Indo-1 and single-wavelength dyes like Fluo-4. Ratio-metric dyes change either their excitation or their emission spectra in response to calcium, allowing the concentration of intracellular calcium to be determined from the ratio of fluorescence emission or excitation at distinct wavelengths. The main advantage of using ratio-metric dyes over single wavelength probes is that the ratio signal is independent of the dye concentration, illumination intensity, and optical path length allowing the concentration of intracellular calcium to be determined independently of these artifacts. One of the most common calcium indicators is Fura-2, which has an emission peak at 505 nM and changes its excitation peak from 340 nm to 380 nm in response to calcium binding. Here we describe the use of Fura-2 to measure intracellular calcium elevations in neurons and other excitable cells.

  8. Ethanol-induced oxidative stress precedes mitochondrially mediated apoptotic death of cultured fetal cortical neurons.

    PubMed

    Ramachandran, Vinitha; Watts, Lora Talley; Maffi, Shivani Kaushal; Chen, Juanjuan; Schenker, Steven; Henderson, George

    2003-11-15

    In utero ethanol exposure elicits apoptotic cell death in the fetal brain, and this may be mediated by oxidative stress. Our studies utilize cultured fetal rat cortical neurons and illustrate that ethanol elicits a rapid onset of oxidative stress, which culminates in mitochondrially mediated apoptotic cell death. Cells exposed to ethanol (2.5 mg/ml) remained attached to their polylysine matrix during a 24-hr exposure, but they exhibited distinct signs of oxidative stress, decreased viability, and apoptosis. Confocal microscopy of live cortical neurons pretreated with dichlorodihydrofluorescein diacetate demonstrated an increase in reactive oxygen species (ROS) within 5 min of ethanol exposure. The levels of ROS further increased by 58% within 1 hr (P <.05) and by 82% within 2 hr (P <.05), accompanied by increases of mitochondrial 4-hydroxynonenal (HNE). These early events were followed by decreased trypan blue exclusion of 10% to 32% (P <.05) at the 6- to 24-hr time points, respectively. This culminates in apoptotic death, with increases of Annexin V binding of 43%, 89%, 123%, and 238%, at 2, 6, 12, and 24 hr of ethanol treatment, respectively, as well as DNA fragmentation increases of 50% and 65% by 12 and 24 hr, respectively. Release of cytochrome c by mitochondria increased by 53% at 6 hr of exposure (P <.05), concomitant with activation of caspase 3 (52% at 12 hr, P <.05). Pretreatment with N-acetylcysteine increased cellular glutathione and prevented apoptosis. These studies provide a time line illustrating that oxidative stress and formation of a proapoptotic lipid peroxidation product, HNE, precede a cascade of mitochondrially mediated events in cultured fetal cortical neurons, culminating in apoptotic death. The prevention of apoptosis by augmentation of glutathione stores also strongly supports a role for oxidative stress in ethanol-mediated apoptotic death of fetal cortical neurons.

  9. Antioxidant and Protective Mechanisms against Hypoxia and Hypoglycaemia in Cortical Neurons in Vitro

    PubMed Central

    Merino, José Joaquín; Roncero, César; Oset-Gasque, María Jesús; Naddaf, Ahmad; González, María Pilar

    2014-01-01

    In the present work, we have studied whether cell death could be induced in cortical neurons from rats subjected to different period of O2 deprivation and low glucose (ODLG). This “in vitro” model is designed to emulate the penumbra area under ischemia. In these conditions, cortical neurons displayed loss of mitochondrial respiratory ability however, nor necrosis neither apoptosis occurred despite ROS production. The absence of cellular death could be a consequence of increased antioxidant responses such as superoxide dismutase-1 (SOD1) and GPX3. In addition, the levels of reduced glutathione were augmented and HIF-1/3α overexpressed. After long periods of ODLG (12–24 h) cortical neurons showed cellular and mitochondrial membrane alterations and did not recuperate cellular viability during reperfusion. This could mean that therapies directed toward prevention of cellular and mitochondrial membrane imbalance or cell death through mechanisms other than necrosis or apoptosis, like authophagy, may be a way to prevent ODLG damage. PMID:24526229

  10. Cyclooxygenase-2 contributes to VX-induced cell death in cultured cortical neurons.

    PubMed

    Tenn, Catherine C; Weiss, M Tracy; Beaup, Claire; Peinnequin, Andre; Wang, Yushan; Dorandeu, Frederic

    2012-04-05

    The link between cell death and increased cyclooxygenases-2 (COX-2) activity has not been clearly established. In this study, we examined whether COX-2 activation contributed to the mechanism of neurotoxicity produced by an organophosphorous nerve agent in cultured rat cortical neurons. Exposure of neuronal cells to the nerve agent, VX resulted in an increase in COX enzyme activity in the culture media. A concentration dependent increase in the activity levels of COX-2 enzyme was observed while there was little to no effect on COX-1. In addition, COX-2 mRNA and protein levels increased several hours post-VX exposure. Pre-treatment of the cortical cells with the COX-2 selective inhibitor, NS 398 resulted in a decrease in both the enzyme activity and prostaglandin (PGE(2) and PGF(2α)) release, as well as in a reduction in cell death. These findings indicate that the increase in COX-2 activity may contribute to the mechanism of VX-induced neurotoxicity in cultured rat cortical neuron.

  11. Microtubule-targeting drugs rescue axonal swellings in cortical neurons from spastin knockout mice

    PubMed Central

    Fassier, Coralie; Tarrade, Anne; Peris, Leticia; Courageot, Sabrina; Mailly, Philippe; Dalard, Cécile; Delga, Stéphanie; Roblot, Natacha; Lefèvre, Julien; Job, Didier; Hazan, Jamilé; Curmi, Patrick A.; Melki, Judith

    2013-01-01

    SUMMARY Mutations in SPG4, encoding the microtubule-severing protein spastin, are responsible for the most frequent form of hereditary spastic paraplegia (HSP), a heterogeneous group of genetic diseases characterized by degeneration of the corticospinal tracts. We previously reported that mice harboring a deletion in Spg4, generating a premature stop codon, develop progressive axonal degeneration characterized by focal axonal swellings associated with impaired axonal transport. To further characterize the molecular and cellular mechanisms underlying this mutant phenotype, we have assessed microtubule dynamics and axonal transport in primary cultures of cortical neurons from spastin-mutant mice. We show an early and marked impairment of microtubule dynamics all along the axons of spastin-deficient cortical neurons, which is likely to be responsible for the occurrence of axonal swellings and cargo stalling. Our analysis also reveals that a modulation of microtubule dynamics by microtubule-targeting drugs rescues the mutant phenotype of cortical neurons. Together, these results contribute to a better understanding of the pathogenesis of SPG4-linked HSP and ascertain the influence of microtubule-targeted drugs on the early axonal phenotype in a mouse model of the disease. PMID:22773755

  12. The presence of cortical neurons in striatal-cortical co-cultures alters the effects of dopamine and BDNF on medium spiny neuron dendritic development

    PubMed Central

    Penrod, Rachel D.; Campagna, Justin; Panneck, Travis; Preese, Laura; Lanier, Lorene M.

    2015-01-01

    Medium spiny neurons (MSNs) are the major striatal neuron and receive synaptic input from both glutamatergic and dopaminergic afferents. These synapses are made on MSN dendritic spines, which undergo density and morphology changes in association with numerous disease and experience-dependent states. Despite wide interest in the structure and function of mature MSNs, relatively little is known about MSN development. Furthermore, most in vitro studies of MSN development have been done in simple striatal cultures that lack any type of non-autologous synaptic input, leaving open the question of how MSN development is affected by a complex environment that includes other types of neurons, glia, and accompanying secreted and cell-associated cues. Here we characterize the development of MSNs in striatal-cortical co-culture, including quantitative morphological analysis of dendritic arborization and spine development, describing progressive changes in density and morphology of developing spines. Overall, MSN growth is much more robust in the striatal-cortical co-culture compared to striatal mono-culture. Inclusion of dopamine (DA) in the co-culture further enhances MSN dendritic arborization and spine density, but the effects of DA on dendritic branching are only significant at later times in development. In contrast, exogenous Brain Derived Neurotrophic Factor (BDNF) has only a minimal effect on MSN development in the co-culture, but significantly enhances MSN dendritic arborization in striatal mono-culture. Importantly, inhibition of NMDA receptors in the co-culture significantly enhances the effect of exogenous BDNF, suggesting that the efficacy of BDNF depends on the cellular environment. Combined, these studies identify specific periods of MSN development that may be particularly sensitive to perturbation by external factors and demonstrate the importance of studying MSN development in a complex signaling environment. PMID:26257605

  13. Local connections of excitatory neurons in motor-associated cortical areas of the rat

    PubMed Central

    Kaneko, Takeshi

    2013-01-01

    In spite of recent progress in brain sciences, the local circuit of the cerebral neocortex, including motor areas, still remains elusive. Morphological works on excitatory cortical circuitry from thalamocortical (TC) afferents to corticospinal neurons (CSNs) in motor-associated areas are reviewed here. First, TC axons of motor thalamic nuclei have been re-examined by the single-neuron labeling method. There are middle layer (ML)-targeting and layer (L) 1-preferring TC axon types in motor-associated areas, being analogous to core and matrix types, respectively, of Jones (1998) in sensory areas. However, the arborization of core-like motor TC axons spreads widely and disregards the columnar structure that is the basis of information processing in sensory areas, suggesting that motor areas adopt a different information-processing framework such as area-wide laminar organization. Second, L5 CSNs receive local excitatory inputs not only from L2/3 pyramidal neurons but also from ML spiny neurons, the latter directly processing cerebellar information of core-like TC neurons (TCNs). In contrast, basal ganglia information is targeted to apical dendrites of L2/3 and L5 pyramidal neurons through matrix TCNs. Third, L6 corticothalamic neurons (CTNs) are most densely innervated by ML spiny neurons located just above CTNs. Since CTNs receive only weak connections from L2/3 and L5 pyramidal neurons, the TC recurrent circuit composed of TCNs, ML spiny neurons and CTNs appears relatively independent of the results of processing in L2/3 and L5. It is proposed that two circuits sharing the same TC projection and ML neurons are embedded in the neocortex: one includes L2/3 and L5 neurons, processes afferent information in a feedforward way and sends the processed information to other cortical areas and subcortical regions; and the other circuit participates in a dynamical system of the TC recurrent circuit and may serve as the basis of autonomous activity of the neocortex. PMID

  14. Simple Cortical and Thalamic Neuron Models for Digital Arithmetic Circuit Implementation

    PubMed Central

    Nanami, Takuya; Kohno, Takashi

    2016-01-01

    Trade-off between reproducibility of neuronal activities and computational efficiency is one of crucial subjects in computational neuroscience and neuromorphic engineering. A wide variety of neuronal models have been studied from different viewpoints. The digital spiking silicon neuron (DSSN) model is a qualitative model that focuses on efficient implementation by digital arithmetic circuits. We expanded the DSSN model and found appropriate parameter sets with which it reproduces the dynamical behaviors of the ionic-conductance models of four classes of cortical and thalamic neurons. We first developed a four-variable model by reducing the number of variables in the ionic-conductance models and elucidated its mathematical structures using bifurcation analysis. Then, expanded DSSN models were constructed that reproduce these mathematical structures and capture the characteristic behavior of each neuron class. We confirmed that statistics of the neuronal spike sequences are similar in the DSSN and the ionic-conductance models. Computational cost of the DSSN model is larger than that of the recent sophisticated Integrate-and-Fire-based models, but smaller than the ionic-conductance models. This model is intended to provide another meeting point for above trade-off that satisfies the demand for large-scale neuronal network simulation with closer-to-biology models. PMID:27242397

  15. Simple Cortical and Thalamic Neuron Models for Digital Arithmetic Circuit Implementation.

    PubMed

    Nanami, Takuya; Kohno, Takashi

    2016-01-01

    Trade-off between reproducibility of neuronal activities and computational efficiency is one of crucial subjects in computational neuroscience and neuromorphic engineering. A wide variety of neuronal models have been studied from different viewpoints. The digital spiking silicon neuron (DSSN) model is a qualitative model that focuses on efficient implementation by digital arithmetic circuits. We expanded the DSSN model and found appropriate parameter sets with which it reproduces the dynamical behaviors of the ionic-conductance models of four classes of cortical and thalamic neurons. We first developed a four-variable model by reducing the number of variables in the ionic-conductance models and elucidated its mathematical structures using bifurcation analysis. Then, expanded DSSN models were constructed that reproduce these mathematical structures and capture the characteristic behavior of each neuron class. We confirmed that statistics of the neuronal spike sequences are similar in the DSSN and the ionic-conductance models. Computational cost of the DSSN model is larger than that of the recent sophisticated Integrate-and-Fire-based models, but smaller than the ionic-conductance models. This model is intended to provide another meeting point for above trade-off that satisfies the demand for large-scale neuronal network simulation with closer-to-biology models.

  16. Chronic ciguatoxin treatment induces synaptic scaling through voltage gated sodium channels in cortical neurons.

    PubMed

    Martín, Víctor; Vale, Carmen; Rubiolo, Juan A; Roel, Maria; Hirama, Masahiro; Yamashita, Shuji; Vieytes, Mercedes R; Botana, Luís M

    2015-06-15

    Ciguatoxins are sodium channels activators that cause ciguatera, one of the most widespread nonbacterial forms of food poisoning, which presents with long-term neurological alterations. In central neurons, chronic perturbations in activity induce homeostatic synaptic mechanisms that adjust the strength of excitatory synapses and modulate glutamate receptor expression in order to stabilize the overall activity. Immediate early genes, such as Arc and Egr1, are induced in response to activity changes and underlie the trafficking of glutamate receptors during neuronal homeostasis. To better understand the long lasting neurological consequences of ciguatera, it is important to establish the role that chronic changes in activity produced by ciguatoxins represent to central neurons. Here, the effect of a 30 min exposure of 10-13 days in vitro (DIV) cortical neurons to the synthetic ciguatoxin CTX 3C on Arc and Egr1 expression was evaluated using real-time polymerase chain reaction approaches. Since the toxin increased the mRNA levels of both Arc and Egr1, the effect of CTX 3C in NaV channels, membrane potential, firing activity, miniature excitatory postsynaptic currents (mEPSCs), and glutamate receptors expression in cortical neurons after a 24 h exposure was evaluated using electrophysiological and western blot approaches. The data presented here show that CTX 3C induced an upregulation of Arc and Egr1 that was prevented by previous coincubation of the neurons with the NaV channel blocker tetrodotoxin. In addition, chronic CTX 3C caused a concentration-dependent shift in the activation voltage of NaV channels to more negative potentials and produced membrane potential depolarization. Moreover, 24 h treatment of cortical neurons with 5 nM CTX 3C decreased neuronal firing and induced synaptic scaling mechanisms, as evidenced by a decrease in the amplitude of mEPSCs and downregulation in the protein level of glutamate receptors that was also prevented by tetrodotoxin

  17. The release of glutamate from cortical neurons regulated by BDNF via the TrkB/Src/PLC-γ1 pathway.

    PubMed

    Zhang, Zitao; Fan, Jin; Ren, Yongxin; Zhou, Wei; Yin, Guoyong

    2013-01-01

    The brain-derived neurotrophic factor (BDNF) participates in the regulation of cortical neurons by influencing the release of glutamate. However, the specific mechanisms are unclear. Hence, we isolated and cultured the cortical neurons of Sprague Dawley rats. Specific inhibitors of TrkB, Src, PLC-γ1, Akt, and MEK1/2 (i.e., K252a, PP2, U73122, LY294002, and PD98059, respectively) were used to treat cortical neurons and to detect the glutamate release from cortical neurons stimulated with BDNF. BDNF significantly increased glutamate release, and simultaneously enhanced phosphorylation levels of TrkB, Src, PLC-γ, Akt, and Erk1/2. For BDNF-stimulated cortical neurons, K252a inhibited glutamate release and inhibited the phosphorylation levels of TrkB, Src, PLC-γ, Erk1/2, and Akt (P < 0.05). PP2 reduced the glutamate release from BDNF-stimulated cortical neurons (P < 0.05) and inhibited the phosphorylation levels of TrkB and PLC-γ1 (P < 0.05). However, PP2 had no effect on the phosphorylation levels of Erk1/2 or Akt (P > 0.05). U73122 inhibited the glutamate release from BDNF-stimulated cortical neurons, but had no influence on the phosphorylation levels of TrkB, Src, Erk1/2, or Akt (P > 0.05). LY294002 and PD98059 did not affect the BDNF-stimulated glutamate release and did not inhibit the phosphorylation levels of TrkB, Src, or PLC-γ1. In summary, BDNF stimulated the glutamate release from cortical neurons via the TrkB/Src/PLC-γ1 signaling pathway.

  18. Homeostatic Changes in GABA and Glutamate Receptors on Excitatory Cortical Neurons during Sleep Deprivation and Recovery

    PubMed Central

    del Cid-Pellitero, Esther; Plavski, Anton; Mainville, Lynda; Jones, Barbara E.

    2017-01-01

    Neuronal activity is regulated in a homeostatic manner through changes in inhibitory GABA and excitatory glutamate (Glu) AMPA (A) receptors (GluARs). Using immunofluorescent staining, we examined whether calcium/calmodulin-dependent protein kinase IIα (CaMKIIα)-labeled (+) excitatory neurons in the barrel cortex undergo such homeostatic regulation following enforced waking with associated cortical activation during the day when mice normally sleep the majority of the time. Sleep deprived mice were prevented from falling asleep by unilateral whisker stimulation and sleep recovery (SR) mice allowed to sleep freely following deprivation. In parallel with changes in c-Fos reflecting changes in activity, (β2-3 subunits of) GABAA Rs were increased on the membrane of CaMKIIα+ neurons with enforced waking and returned to baseline levels with SR in barrel cortex on sides both contra- and ipsilateral to the whisker stimulation. The GABAAR increase was correlated with increased gamma electroencephalographic (EEG) activity across conditions. On the other hand, (GluA1 subunits of) AMPA Rs were progressively removed from the membrane of CaMKIIα+ neurons by (Rab5+) early endosomes during enforced waking and returned to the membrane by (Rab11+) recycling endosomes during SR. The internalization of the GluA1Rs paralleled the expression of Arc, which mediates homeostatic regulation of AMPA receptors through an endocytic pathway. The reciprocal changes in GluA1Rs relative to GABAARs suggest homeostatic down-scaling during enforced waking and sensory stimulation and restorative up-scaling during recovery sleep. Such homeostatic changes with sleep-wake states and their associated cortical activities could stabilize excitability and activity in excitatory cortical neurons. PMID:28408870

  19. Kinesin KIF4A transports integrin β1 in developing axons of cortical neurons.

    PubMed

    Heintz, Tristan G; Heller, Janosch P; Zhao, Rongrong; Caceres, Alfredo; Eva, Richard; Fawcett, James W

    2014-11-01

    CNS axons have poor regenerative ability compared to PNS axons, and mature axons regenerate less well than immature embryonic axons. The loss of regenerative ability with maturity is accompanied by the setting up of a selective transport filter in axons, restricting the types of molecule that are present. We confirm that integrins (represented by subunits β1 and α5) are present in early cortical axons in vitro but are excluded from mature axons. Ribosomal protein and L1 show selective axonal transport through association with kinesin kif4A; we have therefore examined the hypothesis that integrin transport might also be in association with kif4A. Kif4A is present in all processes of immature cortical neurons cultured at E18, then downregulated by 14days in vitro, coinciding with the exclusion of integrin from axons. Kif4a co-localises with β1 integrin in vesicles in neurons and non-neuronal cells, and the two molecules co-immunoprecipitate. Knockdown of KIF4A expression with shRNA reduced the level of integrin β1 in axons of developing neurons and reduced neurite elongation on laminin, an integrin-dependent substrate. Overexpression of kif4A triggered apoptosis in neuronal and non-neuronal cells. In mature neurons expression of kif4A-GFP at a modest level did not kill the cells, and the kif4A was detectable in their axons. However this was not accompanied by an increase in integrin β1 axonal transport, suggesting that kif4A is not the only integrin transporter, and that integrin exclusion from axons is controlled by factors other than the kif4A level. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Immediate Effects of Repetitive Magnetic Stimulation on Single Cortical Pyramidal Neurons

    PubMed Central

    Banerjee, Jineta; Sorrell, Mary E.; Celnik, Pablo A.; Pelled, Galit

    2017-01-01

    Repetitive Transcranial Magnetic Stimulation (rTMS) has been successfully used as a non-invasive therapeutic intervention for several neurological disorders in the clinic as well as an investigative tool for basic neuroscience. rTMS has been shown to induce long-term changes in neuronal circuits in vivo. Such long-term effects of rTMS have been investigated using behavioral, imaging, electrophysiological, and molecular approaches, but there is limited understanding of the immediate effects of TMS on neurons. We investigated the immediate effects of high frequency (20 Hz) rTMS on the activity of cortical neurons in an effort to understand the underlying cellular mechanisms activated by rTMS. We used whole-cell patch-clamp recordings in acute rat brain slices and calcium imaging of cultured primary neurons to examine changes in neuronal activity and intracellular calcium respectively. Our results indicate that each TMS pulse caused an immediate and transient activation of voltage gated sodium channels (9.6 ± 1.8 nA at -45 mV, p value < 0.01) in neurons. Short 500 ms 20 Hz rTMS stimulation induced action potentials in a subpopulation of neurons, and significantly increased the steady state current of the neurons at near threshold voltages (at -45 mV: before TMS: I = 130 ± 17 pA, during TMS: I = 215 ± 23 pA, p value = 0.001). rTMS stimulation also led to a delayed increase in intracellular calcium (153.88 ± 61.94% increase from baseline). These results show that rTMS has an immediate and cumulative effect on neuronal activity and intracellular calcium levels, and suggest that rTMS may enhance neuronal responses when combined with an additional motor, sensory or cognitive stimulus. Thus, these results could be translated to optimize rTMS protocols for clinical as well as basic science applications. PMID:28114421

  1. Pink1 protects cortical neurons from thapsigargin-induced oxidative stress and neuronal apoptosis

    PubMed Central

    Li, Lin; Hu, Guo-ku

    2015-01-01

    Apoptosis mediates the precise and programmed natural death of neurons and is a physiologically important process in neurogenesis during maturation of the central nervous system. However, premature apoptosis and/or an aberration in apoptosis regulation are implicated in the pathogenesis of neurodegeneration. Thus, it is important to identify neuronal pathways/factors controlling apoptosis. Pink1 [phosphatase and tensin homologue (PTEN)-induced kinase 1] is a ubiquitously expressed gene and has been reported to have a physiological role in mitochondrial maintenance, suppressing mitochondrial oxidative stress, fission and autophagy. However, how Pink1 is involved in neuronal survival against oxidative stress remains not well understood. In the present paper, we demonstrate that thapsigargin, a specific irreversible inhibitor of endoplasmic reticulum (ER) calcium-ATPase, could lead to dramatic oxidative stress and neuronal apoptosis by ectopic calcium entry. Importantly, the neuronal toxicity of thapsigargin inhibits antioxidant gene Pink1 expression. Although Pink1 knockdown enhances the neuronal apoptosis by thapsigargin, its overexpression restores it. Our findings have established the neuronal protective role of Pink1 against oxidative stress and afford rationale for developing new strategy to the therapy of neurodegenerative diseases. PMID:25608948

  2. In vivo multi-photon nanosurgery on cortical neurons: focusing on network organization

    NASA Astrophysics Data System (ADS)

    Sacconi, L.; O'Connor, R. P.; Jasaitis, A.; Masi, A.; Buffelli, M.; Pavone, F. S.

    2008-02-01

    Two-photon microscopy has been used to perform high spatial resolution imaging of spine plasticity in the intact neocortex of living mice. Multi-photon absorption has also been used as a tool for the selective disruption of cellular structures in living cells and simple organisms. In this work we exploit the spatial localization of multi-photon excitation to perform selective lesions on the neuronal processes of cortical neurons in living mice expressing fluorescent proteins. This methodology was applied to dissect single dendrites with sub-micrometric precision without causing any visible collateral damage to the surrounding neuronal structures. The spatial precision of this method was demonstrated by ablating individual dendritic spines, while sparing the adjacent spines and the structural integrity of the dendrite. The morphological consequences were then characterized with time lapse 3D two-photon imaging over a period of minutes to days after the procedure. Here we present the results of our systematic study of the morphological response of cortical pyramidal neurons to nanosurgical perturbations. Dendritic branches were followed after transecting distal segments, whilst the plasticity and remodeling of individual dendritic spines on a given branch was also followed after removing of a subset of spines.

  3. Aberrant neuronal avalanches in cortical tissue removed from juvenile epilepsy patients.

    PubMed

    Hobbs, Jon P; Smith, Jodi L; Beggs, John M

    2010-12-01

    Some forms of epilepsy may arise as a result of pathologic interactions among neurons. Many forms of collective activity have been identified, including waves, spirals, oscillations, synchrony, and neuronal avalanches. All these emergent activity patterns have been hypothesized to show pathologic signatures associated with epilepsy. Here, the authors used 60-channel multielectrode arrays to record neuronal avalanches in cortical tissue removed from juvenile epilepsy patients. For comparison, they also recorded activity in rat cortical slices. The authors found that some human tissue removed from epilepsy patients exhibited prolonged periods of hyperactivity not seen in rat slices. In addition, they found a positive correlation between the branching parameter, a measure of network gain, and firing rate in human slices during periods of hyperactivity. This relationship was not present in rat slices. The authors suggest that this positive correlation between the branching parameter and the firing rate is part of a positive feedback loop and may contribute to some forms of epilepsy. These results also indicate that neuronal avalanches are abnormally regulated in slices removed from pediatric epilepsy patients.

  4. Neuronal avalanches imply maximum dynamic range in cortical networks at criticality.

    PubMed

    Shew, Woodrow L; Yang, Hongdian; Petermann, Thomas; Roy, Rajarshi; Plenz, Dietmar

    2009-12-09

    Spontaneous neuronal activity is a ubiquitous feature of cortex. Its spatiotemporal organization reflects past input and modulates future network output. Here we study whether a particular type of spontaneous activity is generated by a network that is optimized for input processing. Neuronal avalanches are a type of spontaneous activity observed in superficial cortical layers in vitro and in vivo with statistical properties expected from a network operating at "criticality." Theory predicts that criticality and, therefore, neuronal avalanches are optimal for input processing, but until now, this has not been tested in experiments. Here, we use cortex slice cultures grown on planar microelectrode arrays to demonstrate that cortical networks that generate neuronal avalanches benefit from a maximized dynamic range, i.e., the ability to respond to the greatest range of stimuli. By changing the ratio of excitation and inhibition in the cultures, we derive a network tuning curve for stimulus processing as a function of distance from criticality in agreement with predictions from our simulations. Our findings suggest that in the cortex, (1) balanced excitation and inhibition establishes criticality, which maximizes the range of inputs that can be processed, and (2) spontaneous activity and input processing are unified in the context of critical phenomena.

  5. Overexpression of Nrf2 Protects Cerebral Cortical Neurons from Ethanol-Induced Apoptotic DeathS⃞

    PubMed Central

    Narasimhan, Madhusudhanan; Mahimainathan, Lenin; Rathinam, Mary Latha; Riar, Amanjot Kaur

    2011-01-01

    Ethanol (ETOH) can cause apoptotic death of neurons by depleting GSH with an associated increase in oxidative stress. The current study illustrates a means to overcome this ETOH-induced neurotoxicity by enhancing GSH through boosting Nrf2, a transcription factor that controls GSH homeostasis. ETOH treatment caused a significant increase in Nrf2 protein, transcript expression, Nrf2-DNA binding activity, and expression of its transcriptional target, NQO1, in primary cortical neuron (PCNs). However, this increase in Nrf2 did not maintain GSH levels in response to ETOH, and apoptotic death still occurred. To elucidate this phenomenon, we silenced Nrf2 in neurons and found that ETOH-induced GSH depletion and the increase in superoxide levels were exacerbated. Furthermore, Nrf2 knockdown resulted in significantly increased (P < 0.05) caspase 3 activity and apoptosis. Adenovirus-mediated overexpression of Nrf2 prevented ETOH-induced depletion of GSH from the medium and high GSH subpopulations and prevented ETOH-related apoptotic death. These studies illustrate the importance of Nrf2-dependent maintenance of GSH homeostasis in cerebral cortical neurons in the defense against oxidative stress and apoptotic death elicited by ETOH exposure. PMID:21873460

  6. Estimation of the orientation of short lines with a realistic population of cortical neurons

    NASA Astrophysics Data System (ADS)

    Shokhirev, Kirill Nikolai

    The inhomogeneous distribution of the receptive fields of cortical neurons influences the cortical representation of the orientation of short lines seen in visual images. A model of the response of populations of neurons in the human primary visual cortex is constructed by combining realistic response properties of individual neurons and cortical maps of orientation and location preferences. The encoding error characterizes the difference between a visual stimulus and its cortical representation, and is calculated using Fisher information, as the square root of the variance of a statistically efficient estimator. The error of encoding orientation varies with the location and orientation of the short line stimulus as modulated by the underlying orientation preference map. The average encoding error depends weakly on the structure of the orientation preference map and is smaller than the human error of estimating orientation. From this comparison I conclude that the actual mechanism of orientation perception does not make efficient use of all the information available in the neuronal responses and that the decoding of visual information from neuronal responses limits psychophysical performance. Two forms of a population vector (PV) estimator were used to test if a simple estimation mechanism can account for the human accuracy of estimation of the orientation. The canonical PV estimator is similar to the models proposed previously for estimation of movement direction in the motor cortex. The "normalized" PV estimator has coefficients scaled by the local density of neurons in the space of preferred parameters. The average variance of either estimator does not increase appreciably when a realistic distribution is used instead of a random distribution of preferred orientations and remains significantly below the psychophysical threshold. However, the bias of the canonical PV estimator increases by approximately a factor of 15 compared with the random distribution. The

  7. Analytical characterization of spontaneous firing in networks of developing rat cultured cortical neurons

    NASA Astrophysics Data System (ADS)

    Tateno, Takashi; Kawana, Akio; Jimbo, Yasuhiko

    2002-05-01

    We have used a multiunit electrode array in extracellular recording to investigate changes in the firing patterns in networks of developing rat cortical neurons. The spontaneous activity of continual asynchronous firing or the alternation of asynchronous spikes and synchronous bursts changed over time so that activity in the later stages consisted exclusively of synchronized bursts. The spontaneous coordinated activity in bursts produced a variability in interburst interval (IBI) sequences that is referred to as ``form.'' The stochastic and nonlinear dynamical analysis of IBI sequences revealed that these sequences reflected a largely random process and that the form for relatively immature neurons was largely oscillatory while the form for the more mature neurons was Poisson-like. The observed IBI sequences thus showed changes in form associated with both the intrinsic properties of the developing cells and the neural response to correlated synaptic inputs due to interaction between the developing neural circuits.

  8. Novel protein transfection of primary rat cortical neurons using an antibody that penetrates living cells.

    PubMed

    Weisbart, R H; Baldwin, R; Huh, B; Zack, D J; Nishimura, R

    2000-06-01

    An Ab-based system to deliver functional proteins into neurons was developed using the murine mAb, mAb 3E10. This was achieved by covalently conjugating catalase to the Ab so that the conjugate retained high activity for the degradation of hydrogen peroxide. Three-dimensional fluorescence microscopy was used to demonstrate penetration of the Ab into the nucleus of living primary cortical neurons. The Ab conjugate localized in both the cytoplasm and nucleus. Retention of catalase activity after penetration and distribution of conjugate was demonstrated by reduction in cell death following exposure of treated neurons to hydrogen peroxide. These studies illustrate the potential of this method for the intracellular delivery of therapeutic proteins.

  9. Stability and Autolysis of Cortical Neurons in Post-Mortem Adult Rat Brains

    PubMed Central

    Sheleg, Sergey V; LoBello, Janine R; Hixon, Hugh; Coons, Stephen W; Lowry, David; Nedzved, Mikhail K

    2008-01-01

    We investigated the dynamics of autolytic damage of the cortical neurons in adult brains for 24 hours at room temperature (+20°C) after cardiac arrest. The progressive histological and ultrastructural changes were documented using routine and immunohistochemical staining as well as electron microscopy. Our results demonstrated that there were no autolytic damages in the ultrastructure of cerebral neurons in the first 6 hours after warm cardiac arrest, in agreement with previous studies in other mammals. Interestingly, the activation of caspase-3 was observed in a significant number of neurons of the cerebellum and neocortex 9 hours following cardiac arrest. No significant changes related to autolysis were observed using amnio-cupric acid and Nissl (thionine) staining. PMID:18784829

  10. Protective effect of panaxydol and panaxynol on sodium nitroprusside-induced apoptosis in cortical neurons.

    PubMed

    Nie, Bao-Ming; Yang, Li-Min; Fu, Sai-Li; Jiang, Xiao-Yan; Lu, Pei-Hua; Lu, Yang

    2006-04-15

    An excess of the free radical nitric oxide (NO) is viewed as a deleterious factor involved in various CNS disorders. The protective effect of panaxydol (PND) and panaxynol (PNN) on sodium nitroprusside (SNP)-induced neuronal apoptosis and potential mechanism were investigated in primary cultured rat cortical neurons. Pretreatment of the cells with PND or PNN for 24 h following 1mM SNP, an exogenous NO donor, exposure for 1h, resulted significantly in reduction of cell death induced by SNP determined by MTT assay, LDH release and Hoechst staining. 5 microM PND and PNN also reduced the up-regulation of the pro-apoptotic gene, Bax, down-regulation of the anti-apoptotic gene, Bcl-2. The observations demonstrated that PND and PNN protect neurons against SNP-induced apoptosis via regulating the apoptotic related genes. The results raise the possibility that PND and PNN reduce neurodegeneration in the Alzheimer's brain.

  11. Additivity of Pyrethroid Actions on Sodium Influx in Cortical Neurons in Cerebrocortical Neurons in Primary Culture

    EPA Science Inventory

    BACKGROUND: Pyrethroid insecticides bind to voltage-gated sodium channels and modify their gating kinetics, thereby disrupting neuronal function. Although previous work has tested the additivity of pyrethroids in vivo, this has not been assessed directly at the primary molecular ...

  12. Additivity of Pyrethroid Actions on Sodium Influx in Cortical Neurons in Cerebrocortical Neurons in Primary Culture

    EPA Science Inventory

    BACKGROUND: Pyrethroid insecticides bind to voltage-gated sodium channels and modify their gating kinetics, thereby disrupting neuronal function. Although previous work has tested the additivity of pyrethroids in vivo, this has not been assessed directly at the primary molecular ...

  13. Concentration-Dependent Dual Role of Thrombin In Protection of Cultured Rat Cortical Neurons

    PubMed Central

    García, Paul S.; Ciavatta, Vincent T.; Fidler, Jonathan A.; Woodbury, Anna; Levy, Jerrold H.; Tyor, William R.

    2015-01-01

    Background Thrombin’s role in the nervous system is not well understood. Under conditions of blood-brain barrier compromise (e.g., neurosurgery or stroke), thrombin can result in neuroapoptosis and the formation of glial scars. Despite this, preconditioning with thrombin has been found to be neuroprotective in models of cerebral ischemia and intracerebral hemorrhage. Methods We investigated the effects of physiologically relevant concentrations of thrombin on cortical neurons using two culture-based assays. We examined thrombin’s effect on neurites by quantitative analysis of fluorescently labeled neurons. To characterize thrombin’s effects on neuron survival, we spectrophotometrically measured changes in enzymatic activity. Using receptor agonists and thrombin inhibitors, we separately examined the role of thrombin and its receptor in neuroprotection. Results We found that low concentrations of thrombin (1 nM) enhances neurite growth and branching, neuron viability, and protects against excitotoxic damage. In contrast, higher concentrations of thrombin (100 nM) are potentially detrimental to neuronal health as evidenced by inhibition of neurite growth. Lower concentrations of thrombin resulted in equivalent neuroprotection as the antifibrinolytic, aprotinin, and the direct thrombin inhibitor, argatroban. Interestingly, exogenous application of the species-specific thrombin inhibitor, antithrombin III, was detrimental to neuronal health; suggesting that some endogenous thrombin is necessary for optimal neuron health in our culture system. Activation of the thrombin receptor, protease-activated receptor - 1 (PAR-1), via micromolar concentrations of the thrombin receptor agonist peptide, TRAP, did not adversely affect neuronal viability. Conclusions An optimal concentration of thrombin exists to enhance neuronal health. Neurotoxic effects of thrombin do not involve activation of PAR receptors and thus separate pharmacologic manipulation of thrombin’s receptor

  14. Rosuvastatin induces delayed preconditioning against oxygen-glucose deprivation in cultured cortical neurons.

    PubMed

    Domoki, Ferenc; Kis, Béla; Gáspár, Tamás; Snipes, James A; Parks, John S; Bari, Ferenc; Busija, David W

    2009-01-01

    We tested whether rosuvastatin (RST) protected against oxygen-glucose deprivation (OGD)-induced cell death in primary rat cortical neuronal cultures. OGD reduced neuronal viability (%naive controls, mean +/- SE, n = 24-96, P < 0.05) to 44 +/- 1%, but 3-day pretreatment with RST (5 microM) increased survival to 82 +/- 2% (P < 0.05). One-day RST treatment was not protective. RST-induced neuroprotection was abolished by mevalonate or geranylgeranyl pyrophosphate (GGPP), but not by cholesterol coapplication. Furthermore, RST-induced decreases in neuronal cholesterol levels were abolished by mevalonate but not by GGPP. Reactive oxygen species (ROS) levels were reduced in RST-preconditioned neurons after OGD, and this effect was also reversed by both mevalonate and GGPP. These data suggested that GGPP, but not cholesterol depletion, were responsible for the induction of neuroprotection. Therefore, we tested whether 3-day treatments with perillic acid, a nonspecific inhibitor of both geranylgeranyl transferase (GGT) GGT 1 and Rab GGT, and the GGT 1-specific inhibitor GGTI-286 would reproduce the effects of RST. Perillic acid, but not GGTI-286, elicited robust neuronal preconditioning against OGD. RST, GGTI-286, and perillic acid all decreased mitochondrial membrane potential and lactate dehydrogenase activity in the cultured neurons, but only RST and perillic acid reduced neuronal ATP and membrane Rab3a protein levels. In conclusion, RST preconditions cultured neurons against OGD via depletion of GGPP, leading to decreased geranylgeranylation of proteins that are probably not isoprenylated by GGT 1. Reduced neuronal ATP levels and ROS production after OGD may be directly involved in the mechanism of neuroprotection.

  15. Allicin protects rat cortical neurons against mechanical trauma injury by regulating nitric oxide synthase pathways.

    PubMed

    Zhou, Yue-fei; Li, Wen-tao; Han, Hong-cheng; Gao, Da-kuan; He, Xiao-sheng; Li, Liang; Song, Jin-ning; Fei, Zhou

    2014-01-01

    Allicin, a small molecule that is responsible for the typical smell and most of the functions of garlic, possesses a broad spectrum of pharmacological activities and is considered to have therapeutic potential in many pathologic conditions. In the present study, we investigated the potential protective effect of allicin in an in vitro model of traumatic brain injury (TBI) using primary cultured rat cortical neurons. We found that allicin treatment significantly reduced mechanical trauma-induced lactate dehydrogenase (LDH) release and inhibited apoptotic neuronal death in a dose-dependent manner. These protective effects were observed even if allicin treatment was delayed to 2h after injury. Allicin significantly decreased the expression of inducible nitric oxide synthase (iNOS) and increased the phosphorylation of endothelial NOS (eNOS) but had no effect on neuronal NOS (nNOS) expression. Allicin-induced protection in cortical neurons was augmented by iNOS and nNOS antagonists and was partly reversed by blocking eNOS phosphorylation. In addition, allicin treatment inhibited the TBI-induced activation of ERK and further enhanced the phosphorylation of Akt in TBI-injured neurons. The Akt inhibitor LY294002 attenuated the allicin-induced increase in eNOS expression and phosphorylation, whereas the ERK inhibitor PD98059 had opposite effects on the expression of iNOS and eNOS. Pretreatment with LY294002 or PD98059 partly prevented or further enhanced allicin-induced neuroprotection, respectively. Collectively, these data demonstrate that allicin treatment may be an effective therapeutic strategy for traumatic neuronal injury and that the potential underlying mechanism involves Akt- and ERK-mediated regulation of NOS pathways.

  16. Modulating motility of intracellular vesicles in cortical neurons with nanomagnetic forces on-chip.

    PubMed

    Kunze, Anja; Murray, Coleman Tylor; Godzich, Chanya; Lin, Jonathan; Owsley, Keegan; Tay, Andy; Di Carlo, Dino

    2017-02-28

    Vesicle transport is a major underlying mechanism of cell communication. Inhibiting vesicle transport in brain cells results in blockage of neuronal signals, even in intact neuronal networks. Modulating intracellular vesicle transport can have a huge impact on the development of new neurotherapeutic concepts, but only if we can specifically interfere with intracellular transport patterns. Here, we propose to modulate motion of intracellular lipid vesicles in rat cortical neurons based on exogenously bioconjugated and cell internalized superparamagnetic iron oxide nanoparticles (SPIONs) within microengineered magnetic gradients on-chip. Upon application of 6-126 pN on intracellular vesicles in neuronal cells, we explored how the magnetic force stimulus impacts the motion pattern of vesicles at various intracellular locations without modulating the entire cell morphology. Altering vesicle dynamics was quantified using, mean square displacement, a caging diameter and the total traveled distance. We observed a de-acceleration of intercellular vesicle motility, while applying nanomagnetic forces to cultured neurons with SPIONs, which can be explained by a decrease in motility due to opposing magnetic force direction. Ultimately, using nanomagnetic forces inside neurons may permit us to stop the mis-sorting of intracellular organelles, proteins and cell signals, which have been associated with cellular dysfunction. Furthermore, nanomagnetic force applications will allow us to wirelessly guide axons and dendrites by exogenously using permanent magnetic field gradients.

  17. Clinacanthus nutans Protects Cortical Neurons Against Hypoxia-Induced Toxicity by Downregulating HDAC1/6.

    PubMed

    Tsai, Hsin-Da; Wu, Jui-Sheng; Kao, Mei-Han; Chen, Jin-Jer; Sun, Grace Y; Ong, Wei-Yi; Lin, Teng-Nan

    2016-09-01

    Many population-based epidemiological studies have unveiled an inverse correlation between intake of herbal plants and incidence of stroke. C. nutans is a traditional herbal medicine widely used for snake bite, viral infection and cancer in Asian countries. However, its role in protecting stroke damage remains to be studied. Despite of growing evidence to support epigenetic regulation in the pathogenesis and recovery of stroke, a clear understanding of the underlying molecular mechanisms is still lacking. In the present study, primary cortical neurons were subjected to in vitro oxygen-glucose deprivation (OGD)-reoxygenation and hypoxic neuronal death was used to investigate the interaction between C. nutans and histone deacetylases (HDACs). Using pharmacological agents (HDAC inhibitor/activator), loss-of-function (HDAC siRNA) and gain-of-function (HDAC plasmid) approaches, we demonstrated an early induction of HDAC1/2/3/8 and HDAC6 in neurons after OGD insult. C. nutans extract selectively inhibited HDAC1 and HDAC6 expression and attenuated neuronal death. Results of reporter analysis further revealed that C. nutans suppressed HDAC1 and HDAC6 transcription. Besides ameliorating neuronal death, C. nutans also protected astrocytes and endothelial cells from hypoxic-induced cell death. In summary, results support ability for C. nutans to suppress post-hypoxic HDACs activation and mitigate against OGD-induced neuronal death. This study further opens a new avenue for the use of herbal medicines to regulate epigenetic control of brain injury.

  18. Online Stimulus Optimization Rapidly Reveals Multidimensional Selectivity in Auditory Cortical Neurons

    PubMed Central

    Hancock, Kenneth E.; Sen, Kamal

    2014-01-01

    Neurons in sensory brain regions shape our perception of the surrounding environment through two parallel operations: decomposition and integration. For example, auditory neurons decompose sounds by separately encoding their frequency, temporal modulation, intensity, and spatial location. Neurons also integrate across these various features to support a unified perceptual gestalt of an auditory object. At higher levels of a sensory pathway, neurons may select for a restricted region of feature space defined by the intersection of multiple, independent stimulus dimensions. To further characterize how auditory cortical neurons decompose and integrate multiple facets of an isolated sound, we developed an automated procedure that manipulated five fundamental acoustic properties in real time based on single-unit feedback in awake mice. Within several minutes, the online approach converged on regions of the multidimensional stimulus manifold that reliably drove neurons at significantly higher rates than predefined stimuli. Optimized stimuli were cross-validated against pure tone receptive fields and spectrotemporal receptive field estimates in the inferior colliculus and primary auditory cortex. We observed, from midbrain to cortex, increases in both level invariance and frequency selectivity, which may underlie equivalent sparseness of responses in the two areas. We found that onset and steady-state spike rates increased proportionately as the stimulus was tailored to the multidimensional receptive field. By separately evaluating the amount of leverage each sound feature exerted on the overall firing rate, these findings reveal interdependencies between stimulus features as well as hierarchical shifts in selectivity and invariance that may go unnoticed with traditional approaches. PMID:24990917

  19. Effects of inorganic lead on the differentiation and growth of cortical neurons in culture.

    PubMed

    Kern, M; Audesirk, T; Audesirk, G

    1993-01-01

    Lead exposure has devastating effects on the developing nervous system, producing morphological, cognitive, and behavioral deficits. To elucidate some of the mechanisms of lead neurotoxicity, we have examined its effects on the differentiation of several types of cultured neurons. Previously, we reported the effects of inorganic lead on several parameters of growth and differentiation of E18 rat hippocampal neurons and two types of neuroblastoma cells cultured in medium with 2% fetal calf serum (FCS) (Audesirk et al., 1991). In the present study, we report the effects of concentrations of lead ranging from 1nM to 1 mM on the differentiation of hippocampal neurons cultured in medium containing 10% FCS. In addition, we investigated lead effects on neurons isolated from the motor cortex region of the E18 rat embryo. Cortical neurons were exposed to lead in concentrations ranging from 0.1 nM to 1 mM in medium with either 10% FCS or 2% FCS for 48 hr. The effects of lead tended to be multimodal. Neurite initiation, which is highly sensitive to neurotoxic compounds, was inhibited by lead at both high and low concentrations, with no effects at intermediate levels. Medium with 10% FCS enhanced certain growth parameters and tended to reduce the effects of lead. There was an overall consistency in the effects of lead on motor cortex and hippocampal neurons.

  20. Potassium channels control the interaction between active dendritic integration compartments in layer 5 cortical pyramidal neurons

    PubMed Central

    Harnett, Mark T.; Xu, Ning-Long; Magee, Jeffrey C.; Williams, Stephen R.

    2013-01-01

    Active dendritic synaptic integration enhances the computational power of neurons. Such nonlinear processing generates an object-localization signal in the apical dendritic tuft of layer 5B cortical pyramidal neurons during sensory-motor behaviour. Here we employ electrophysiological and optical approaches in brain-slices and behaving animals to investigate how excitatory synaptic input to this distal dendritic compartment influences neuronal output. We find that active dendritic integration throughout the apical dendritic tuft is highly compartmentalized by voltage-gated potassium (KV) channels. A high-density of both transient and sustained KV channels was observed in all apical dendritic compartments. These channels potently regulated the interaction between apical dendritic tuft, trunk, and axo-somatic integration zones to control neuronal output in vitro as well as the engagement of dendritic nonlinear processing in vivo during sensory-motor behaviour. Thus, KV channels dynamically tune the interaction between active dendritic integration compartments in layer 5B pyramidal neurons to shape behaviourally relevant neuronal computations. PMID:23931999

  1. Ect2, an ortholog of Drosophila Pebble, regulates formation of growth cones in primary cortical neurons

    PubMed Central

    Tsuji, Takahiro; Higashida, Chiharu; Aoki, Yoshihiko; Islam, Mohammad Saharul; Dohmoto, Mitsuko; Higashida, Haruhiro

    2016-01-01

    In collaboration with Marshall Nirenberg, we performed in vivo RNA interference (RNAi) genome-wide screening in Drosophila embryos. Pebble has been shown to be involved in Drosophila neuronal development. We have also reported that depletion of Ect2, a mammalian ortholog of Pebble, induces differentiation in NG108-15 neuronal cells. However, the precise role of Ect2 in neuronal development has yet to be studied. Here, we confirmed in PC12 pheochromocytoma cells that inhibition of Ect2 expression by RNAi stimulated neurite outgrowth, and in the mouse embryonic cortex that Ect2 was accumulated throughout the ventricular and subventricular zones with neuronal progenitor cells. Next, the effects of Ect2 depletion were studied in primary cultures of mouse embryonic cortical neurons: Loss of Ect2 did not affect the differentiation stages of neuritogenesis, the number of neurites, or axon length, while the numbers of growth cones and growth cone-like structures were increased. Taken together, our results suggest that Ect2 contributes to neuronal morphological differentiation through regulation of growth cone dynamics. PMID:22366651

  2. Dendritic vulnerability in neurodegenerative disease: insights from analyses of cortical pyramidal neurons in transgenic mouse models

    PubMed Central

    Weaver, Christina M.; Rocher, Anne B.; Rodriguez, Alfredo; Crimins, Johanna L.; Dickstein, Dara L.; Wearne, Susan L.; Hof, Patrick R.

    2011-01-01

    In neurodegenerative disorders, such as Alzheimer’s disease, neuronal dendrites and dendritic spines undergo significant pathological changes. Because of the determinant role of these highly dynamic structures in signaling by individual neurons and ultimately in the functionality of neuronal networks that mediate cognitive functions, a detailed understanding of these changes is of paramount importance. Mutant murine models, such as the Tg2576 APP mutant mouse and the rTg4510 tau mutant mouse have been developed to provide insight into pathogenesis involving the abnormal production and aggregation of amyloid and tau proteins, because of the key role that these proteins play in neurodegenerative disease. This review showcases the multidimensional approach taken by our collaborative group to increase understanding of pathological mechanisms in neurodegenerative disease using these mouse models. This approach includes analyses of empirical 3D morphological and electrophysiological data acquired from frontal cortical pyramidal neurons using confocal laser scanning microscopy and whole-cell patch-clamp recording techniques, combined with computational modeling methodologies. These collaborative studies are designed to shed insight on the repercussions of dystrophic changes in neocortical neurons, define the cellular phenotype of differential neuronal vulnerability in relevant models of neurodegenerative disease, and provide a basis upon which to develop meaningful therapeutic strategies aimed at preventing, reversing, or compensating for neurodegenerative changes in dementia. PMID:20177698

  3. Online stimulus optimization rapidly reveals multidimensional selectivity in auditory cortical neurons.

    PubMed

    Chambers, Anna R; Hancock, Kenneth E; Sen, Kamal; Polley, Daniel B

    2014-07-02

    Neurons in sensory brain regions shape our perception of the surrounding environment through two parallel operations: decomposition and integration. For example, auditory neurons decompose sounds by separately encoding their frequency, temporal modulation, intensity, and spatial location. Neurons also integrate across these various features to support a unified perceptual gestalt of an auditory object. At higher levels of a sensory pathway, neurons may select for a restricted region of feature space defined by the intersection of multiple, independent stimulus dimensions. To further characterize how auditory cortical neurons decompose and integrate multiple facets of an isolated sound, we developed an automated procedure that manipulated five fundamental acoustic properties in real time based on single-unit feedback in awake mice. Within several minutes, the online approach converged on regions of the multidimensional stimulus manifold that reliably drove neurons at significantly higher rates than predefined stimuli. Optimized stimuli were cross-validated against pure tone receptive fields and spectrotemporal receptive field estimates in the inferior colliculus and primary auditory cortex. We observed, from midbrain to cortex, increases in both level invariance and frequency selectivity, which may underlie equivalent sparseness of responses in the two areas. We found that onset and steady-state spike rates increased proportionately as the stimulus was tailored to the multidimensional receptive field. By separately evaluating the amount of leverage each sound feature exerted on the overall firing rate, these findings reveal interdependencies between stimulus features as well as hierarchical shifts in selectivity and invariance that may go unnoticed with traditional approaches.

  4. Ect2, an ortholog of Drosophila Pebble, regulates formation of growth cones in primary cortical neurons.

    PubMed

    Tsuji, Takahiro; Higashida, Chiharu; Aoki, Yoshihiko; Islam, Mohammad Saharul; Dohmoto, Mitsuko; Higashida, Haruhiro

    2012-11-01

    In collaboration with Marshall Nirenberg, we performed in vivo RNA interference (RNAi) genome-wide screening in Drosophila embryos. Pebble has been shown to be involved in Drosophila neuronal development. We have also reported that depletion of Ect2, a mammalian ortholog of Pebble, induces differentiation in NG108-15 neuronal cells. However, the precise role of Ect2 in neuronal development has yet to be studied. Here, we confirmed in PC12 pheochromocytoma cells that inhibition of Ect2 expression by RNAi stimulated neurite outgrowth, and in the mouse embryonic cortex that Ect2 was accumulated throughout the ventricular and subventricular zones with neuronal progenitor cells. Next, the effects of Ect2 depletion were studied in primary cultures of mouse embryonic cortical neurons: Loss of Ect2 did not affect the differentiation stages of neuritogenesis, the number of neurites, or axon length, while the numbers of growth cones and growth cone-like structures were increased. Taken together, our results suggest that Ect2 contributes to neuronal morphological differentiation through regulation of growth cone dynamics.

  5. Dynamics and effective topology underlying synchronization in networks of cortical neurons.

    PubMed

    Eytan, Danny; Marom, Shimon

    2006-08-16

    Cognitive processes depend on synchronization and propagation of electrical activity within and between neuronal assemblies. In vivo measurements show that the size of individual assemblies depends on their function and varies considerably, but the timescale of assembly activation is in the range of 0.1-0.2 s and is primarily independent of assembly size. Here we use an in vitro experimental model of cortical assemblies to characterize the process underlying the timescale of synchronization, its relationship to the effective topology of connectivity within an assembly, and its impact on propagation of activity within and between assemblies. We show that the basic mode of assembly activation, "network spike," is a threshold-governed, synchronized population event of 0.1-0.2 s duration and follows the logistics of neuronal recruitment in an effectively scale-free connected network. Accordingly, the sequence of neuronal activation within a network spike is nonrandom and hierarchical; a small subset of neurons is consistently recruited tens of milliseconds before others. Theory predicts that scale-free topology allows for synchronization time that does not increase markedly with network size; our experiments with networks of different densities support this prediction. The activity of early-to-fire neurons reliably forecasts an upcoming network spike and provides means for expedited propagation between assemblies. We demonstrate this capacity by observing the dynamics of two artificially coupled assemblies in vitro, using neuronal activity of one as a trigger for electrical stimulation of the other.

  6. Lactate modulates the activity of primary cortical neurons through a receptor-mediated pathway.

    PubMed

    Bozzo, Luigi; Puyal, Julien; Chatton, Jean-Yves

    2013-01-01

    Lactate is increasingly described as an energy substrate of the brain. Beside this still debated metabolic role, lactate may have other effects on brain cells. Here, we describe lactate as a neuromodulator, able to influence the activity of cortical neurons. Neuronal excitability of mouse primary neurons was monitored by calcium imaging. When applied in conjunction with glucose, lactate induced a decrease in the spontaneous calcium spiking frequency of neurons. The effect was reversible and concentration dependent (IC50 ∼4.2 mM). To test whether lactate effects are dependent on energy metabolism, we applied the closely related substrate pyruvate (5 mM) or switched to different glucose concentrations (0.5 or 10 mM). None of these conditions reproduced the effect of lactate. Recently, a Gi protein-coupled receptor for lactate called HCA1 has been introduced. To test if this receptor is implicated in the observed lactate sensitivity, we incubated cells with pertussis toxin (PTX) an inhibitor of Gi-protein. PTX prevented the decrease of neuronal activity by L-lactate. Moreover 3,5-dyhydroxybenzoic acid, a specific agonist of the HCA1 receptor, mimicked the action of lactate. This study indicates that lactate operates a negative feedback on neuronal activity by a receptor-mediated mechanism, independent from its intracellular metabolism.

  7. Lactate Modulates the Activity of Primary Cortical Neurons through a Receptor-Mediated Pathway

    PubMed Central

    Bozzo, Luigi; Puyal, Julien; Chatton, Jean-Yves

    2013-01-01

    Lactate is increasingly described as an energy substrate of the brain. Beside this still debated metabolic role, lactate may have other effects on brain cells. Here, we describe lactate as a neuromodulator, able to influence the activity of cortical neurons. Neuronal excitability of mouse primary neurons was monitored by calcium imaging. When applied in conjunction with glucose, lactate induced a decrease in the spontaneous calcium spiking frequency of neurons. The effect was reversible and concentration dependent (IC50 ∼4.2 mM). To test whether lactate effects are dependent on energy metabolism, we applied the closely related substrate pyruvate (5 mM) or switched to different glucose concentrations (0.5 or 10 mM). None of these conditions reproduced the effect of lactate. Recently, a Gi protein-coupled receptor for lactate called HCA1 has been introduced. To test if this receptor is implicated in the observed lactate sensitivity, we incubated cells with pertussis toxin (PTX) an inhibitor of Gi-protein. PTX prevented the decrease of neuronal activity by L-lactate. Moreover 3,5-dyhydroxybenzoic acid, a specific agonist of the HCA1 receptor, mimicked the action of lactate. This study indicates that lactate operates a negative feedback on neuronal activity by a receptor-mediated mechanism, independent from its intracellular metabolism. PMID:23951229

  8. Modulation of Specific Sensory Cortical Areas by Segregated Basal Forebrain Cholinergic Neurons Demonstrated by Neuronal Tracing and Optogenetic Stimulation in Mice

    PubMed Central

    Chaves-Coira, Irene; Barros-Zulaica, Natali; Rodrigo-Angulo, Margarita; Núñez, Ángel

    2016-01-01

    Neocortical cholinergic activity plays a fundamental role in sensory processing and cognitive functions. Previous results have suggested a refined anatomical and functional topographical organization of basal forebrain (BF) projections that may control cortical sensory processing in a specific manner. We have used retrograde anatomical procedures to demonstrate the existence of specific neuronal groups in the BF involved in the control of specific sensory cortices. Fluoro-Gold (FlGo) and Fast Blue (FB) fluorescent retrograde tracers were deposited into the primary somatosensory (S1) and primary auditory (A1) cortices in mice. Our results revealed that the BF is a heterogeneous area in which neurons projecting to different cortical areas are segregated into different neuronal groups. Most of the neurons located in the horizontal limb of the diagonal band of Broca (HDB) projected to the S1 cortex, indicating that this area is specialized in the sensory processing of tactile stimuli. However, the nucleus basalis magnocellularis (B) nucleus shows a similar number of cells projecting to the S1 as to the A1 cortices. In addition, we analyzed the cholinergic effects on the S1 and A1 cortical sensory responses by optogenetic stimulation of the BF neurons in urethane-anesthetized transgenic mice. We used transgenic mice expressing the light-activated cation channel, channelrhodopsin-2, tagged with a fluorescent protein (ChR2-YFP) under the control of the choline-acetyl transferase promoter (ChAT). Cortical evoked potentials were induced by whisker deflections or by auditory clicks. According to the anatomical results, optogenetic HDB stimulation induced more extensive facilitation of tactile evoked potentials in S1 than auditory evoked potentials in A1, while optogenetic stimulation of the B nucleus facilitated either tactile or auditory evoked potentials equally. Consequently, our results suggest that cholinergic projections to the cortex are organized into segregated

  9. A New Role for TIMP-1 in Modulating Neurite Outgrowth and Morphology of Cortical Neurons

    PubMed Central

    Ould-yahoui, Adlane; Tremblay, Evelyne; Sbai, Oualid; Ferhat, Lotfi; Bernard, Anne; Charrat, Eliane; Gueye, Yatma; Lim, Ngee Han; Brew, Keith; Risso, Jean-Jacques; Dive, Vincent; Khrestchatisky, Michel; Rivera, Santiago

    2009-01-01

    Background Tissue inhibitor of metalloproteinases-1 (TIMP-1) displays pleiotropic activities, both dependent and independent of its inhibitory activity on matrix metalloproteinases (MMPs). In the central nervous system (CNS), TIMP-1 is strongly upregulated in reactive astrocytes and cortical neurons following excitotoxic/inflammatory stimuli, but no information exists on its effects on growth and morphology of cortical neurons. Principal Findings We found that 24 h incubation with recombinant TIMP-1 induced a 35% reduction in neurite length and significantly increased growth cones size and the number of F-actin rich microprocesses. TIMP-1 mediated reduction in neurite length affected both dendrites and axons after 48 h treatment. The effects on neurite length and morphology were not elicited by a mutated form of TIMP-1 inactive against MMP-1, -2 and -3, and still inhibitory for MMP-9, but were mimicked by a broad spectrum MMP inhibitor. MMP-9 was poorly expressed in developing cortical neurons, unlike MMP-2 which was present in growth cones and whose selective inhibition caused neurite length reductions similar to those induced by TIMP-1. Moreover, TIMP-1 mediated changes in cytoskeleton reorganisation were not accompanied by modifications in the expression levels of actin, βIII-tubulin, or microtubule assembly regulatory protein MAP2c. Transfection-mediated overexpression of TIMP-1 dramatically reduced neuritic arbour extension in the absence of detectable levels of released extracellular TIMP-1. Conclusions Altogether, TIMP-1 emerges as a modulator of neuronal outgrowth and morphology in a paracrine and autrocrine manner through the inhibition, at least in part, of MMP-2 and not MMP-9. These findings may help us understand the role of the MMP/TIMP system in post-lesion pre-scarring conditions. PMID:20011518

  10. Effects of the analgesic acetaminophen (Paracetamol) and its para-aminophenol metabolite on viability of mouse-cultured cortical neurons.

    PubMed

    Schultz, Stephen; DeSilva, Mauris; Gu, Ting Ting; Qiang, Mei; Whang, Kyumin

    2012-02-01

    Acetaminophen has been used as an analgesic for more than a hundred years, but its mechanism of action has remained elusive. Recently, it has been shown that acetaminophen produces analgesia by the activation of the brain endocannabinoid receptor CB1 through its para-aminophenol (p-aminophenol) metabolite. The objective of this study was to determine whether p-aminophenol could be toxic for in vitro developing mouse cortical neurons as a first step in establishing a link between acetaminophen use and neuronal apoptosis. We exposed developing mouse cortical neurons to various concentrations of drugs for 24 hr in vitro. Acetaminophen itself was not toxic to developing mouse cortical neurons at therapeutic concentrations of 10-250 μg/ml. However, concentrations of p-aminophenol from 1 to 100 μg/ml produced significant (p < 0.05) loss of mouse cortical neuron viability at 24 hr compared to the controls. The naturally occurring endocannabinoid anandamide also caused similar 24-hr loss of cell viability in developing mouse cortical neurons at concentrations from 1 to 100 μg/ml, which indicates the mechanism of cell death could be through the cannabinoid receptors. The results of our experiments have shown a detrimental effect of the acetaminophen metabolite p-aminophenol on in vitro developing cortical neuron viability which could act through CB1 receptors of the endocannabinoid system. These results could be especially important in recommending an analgesic for children or individuals with traumatic brain injury who have developing cortical neurons. Published 2011. This article is a U.S. Government work and is in the public domain in the USA.

  11. High-frequency EEG covaries with spike burst patterns detected in cortical neurons

    PubMed Central

    Baker, Stuart N.; Herz, Andreas V. M.; Curio, Gabriel

    2011-01-01

    Invasive microelectrode recordings measure neuronal spikes, which are commonly considered inaccessible through standard surface electroencephalogram (EEG). Yet high-frequency EEG potentials (hf-EEG, f > 400 Hz) found in somatosensory evoked potentials of primates may reflect the mean population spike responses of coactivated cortical neurons. Since cortical responses to electrical nerve stimulation vary strongly from trial to trial, we investigated whether the hf-EEG signal can also echo single-trial variability observed at the single-unit level. We recorded extracellular single-unit activity in the primary somatosensory cortex of behaving macaque monkeys and identified variable spike burst responses following peripheral stimulation. Each of these responses was classified according to the timing of its spike constituents, conforming to one of a discrete set of spike patterns. We here show that these spike patterns are accompanied by variations in the concomitant epidural hf-EEG. These variations cannot be explained by fluctuating stimulus efficacy, suggesting that they were generated within the thalamocortical network. As high-frequency EEG signals can also be reliably recorded from the scalp of human subjects, they may provide a noninvasive window on fluctuating cortical spike activity in humans. PMID:21490283

  12. TFP5 prevents 1-methyl-4-phenyl pyridine ion-induced neurotoxicity in mouse cortical neurons

    PubMed Central

    Zhang, Qi-Shan; Liao, Yuan-Gao; Ji, Zhong; Gu, Yong; Jiang, Hai-Shan; Xie, Zuo-Shan; Pan, Su-Yue; Hu, Ya-Fang

    2016-01-01

    The present study aimed to investigate the protective effect of a modified p5 peptide, TFP5, on 1-methyl-4-phenyl pyridine ion (MPP+)-induced neurotoxicity in cortical neurons and explore the therapeutic effect of TFP5 on Parkinson's disease (PD). MPP+ was applied to a primary culture of mouse cortical neurons to establish the cell model of PD. Neurons were divided into four groups: Control, model (MPP+), scrambled peptide (Scb) (Scb + MPP+) and TFP5 (TFP5 + MPP+) groups. Pretreatment with Scb or TFP5 was applied to the latter two groups, respectively, for 3 h, while phosphate-buffered saline was applied to the control and model groups. MPP+ was then applied to all groups, with the exception of the control group, and neurons were cultured for an additional 24 h. Neuron viability was evaluated using a Cell Counting kit-8 (CCK8) assay. To explore the mechanism underlying the protective effects of TFP5, the expression levels of p35, p25 and phosphorylated myocyte enhancer factor 2 (p-MEF2D) were determined by western blotting. Fluorescence microscopy showed that TFP5 was able to pass through cell membranes and distribute around the nucleus. CCK8 assay showed that neuronal apoptosis was dependent on MPP+ concentration and exposure time. Cell viability decreased significantly in the model group compared with the control group (55±7 vs. 100±0%; P<0.01), and increased significantly in the TFP5 group compared with the model group (98±2 vs. 55±5%; P<0.01) and Scb group (98±2 vs. 54±4%; P<0.01). Scb exhibited no protective effect. Western blotting results showed that MPP+ induced p25 and p-MEF2D expression, TFP5 and Scb did not affect MPP+-induced p25 expression, but TFP5 reduced MPP+-induced p-MEF2D expression. In summary, TFP5 protects against MPP+-induced neurotoxicity in mouse cortical neurons, possibly through inhibiting the MPP+-induced formation and elevated kinase activity of a cyclin-dependent kinase 5/p25 complex. PMID:27698762

  13. Passive Synaptic Normalization and Input Synchrony-Dependent Amplification of Cortical Feedback in Thalamocortical Neuron Dendrites

    PubMed Central

    Connelly, William M.; Crunelli, Vincenzo

    2016-01-01

    significantly increase the influence of corticothalamic feedback on sensory information transfer. SIGNIFICANCE STATEMENT Neurons in first-order thalamic nuclei transmit sensory information from the periphery to the cortex. However, the numerically dominant synaptic input to thalamocortical neurons comes from the cortex, which provides a strong, activity-dependent modulatory feedback influence on information flow through the thalamus. Here, we reveal how individual quantal-sized corticothalamic EPSPs propagate within thalamocortical neuron dendrites and how different spatial and temporal input patterns are integrated by these cells. We find that thalamocortical neurons have voltage- and synchrony-dependent postsynaptic mechanisms, involving NMDA receptors and T-type Ca2+ channels that allow nonlinear amplification of integrated corticothalamic EPSPs. These mechanisms significantly increase the responsiveness of thalamocortical neurons to cortical excitatory input and broaden the “modulatory” influence exerted by corticothalamic synapses. PMID:27030759

  14. TC10β/CDC42 GTPase activating protein is required for the growth of cortical neuron dendrites.

    PubMed

    Shen, P-C; Xu, D-F; Liu, J-W; Li, K; Lin, M; Wang, H-T; Wang, R; Zheng, J

    2011-12-29

    Neuronal morphogenesis plays an important role in neuronal development. TC10β/CDC42 GTPase-activating protein (TCGAP) is known to be a brain-enriched multiple domain protein, but its role in neuronal development process remains poorly understood. In the present study, we showed that TCGAP positively regulated dendritic outgrowth and spine formation in developing cortical neurons. Knocking down TCGAP by RNA interference led to a decrease in the overall length of dendrite arbors and the number of dendrite branches both in vitro and in vivo. Overexpressing TCGAP in cultured cortical neurons increased dendritic outgrowth and branching. Moreover, overexpressing TCGAP lead to an increase of spine density while knocking-down TCGAP decreased spine density in vivo. The defect by downregulating TCGAP could be rescued by expressing a knock-down resistant form of TCGAP both in vivo and in vitro. In contrast, neither downregulating nor overexpressing TCGAP had any effect on axonal morphogenesis in primary cortical neuron cultures. Together, our findings suggest that TCGAP regulates neuronal morphogenesis in developing cortical neurons at both early and late stage.

  15. Genetic enhancement of visual learning by activation of protein kinase C pathways in small groups of rat cortical neurons.

    PubMed

    Zhang, Guo-Rong; Wang, Xiaodan; Kong, Lingxin; Lu, Xiu-Gui; Lee, Brian; Liu, Meng; Sun, Mei; Franklin, Corinna; Cook, Robert G; Geller, Alfred I

    2005-09-14

    Although learning and memory theories hypothesize that memories are encoded by specific circuits, it has proven difficult to localize learning within a cortical area. Neural network theories predict that activation of a small fraction of the neurons in a circuit can activate that circuit. Consequently, altering the physiology of a small group of neurons might potentiate a specific circuit and enhance learning, thereby localizing learning to that circuit. In this study, we activated protein kinase C (PKC) pathways in small groups of neurons in rat postrhinal (POR) cortex. We microinjected helper virus-free herpes simplex virus vectors that expressed a constitutively active PKC into POR cortex. This PKC was expressed predominantly in glutamatergic and GABAergic neurons in POR cortex. This intervention increased phosphorylation of five PKC substrates that play critical roles in neurotransmitter release (GAP-43 and dynamin) or glutamatergic neurotransmission (specific subunits of AMPA or NMDA receptors and myristoylated alanine-rich C kinase substrate). Additionally, activation of PKC pathways in cultured cortical neurons supported activation-dependent increases in release of glutamate and GABA. This intervention enhanced the learning rate and accuracy of visual object discriminations. In individual rats, the numbers of transfected neurons positively correlated with this learning. During learning, neuronal activity was increased in neurons proximal to the transfected neurons. These results demonstrate that potentiating small groups of glutamatergic and GABAergic neurons in POR cortex enhances visual object learning. More generally, these results suggest that learning can be mediated by specific cortical circuits.

  16. Cortical excitatory neurons become protected from cell division during neurogenesis in an Rb family-dependent manner.

    PubMed

    Oshikawa, Mio; Okada, Kei; Nakajima, Kazunori; Ajioka, Itsuki

    2013-06-01

    Cell cycle dysregulation leads to abnormal proliferation and cell death in a context-specific manner. Cell cycle progression driven via the Rb pathway forces neurons to undergo S-phase, resulting in cell death associated with the progression of neuronal degeneration. Nevertheless, some Rb- and Rb family (Rb, p107 and p130)-deficient differentiating neurons can proliferate and form tumors. Here, we found in mouse that differentiating cerebral cortical excitatory neurons underwent S-phase progression but not cell division after acute Rb family inactivation in differentiating neurons. However, the differentiating neurons underwent cell division and proliferated when Rb family members were inactivated in cortical progenitors. Differentiating neurons generated from Rb(-/-); p107(-/-); p130(-/-) (Rb-TKO) progenitors, but not acutely inactivated Rb-TKO differentiating neurons, activated the DNA double-strand break (DSB) repair pathway without increasing trimethylation at lysine 20 of histone H4 (H4K20), which has a role in protection against DNA damage. The activation of the DSB repair pathway was essential for the cell division of Rb-TKO differentiating neurons. These results suggest that newly born cortical neurons from progenitors become epigenetically protected from DNA damage and cell division in an Rb family-dependent manner.

  17. Near infrared radiation rescues mitochondrial dysfunction in cortical neurons after oxygen-glucose deprivation.

    PubMed

    Yu, Zhanyang; Liu, Ning; Zhao, Jianhua; Li, Yadan; McCarthy, Thomas J; Tedford, Clark E; Lo, Eng H; Wang, Xiaoying

    2015-04-01

    Near infrared radiation (NIR) is known to penetrate and affect biological systems in multiple ways. Recently, a series of experimental studies suggested that low intensity NIR may protect neuronal cells against a wide range of insults that mimic diseases such as stroke, brain trauma and neurodegeneration. However, the potential molecular mechanisms of neuroprotection with NIR remain poorly defined. In this study, we tested the hypothesis that low intensity NIR may attenuate hypoxia/ischemia-induced mitochondrial dysfunction in neurons. Primary cortical mouse neuronal cultures were subjected to 4 h oxygen-glucose deprivation followed by reoxygenation for 2 h, neurons were then treated with a 2 min exposure to 810-nm NIR. Mitochondrial function markers including MTT reduction and mitochondria membrane potential were measured at 2 h after treatment. Neurotoxicity was quantified 20 h later. Our results showed that 4 h oxygen-glucose deprivation plus 20 h reoxygenation caused 33.8 ± 3.4 % of neuron death, while NIR exposure significantly reduced neuronal death to 23.6 ± 2.9 %. MTT reduction rate was reduced to 75.9 ± 2.7 % by oxygen-glucose deprivation compared to normoxic controls, but NIR exposure significantly rescued MTT reduction to 87.6 ± 4.5 %. Furthermore, after oxygen-glucose deprivation, mitochondria membrane potential was reduced to 48.9 ± 4.39 % of normoxic control, while NIR exposure significantly ameliorated this reduction to 89.6 ± 13.9 % of normoxic control. Finally, NIR significantly rescued OGD-induced ATP production decline at 20 min after NIR. These findings suggest that low intensity NIR can protect neurons against oxygen-glucose deprivation by rescuing mitochondrial function and restoring neuronal energetics.

  18. [Protective effect of musk extract on rat's cerebral cortical neurons with inflammatory injury].

    PubMed

    Shi, Jin-Feng; Zhang, Bo-Ai; Jia, Yan-Jie

    2010-06-01

    To investigate the protective effects of musk extract (ME) and its possible mechanism on rat's cerebral cortical neurons with inflammatory injury induced by lipopolysaccharide (LPS). Neurons and astrocytes from newborn rat cerebral cortex were cultured in vitro respectively, and the astrocyte conditioned medium (ACM), obtained by treating astrocytes with 10 mg/L LPS and different concentrations of ME for 24 h, was added in the culture fluid of neurons. The survival rate and apoptotic rate of neurons were measured by MTT method and AO/EB stain; and the changes of inflammatory factors in the ACM were determined by ELISA. The survival rate (%) of neurons treated by ACM with ME in concentrations of 18 mg/L, 36 mg/L, 72 mg/L and 144 mg/L was 52.55 +/- 3.52, 55.77 +/- 2.36, 64.89 +/- 3.45 and 73.67 +/- 1.80, respectively, significantly higher than that in the model neurons (43.62 +/- 4. 51, P < 0.05), while the apoptotic rate (%) in them, 68.11 +/- 2.16, 44.27 +/- 3.68, 32.56 +/- 2.14 and 21.89 +/- 2.46, respectively, was significantly lower than that in model neurons (71.33 +/- 3.25, P < 0.05 or P < 0.01). Level of IL-6 was decreasing along with the raising of ME concentration in the ACM, showing a concentration-dependent state. ME shows apparent protective effect on neurons against inflammatory injury, especially in a high concentration (144 mg/L), which may be associated with the reduction of IL-6 secreted by astrocytes.

  19. Human endothelial progenitor cells rescue cortical neurons from oxygen-glucose deprivation induced death.

    PubMed

    Bacigaluppi, Susanna; Donzelli, Elisabetta; De Cristofaro, Valentina; Bragazzi, Nicola Luigi; D'Amico, Giovanna; Scuteri, Arianna; Tredici, Giovanni

    2016-09-19

    Cerebral ischemia is characterized by both acute and delayed neuronal injuries. Neuro-protection is a major issue that should be properly addressed from a pharmacological point of view, and cell-based treatment approaches are of interest due to their potential pleiotropic effects. Endothelial progenitor cells have the advantage of being mobilized from the bone marrow into the circulation, but have been less studied than other stem cells, such as mesenchymal stem cells. Therefore, the comparison between human endothelial progenitor cells (hEPC) and human mesenchymal progenitor cells (hMSC) in terms of efficacy in rescuing neurons from cell death after transitory ischemia is the aim of the current study, in the effort to address further directions. In vitro model of oxygen-glucose deprivation (OGD) on a primary culture of rodent cortical neurons was set up with different durations of exposure: 1, 2 and 3hrs with assessment of neuron survival. The 2hrs OGD was chosen for the subsequent experiments. After 2hrs OGD neurons were either placed in indirect co-culture with hMSC or hEPC or cultured in hMSC or hEPC conditioned medium and cell viability was evaluated by MTT assay. At day 2 after 2hrs OGD exposure, mean neuronal survival was 47.9±24.2%. In contrast, after treatment with hEPC and hMSC indirect co-culture was 74.1±27.3%; and 69.4±18.8%, respectively. In contrast, treatment with conditioned medium did not provide any advantage in terms of survival to OGD neurons The study shows the efficacy of hEPC in indirect co-culture to rescue neurons from cell death after OGD, comparable to that of hMSC. hEPC deserve further studies given their potential interest for ischemia. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Sonic hedgehog promotes neurite outgrowth of cortical neurons under oxidative stress: Involving of mitochondria and energy metabolism.

    PubMed

    He, Weiliang; Cui, Lili; Zhang, Cong; Zhang, Xiangjian; He, Junna; Xie, Yanzhao; Chen, Yanxia

    2017-01-01

    Oxidative stress has been demonstrated to be involved in the etiology of several neurobiological disorders. Sonic hedgehog (Shh), a secreted glycoprotein factor, has been implicated in promoting several aspects of brain remodeling process. Mitochondria may play an important role in controlling fundamental processes in neuroplasticity. However, little evidence is available about the effect and the potential mechanism of Shh on neurite outgrowth in primary cortical neurons under oxidative stress. Here, we revealed that Shh treatment significantly increased the viability of cortical neurons in a dose-dependent manner, which was damaged by hydrogen peroxide (H2O2). Shh alleviated the apoptosis rate of H2O2-induced neurons. Shh also increased neuritogenesis injuried by H2O2 in primary cortical neurons. Moreover, Shh reduced the generation of reactive oxygen species (ROS), increased the activities of SOD and and decreased the productions of MDA. In addition, Shh protected mitochondrial functions, elevated the cellular ATP levels and amelioratesd the impairment of mitochondrial complex II activities of cortical neurons induced by H2O2. In conclusion, all these results suggest that Shh acts as a prosurvival factor playing an essential role to neurite outgrowth of cortical neuron under H2O2 -induced oxidative stress, possibly through counteracting ROS release and preventing mitochondrial dysfunction and ATP as well as mitochondrial complex II activities against oxidative stress.

  1. Lamin B1 protein is required for dendrite development in primary mouse cortical neurons.

    PubMed

    Giacomini, Caterina; Mahajani, Sameehan; Ruffilli, Roberta; Marotta, Roberto; Gasparini, Laura

    2016-01-01

    Lamin B1, a key component of the nuclear lamina, plays an important role in brain development and function. A duplication of the human lamin B1 (LMNB1) gene has been linked to adult-onset autosomal dominant leukodystrophy, and mouse and human loss-of-function mutations in lamin B1 are susceptibility factors for neural tube defects. In the mouse, experimental ablation of endogenous lamin B1 (Lmnb1) severely impairs embryonic corticogenesis. Here we report that in primary mouse cortical neurons, LMNB1 overexpression reduces axonal outgrowth, whereas deficiency of endogenous Lmnb1 results in aberrant dendritic development. In the absence of Lmnb1, both the length and complexity of dendrites are reduced, and their growth is unresponsive to KCl stimulation. This defective dendritic outgrowth stems from impaired ERK signaling. In Lmnb1-null neurons, ERK is correctly phosphorylated, but phospho-ERK fails to translocate to the nucleus, possibly due to delocalization of nuclear pore complexes (NPCs) at the nuclear envelope. Taken together, these data highlight a previously unrecognized role of lamin B1 in dendrite development of mouse cortical neurons through regulation of nuclear shuttling of specific signaling molecules and NPC distribution.

  2. Information Capacity and Transmission Are Maximized in Balanced Cortical Networks with Neuronal Avalanches

    PubMed Central

    Shew, Woodrow L.; Yang, Hongdian; Yu, Shan; Roy, Rajarshi; Plenz, Dietmar

    2010-01-01

    The repertoire of neural activity patterns that a cortical network can produce constrains the ability of the network to transfer and process information. Here, we measured activity patterns obtained from multisite local field potential recordings in cortex cultures, urethane-anesthetized rats, and awake macaque monkeys. First, we quantified the information capacity of the pattern repertoire of ongoing and stimulus-evoked activity using Shannon entropy. Next, we quantified the efficacy of information transmission between stimulus and response using mutual information. By systematically changing the ratio of excitation/inhibition (E/I) in vitro and in a network model, we discovered that both information capacity and information transmission are maximized at a particular intermediate E/I, at which ongoing activity emerges as neuronal avalanches. Next, we used our in vitro and model results to correctly predict in vivo information capacity and interactions between neuronal groups during ongoing activity. Close agreement between our experiments and model suggest that neuronal avalanches and peak information capacity arise because of criticality and are general properties of cortical networks with balanced E/I. PMID:21209189

  3. Information capacity and transmission are maximized in balanced cortical networks with neuronal avalanches.

    PubMed

    Shew, Woodrow L; Yang, Hongdian; Yu, Shan; Roy, Rajarshi; Plenz, Dietmar

    2011-01-05

    The repertoire of neural activity patterns that a cortical network can produce constrains the ability of the network to transfer and process information. Here, we measured activity patterns obtained from multisite local field potential recordings in cortex cultures, urethane-anesthetized rats, and awake macaque monkeys. First, we quantified the information capacity of the pattern repertoire of ongoing and stimulus-evoked activity using Shannon entropy. Next, we quantified the efficacy of information transmission between stimulus and response using mutual information. By systematically changing the ratio of excitation/inhibition (E/I) in vitro and in a network model, we discovered that both information capacity and information transmission are maximized at a particular intermediate E/I, at which ongoing activity emerges as neuronal avalanches. Next, we used our in vitro and model results to correctly predict in vivo information capacity and interactions between neuronal groups during ongoing activity. Close agreement between our experiments and model suggest that neuronal avalanches and peak information capacity arise because of criticality and are general properties of cortical networks with balanced E/I.

  4. Contrasting roles for parvalbumin-expressing inhibitory neurons in two forms of adult visual cortical plasticity

    PubMed Central

    Kaplan, Eitan S; Cooke, Sam F; Komorowski, Robert W; Chubykin, Alexander A; Thomazeau, Aurore; Khibnik, Lena A; Gavornik, Jeffrey P; Bear, Mark F

    2016-01-01

    The roles played by cortical inhibitory neurons in experience-dependent plasticity are not well understood. Here we evaluate the participation of parvalbumin-expressing (PV+) GABAergic neurons in two forms of experience-dependent modification of primary visual cortex (V1) in adult mice: ocular dominance (OD) plasticity resulting from monocular deprivation and stimulus-selective response potentiation (SRP) resulting from enriched visual experience. These two forms of plasticity are triggered by different events but lead to a similar increase in visual cortical response. Both also require the NMDA class of glutamate receptor (NMDAR). However, we find that PV+ inhibitory neurons in V1 play a critical role in the expression of SRP and its behavioral correlate of familiarity recognition, but not in the expression of OD plasticity. Furthermore, NMDARs expressed within PV+ cells, reversibly inhibited by the psychotomimetic drug ketamine, play a critical role in SRP, but not in the induction or expression of adult OD plasticity. DOI: http://dx.doi.org/10.7554/eLife.11450.001 PMID:26943618

  5. Cortical regulation of dopamine depletion-induced dendritic spine loss in striatal medium spiny neurons.

    PubMed

    Neely, M D; Schmidt, D E; Deutch, A Y

    2007-10-26

    The proximate cause of Parkinson's disease is striatal dopamine depletion. Although no overt toxicity to striatal neurons has been reported in Parkinson's disease, one of the consequences of striatal dopamine loss is a decrease in the number of dendritic spines on striatal medium spiny neurons (MSNs). Dendrites of these neurons receive cortical glutamatergic inputs onto the dendritic spine head and dopaminergic inputs from the substantia nigra onto the spine neck. This synaptic arrangement suggests that dopamine gates corticostriatal glutamatergic drive onto spines. Using triple organotypic slice cultures composed of ventral mesencephalon, striatum, and cortex of the neonatal rat, we examined the role of the cortex in dopamine depletion-induced dendritic spine loss in MSNs. The striatal dopamine innervation was lesioned by treatment of the cultures with the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium (MPP+) or by removing the mesencephalon. Both MPP+ and mesencephalic ablation decreased MSN dendritic spine density. Analysis of spine morphology revealed that thin spines were preferentially lost after dopamine depletion. Removal of the cortex completely prevented dopamine depletion-induced spine loss. These data indicate that the dendritic remodeling of MSNs seen in parkinsonism occurs secondary to increases in corticostriatal glutamatergic drive, and suggest that modulation of cortical activity may be a useful therapeutic strategy in Parkinson's disease.

  6. Impact of calcium-activated potassium channels on NMDA spikes in cortical layer 5 pyramidal neurons

    PubMed Central

    Bock, Tobias

    2016-01-01

    Active electrical events play an important role in shaping signal processing in dendrites. As these events are usually associated with an increase in intracellular calcium, they are likely to be under the control of calcium-activated potassium channels. Here, we investigate the impact of calcium-activated potassium channels on N-methyl-d-aspartate (NMDA) receptor-dependent spikes, or NMDA spikes, evoked by glutamate iontophoresis onto basal dendrites of cortical layer 5 pyramidal neurons. We found that small-conductance calcium-activated potassium channels (SK channels) act to reduce NMDA spike amplitude but at the same time, also decrease the iontophoretic current required for their generation. This SK-mediated decrease in NMDA spike threshold was dependent on R-type voltage-gated calcium channels and indicates a counterintuitive, excitatory effect of SK channels on NMDA spike generation, whereas the capacity of SK channels to suppress NMDA spike amplitude is in line with the expected inhibitory action of potassium channels on dendritic excitability. Large-conductance calcium-activated potassium channels had no significant impact on NMDA spikes, indicating that these channels are either absent from basal dendrites or not activated by NMDA spikes. These experiments reveal complex and opposing interactions among NMDA receptors, SK channels, and voltage-gated calcium channels in basal dendrites of cortical layer 5 pyramidal neurons during NMDA spike generation, which are likely to play an important role in regulating the way these neurons integrate the thousands of synaptic inputs they receive. PMID:26936985

  7. Cortical Regulation of Dopamine Depletion-Induced Dendritic Spine Loss in Striatal Medium Spiny Neurons

    PubMed Central

    Neely, M. Diana; Schmidt, Dennis E.; Deutch, Ariel Y.

    2007-01-01

    The proximate cause of Parkinson’s Disease is striatal dopamine depletion. Although no overt toxicity to striatal neurons has been reported in Parkinson’s Disease, one of the consequences of striatal dopamine loss is a decrease in the number of dendritic spines on striatal medium spiny neurons (MSNs). Dendrites of these neurons receive cortical glutamatergic inputs onto the dendritic spine head and dopaminergic inputs from the substantia nigra onto the spine neck. This synaptic arrangement suggests that dopamine gates corticostriatal glutamatergic drive onto spines. Using triple organotypic slice cultures comprised of ventral mesencephalon, striatum, and cortex, we examined the role of the cortex in dopamine depletion-induced dendritic spine loss in MSNs. The striatal dopamine innervation was lesioned by treatment of the cultures with the dopaminergic neurotoxin MPP+ or by removing the mesencephalon. Both MPP+ and mesencephalic ablation decreased MSN dendritic spine density. Analysis of spine morphology revealed that thin spines were preferentially lost after dopamine depletion. Removal of the cortex completely prevented dopamine depletion-induced spine loss. These data indicate that the dendritic remodeling of MSNs seen in parkinsonism occurs secondary to increases in corticostriatal glutamatergic drive, and suggest that modulation of cortical activity may be a useful therapeutic strategy in Parkinson’s Disease. PMID:17888581

  8. Amyloid beta-peptide disrupts carbachol-induced muscarinic cholinergic signal transduction in cortical neurons.

    PubMed Central

    Kelly, J F; Furukawa, K; Barger, S W; Rengen, M R; Mark, R J; Blanc, E M; Roth, G S; Mattson, M P

    1996-01-01

    Cholinergic pathways serve important functions in learning and memory processes, and deficits in cholinergic transmission occur in Alzheimer disease (AD). A subset of muscarinic cholinergic receptors are linked to G-proteins that activate phospholipase C, resulting in the liberation of inositol trisphosphate and Ca2+ release from intracellular stores. We now report that amyloid beta-peptide (Abeta), which forms plaques in the brain in AD, impairs muscarinic receptor activation of G proteins in cultured rat cortical neurons. Exposure of rodent fetal cortical neurons to Abeta25-35 and Abeta1-40 resulted in a concentration and time-dependent attenuation of carbachol-induced GTPase activity without affecting muscarinic receptor ligand binding parameters. Downstream events in the signal transduction cascade were similarly attenuated by Abeta. Carbachol-induced accumulation of inositol phosphates (IP, IP2, IP3, and IP4) was decreased and calcium imaging studies revealed that carbachol-induced release of calcium was severely impaired in neurons pretreated with Abeta. Muscarinic cholinergic signal transduction was disrupted with subtoxic levels of exposure to AP. The effects of Abeta on carbachol-induced GTPase activity and calcium release were attenuated by antioxidants, implicating free radicals in the mechanism whereby Abeta induced uncoupling of muscarinic receptors. These data demonstrate that Abeta disrupts muscarinic receptor coupling to G proteins that mediate induction of phosphoinositide accumulation and calcium release, findings that implicate Abeta in the impairment of cholinergic transmission that occurs in AD. PMID:8692890

  9. Lamin B1 protein is required for dendrite development in primary mouse cortical neurons

    PubMed Central

    Giacomini, Caterina; Mahajani, Sameehan; Ruffilli, Roberta; Marotta, Roberto; Gasparini, Laura

    2016-01-01

    Lamin B1, a key component of the nuclear lamina, plays an important role in brain development and function. A duplication of the human lamin B1 (LMNB1) gene has been linked to adult-onset autosomal dominant leukodystrophy, and mouse and human loss-of-function mutations in lamin B1 are susceptibility factors for neural tube defects. In the mouse, experimental ablation of endogenous lamin B1 (Lmnb1) severely impairs embryonic corticogenesis. Here we report that in primary mouse cortical neurons, LMNB1 overexpression reduces axonal outgrowth, whereas deficiency of endogenous Lmnb1 results in aberrant dendritic development. In the absence of Lmnb1, both the length and complexity of dendrites are reduced, and their growth is unresponsive to KCl stimulation. This defective dendritic outgrowth stems from impaired ERK signaling. In Lmnb1-null neurons, ERK is correctly phosphorylated, but phospho-ERK fails to translocate to the nucleus, possibly due to delocalization of nuclear pore complexes (NPCs) at the nuclear envelope. Taken together, these data highlight a previously unrecognized role of lamin B1 in dendrite development of mouse cortical neurons through regulation of nuclear shuttling of specific signaling molecules and NPC distribution. PMID:26510501

  10. Parallel changes in cortical neuron biochemistry and motor function in protein-energy malnourished adult rats.

    PubMed

    Alaverdashvili, Mariam; Hackett, Mark J; Caine, Sally; Paterson, Phyllis G

    2017-04-01

    While protein-energy malnutrition in the adult has been reported to induce motor abnormalities and exaggerate motor deficits caused by stroke, it is not known if alterations in mature cortical neurons contribute to the functional deficits. Therefore, we explored if PEM in adult rats provoked changes in the biochemical profile of neurons in the forelimb and hindlimb regions of the motor cortex. Fourier transform infrared spectroscopic imaging using a synchrotron generated light source revealed for the first time altered lipid composition in neurons and subcellular domains (cytosol and nuclei) in a cortical layer and region-specific manner. This change measured by the area under the curve of the δ(CH2) band may indicate modifications in membrane fluidity. These PEM-induced biochemical changes were associated with the development of abnormalities in forelimb use and posture. The findings of this study provide a mechanism by which PEM, if not treated, could exacerbate the course of various neurological disorders and diminish treatment efficacy.

  11. Functional characterization and spatial clustering of visual cortical neurons in the predatory grasshopper mouse Onychomys arenicola.

    PubMed

    Scholl, Benjamin; Pattadkal, Jagruti J; Rowe, Ashlee; Priebe, Nicholas J

    2017-03-01

    Mammalian neocortical circuits are functionally organized such that the selectivity of individual neurons systematically shifts across the cortical surface, forming a continuous map. Maps of the sensory space exist in cortex, such as retinotopic maps in the visual system or tonotopic maps in the auditory system, but other functional response properties also may be similarly organized. For example, many carnivores and primates possess a map for orientation selectivity in primary visual cortex (V1), whereas mice, rabbits, and the gray squirrel lack orientation maps. In this report we show that a carnivorous rodent with predatory behaviors, the grasshopper mouse (Onychomys arenicola), lacks a canonical columnar organization of orientation preference in V1; however, neighboring neurons within 50 μm exhibit related tuning preference. Using a combination of two-photon microscopy and extracellular electrophysiology, we demonstrate that the functional organization of visual cortical neurons in the grasshopper mouse is largely the same as in the C57/BL6 laboratory mouse. We also find similarity in the selectivity for stimulus orientation, direction, and spatial frequency. Our results suggest that the properties of V1 neurons across rodent species are largely conserved.NEW & NOTEWORTHY Carnivores and primates possess a map for orientation selectivity in primary visual cortex (V1), whereas rodents and lagomorphs lack this organization. We examine, for the first time, V1 of a wild carnivorous rodent with predatory behaviors, the grasshopper mouse (Onychomys arenicola). We demonstrate the cellular organization of V1 in the grasshopper mouse is largely the same as the C57/BL6 laboratory mouse, suggesting that V1 neuron properties across rodent species are largely conserved. Copyright © 2017 the American Physiological Society.

  12. Identification of axon-enriched microRNAs localized to growth cones of cortical neurons.

    PubMed

    Sasaki, Yukio; Gross, Christina; Xing, Lei; Goshima, Yoshio; Bassell, Gary J

    2014-03-01

    There is increasing evidence that localized mRNAs in axons and growth cones play an important role in axon extension and pathfinding via local translation. A few studies have revealed the presence of microRNAs (miRNAs) in axons, which may control local protein synthesis during axon development. However, so far, there has been no attempt to screen for axon-enriched miRNAs and to validate their possible localization to growth cones of developing axons from neurons of the central nervous system. In this study, the localization of miRNAs in axons and growth cones in cortical neurons was examined using a "neuron ball" culture method that is suitable to prepare axonal miRNAs with high yield and purity. Axonal miRNAs prepared from the neuron ball cultures of mouse cortical neurons were analyzed by quantitative real-time RT-PCR. Among 375 miRNAs that were analyzed, 105 miRNAs were detected in axons, and six miRNAs were significantly enriched in axonal fractions when compared with cell body fractions. Fluorescence in situ hybridization revealed that two axon-enriched miRNAs, miR-181a-1* and miR-532, localized as distinct granules in distal axons and growth cones. The association of these miRNAs with the RNA-induced silencing complex further supported their function to regulate mRNA levels or translation in the brain. These results suggest a mechanism to localize specific miRNAs to distal axons and growth cones, where they could be involved in local mRNA regulation. These findings provide new insight into the presence of axonal miRNAs and motivate further analysis of their function in local protein synthesis underlying axon guidance.

  13. Olfactory and cortical projections to bulbar and hippocampal adult-born neurons

    PubMed Central

    De La Rosa-Prieto, Carlos; De Moya-Pinilla, Miguel; Saiz-Sanchez, Daniel; Ubeda-banon, Isabel; Arzate, Dulce M.; Flores-Cuadrado, Alicia; Liberia, Teresa; Crespo, Carlos; Martinez-Marcos, Alino

    2015-01-01

    New neurons are continually generated in the subependymal layer of the lateral ventricles and the subgranular zone of dentate gyrus during adulthood. In the subventricular zone, neuroblasts migrate a long distance to the olfactory bulb where they differentiate into granule or periglomerular interneurons. In the hippocampus, neuroblasts migrate a short distance from the subgranular zone to the granule cell layer of the dentate gyrus to become granule neurons. In addition to the short-distance inputs, bulbar interneurons receive long-distance centrifugal afferents from olfactory-recipient structures. Similarly, dentate granule cells receive differential inputs from the medial and lateral entorhinal cortices through the perforant pathway. Little is known concerning these new inputs on the adult-born cells. In this work, we have characterized afferent inputs to 21-day old newly-born neurons. Mice were intraperitoneally injected with bromodeoxyuridine. Two weeks later, rhodamine-labeled dextran-amine was injected into the anterior olfactory nucleus, olfactory tubercle, piriform cortex and lateral and medial entorhinal cortices. One week later, animals were perfused and immunofluorescences were carried out. The data show that projection neurons from the mentioned structures, establish putative synaptic contacts onto 21-day-old neurons in the olfactory bulb and dentate gyrus, in some cases even before they start to express specific subpopulation proteins. Long-distance afferents reach middle and outer one-third portions of the molecular layer of the dentate gyrus and granule and, interestingly, periglomerular layers of the olfactory bulb. In the olfactory bulb, these fibers appear to establish presumptive axo-somatic contacts onto newly-born granule and periglomerular cells. PMID:25698936

  14. Morphological and Functional Differences between Athletes and Novices in Cortical Neuronal Networks

    PubMed Central

    Tan, Xiao-Ying; Pi, Yan-Ling; Wang, Jue; Li, Xue-Pei; Zhang, Lan-Lan; Dai, Wen; Zhu, Hua; Ni, Zhen; Zhang, Jian; Wu, Yin

    2017-01-01

    The cortical structural and functional differences in athletes and novices were investigated with a cross-sectional paradigm. We measured the gray matter volumes and resting-state functional connectivity in 21 basketball players and 21 novices with magnetic resonance imaging (MRI) techniques. It was found that gray matter volume in the left anterior insula (AI), inferior frontal gyrus (IFG), inferior parietal lobule (IPL) and right anterior cingulate cortex (ACC), precuneus is greater in basketball players than that in novices. These five brain regions were selected as the seed regions for testing the resting-state functional connectivity in the second experiment. We found higher functional connectivity in default mode network, salience network and executive control network in basketball players compared to novices. We conclude that the morphology and functional connectivity in cortical neuronal networks in athletes and novices are different. PMID:28101012

  15. Morphological and Functional Differences between Athletes and Novices in Cortical Neuronal Networks.

    PubMed

    Tan, Xiao-Ying; Pi, Yan-Ling; Wang, Jue; Li, Xue-Pei; Zhang, Lan-Lan; Dai, Wen; Zhu, Hua; Ni, Zhen; Zhang, Jian; Wu, Yin

    2016-01-01

    The cortical structural and functional differences in athletes and novices were investigated with a cross-sectional paradigm. We measured the gray matter volumes and resting-state functional connectivity in 21 basketball players and 21 novices with magnetic resonance imaging (MRI) techniques. It was found that gray matter volume in the left anterior insula (AI), inferior frontal gyrus (IFG), inferior parietal lobule (IPL) and right anterior cingulate cortex (ACC), precuneus is greater in basketball players than that in novices. These five brain regions were selected as the seed regions for testing the resting-state functional connectivity in the second experiment. We found higher functional connectivity in default mode network, salience network and executive control network in basketball players compared to novices. We conclude that the morphology and functional connectivity in cortical neuronal networks in athletes and novices are different.

  16. Yawn duration predicts brain weight and cortical neuron number in mammals.

    PubMed

    Gallup, Andrew C; Church, Allyson M; Pelegrino, Anthony J

    2016-10-01

    Research indicates that the motor action pattern of yawning functions to promote cortical arousal and state change through enhanced intracranial circulation and brain cooling. Because the magnitude of this response likely corresponds to the degree of neurophysiological change, we hypothesized that interspecies variation in yawn duration would correlate with underlying neurological differences. Using openly accessible data, we show that both the mean and variance in yawn duration are robust predictors of mammalian brain weight and cortical neuron number (ρ-values > 0.9). Consistent with these effects, primates tend to have longer and more variable yawn durations compared with other mammals. Although yawning has long been considered a stereotyped action pattern, these findings reveal substantial variation in this response and highlight the importance of measuring yawn duration in future research. © 2016 The Author(s).

  17. Trans-anethole protects cortical neuronal cells against oxygen-glucose deprivation/reoxygenation.

    PubMed

    Ryu, Sangwoo; Seol, Geun Hee; Park, Hyeon; Choi, In-Young

    2014-10-01

    Trans-anethole has been studied on pharmacological properties such as anti-inflammation, anti-oxidative stress, antifungal and anticancer. However, to date, the anti-ischemic effects of trans-anethole have not been assessed. Therefore, we investigated the neuroprotection of trans-anethole against oxygen-glucose deprivation/reoxygenation (OGD/R)-induced cortical neuronal cell injury, an in vitro model of ischemia. The abilities of trans-anethole to block excitotoxicity, oxidative stress and mitochondrial dysfunction were evaluated in OGD/R-induced neurons. Trans-anethole significantly ameliorated OGD/R-induced neuronal cell injury by attenuating the intracellular calcium overload via the activation of NMDA receptors. Trans-anethole also inhibited OGD/R-induced reactive oxygen species overproduction, which may be derived from the scavenging activity in peroxyl radicals, assessed in an oxygen radical absorbance capacity assay. Furthermore, trans-anethole was shown to attenuate the depolarization of mitochondrial transmembrane. These results indicated that the neuroprotective effect of trans-anethole on OGD/R-induced neuronal injury might be due to its ability to inhibit excitotoxicity, oxidative stress and mitochondrial dysfunction. Considering these multiple pathways causing ischemic neuronal damage, the multi-functional effect of trans-anethole suggested that it may be effective in treating ischemic stroke.

  18. Expression of Nampt in Hippocampal and Cortical Excitatory Neurons Is Critical for Cognitive Function

    PubMed Central

    Stein, Liana Roberts; Wozniak, David F.; Dearborn, Joshua T.; Kubota, Shunsuke; Apte, Rajendra S.; Izumi, Yukitoshi; Zorumski, Charles F.

    2014-01-01

    Nicotinamide adenine dinucleotide (NAD+) is an enzyme cofactor or cosubstrate in many essential biological pathways. To date, the primary source of neuronal NAD+ has been unclear. NAD+ can be synthesized from several different precursors, among which nicotinamide is the substrate predominantly used in mammals. The rate-limiting step in the NAD+ biosynthetic pathway from nicotinamide is performed by nicotinamide phosphoribosyltransferase (Nampt). Here, we tested the hypothesis that neurons use intracellular Nampt-mediated NAD+ biosynthesis by generating and evaluating mice lacking Nampt in forebrain excitatory neurons (CaMKIIαNampt−/− mice). CaMKIIαNampt−/− mice showed hippocampal and cortical atrophy, astrogliosis, microgliosis, and abnormal CA1 dendritic morphology by 2–3 months of age. Importantly, these histological changes occurred with altered intrahippocampal connectivity and abnormal behavior; including hyperactivity, some defects in motor skills, memory impairment, and reduced anxiety, but in the absence of impaired sensory processes or long-term potentiation of the Schaffer collateral pathway. These results clearly demonstrate that forebrain excitatory neurons mainly use intracellular Nampt-mediated NAD+ biosynthesis to mediate their survival and function. Studying this particular NAD+ biosynthetic pathway in these neurons provides critical insight into their vulnerability to pathophysiological stimuli and the development of therapeutic and preventive interventions for their preservation. PMID:24760840

  19. PACAP38 protects rat cortical neurons against the neurotoxicity evoked by sodium nitroprusside and thrombin

    PubMed Central

    Sanchez, Alma; Rao, Haripriya Vittal; Grammas, Paula

    2009-01-01

    Pituitary adenylate cyclase-activating polypeptide (PACAP) 38 is a multifunctional anti-inflammatory and anti-apoptotic neuropeptide widely distributed in the nervous system. The objective of this study is to determine whether PACAP38 is neuroprotective against sodium nitroprusside (SNP) and thrombin, two mechanistically distinct neurotoxic agents. Treatment of primary cortical neuronal cultures with 1 mM SNP for 4 h causes neuronal cell death that is significantly reduced by 100 nM PACAP38. PACAP38 down-regulates SNP-induced cell cycle protein (cyclin E) expression and up-regulates p57KIP2, a cyclin-dependent kinase inhibitor as well as the anti-apoptotic protein Bcl-2. Similarly, neuronal death induced by 100 nM thrombin or the thrombin receptor activating peptide (TRAP 6) is reduced by PACAP38 treatment. Thrombin-stimulated cell cycle protein (cdk4) expression is decreased by PACAP38 while PACAP38 inhibits thrombin-mediated reduction of p57KIP2. However, the decrease in Bcl-2 evoked by thrombin is not affected by PACAP38. Finally, both SNP and thrombin (or TRAP) increase caspase 3 activity, an effect that is decreased by PACAP38. These data show that PACAP38 supports neuronal survival in vitro suppressing cell cycle progression and enhancing anti-apoptotic proteins. Our results support the possibility that PACAP could be a useful therapeutic agent for reducing neuronal cell death in neurodegenerative diseases. PMID:18682263

  20. Olanzapine Prevents the PCP-induced Reduction in the Neurite Outgrowth of Prefrontal Cortical Neurons via NRG1

    PubMed Central

    Zhang, Qingsheng; Yu, Yinghua; Huang, Xu-Feng

    2016-01-01

    Accumulating evidence suggests that reducing neurite outgrowth and synaptic plasticity plays a critical role in the pathology of cognitive deficits in schizophrenia. The N-methyl-D-aspartate receptor antagonist phencyclidine (PCP) can induce symptoms of schizophrenia as well as reduce dendritic spine density and neurite growth. The antipsychotic drug olanzapine may improve these deficits. This study aimed to investigate: (1) if olanzapine prevents PCP-induced suppression of neurite outgrowth and synaptic protein expression; (2) if olanzapine affects the Akt-GSK3 signaling pathway; and (3) the role of neuregulin 1 (NRG1) in this process. Immunofluorescence revealed that PCP treatment for 24 hours reduces both neurite length (28.5%) and the number of neurite branches (35.6%) in primary prefrontal cortical neuron cultures. PCP reduced protein and mRNA expressions of synaptophysin (24.9% and 23.2%, respectively) and PSD95 (31.5% and 21.4%, respectively), and the protein expression of p-Akt (26.7%) and p-GSK3β (35.2%). Olanzapine co-treatment prevented these PCP-induced effects in normal neurons but not in neurons from NRG1-knockout mice. These results indicate that NRG1 mediates the preventive effects of olanzapine on the PCP-induced impairment of neurite outgrowth and synaptic protein expression. This study provides potential targets for interventions on improving the efficacy of olanzapine on preventing cognitive deficits in schizophrenia. PMID:26781398

  1. Olanzapine Prevents the PCP-induced Reduction in the Neurite Outgrowth of Prefrontal Cortical Neurons via NRG1.

    PubMed

    Zhang, Qingsheng; Yu, Yinghua; Huang, Xu-Feng

    2016-01-19

    Accumulating evidence suggests that reducing neurite outgrowth and synaptic plasticity plays a critical role in the pathology of cognitive deficits in schizophrenia. The N-methyl-D-aspartate receptor antagonist phencyclidine (PCP) can induce symptoms of schizophrenia as well as reduce dendritic spine density and neurite growth. The antipsychotic drug olanzapine may improve these deficits. This study aimed to investigate: (1) if olanzapine prevents PCP-induced suppression of neurite outgrowth and synaptic protein expression; (2) if olanzapine affects the Akt-GSK3 signaling pathway; and (3) the role of neuregulin 1 (NRG1) in this process. Immunofluorescence revealed that PCP treatment for 24 hours reduces both neurite length (28.5%) and the number of neurite branches (35.6%) in primary prefrontal cortical neuron cultures. PCP reduced protein and mRNA expressions of synaptophysin (24.9% and 23.2%, respectively) and PSD95 (31.5% and 21.4%, respectively), and the protein expression of p-Akt (26.7%) and p-GSK3β (35.2%). Olanzapine co-treatment prevented these PCP-induced effects in normal neurons but not in neurons from NRG1-knockout mice. These results indicate that NRG1 mediates the preventive effects of olanzapine on the PCP-induced impairment of neurite outgrowth and synaptic protein expression. This study provides potential targets for interventions on improving the efficacy of olanzapine on preventing cognitive deficits in schizophrenia.

  2. Reducing GABAA-mediated inhibition improves forelimb motor function after focal cortical stroke in mice

    PubMed Central

    Alia, Claudia; Spalletti, Cristina; Lai, Stefano; Panarese, Alessandro; Micera, Silvestro; Caleo, Matteo

    2016-01-01

    A deeper understanding of post-stroke plasticity is critical to devise more effective pharmacological and rehabilitative treatments. The GABAergic system is one of the key modulators of neuronal plasticity, and plays an important role in the control of “critical periods” during brain development. Here, we report a key role for GABAergic inhibition in functional restoration following ischemia in the adult mouse forelimb motor cortex. After stroke, the majority of cortical sites in peri-infarct areas evoked simultaneous movements of forelimb, hindlimb and tail, consistent with a loss of inhibitory signalling. Accordingly, we found a delayed decrease in several GABAergic markers that accompanied cortical reorganization. To test whether reductions in GABAergic signalling were causally involved in motor improvements, we treated animals during an early post-stroke period with a benzodiazepine inverse agonist, which impairs GABAA receptor function. We found that hampering GABAA signalling led to significant restoration of function in general motor tests (i.e., gridwalk and pellet reaching tasks), with no significant impact on the kinematics of reaching movements. Improvements were persistent as they remained detectable about three weeks after treatment. These data demonstrate a key role for GABAergic inhibition in limiting motor improvements after cortical stroke. PMID:27897203

  3. CNTF-Treated Astrocyte Conditioned Medium Enhances Large-Conductance Calcium-Activated Potassium Channel Activity in Rat Cortical Neurons.

    PubMed

    Sun, Meiqun; Liu, Hongli; Xu, Huanbai; Wang, Hongtao; Wang, Xiaojing

    2016-08-01

    Seizure activity is linked to astrocyte activation as well as dysfunctional cortical neuron excitability produced from changes in calcium-activated potassium (KCa) channel function. Ciliary neurotrophic factor-treated astrocyte conditioned medium (CNTF-ACM) can be used to investigate the peripheral effects of activated astrocytes upon cortical neurons. However, CNTF-ACM's effect upon KCa channel activity in cultured cortical neurons has not yet been investigated. Whole-cell patch clamp recordings were performed in rat cortical neurons to evaluate CNTF-ACM's effects upon charybdotoxin-sensitive large-conductance KCa (BK) channel currents and apamin-sensitive small-conductance KCa (SK) channel current. Biotinylation and RT-PCR were applied to assess CNTF-ACM's effects upon the protein and mRNA expression, respectively, of the SK channel subunits SK2 and SK3 and the BK channel subunits BKα1 and BKβ3. An anti-fibroblast growth factor-2 (FGF-2) monoclonal neutralizing antibody was used to assess the effects of the FGF-2 component of CNTF-ACM. CNTF-ACM significantly increased KCa channel current density, which was predominantly attributable to gains in BK channel activity (p < 0.05). CNTF-ACM produced a significant increase in BKα1 and BKβ3 expression (p < 0.05) but had no significant effect upon SK2 or SK3 expression (p > 0.05). Blocking FGF-2 produced significant reductions in KCa channel current density (p > 0.05) as well as BKα1 and BKβ3 expression in CNTF-ACM-treated neurons (p > 0.05). CNTF-ACM significantly enhances BK channel activity in rat cortical neurons and that FGF-2 is partially responsible for these effects. CNTF-induced astrocyte activation results in secretion of neuroactive factors which may affect neuronal excitability and resultant seizure activity in mammalian cortical neurons.

  4. [HOMOCYSTEINE-INDUCED MEMBRANE CURRENTS, CALCIUM RESPONSES AND CHANGES OF MITOCHONDRIAL POTENTIAL IN RAT CORTICAL NEURONS].

    PubMed

    Abushik, P A; Karelina, T V; Sibarov, D A; Stepanenko, J D; Giniatullin, R; Antonov, S M

    2015-01-01

    Homocysteine, a sulfur-containing amino acid, exhibits neurotoxic effects and is involved in the pathogenesis of several major neurodegenerative disorders. In contrast to well studied excitoxicity of glutamate, the mechanism of homocysteine neurotoxicity is not clearly understood. By using whole-cell patch-clamp, calcium imaging (fluo-3) and measurements of mitochondrial membrane potential (rhodamine 123) we studied transmembrane currents, calcium signals and changes in mitochondrial membrane potential induced by homocysteine versus responses induced by NMDA and glutamate in cultured rat cortical neurons. L-homocysteine (50 µM) induced inward currents that could be completely blocked by the selective antagonist of NMDA receptors - AP-5. In contrast to NMDA-induced currents, homocysteine-induced currents had a smaller steady-state amplitude. Comparison of calcium responses to homocysteine, NMDA or glutamate demonstrated that in all cortical neurons homocysteine elicited short, oscillatory-type calcium responses, whereas NMDA or glutamate induced sustained increase of intracellular calcium. Analysis of mitochondrial changes demonstrated that in contrast to NMDA homocysteine did not cause a drop of mitochondrial membrane potential at the early stages of action. However, after its long-term action, as in the case of NMDA and glutamate, the changes in mitochondrial membrane potential were comparable with the full drop of respiratory chain induced by protonophore FCCP. Our data suggest that in cultured rat cortical neuron homocysteine at the first stages of action induces neurotoxic effects through activation of NMDA-type ionotropic glutamate receptors with strong calcium influx through the channels of these receptors. The long-term action of homocysteine may lead to mitochondrial disfuction and appears as a drop of mitochondrial membrane potential.

  5. Progressive Cortical Neuronal Damage and Chronic Hemodynamic Impairment in Atherosclerotic Major Cerebral Artery Disease.

    PubMed

    Yamauchi, Hiroshi; Kagawa, Shinya; Kishibe, Yoshihiko; Takahashi, Masaaki; Higashi, Tatsuya

    2016-06-01

    Cross-sectional studies suggest that chronic hemodynamic impairment may cause selective cortical neuronal damage in patients with atherosclerotic internal carotid artery or middle cerebral artery occlusive disease. The purpose of this longitudinal study was to determine whether the progression of cortical neuronal damage, evaluated as a decrease in central benzodiazepine receptors (BZRs), is associated with hemodynamic impairment at baseline or hemodynamic deterioration during follow-up. We evaluated the distribution of BZRs twice using positron emission tomography and (11)C-flumazenil over time in 80 medically treated patients with atherosclerotic internal carotid artery or middle cerebral artery occlusive disease that had no ischemic episodes during follow-up. Using 3D stereotactic surface projections, we quantified abnormal decreases in the BZRs in the cerebral cortex within the middle cerebral artery distribution and correlated changes in the BZR index with the mean hemispheric values of hemodynamic parameters obtained from (15)O gas positron emission tomography. In the hemisphere affected by arterial disease, the BZR index in 40 patients (50%) was increased during follow-up (mean 26±20 months). In multivariable logistic regression analyses, increases in the BZR index were associated with the decreased cerebral blood flow at baseline and an increased oxygen extraction fraction during follow-up. Increases in the oxygen extraction fraction during follow-up were associated with a lack of statin use. In patients with atherosclerotic internal carotid artery or middle cerebral artery disease, the progression of cortical neuronal damage was associated with hemodynamic impairment at baseline and hemodynamic deterioration during follow-up. Statin use may be beneficial against hemodynamic deterioration and therefore neuroprotective. © 2016 American Heart Association, Inc.

  6. Cortical parvalbumin and somatostatin GABA neurons express distinct endogenous modulators of nicotinic acetylcholine receptors.

    PubMed

    Demars, Michael P; Morishita, Hirofumi

    2014-10-31

    Inhibition from GABAergic interneurons in brain circuits is a critical component of cognitive function. This inhibition is regulated through a diverse network of neuromodulation. A number of recent studies suggest that one of the major regulators of interneuron function is nicotinic acetylcholinergic transmission and dysregulation of both systems is common in psychiatric conditions. However, how nicotinic modulation impacts specific subpopulations of diverse GABAergic interneurons remains in question. One potential way of conferring specificity to the convergence of GABAergic and nicotinic signaling is through the expression of a unique family of nicotinic acetycholine receptor modulators, the Lynx family. The present study sought to identify members of the Lynx family enriched in cortical interneurons and to elucidate subpopulations of GABAergic neurons that express unique nicotinic modulators. We utilize double fluorescence in situ hybridization to examine the interneuronal expression of the Lynx family in adult mouse visual cortex. We find that two of the Lynx family members, Lynx1 and Lypd6, are enriched in interneuron populations in cortex. Nearly all parvalbumin interneurons express Lynx1 but we did not detect Lypd6 in this population. Conversely, in somatostatin interneurons Lypd6 was found in a subset localized to deep cortical layers but no somatostatin neurons show detectable levels of Lynx1. Using a combination of genetic and viral manipulations we further show that a subpopulation of deep-layer cortico-cortical long-range somatostatin neurons also express Lypd6. This work shows that distinct subpopulations of GABAergic interneurons express unique Lynx family members. The pattern of expression of Lynx family members within interneurons places them in a unique position to potentially regulate the convergence of GABAergic and nicotinic systems, dysfunction of which are characteristic of psychiatric disorders.

  7. Autophagy fails to prevent glucose deprivation/glucose reintroduction-induced neuronal death due to calpain-mediated lysosomal dysfunction in cortical neurons

    PubMed Central

    Gerónimo-Olvera, Cristian; Montiel, Teresa; Rincon-Heredia, Ruth; Castro-Obregón, Susana; Massieu, Lourdes

    2017-01-01

    Autophagy is triggered during nutrient and energy deprivation in a variety of cells as a homeostatic response to metabolic stress. In the CNS, deficient autophagy has been implicated in neurodegenerative diseases and ischemic brain injury. However, its role in hypoglycemic damage is poorly understood and the dynamics of autophagy during the hypoglycemic and the glucose reperfusion periods, has not been fully described. In the present study, we analyzed the changes in the content of the autophagy proteins BECN1, LC3-II and p62/SQSTM1 by western blot, and autophagosome formation was followed through time-lapse experiments, during glucose deprivation (GD) and glucose reintroduction (GR) in cortical cultures. According to the results, autophagosome formation rapidly increased during GD, and was followed by an active autophagic flux early after glucose replenishment. However, cells progressively died during GR and autophagy inhibition reduced neuronal death. Neurons undergoing apoptosis during GR did not form autophagosomes, while those surviving up to late GR showed autophagosomes. Calpain activity strongly increased during GR and remained elevated during progressive neuronal death. Its activation led to the cleavage of LAMP2 resulting in lysosome membrane permeabilization (LMP) and release of cathepsin B to the cytosol. Calpain inhibition prevented LMP and increased the number of neurons containing lysosomes and autophagosomes increasing cell viability. Taken together, the present results suggest that calpain-mediated lysosome dysfunction during GR turns an adaptive autophagy response to energy stress into a defective autophagy pathway, which contributes to neuronal death. In these conditions, autophagy inhibition results in the improvement of cell survival. PMID:28661473

  8. Autophagy fails to prevent glucose deprivation/glucose reintroduction-induced neuronal death due to calpain-mediated lysosomal dysfunction in cortical neurons.

    PubMed

    Gerónimo-Olvera, Cristian; Montiel, Teresa; Rincon-Heredia, Ruth; Castro-Obregón, Susana; Massieu, Lourdes

    2017-06-29

    Autophagy is triggered during nutrient and energy deprivation in a variety of cells as a homeostatic response to metabolic stress. In the CNS, deficient autophagy has been implicated in neurodegenerative diseases and ischemic brain injury. However, its role in hypoglycemic damage is poorly understood and the dynamics of autophagy during the hypoglycemic and the glucose reperfusion periods, has not been fully described. In the present study, we analyzed the changes in the content of the autophagy proteins BECN1, LC3-II and p62/SQSTM1 by western blot, and autophagosome formation was followed through time-lapse experiments, during glucose deprivation (GD) and glucose reintroduction (GR) in cortical cultures. According to the results, autophagosome formation rapidly increased during GD, and was followed by an active autophagic flux early after glucose replenishment. However, cells progressively died during GR and autophagy inhibition reduced neuronal death. Neurons undergoing apoptosis during GR did not form autophagosomes, while those surviving up to late GR showed autophagosomes. Calpain activity strongly increased during GR and remained elevated during progressive neuronal death. Its activation led to the cleavage of LAMP2 resulting in lysosome membrane permeabilization (LMP) and release of cathepsin B to the cytosol. Calpain inhibition prevented LMP and increased the number of neurons containing lysosomes and autophagosomes increasing cell viability. Taken together, the present results suggest that calpain-mediated lysosome dysfunction during GR turns an adaptive autophagy response to energy stress into a defective autophagy pathway, which contributes to neuronal death. In these conditions, autophagy inhibition results in the improvement of cell survival.

  9. Prenatal Exposure to Benzo(a)pyrene Impairs Later-Life Cortical Neuronal Function

    PubMed Central

    McCallister, Monique M.; Maguire, Mark; Ramesh, Aramandla; Aimin, Qiao; Liu, Sheng; Khoshbouei, Habibeh; Aschner, Michael; Ebner, Ford F.; Hood, Darryl B.

    2009-01-01

    Prenatal exposure to environmental contaminants, such as Benzo(a)pyrene [B(a)P] has been shown to impair brain development. The overarching hypothesis of our work is that glutamate receptor subunit expression is crucial for cortical evoked responses and that prenatal B(a)P exposure modulates the temporal developmental expression of glutamatergic receptor subunits in the somatosensory cortex. To characterize prenatal B(a)P exposure on the development of cortical function, pregnant Long Evans rats were exposed to low-level B(a)P (300μg/kg BW) by oral gavage on gestational days 14 to 17. At this exposure dose, there was no significant effect of B(a)P on 1) the number of pups born per litter, 2) the pre-weaning growth curves and 3) initial and final brain to body weight ratios. Control and B(a)P-exposed offspring were profiled for B(a)P metabolites in plasma and whole brain during the pre-weaning period. No detectable levels of metabolites were found in the control offspring. However, a time-dependent decrease in total metabolite concentration was observed in B(a)P-exposed offspring. On PND100-120, cerebrocortical mRNA expression was determined for the glutamatergic NMDA receptor subunit (NR2B) in control and B(a)P-exposed offspring. Neural activity was also recorded from neurons in primary somatic sensory (barrel) cortex. Semiquantitative PCR from B(a)P-exposed offspring revealed a significant 50% reduction in NR2B mRNA expression in B(a)P-exposed offspring relative to controls. Recordings from B(a)P-exposed offspring revealed that N-methyl-D-aspartate (NMDA) receptor -dependent neuronal activity in barrel cortex evoked by whisker stimulation was also significantly reduced (70%) as compared to controls. Analysis showed that the greatest deficit in cortical neuronal responses occurred in the shorter latency epochs from 5-20ms post-stimulus. The results suggest that in utero exposure to benzo(a)pyrene results in diminished mRNA expression of the NMDA NR2B receptor

  10. Regulation and subcellular localization of the microtubule-destabilizing stathmin family phosphoproteins in cortical neurons.

    PubMed

    Gavet, Olivier; El Messari, Saïd; Ozon, Sylvie; Sobel, André

    2002-06-01

    Stathmin is a ubiquitous cytosolic phosphoprotein, preferentially expressed in the nervous system, and the generic element of a protein family that includes the neural-specific proteins SCG10, SCLIP, and RB3 and its splice variants, RB3' and RB3". All phosphoproteins of the family share with stathmin its tubulin binding and microtubule (MT)-destabilizing activities. To understand better the specific roles of these proteins in neuronal cells, we performed a comparative study of their expression, regulation, and intracellular distribution in embryonic cortical neurons in culture. We found that stathmin is highly expressed ( approximately 0.25% of total proteins) and uniformly present in the various neuronal compartments (cell body, dendrites, axon, growth cones). It appeared mainly unphosphorylated or weakly phosphorylated on one site, and antisera to specific phosphorylated sites (serines 16, 25, or 38) did not reveal a differential regulation of its phosphorylation among neuronal cell compartments. However, they revealed a subpopulation of cells in which stathmin was highly phosphorylated on serine 16, possibly by CaM kinase II also active in a similar subpopulation. The other proteins of the stathmin family are expressed about 100-fold less than stathmin in partially distinct neuronal populations, RB3 being detected in only about 20% of neurons in culture. In contrast to stathmin, they are each mostly concentrated at the Golgi apparatus and are also present along dendrites and axons, including growth cones. Altogether, our results suggest that the different members of the stathmin family have complementary, at least partially distinct functions in neuronal cell regulation, in particular in relation to MT dynamics. Copyright 2002 Wiley-Liss, Inc.

  11. Sparse and powerful cortical spikes.

    PubMed

    Wolfe, Jason; Houweling, Arthur R; Brecht, Michael

    2010-06-01

    Activity in cortical networks is heterogeneous, sparse and often precisely timed. The functional significance of sparseness and precise spike timing is debated, but our understanding of the developmental and synaptic mechanisms that shape neuronal discharge patterns has improved. Evidence for highly specialized, selective and abstract cortical response properties is accumulating. Singe-cell stimulation experiments demonstrate a high sensitivity of cortical networks to the action potentials of some, but not all, single neurons. It is unclear how this sensitivity of cortical networks to small perturbations comes about and whether it is a generic property of cortex. The unforeseen sensitivity to cortical spikes puts serious constraints on the nature of neural coding schemes.

  12. Diversity of intrinsic frequency encoding patterns in rat cortical neurons--mechanisms and possible functions.

    PubMed

    Kang, Jing; Robinson, Hugh P C; Feng, Jianfeng

    2010-03-19

    Extracellular recordings of single neurons in primary and secondary somatosensory cortices of monkeys in vivo have shown that their firing rate can increase, decrease, or remain constant in different cells, as the external stimulus frequency increases. We observed similar intrinsic firing patterns (increasing, decreasing or constant) in rat somatosensory cortex in vitro, when stimulated with oscillatory input using conductance injection (dynamic clamp). The underlying mechanism of this observation is not obvious, and presents a challenge for mathematical modelling. We propose a simple principle for describing this phenomenon using a leaky integrate-and-fire model with sinusoidal input, an intrinsic oscillation and Poisson noise. Additional enhancement of the gain of encoding could be achieved by local network connections amongst diverse intrinsic response patterns. Our work sheds light on the possible cellular and network mechanisms underlying these opposing neuronal responses, which serve to enhance signal detection.

  13. State and location dependence of action potential metabolic cost in cortical pyramidal neurons.

    PubMed

    Hallermann, Stefan; de Kock, Christiaan P J; Stuart, Greg J; Kole, Maarten H P

    2012-06-03

    Action potential generation and conduction requires large quantities of energy to restore Na(+) and K(+) ion gradients. We investigated the subcellular location and voltage dependence of this metabolic cost in rat neocortical pyramidal neurons. Using Na(+)/K(+) charge overlap as a measure of action potential energy efficiency, we found that action potential initiation in the axon initial segment (AIS) and forward propagation into the axon were energetically inefficient, depending on the resting membrane potential. In contrast, action potential backpropagation into dendrites was efficient. Computer simulations predicted that, although the AIS and nodes of Ranvier had the highest metabolic cost per membrane area, action potential backpropagation into the dendrites and forward propagation into axon collaterals dominated energy consumption in cortical pyramidal neurons. Finally, we found that the high metabolic cost of action potential initiation and propagation down the axon is a trade-off between energy minimization and maximization of the conduction reliability of high-frequency action potentials.

  14. Tangentially migrating neurons assemble a primary cilium that promotes their reorientation to the cortical plate.

    PubMed

    Baudoin, Jean-Pierre; Viou, Lucie; Launay, Pierre-Serge; Luccardini, Camilla; Espeso Gil, Sergio; Kiyasova, Vera; Irinopoulou, Théano; Alvarez, Chantal; Rio, Jean-Paul; Boudier, Thomas; Lechaire, Jean-Pierre; Kessaris, Nicoletta; Spassky, Nathalie; Métin, Christine

    2012-12-20

    In migrating neurons, the centrosome nucleates and anchors a polarized network of microtubules that directs organelle movements. We report here that the mother centriole of neurons migrating tangentially from the medial ganglionic eminence (MGE) assembles a short primary cilium and exposes this cilium to the cell surface by docking to the plasma membrane in the leading process. Primary cilia are built by intraflagellar transport (IFT), which is also required for Sonic hedgehog (Shh) signal transduction in vertebrates. We show that Shh pathway perturbations influenced the leading process morphology and dynamics of MGE cells. Whereas Shh favored the exit of MGE cells away from their tangential migratory paths in the developing cortex, cyclopamine or invalidation of IFT genes maintained MGE cells in the tangential paths. Our findings show that signals transmitted through the primary cilium promote the escape of future GABAergic interneurons from their tangential routes to colonize the cortical plate.

  15. From Cortical Blindness to Conscious Visual Perception: Theories on Neuronal Networks and Visual Training Strategies.

    PubMed

    Hadid, Vanessa; Lepore, Franco

    2017-01-01

    Homonymous hemianopia (HH) is the most common cortical visual impairment leading to blindness in the contralateral hemifield. It is associated with many inconveniences and daily restrictions such as exploration and visual orientation difficulties. However, patients with HH can preserve the remarkable ability to unconsciously perceive visual stimuli presented in their blindfield, a phenomenon known as blindsight. Unfortunately, the nature of this captivating residual ability is still misunderstood and the rehabilitation strategies in terms of visual training have been insufficiently exploited. This article discusses type I and type II blindsight in a neuronal framework of altered global workspace, resulting from inefficient perception, attention and conscious networks. To enhance synchronization and create global availability for residual abilities to reach visual consciousness, rehabilitation tools need to stimulate subcortical extrastriate pathways through V5/MT. Multisensory bottom-up compensation combined with top-down restitution training could target pre-existing and new neuronal mechanisms to recreate a framework for potential functionality.

  16. Improving data quality in neuronal population recordings

    PubMed Central

    Harris, Kenneth D.; Quian Quiroga, Rodrigo; Freeman, Jeremy; Smith, Spencer

    2017-01-01

    Understanding how the brain operates requires understanding how large sets of neurons function together. Modern recording technology makes it possible to simultaneously record the activity of hundreds of neurons, and technological developments will soon allow recording of thousands or tens of thousands. As with all experimental techniques, these methods are subject to confounds that complicate the interpretation of such recordings, and could lead to erroneous scientific conclusions. Here, we discuss methods for assessing and improving the quality of data from these techniques, and outline likely future directions in this field. PMID:27571195

  17. Differential effects of cortical neurotrophic factors on development of lateral geniculate nucleus and superior colliculus neurons: anterograde and retrograde actions.

    PubMed

    Wahle, Petra; Di Cristo, Graziella; Schwerdtfeger, Gudrun; Engelhardt, Maren; Berardi, Nicoletta; Maffei, Lamberto

    2003-02-01

    Neurotrophins strongly affect visual system development and plasticity. However, the mode of delivery and targets of neurotrophin action are still under debate. For instance, cortical NT-4/5 (neurotrophin 4/5; Ntf4/5) was shown to rescue lateral geniculate nucleus (LGN) neurons from monocular deprivation-induced atrophy suggesting a retrograde action on thalamic afferents. It is still unclear whether LGN neurons respond to NT-4/5 and other neurotrophins during development in animals with normal vision. We now show that infusions of NT-4/5 and NGF (nerve growth factor) into visual cortex at the onset and the peak of the critical period accelerated LGN neuron growth. BDNF (brain-derived neurotrophic factor) was ineffective. The effects of neurotrophin on LGN development were clearly dissociated from the effects at cortical level because soma growth of cortical layer IV and VI neurons was strongly promoted by BDNF. NT-4/5 was only effective at the onset, but no longer at the peak of the critical period suggesting a switch in neurotrophin dependency for these cortical cell classes. To dissociate retrograde and anterograde effects of the TrkB ligands, we analyzed the stratum griseum superficiale (SGS) of the superior colliculus, a target of visual cortical efferents. Indeed, TrkB-expressing inhibitory SGS neurons responded to cortical NT-4/5 infusion with somatic growth. Strikingly, the TrkB-expressing excitatory tectothalamic calbindin neurons in the SGS did not respond. This demonstrated for the first time a selective cell type-specific anterograde action of NT-4/5 and suggested for the LGN that anterograde as well as retrograde effects contribute to soma size regulation. Strikingly, cortical infusion of the cytokine LIF, which affects development of visual cortex neurochemical architecture, transiently inhibited growth of neurons in LGN, cortical layer IV and VI and SGS. In summary, the study presents three important results. First, central neurons regulate soma size

  18. Attenuation of Responses to Self-Generated Sounds in Auditory Cortical Neurons.

    PubMed

    Rummell, Brian P; Klee, Jan L; Sigurdsson, Torfi

    2016-11-23

    Many of the sounds that we perceive are caused by our own actions, for example when speaking or moving, and must be distinguished from sounds caused by external events. Studies using macroscopic measurements of brain activity in human subjects have consistently shown that responses to self-generated sounds are attenuated in amplitude. However, the underlying manifestation of this phenomenon at the cellular level is not well understood. To address this, we recorded the activity of neurons in the auditory cortex of mice in response to sounds generated by their own behavior. We found that the responses of auditory cortical neurons to these self-generated sounds were consistently attenuated, compared with the same sounds generated independently of the animals' behavior. This effect was observed in both putative pyramidal neurons and in interneurons and was stronger in lower layers of auditory cortex. Downstream of the auditory cortex, we found that responses of hippocampal neurons to self-generated sounds were almost entirely suppressed. Responses to self-generated optogenetic stimulation of auditory thalamocortical terminals were also attenuated, suggesting a cortical contribution to this effect. Further analyses revealed that the attenuation of self-generated sounds was not simply due to the nonspecific effects of movement or behavioral state on auditory responsiveness. However, the strength of attenuation depended on the degree to which self-generated sounds were expected to occur, in a cell-type-specific manner. Together, these results reveal the cellular basis underlying attenuated responses to self-generated sounds and suggest that predictive processes contribute to this effect.

  19. Rapid modulation of synaptogenesis and spinogenesis by 17β-estradiol in primary cortical neurons

    PubMed Central

    Sellers, Katherine J.; Erli, Filippo; Raval, Pooja; Watson, Iain A.; Chen, Ding; Srivastava, Deepak P.

    2015-01-01

    In the mammalian forebrain, the majority of excitatory synapses occur on dendritic spines. Changes in the number of these structures is important for brain development, plasticity and the refinement of neuronal circuits. The formation of excitatory synapses involves the coordinated formation of dendritic spines and targeting of multi-protein complexes to nascent connections. Recent studies have demonstrated that the estrogen 17β-estradiol (E2) can rapidly increase the number of dendritic spines, an effect consistent with the ability of E2 to rapidly influence cognitive function. However, the molecular composition of E2-induced spines and whether these protrusions form synaptic connections has not been fully elucidated. Moreover, which estrogen receptor(s) (ER) mediate these spine-morphogenic responses are not clear. Here, we report that acute E2 treatment results in the recruitment of postsynaptic density protein 95 (PSD-95) to novel dendritic spines. In addition neuroligin 1 (Nlg-1) and the NMDA receptor subunit GluN1 are recruited to nascent synapses in cortical neurons. The presence of these synaptic proteins at nascent synapses suggests that the machinery to allow pre- and post-synapses to form connections are present in E2-induced spines. We further demonstrate that E2 treatment results in the rapid and transient activation of extracellular signal-regulated kinase 1/2 (ERK1/2), Akt and the mammalian target of rapamycin (mTOR) signaling pathways. However, only ERK1/2 and Akt are required for E2-mediated spinogenesis. Using synthetic receptor modulators, we further demonstrate that activation of the estrogen receptor beta (ERβ) but not alpha (ERα) mimics rapid E2-induced spinogenesis and synaptogenesis. Taken together these findings suggest that in primary cortical neurons, E2 signaling via ERβ, but not through ERα, is capable of remodeling neuronal circuits by increasing the number of excitatory synapses. PMID:25926772

  20. Neuronal avalanches organize as nested theta- and beta/gamma-oscillations during development of cortical layer 2/3.

    PubMed

    Gireesh, Elakkat D; Plenz, Dietmar

    2008-05-27

    Maturation of the cerebral cortex involves the spontaneous emergence of distinct patterns of neuronal synchronization, which regulate neuronal differentiation, synapse formation, and serve as a substrate for information processing. The intrinsic activity patterns that characterize the maturation of cortical layer 2/3 are poorly understood. By using microelectrode array recordings in vivo and in vitro, we show that this development is marked by the emergence of nested - and beta/gamma-oscillations that require NMDA- and GABA(A)-mediated synaptic transmission. The oscillations organized as neuronal avalanches, i.e., they were synchronized across cortical sites forming diverse and millisecond-precise spatiotemporal patterns that distributed in sizes according to a power law with a slope of -1.5. The correspondence between nested oscillations and neuronal avalanches required activation of the dopamine D(1) receptor. We suggest that the repetitive formation of neuronal avalanches provides an intrinsic template for the selective linking of external inputs to developing superficial layers.

  1. Proneural transcription factors regulate different steps of cortical neuron migration through Rnd-mediated inhibition of RhoA signaling.

    PubMed

    Pacary, Emilie; Heng, Julian; Azzarelli, Roberta; Riou, Philippe; Castro, Diogo; Lebel-Potter, Mélanie; Parras, Carlos; Bell, Donald M; Ridley, Anne J; Parsons, Maddy; Guillemot, François

    2011-03-24

    Little is known of the intracellular machinery that controls the motility of newborn neurons. We have previously shown that the proneural protein Neurog2 promotes the migration of nascent cortical neurons by inducing the expression of the atypical Rho GTPase Rnd2. Here, we show that another proneural factor, Ascl1, promotes neuronal migration in the cortex through direct regulation of a second Rnd family member, Rnd3. Both Rnd2 and Rnd3 promote neuronal migration by inhibiting RhoA signaling, but they control distinct steps of the migratory process, multipolar to bipolar transition in the intermediate zone and locomotion in the cortical plate, respectively. Interestingly, these divergent functions directly result from the distinct subcellular distributions of the two Rnd proteins. Because Rnd proteins also regulate progenitor divisions and neurite outgrowth, we propose that proneural factors, through spatiotemporal regulation of Rnd proteins, integrate the process of neuronal migration with other events in the neurogenic program.

  2. The Marine Guanidine Alkaloid Crambescidin 816 Induces Calcium Influx and Cytotoxicity in Primary Cultures of Cortical Neurons through Glutamate Receptors.

    PubMed

    Mendez, Aida G; Juncal, Andrea Boente; Silva, Siguara B L; Thomas, Olivier P; Martín Vázquez, Víctor; Alfonso, Amparo; Vieytes, Mercedes R; Vale, Carmen; Botana, Luís M

    2017-07-19

    Crambescidin 816 is a guanidine alkaloid produced by the sponge Crambe crambe with known antitumoral activity. While the information describing the effects of this alkaloid in central neurons is scarce, Cramb816 is known to block voltage dependent calcium channels being selective for L-type channels. Moreover, Cramb816 reduced neuronal viability through an unknown mechanism. Here, we aimed to describe the toxic activity of Cramb816 in cortical neurons. Since calcium influx is considered the main mechanism responsible for neuronal cell death, the effects of Cramb816 in the cytosolic calcium concentration of cortical neurons were studied. The alkaloid decreased neuronal viability and induced a dose-dependent increase in cytosolic calcium that was also related to the presence of calcium in the extracellular media. The increase in calcium influx was age dependent, being higher in younger neurons. Moreover, this effect was prevented by glutamate receptor antagonists, which did not fully block the cytotoxic effect of Cramb816 after 24 h of treatment but completely prevented Cramb816 cytotoxicity after 10 min exposure. Therefore, the findings presented herein provide new insights into the cytotoxic effect of Cramb816 in cortical neurons.

  3. Golli Myelin Basic Proteins Modulate Voltage-Operated Ca(++) Influx and Development in Cortical and Hippocampal Neurons.

    PubMed

    Vt, Cheli; DA, Santiago González; V, Spreuer; V, Handley; At, Campagnoni; Pm, Paez

    2016-10-01

    The golli proteins, products of the myelin basic protein gene, are widely expressed in oligodendrocyte progenitor cells and neurons during the postnatal development of the brain. While golli appears to be important for oligodendrocyte migration and differentiation, its function in neuronal development is completely unknown. We have found that golli proteins function as new and novel modulators of voltage-operated Ca(++) channels (VOCCs) in neurons. In vitro, golli knock-out (KO) neurons exhibit decreased Ca(++) influx after plasma membrane depolarization and a substantial maturational delay. Increased expression of golli proteins enhances L-type Ca(++) entry and processes outgrowth in cortical neurons, and pharmacological activation of L-type Ca(++) channels stimulates maturation and prevents cell death in golli-KO neurons. In situ, Ca(++) influx mediated by L-type VOCCs was significantly decreased in cortical and hippocampal neurons of the golli-KO brain. These Ca(++) alterations affect cortical and hippocampal development and the proliferation and survival of neural progenitor cells during the postnatal development of the golli-KO brain. The CA1/3 sections and the dentate gyrus of the hippocampus were reduced in the golli-KO mice as well as the density of dendrites in the somatosensory cortex. Furthermore, the golli-KO mice display abnormal behavior including deficits in episodic memory and reduced anxiety. Because of the expression of the golli proteins within neurons in learning and memory centers of the brain, this work has profound implication in neurodegenerative diseases and neurological disorders.

  4. Imaging separation of neuronal from vascular effects of cocaine on rat cortical brain in vivo

    SciTech Connect

    Yuan, Z.; Du, C.; Yuan, Z.; Luo, Z.; Volkow, N.D.; Pan, Y.; Du, C.

    2010-09-08

    MRI techniques to study brain function assume coupling between neuronal activity, metabolism and flow. However, recent evidence of physiological uncoupling between neuronal and cerebrovascular events highlights the need for methods to simultaneously measure these three properties. We report a multimodality optical approach that integrates dual-wavelength laser speckle imaging (measures changes in blood flow, blood volume and hemoglobin oxygenation), digital-frequency-ramping optical coherence tomography (images quantitative 3D vascular network) and Rhod2 fluorescence (images intracellular calcium for measure of neuronal activity) at high spatiotemporal resolutions (30 {micro}m, 10 Hz) and over a large field of view (3 x 5 mm{sup 2}). We apply it to assess cocaine's effects in rat cortical brain and show an immediate decrease 3.5 {+-} 0.9 min, phase (1) in the oxygen content of hemoglobin and the cerebral blood flow followed by an overshoot 7.1 {+-} 0.2 min, phase (2) lasting over 20 min whereas Ca{sup 2+} increased immediately (peaked at t = 4.1 {+-} 0.4 min) and remained elevated. This enabled us to identify a delay (2.9 {+-} 0.5 min) between peak neuronal and vascular responses in phase 2. The ability of this multimodality optical approach for simultaneous imaging at high spatiotemporal resolutions permits us to distinguish the vascular versus cellular changes of the brain, thus complimenting other neuroimaging modalities for brain functional studies (e. g., PET, fMRI).

  5. Molecular Pathways Underlying Projection Neuron Production and Migration during Cerebral Cortical Development

    PubMed Central

    Ohtaka-Maruyama, Chiaki; Okado, Haruo

    2015-01-01

    Glutamatergic neurons of the mammalian cerebral cortex originate from radial glia (RG) progenitors in the ventricular zone (VZ). During corticogenesis, neuroblasts migrate toward the pial surface using two different migration modes. One is multipolar (MP) migration with random directional movement, and the other is locomotion, which is a unidirectional movement guided by the RG fiber. After reaching their final destination, the neurons finalize their migration by terminal translocation, which is followed by maturation via dendrite extension to initiate synaptogenesis and thereby complete neural circuit formation. This switching of migration modes during cortical development is unique in mammals, which suggests that the RG-guided locomotion mode may contribute to the evolution of the mammalian neocortical 6-layer structure. Many factors have been reported to be involved in the regulation of this radial neuronal migration process. In general, the radial migration can be largely divided into four steps; (1) maintenance and departure from the VZ of neural progenitor cells, (2) MP migration and transition to bipolar cells, (3) RG-guided locomotion, and (4) terminal translocation and dendrite maturation. Among these, many different gene mutations or knockdown effects have resulted in failure of the MP to bipolar transition (step 2), suggesting that it is a critical step, particularly in radial migration. Moreover, this transition occurs at the subplate layer. In this review, we summarize recent advances in our understanding of the molecular mechanisms underlying each of these steps. Finally, we discuss the evolutionary aspects of neuronal migration in corticogenesis. PMID:26733777

  6. Complex Spectral Interactions Encoded by Auditory Cortical Neurons: Relationship Between Bandwidth and Pattern

    PubMed Central

    O'Connor, Kevin N.; Yin, Pingbo; Petkov, Christopher I.; Sutter, Mitchell L.

    2010-01-01

    The focus of most research on auditory cortical neurons has concerned the effects of rather simple stimuli, such as pure tones or broad-band noise, or the modulation of a single acoustic parameter. Extending these findings to feature coding in more complex stimuli such as natural sounds may be difficult, however. Generalizing results from the simple to more complex case may be complicated by non-linear interactions occurring between multiple, simultaneously varying acoustic parameters in complex sounds. To examine this issue in the frequency domain, we performed a parametric study of the effects of two global features, spectral pattern (here ripple frequency) and bandwidth, on primary auditory (A1) neurons in awake macaques. Most neurons were tuned for one or both variables and most also displayed an interaction between bandwidth and pattern implying that their effects were conditional or interdependent. A spectral linear filter model was able to qualitatively reproduce the basic effects and interactions, indicating that a simple neural mechanism may be able to account for these interdependencies. Our results suggest that the behavior of most A1 neurons is likely to depend on multiple parameters, and so most are unlikely to respond independently or invariantly to specific acoustic features. PMID:21152347

  7. Conditioning of cortical neurons in cats with antidromic activation as the unconditioned stimulus.

    PubMed

    O'Brien, J H; Wilder, M B; Stevens, C D

    1977-08-01

    Single-cell activity was recorded from the postcruciate cortex of acutely prepared cats during a differential classical conditioning procedure. The conditioned stimuli (CS) were hind paw stimuli, and the unconditioned stimulus (US) was pyramidal tract stimulation that produced an antidromic response in the recorded cortical neuron. A control group was also examined in which the pyramidal stimulus was set below the threshold to produce an antidromic response. Clear differential conditioning was found for the experimental group, with antidromic activation of the neuron as the US. There was no evidence of differential conditioning in the control group without antidromic activation. Any activation of orthodromic pathways should have been the same in the control and experimental groups. The absence of conditioning in the control group demonstrated that orthodromic pathways were not contributing to the differential conditioning observed in the experimental group. This indicates that it was activation of the neuron produced by antidromic firing which was important for conditioning. All the evidence suggests that the site of learning was in the cortex. It is concluded that the the role of the US in conditioning may be simply to activate the neuron at an appropriate interval following the CS.

  8. Distinct regulation of activity-dependent transcription of immediate early genes in cultured rat cortical neurons.

    PubMed

    Fukuchi, Mamoru; Sanabe, Tomofumi; Watanabe, Toshifumi; Kubota, Takane; Tabuchi, Akiko; Tsuda, Masaaki

    2017-08-26

    The activity-regulated expression of immediate early genes (IEGs) contributes to long-lasting neuronal functions underlying long-term memory. However, their response properties following neuronal activity are unique and remain poorly understood. To address this knowledge gap, here we further investigated the response properties of two representative IEGs, c-fos and brain-derived neurotrophic factor (Bdnf). Treatment of cultured cortical cells with KCl produces a depolarization process that results in the increase of intracellular calcium concentration in a KCl concentration-dependent manner. Consistent with this increase, c-fos expression was induced in a KCl concentration-dependent manner. In contrast, however, Bdnf expression was optimally activated by both 25 and 50 mM concentration of KCl. Similar results were observed when the cells were treated with okadaic acid, which inhibits protein phosphatases and elicits the hyper-phosphorylation of signaling molecules. Thus, Bdnf expression is strictly regulated by a neuronal activity threshold in an all or nothing manner, whereas c-fos expression is activated in a neuronal activity-dependent manner. Our findings also suggest that these differential responses might be due to the presence or absence of a TATA box. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Angiotensin protects cortical neurons from hypoxic-induced apoptosis via the angiotensin type 2 receptor.

    PubMed

    Grammatopoulos, Tom; Morris, Katherine; Ferguson, Paul; Weyhenmeyer, James

    2002-03-28

    The effects of angiotensin on mouse cortical neuronal cultures exposed to chemical-induced hypoxia was investigated. Cultures exposed to 10 mM sodium azide for 5 min showed a 17% increase in apoptosis when assayed 24 h postinsult. The N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 blocked sodium azide-induced cell death suggesting that the NMDA receptor contributes to the mediated cell death. Pretreatment of cultured neurons with angiotensin decreased sodium azide-induced apoptosis by 94%. When the AT(1) receptor was blocked by its receptor antagonist, losartan, angiotensin activation of the AT(2) receptor completely inhibited sodium azide-induced apoptosis. Pretreatment of neurons with the AT(2) receptor antagonist PD123319 resulted in angiotensin reducing sodium azide-induced apoptosis by 48%. These results demonstrate that angiotensin can significantly attenuate sodium azide-induced apoptosis primarily through activation of the AT(2) receptor and suggests that angiotensin may have a protective role in neurons undergoing ischemic injury.

  10. Modeling the formation process of grouping stimuli sets through cortical columns and microcircuits to feature neurons.

    PubMed

    Klefenz, Frank; Williamson, Adam

    2013-01-01

    A computational model of a self-structuring neuronal net is presented in which repetitively applied pattern sets induce the formation of cortical columns and microcircuits which decode distinct patterns after a learning phase. In a case study, it is demonstrated how specific neurons in a feature classifier layer become orientation selective if they receive bar patterns of different slopes from an input layer. The input layer is mapped and intertwined by self-evolving neuronal microcircuits to the feature classifier layer. In this topical overview, several models are discussed which indicate that the net formation converges in its functionality to a mathematical transform which maps the input pattern space to a feature representing output space. The self-learning of the mathematical transform is discussed and its implications are interpreted. Model assumptions are deduced which serve as a guide to apply model derived repetitive stimuli pattern sets to in vitro cultures of neuron ensembles to condition them to learn and execute a mathematical transform.

  11. Panaxydol and panaxynol protect cultured cortical neurons against Abeta25-35-induced toxicity.

    PubMed

    Nie, Bao-Ming; Jiang, Xiao-Yan; Cai, Jin-Xian; Fu, Sai-Li; Yang, Li-Min; Lin, Lin; Hang, Qin; Lu, Pei-Lua; Lu, Yang

    2008-04-01

    Amyloid beta protein (Abeta), the central constituent of senile plaques in Alzheimer's disease (AD), is known to exert toxic effects on cultured neurons. In the present study, the protective effect of panaxydol (PND) and panaxynol (PNN) on Abeta25-35-induced neuronal apoptosis and potential mechanisms were investigated in primary cultured rat cortical neurons. Pretreatment of the cells with PND or PNN prior to 10 microM Abeta25-35 exposure resulted significantly in elevation of cell survival determined by MTT assay, TUNEL/Hoechst staining and western blot. Furthermore, a marked increase in calcium influx and intracellular free radical generation was found after Abeta25-35 exposure, which could be almost completely reversed by pretreatment of PND or PNN. PND and PNN could also alleviate Abeta25-35-induced early-stage neuronal degeneration. These results indicated that inhibition of calcium influx and free radical generation is a mechanism of the anti-apoptotic action of PND and PNN. Since Abeta plays critical roles in the pathogenesis of AD, these findings raise the possibility that PND and PNN reduce neurodegeneration in AD.

  12. Modeling the Formation Process of Grouping Stimuli Sets through Cortical Columns and Microcircuits to Feature Neurons

    PubMed Central

    Williamson, Adam

    2013-01-01

    A computational model of a self-structuring neuronal net is presented in which repetitively applied pattern sets induce the formation of cortical columns and microcircuits which decode distinct patterns after a learning phase. In a case study, it is demonstrated how specific neurons in a feature classifier layer become orientation selective if they receive bar patterns of different slopes from an input layer. The input layer is mapped and intertwined by self-evolving neuronal microcircuits to the feature classifier layer. In this topical overview, several models are discussed which indicate that the net formation converges in its functionality to a mathematical transform which maps the input pattern space to a feature representing output space. The self-learning of the mathematical transform is discussed and its implications are interpreted. Model assumptions are deduced which serve as a guide to apply model derived repetitive stimuli pattern sets to in vitro cultures of neuron ensembles to condition them to learn and execute a mathematical transform. PMID:24369455

  13. Cortical neurons of bats respond best to echoes from nearest targets when listening to natural biosonar multi-echo streams

    PubMed Central

    Beetz, M. Jerome; Hechavarría, Julio C.; Kössl, Manfred

    2016-01-01

    Bats orientate in darkness by listening to echoes from their biosonar calls, a behaviour known as echolocation. Recent studies showed that cortical neurons respond in a highly selective manner when stimulated with natural echolocation sequences that contain echoes from single targets. However, it remains unknown how cortical neurons process echolocation sequences containing echo information from multiple objects. In the present study, we used echolocation sequences containing echoes from three, two or one object separated in the space depth as stimuli to study neuronal activity in the bat auditory cortex. Neuronal activity was recorded with multi-electrode arrays placed in the dorsal auditory cortex, where neurons tuned to target-distance are found. Our results show that target-distance encoding neurons are mostly selective to echoes coming from the closest object, and that the representation of echo information from distant objects is selectively suppressed. This suppression extends over a large part of the dorsal auditory cortex and may override possible parallel processing of multiple objects. The presented data suggest that global cortical suppression might establish a cortical “default mode” that allows selectively focusing on close obstacle even without active attention from the animals. PMID:27786252

  14. A novel role for PTEN in the inhibition of neurite outgrowth by Myelin-associated glycoprotein in cortical neurons

    PubMed Central

    Perdigoto, Ana Luisa; Chaudhry, Nagarathnamma; Barnes, Gregory N.; Filbin, Marie T.; Carter, Bruce D.

    2010-01-01

    Axonal regeneration in the central nervous system is prevented, in part, by inhibitory proteins expressed by myelin, including Myelin-associated glycoprotein (MAG). Although injury to the corticospinal tract can result in permanent disability, little is known regarding the mechanisms by which MAG affects cortical neurons. Here, we demonstrate that cortical neurons plated on MAG expressing CHO cells, exhibit a striking reduction in process outgrowth. Interestingly, none of the receptors previously implicated in MAG signaling, including the p75 neurotrophin receptor or gangliosides, contributed significantly to MAG-mediated inhibition. However, blocking the small GTPase Rho or its downstream effector kinase, ROCK, partially reversed the effects of MAG on the neurons. In addition, we identified the lipid phosphatase PTEN as a mediator of MAG’s inhibitory effects on neurite outgrowth. Knockdown or gene deletion of PTEN or over expression of activated AKT in cortical neurons resulted in significant, although partial, rescue of neurite outgrowth on MAG-CHO cells. Moreover, MAG decreased the levels of phospho-Akt, suggesting that it activates PTEN in the neurons. Taken together, these results suggest a novel pathway activated by MAG in cortical neurons involving the PTEN/PI3K/AKT axis. PMID:20869442

  15. Effects of Aging on Paired-Pulse Behavior of Rat Somatosensory Cortical Neurons

    PubMed Central

    Dinse, Hubert R.

    2010-01-01

    Aging affects all levels of neural processing including changes of intracortical inhibition and cortical excitability. The paired-pulse stimulation protocol, the application of 2 stimuli in close succession, is used to investigate cortical excitability. The paired-pulse behavior is characterized by the fact that the second response is significantly suppressed at short interstimulus intervals (ISIs) but approaches the first response with increasing ISIs. However, there are controversial reports about the influence of age on paired-pulse behavior. We therefore used pairs of tactile stimuli (ISIs from tens to hundreds of milliseconds) to record extracellular responses of somatosensory cortical neurons of young and aged rats. Paired-pulse behavior was quantified as the ratio of the amplitude of the second response divided by the first. For all ISIs, we found significantly higher ratios in the old animals indicating reduced paired-pulse suppression (PPS). Evaluation of the single response components revealed a significant reduction of the response to the first stimulus for old animals but no age-dependent decrement to the second. Changes in PPS are usually mediated by modulating the second response characteristics. Thus, our data demonstrate reduced PPS due to an overall reduction of the first response as a form of modified PPS developing at old age. PMID:19745019

  16. Effects of the muscarinic antagonists pirenzepine and gallamine on spontaneous and evoked responses of rat cerebral cortical neurones.

    PubMed Central

    Swanson, T. H.; Phillis, J. W.

    1988-01-01

    1. The muscarinic receptor antagonists gallamine and pirenzepine were iontophoretically applied to rat cerebral cortical cholinoceptive neurones, including corticospinal neurones, to assess their effects on spontaneous firing, and firing induced by: stimulation of the nucleus basalis magnocellularis (NBM); contralateral hindpaw stimulation; application of acetylcholine (ACh); and application of glutamate. 2. Both compounds potently inhibited firing induced by ACh iontophoresis, whilst neither compound consistently altered firing induced by application of glutamate. 3. Gallamine was very effective and pirenzepine less effective, at inhibiting both spontaneous firing and the delayed firing induced by NBM stimulation. The short-latency excitations elicited by NBM stimulation were enhanced by these muscarinic antagonists. 4. Gallamine and pirenzepine enhanced cortical cholinoceptive cell firing induced by contralateral hindpaw stimulation. 5. It is concluded that gallamine depresses spontaneous activity more than pirenzepine, and that both compounds can affect the cortical cell firing evoked by stimulation of the NBM and of thalamo-cortical afferent fibres. PMID:3401638

  17. The cortical innate immune response increases local neuronal excitability leading to seizures

    PubMed Central

    Rodgers, Krista M.; Hutchinson, Mark R.; Northcutt, Alexis; Maier, Steven F.; Watkins, Linda R.

    2009-01-01

    Brain glial cells, five times more prevalent than neurons, have recently received attention for their potential involvement in epileptic seizures. Microglia and astrocytes, associated with inflammatory innate immune responses, are responsible for surveillance of brain damage that frequently results in seizures. Thus, an intriguing suggestion has been put forward that seizures may be facilitated and perhaps triggered by brain immune responses. Indeed, recent evidence strongly implicates innate immune responses in lowering seizure threshold in experimental models of epilepsy, yet, there is no proof that they can play an independent role in initiating seizures in vivo. Here, we show that cortical innate immune responses alone produce profound increases of brain excitability resulting in focal seizures. We found that cortical application of lipopolysaccharide, binding to toll-like receptor 4 (TLR4), triples evoked field potential amplitudes and produces focal epileptiform discharges. These effects are prevented by pre-application of interleukin-1 receptor antagonist. Our results demonstrate how the innate immune response may participate in acute seizures, increasing neuronal excitability through interleukin-1 release in response to TLR4 detection of the danger signals associated with infections of the central nervous system and with brain injury. These results suggest an important role of innate immunity in epileptogenesis and focus on glial inhibition, through pharmacological blockade of TLR4 and the pro-inflammatory mediators released by activated glia, in the study and treatment of seizure disorders in humans. PMID:19567702

  18. The responses of pericruciate cortical neurones to distal forepaw electrical stimulation in the unanaesthetized, unrestrained cat.

    PubMed

    Palmer, C I; Massion, J; Dufossé, M

    1986-01-01

    Experiments were performed to examine the responses of cortical neurons in the pericruciate cortex to cutaneous afferent input from the distal forepaw. Ninety-nine cortical neurons responding to electrical stimulation of the forepaw were recorded from four cats. Their response latencies ranged from 6 to 23 ms. The units had cutaneous receptive fields which ranged in size from those restricted to one digit to those extending over the whole forelimb. They were recorded from area 4 and area 3. Intracortical microstimulation at the recording sites activated either the distal or proximal musculature of the forelimb. When the characteristics obtained from each recording site were examined as a group of features, a uniform population emerged which was significantly different from the rest of the sample. These units had the shortest latency responses to distal forepaw electrical stimulation, the shortest duration of evoked discharge, the smallest distal cutaneous receptive fields. Such units were recorded at the border between areas 3 and 4, at sites which on microstimulation resulted in movements of the distal forepaw musculature.

  19. Neuronal Oscillations Indicate Sleep-dependent Changes in the Cortical Memory Trace.

    PubMed

    Köster, Moritz; Finger, Holger; Kater, Maren-Jo; Schenk, Christoph; Gruber, Thomas

    2017-04-01

    Sleep promotes the consolidation of newly acquired associative memories. Here we used neuronal oscillations in the human EEG to investigate sleep-dependent changes in the cortical memory trace. The retrieval activity for object-color associations was assessed immediately after encoding and after 3 hr of sleep or wakefulness. Sleep had beneficial effects on memory performance and led to reduced event-related theta and gamma power during the retrieval of associative memories. Furthermore, event-related alpha suppression was attenuated in the wake group for memorized and novel stimuli. There were no sleep-dependent changes in retrieval activity for missed items or items retrieved without color. Thus, the sleep-dependent reduction in theta and gamma oscillations was specific for the retrieval of associative memories. In line with theoretical accounts on sleep-dependent memory consolidation, decreased theta may indicate reduced mediotemporal activity because of a transfer of information into neocortical networks during sleep, whereas reduced parietal gamma may reflect effects of synaptic downscaling. Changes in alpha suppression in the wake group possibly index reduced attentional resources that may also contribute to a lower memory performance in this group. These findings indicate that the consolidation of associative memories during sleep is associated with profound changes in the cortical memory trace and relies on multiple neuronal processes working in concert.

  20. Neurites regrowth of cortical neurons by GSK3beta inhibition independently of Nogo receptor 1.

    PubMed

    Seira, Oscar; Gavín, Rosalina; Gil, Vanessa; Llorens, Franc; Rangel, Alejandra; Soriano, Eduardo; del Río, José Antonio

    2010-06-01

    Lesioned axons do not regenerate in the adult mammalian CNS, owing to the over-expression of inhibitory molecules such as myelin-derived proteins or chondroitin sulphate proteoglycans. In order to overcome axon inhibition, strategies based on extrinsic and intrinsic treatments have been developed. For myelin-associated inhibition, blockage with NEP1-40, receptor bodies or IN-1 antibodies has been used. In addition, endogenous blockage of cell signalling mechanisms induced by myelin-associated proteins is a potential tool for overcoming axon inhibitory signals. We examined the participation of glycogen synthase kinase 3beta (GSK3beta) and extracellular-related kinase (ERK) 1/2 in axon regeneration failure in lesioned cortical neurons. We also investigated whether pharmacological blockage of GSK3beta and ERK1/2 activities facilitates regeneration after myelin-directed inhibition in two models: (i) cerebellar granule cells and (ii) lesioned entorhino-hippocampal pathway in slice cultures, and whether the regenerative effects are mediated by Nogo Receptor 1 (NgR1). We demonstrate that, in contrast to ERK1/2 inhibition, the pharmacological treatment of GSK3beta inhibition strongly facilitated regrowth of cerebellar granule neurons over myelin independently of NgR1. Finally, these regenerative effects were corroborated in the lesioned entorhino-hippocampal pathway in NgR1-/- mutant mice. These results provide new findings for the development of new assays and strategies to enhance axon regeneration in injured cortical connections.

  1. TRPV1 stimulation triggers apoptotic cell death of rat cortical neurons

    SciTech Connect

    Shirakawa, Hisashi; Yamaoka, Tomoko; Sanpei, Kazuaki; Sasaoka, Hirotoshi; Nakagawa, Takayuki; Kaneko, Shuji

    2008-12-26

    Transient receptor potential vanilloid 1 (TRPV1) functions as a polymodal nociceptor and is activated by several vanilloids, including capsaicin, protons and heat. Although TRPV1 channels are widely distributed in the brain, their roles remain unclear. Here, we investigated the roles of TRPV1 in cytotoxic processes using TRPV1-expressing cultured rat cortical neurons. Capsaicin induced severe neuronal death with apoptotic features, which was completely inhibited by the TRPV1 antagonist capsazepine and was dependent on extracellular Ca{sup 2+} influx. Interestingly, nifedipine, a specific L-type Ca{sup 2+} channel blocker, attenuated capsaicin cytotoxicity, even when applied 2-4 h after the capsaicin. ERK inhibitor PD98059 and several antioxidants, but not the JNK and p38 inhibitors, attenuated capsaicin cytotoxicity. Together, these data indicate that TRPV1 activation triggers apoptotic cell death of rat cortical cultures via L-type Ca{sup 2+} channel opening, Ca{sup 2+} influx, ERK phosphorylation, and reactive oxygen species production.

  2. Neuroprotective effect of the endogenous neural peptide apelin in cultured mouse cortical neurons

    SciTech Connect

    Zeng, Xiang Jun; Yu, Shan Ping; Zhang, Like; Wei, Ling

    2010-07-01

    The adipocytokine apelin and its G protein-coupled APJ receptor were initially isolated from a bovine stomach and have been detected in the brain and cardiovascular system. Recent studies suggest that apelin can protect cardiomyocytes from ischemic injury. Here, we investigated the effect of apelin on apoptosis in mouse primary cultures of cortical neurons. Exposure of the cortical cultures to a serum-free medium for 24 h induced nuclear fragmentation and apoptotic death; apelin-13 (1.0-5.0 nM) markedly prevented the neuronal apoptosis. Apelin neuroprotective effects were mediated by multiple mechanisms. Apelin-13 reduced serum deprivation (SD)-induced ROS generation, mitochondria depolarization, cytochrome c release and activation of caspase-3. Apelin-13 prevented SD-induced changes in phosphorylation status of Akt and ERK1/2. In addition, apelin-13 attenuated NMDA-induced intracellular Ca{sup 2+} accumulation. These results indicate that apelin is an endogenous neuroprotective adipocytokine that may block apoptosis and excitotoxic death via cellular and molecular mechanisms. It is suggested that apelins may be further explored as a potential neuroprotective reagent for ischemia-induced brain damage.

  3. Generation of human cortical neurons from a new immortal fetal neural stem cell line

    SciTech Connect

    Cacci, E.; Villa, A.; Parmar, M.; Cavallaro, M.; Mandahl, N.; Lindvall, O.; Martinez-Serrano, A.; Kokaia, Z. . E-mail: Zaal.Kokaia@med.lu.se

    2007-02-01

    Isolation and expansion of neural stem cells (NSCs) of human origin are crucial for successful development of cell therapy approaches in neurodegenerative diseases. Different epigenetic and genetic immortalization strategies have been established for long-term maintenance and expansion of these cells in vitro. Here we report the generation of a new, clonal NSC (hc-NSC) line, derived from human fetal cortical tissue, based on v-myc immortalization. Using immunocytochemistry, we show that these cells retain the characteristics of NSCs after more than 50 passages. Under proliferation conditions, when supplemented with epidermal and basic fibroblast growth factors, the hc-NSCs expressed neural stem/progenitor cell markers like nestin, vimentin and Sox2. When growth factors were withdrawn, proliferation and expression of v-myc and telomerase were dramatically reduced, and the hc-NSCs differentiated into glia and neurons (mostly glutamatergic and GABAergic, as well as tyrosine hydroxylase-positive, presumably dopaminergic neurons). RT-PCR analysis showed that the hc-NSCs retained expression of Pax6, Emx2 and Neurogenin2, which are genes associated with regionalization and cell commitment in cortical precursors during brain development. Our data indicate that this hc-NSC line could be useful for exploring the potential of human NSCs to replace dead or damaged cortical cells in animal models of acute and chronic neurodegenerative diseases. Taking advantage of its clonality and homogeneity, this cell line will also be a valuable experimental tool to study the regulatory role of intrinsic and extrinsic factors in human NSC biology.

  4. Encoding of High Frequencies Improves with Maturation of Action Potential Generation in Cultured Neocortical Neurons

    PubMed Central

    Nikitin, Evgeny S.; Bal, Natalia V.; Malyshev, Aleksey; Ierusalimsky, Victor N.; Spivak, Yulia; Balaban, Pavel M.; Volgushev, Maxim

    2017-01-01

    The ability of neocortical neurons to detect and encode rapid changes at their inputs is crucial for basic neuronal computations, such as coincidence detection, precise synchronization of activity and spike-timing dependent plasticity. Indeed, populations of cortical neurons can respond to subtle changes of the input very fast, on a millisecond time scale. Theoretical studies and model simulations linked the encoding abilities of neuronal populations to the fast onset dynamics of action potentials (APs). Experimental results support this idea, however mechanisms of fast onset of APs in cortical neurons remain elusive. Studies in neuronal cultures, that are allowing for accurate control over conditions of growth and microenvironment during the development of neurons and provide better access to the spike initiation zone, may help to shed light on mechanisms of AP generation and encoding. Here we characterize properties of AP encoding in neocortical neurons grown for 11–25 days in culture. We show that encoding of high frequencies improves upon culture maturation, which is accompanied by the development of passive electrophysiological properties and AP generation. The onset of APs becomes faster with culture maturation. Statistical analysis using correlations and linear model approaches identified the onset dynamics of APs as a major predictor of age-dependent changes of encoding. Encoding of high frequencies strongly correlated also with the input resistance of neurons. Finally, we show that maturation of encoding properties of neurons in cultures is similar to the maturation of encoding in neurons studied in slices. These results show that maturation of AP generators and encoding is, to a large extent, determined genetically and takes place even without normal micro-environment and activity of the whole brain in vivo. This establishes neuronal cultures as a valid experimental model for studying mechanisms of AP generation and encoding, and their maturation. PMID

  5. Augmented neuronal death in CA3 hippocampus following hyperventilation early after controlled cortical impact.

    PubMed

    Forbes, M L; Clark, R S; Dixon, C E; Graham, S H; Marion, D W; DeKosky, S T; Schiding, J K; Kochanek, P M

    1998-03-01

    Minimizing secondary injury after severe traumatic brain injury (TBI) is the primary goal of cerebral resuscitation. For more than two decades, hyperventilation has been one of the most often used strategies in the management of TBI. Laboratory and clinical studies, however, have verified a post-TBI state of reduced cerebral perfusion that may increase the brain's vulnerability to secondary injury. In addition, it has been suggested in a clinical study that hyperventilation may worsen outcome after TBI. Using the controlled cortical impact model in rats, the authors tested the hypothesis that aggressive hyperventilation applied immediately after TBI would worsen functional outcome, expand the contusion, and promote neuronal death in selectively vulnerable hippocampal neurons. Twenty-six intubated, mechanically ventilated, isoflurane-anesthetized male Sprague-Dawley rats were subjected to controlled cortical impact (4 m/second, 2.5-mm depth of deformation) and randomized after 10 minutes to either hyperventilation (PaCO2 = 20.3 +/- 0.7 mm Hg) or normal ventilation groups (PaCO2 = 34.9 +/- 0.3 mm Hg) containing 13 rats apiece and were treated for 5 hours. Beam balance and Morris water maze (MWM) performance latencies were measured in eight rats from each group on Days 1 to 5 and 7 to 11, respectively, after controlled cortical impact. The rats were killed at 14 days postinjury, and serial coronal sections of their brains were studied for contusion volume and hippocampal neuron counting (CA1, CA3) by an observer who was blinded to their treatment group. Mortality rates were similar in both groups (two of 13 in the normal ventilation compared with three of 13 in the hyperventilation group, not significant [NS]). There were no differences between the groups in mean arterial blood pressure, brain temperature, and serum glucose concentration. There were no differences between groups in performance latencies for both beam balance and MWM or contusion volume (27.8 +/- 5

  6. Self-organized two-state membrane potential transitions in a network of realistically modeled cortical neurons.

    PubMed

    Kang, Siu; Kitano, Katsunori; Fukai, Tomoki

    2004-04-01

    Recent studies have revealed that in vivo cortical neurons show spontaneous transitions between two subthreshold levels of the membrane potentials, 'up' and 'down' states. The neural mechanism of generating those spontaneous states transitions, however, remains unclear. Recent electrophysiological studies have suggested that those state transitions may occur through activation of a hyperpolarization-activated cation current (H-current), possibly by inhibitory synaptic inputs. Here, we demonstrate that two-state membrane potential fluctuations similar to those exhibited by in vivo neurons can be generated through a spike-timing-dependent self-organizing process in a network of inhibitory neurons and excitatory neurons expressing the H-current.

  7. In Utero Electroporation: Assay System for Migration of Cerebral Cortical Neurons

    NASA Astrophysics Data System (ADS)

    Tabata, Hidenori; Nakajima, Kazunori

    During the development of the cerebral cortex, the majority of cortical neurons are generated in the ventricular zone (VZ) facing the lateral ventricle and then migrate toward the pial surface to form the highly organized 6-layered cerebral cortex. Detailed profiles of these processes and their molecular mechanisms had been largely unknown because of the absence of an efficient assay system. The in vivo electroporation system was initially devised for use within chick embryos (Funahashi et al., 1999; Itasaki et al., 1999; Momose et al., 1999; Muramatsu et al., 1997), and we and other groups have used that system as a basis for developing an in utero electroporation system, which allows plasmid DNA to be introduced into cortical progenitor cells in developing mouse embryos in the uterus (Fukuchi-Shimogori and Grove, 2001; Saito and Nakatsuji, 2001; Tabata and Nakajima, 2001; Takahashi et al., 2002). In utero electroporation of other sites in the brain, including the hippocampus (Navarro-Quiroga et al., 2007), cerebral basal ganglia (Borrell et al., 2005; Nakahira et al., 2006), cortical hem (Takiguchi-Hayashi et al., 2004), and dorsal thalamus (Bonnin et al., 2007), has recently been reported. Introducing green fluorescent protein (GFP) enables the entire processes of migration and layer formation to be visualized (Ajioka and Nakajima, 2005; Sasaki et al., 2008; Tabata and Nakajima, 2002, 2003), and the role of any gene involved in these processes can be easily assessed by overexpressing the proteins or their mutants (Ohshima et al., 2007), or by knocking down the genes by the RNA interference technique (Bai et al., 2003). Furthermore, the Tet-On/Off system and/or other plasmid- vector-based technologies will expand the potential of the analyses. In this section we review the principles and methods of gene transfer into the cortical wall of mouse embryos by means of the in utero electroporation system.

  8. Maximal variability of phase synchrony in cortical networks with neuronal avalanches

    PubMed Central

    Yang, Hongdian; Shew, Woodrow L.; Roy, Rajarshi; Plenz, Dietmar

    2012-01-01

    Ongoing interactions among cortical neurons often manifest as network-level synchrony. Understanding the spatiotemporal dynamics of such spontaneous synchrony is important because it may 1) influence network response to input, 2) shape activity-dependent microcircuit structure, and 3) reveal fundamental network properties, such as an imbalance of excitation (E) and inhibition (I). Here we delineate the spatiotemporal character of spontaneous synchrony in rat cortex slice cultures and a computational model over a range of different E-I conditions including disfacilitated (antagonized AMPA, NMDA receptors), unperturbed, and disinhibited (antagonized GABAA receptors). Local field potential was recorded with multi-electrode arrays during spontaneous burst activity. Synchrony among neuronal groups was quantified based on phase-locking among recording sites. As network excitability was increased from low to high, we discovered three phenomena at an intermediate excitability level: 1) onset of synchrony, 2) maximized variability of synchrony, and 3) neuronal avalanches. Our computational model predicted that these three features occur when the network operates near a unique balanced E-I condition called ‘criticality’. These results were invariant to changes in the measurement spatial extent, spatial resolution, and frequency bands. Our findings indicate that moderate average synchrony, which is required to avoid pathology, occurs over a limited range of E-I conditions and emerges together with maximally variable synchrony. If variable synchrony is detrimental to cortical function, this is a cost paid for moderate average synchrony. However, if variable synchrony is beneficial, then by operating near criticality the cortex may doubly benefit from moderate mean and maximized variability of synchrony. PMID:22262904

  9. The Dynamic Brain: From Spiking Neurons to Neural Masses and Cortical Fields

    PubMed Central

    Deco, Gustavo; Jirsa, Viktor K.; Robinson, Peter A.; Breakspear, Michael; Friston, Karl

    2008-01-01

    The cortex is a complex system, characterized by its dynamics and architecture, which underlie many functions such as action, perception, learning, language, and cognition. Its structural architecture has been studied for more than a hundred years; however, its dynamics have been addressed much less thoroughly. In this paper, we review and integrate, in a unifying framework, a variety of computational approaches that have been used to characterize the dynamics of the cortex, as evidenced at different levels of measurement. Computational models at different space–time scales help us understand the fundamental mechanisms that underpin neural processes and relate these processes to neuroscience data. Modeling at the single neuron level is necessary because this is the level at which information is exchanged between the computing elements of the brain; the neurons. Mesoscopic models tell us how neural elements interact to yield emergent behavior at the level of microcolumns and cortical columns. Macroscopic models can inform us about whole brain dynamics and interactions between large-scale neural systems such as cortical regions, the thalamus, and brain stem. Each level of description relates uniquely to neuroscience data, from single-unit recordings, through local field potentials to functional magnetic resonance imaging (fMRI), electroencephalogram (EEG), and magnetoencephalogram (MEG). Models of the cortex can establish which types of large-scale neuronal networks can perform computations and characterize their emergent properties. Mean-field and related formulations of dynamics also play an essential and complementary role as forward models that can be inverted given empirical data. This makes dynamic models critical in integrating theory and experiments. We argue that elaborating principled and informed models is a prerequisite for grounding empirical neuroscience in a cogent theoretical framework, commensurate with the achievements in the physical sciences

  10. Maximal variability of phase synchrony in cortical networks with neuronal avalanches.

    PubMed

    Yang, Hongdian; Shew, Woodrow L; Roy, Rajarshi; Plenz, Dietmar

    2012-01-18

    Ongoing interactions among cortical neurons often manifest as network-level synchrony. Understanding the spatiotemporal dynamics of such spontaneous synchrony is important because it may (1) influence network response to input, (2) shape activity-dependent microcircuit structure, and (3) reveal fundamental network properties, such as an imbalance of excitation (E) and inhibition (I). Here we delineate the spatiotemporal character of spontaneous synchrony in rat cortex slice cultures and a computational model over a range of different E-I conditions including disfacilitated (antagonized AMPA, NMDA receptors), unperturbed, and disinhibited (antagonized GABA(A) receptors). Local field potential was recorded with multielectrode arrays during spontaneous burst activity. Synchrony among neuronal groups was quantified based on phase-locking among recording sites. As network excitability was increased from low to high, we discovered three phenomena at an intermediate excitability level: (1) onset of synchrony, (2) maximized variability of synchrony, and (3) neuronal avalanches. Our computational model predicted that these three features occur when the network operates near a unique balanced E-I condition called "criticality." These results were invariant to changes in the measurement spatial extent, spatial resolution, and frequency bands. Our findings indicate that moderate average synchrony, which is required to avoid pathology, occurs over a limited range of E-I conditions and emerges together with maximally variable synchrony. If variable synchrony is detrimental to cortical function, this is a cost paid for moderate average synchrony. However, if variable synchrony is beneficial, then by operating near criticality the cortex may doubly benefit from moderate mean and maximized variability of synchrony.

  11. Tissue-type plasminogen activator induces synaptic vesicle endocytosis in cerebral cortical neurons.

    PubMed

    Yepes, M; Wu, F; Torre, E; Cuellar-Giraldo, D; Jia, D; Cheng, L

    2016-04-05

    The release of the serine proteinase tissue-type plasminogen activator (tPA) from the presynaptic terminal of cerebral cortical neurons plays a central role in the development of synaptic plasticity, adaptation to metabolic stress and neuronal survival. Our earlier studies indicate that by inducing the recruitment of the cytoskeletal protein βII-spectrin and voltage-gated calcium channels to the active zone, tPA promotes Ca(2+)-dependent translocation of synaptic vesicles (SVs) to the synaptic release site where they release their load of neurotransmitters into the synaptic cleft. Here we used a combination of in vivo and in vitro experiments to investigate whether this effect leads to depletion of SVs in the presynaptic terminal. Our data indicate that tPA promotes SV endocytosis via a mechanism that does not require the conversion of plasminogen into plasmin. Instead, we show that tPA induces calcineurin-mediated dynamin I dephosphorylation, which is followed by dynamin I-induced recruitment of the actin-binding protein profilin II to the presynaptic membrane, and profilin II-induced F-actin formation. We report that this tPA-induced sequence of events leads to the association of newly formed SVs with F-actin clusters in the endocytic zone. In summary, the data presented here indicate that following the exocytotic release of neurotransmitters tPA activates the mechanism whereby SVs are retrieved from the presynaptic membrane and endocytosed to replenish the pool of vesicles available for a new cycle of exocytosis. Together, these results indicate that in murine cerebral cortical neurons tPA plays a central role coupling SVs exocytosis and endocytosis.

  12. Combined small-molecule inhibition accelerates the derivation of functional cortical neurons from human pluripotent stem cells.

    PubMed

    Qi, Yuchen; Zhang, Xin-Jun; Renier, Nicolas; Wu, Zhuhao; Atkin, Talia; Sun, Ziyi; Ozair, M Zeeshan; Tchieu, Jason; Zimmer, Bastian; Fattahi, Faranak; Ganat, Yosif; Azevedo, Ricardo; Zeltner, Nadja; Brivanlou, Ali H; Karayiorgou, Maria; Gogos, Joseph; Tomishima, Mark; Tessier-Lavigne, Marc; Shi, Song-Hai; Studer, Lorenz

    2017-02-01

    Considerable progress has been made in converting human pluripotent stem cells (hPSCs) into functional neurons. However, the protracted timing of human neuron specification and functional maturation remains a key challenge that hampers the routine application of hPSC-derived lineages in disease modeling and regenerative medicine. Using a combinatorial small-molecule screen, we previously identified conditions to rapidly differentiate hPSCs into peripheral sensory neurons. Here we generalize the approach to central nervous system (CNS) fates by developing a small-molecule approach for accelerated induction of early-born cortical neurons. Combinatorial application of six pathway inhibitors induces post-mitotic cortical neurons with functional electrophysiological properties by day 16 of differentiation, in the absence of glial cell co-culture. The resulting neurons, transplanted at 8 d of differentiation into the postnatal mouse cortex, are functional and establish long-distance projections, as shown using iDISCO whole-brain imaging. Accelerated differentiation into cortical neuron fates should facilitate hPSC-based strategies for disease modeling and cell therapy in CNS disorders.

  13. Graded defragmentation of cortical neuronal firing during recovery of consciousness in rats.

    PubMed

    Vizuete, J A; Pillay, S; Ropella, K M; Hudetz, A G

    2014-09-05

    State-dependent neuronal firing patterns reflect changes in ongoing information processing and cortical function. A disruption of neuronal coordination has been suggested as the neural correlate of anesthesia. Here, we studied the temporal correlation patterns of ongoing spike activity, during a stepwise reduction of the volatile anesthetic desflurane, in the cerebral cortex of freely moving rats. We hypothesized that the recovery of consciousness from general anesthesia is accompanied by specific changes in the spatiotemporal pattern and correlation of neuronal activity. Sixty-four contact microelectrode arrays were chronically implanted in the primary visual cortex (contacts spanning 1.4-mm depth and 1.4-mm width) for recording of extracellular unit activity at four steady-state levels of anesthesia (8-2% desflurane) and wakefulness. Recovery of consciousness was defined as the regaining of the righting reflex (near 4%). High-intensity firing (HI) periods were segmented using a threshold (200-ms) representing the minimum in the neurons' bimodal interspike interval histogram under anesthesia. We found that the HI periods were highly fragmented in deep anesthesia and gradually transformed to a near-continuous firing pattern at wakefulness. As the anesthetic was withdrawn, HI periods became longer and increasingly correlated among the units both locally and across remote recording sites. Paradoxically, in 4 of 8 animals, HI correlation was also high at the deepest level of anesthesia (8%) when local field potentials (LFP) were burst-suppressed. We conclude that recovery from desflurane anesthesia is accompanied by a graded defragmentation of neuronal activity in the cerebral cortex. Hypersynchrony during deep anesthesia is an exception that occurs only with LFP burst suppression. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  14. Orbitofrontal Cortical Neurons Encode Expectation-Driven Initiation of Reward-Seeking

    PubMed Central

    Aston-Jones, Gary

    2014-01-01

    Adaptive execution and inhibition of behavior are guided by the activity of neuronal populations across multiple frontal cortical areas. The rodent medial prefrontal cortex has been well studied with respect to these behaviors, influencing behavioral execution/inhibition based on context. Other frontal regions, in particular the orbitofrontal cortex (OFC), are critical in directing behavior to obtain rewards, but the relationship between OFC neuronal activity and response execution or inhibition has been poorly characterized. In particular, little is known about OFC with respect to extinction learning, an important example of context-guided response inhibition. Here, we recorded the activity of OFC neurons while rats performed a discriminative-stimulus (DS)-driven sucrose-seeking task followed by multiple days of extinction of the DS. OFC neuronal activity was maximally responsive (1) to reward-predicting stimuli (RS) that triggered a lever press (i.e., lever-response initiation) and (2) during reward-well approach in pursuit of sucrose (i.e., well-response initiation). RS presentation that was not followed by a lever press or RS presentation during extinction produced weak activation, as did nonrewarded stimulus (NS) presentation regardless of response (press or withhold) or session (DS-sucrose or extinction). Activity related to nonrewarded well entry was minor, and activity was significantly inhibited during reward consumption. Finally, OFC neuronal activity switched selectivity to track rewarded behaviors when the RS/NS contingencies were reversed. Thus, rather than signaling variables related to extinction or response inhibition, activity in OFC was strongest at the initiation of multiple components of reward-seeking behavior, most prominently when valid reward-predicting cues drove these behaviors. PMID:25080585

  15. Orbitofrontal cortical neurons encode expectation-driven initiation of reward-seeking.

    PubMed

    Moorman, David E; Aston-Jones, Gary

    2014-07-30

    Adaptive execution and inhibition of behavior are guided by the activity of neuronal populations across multiple frontal cortical areas. The rodent medial prefrontal cortex has been well studied with respect to these behaviors, influencing behavioral execution/inhibition based on context. Other frontal regions, in particular the orbitofrontal cortex (OFC), are critical in directing behavior to obtain rewards, but the relationship between OFC neuronal activity and response execution or inhibition has been poorly characterized. In particular, little is known about OFC with respect to extinction learning, an important example of context-guided response inhibition. Here, we recorded the activity of OFC neurons while rats performed a discriminative-stimulus (DS)-driven sucrose-seeking task followed by multiple days of extinction of the DS. OFC neuronal activity was maximally responsive (1) to reward-predicting stimuli (RS) that triggered a lever press (i.e., lever-response initiation) and (2) during reward-well approach in pursuit of sucrose (i.e., well-response initiation). RS presentation that was not followed by a lever press or RS presentation during extinction produced weak activation, as did nonrewarded stimulus (NS) presentation regardless of response (press or withhold) or session (DS-sucrose or extinction). Activity related to nonrewarded well entry was minor, and activity was significantly inhibited during reward consumption. Finally, OFC neuronal activity switched selectivity to track rewarded behaviors when the RS/NS contingencies were reversed. Thus, rather than signaling variables related to extinction or response inhibition, activity in OFC was strongest at the initiation of multiple components of reward-seeking behavior, most prominently when valid reward-predicting cues drove these behaviors.

  16. Use of cortical neuronal networks for in vitro material biocompatibility testing.

    PubMed

    Charkhkar, Hamid; Frewin, Christopher; Nezafati, Maysam; Knaack, Gretchen L; Peixoto, Nathalia; Saddow, Stephen E; Pancrazio, Joseph J

    2014-03-15

    Neural interfaces aim to restore neurological function lost during disease or injury. Novel implantable neural interfaces increasingly capitalize on novel materials to achieve microscale coupling with the nervous system. Like any biomedical device, neural interfaces should consist of materials that exhibit biocompatibility in accordance with the international standard ISO10993-5, which describes in vitro testing involving fibroblasts where cytotoxicity serves as the main endpoint. In the present study, we examine the utility of living neuronal networks as functional assays for in vitro material biocompatibility, particularly for materials that comprise implantable neural interfaces. Embryonic mouse cortical tissue was cultured to form functional networks where spontaneous action potentials, or spikes, can be monitored non-invasively using a substrate-integrated microelectrode array. Taking advantage of such a platform, we exposed established positive and negative control materials to the neuronal networks in a consistent method with ISO 10993-5 guidance. Exposure to the negative controls, gold and polyethylene, did not significantly change the neuronal activity whereas the positive controls, copper and polyvinyl chloride (PVC), resulted in reduction of network spike rate. We also compared the functional assay with an established cytotoxicity measure using L929 fibroblast cells. Our findings indicate that neuronal networks exhibit enhanced sensitivity to positive control materials. In addition, we assessed functional neurotoxicity of tungsten, a common microelectrode material, and two conducting polymer formulations that have been used to modify microelectrode properties for in vivo recording and stimulation. These data suggest that cultured neuronal networks are a useful platform for evaluating the functional toxicity of materials intended for implantation in the nervous system.

  17. Synaptic responsiveness of cortical and thalamic neurones during various phases of slow sleep oscillation in cat.

    PubMed Central

    Timofeev, I; Contreras, D; Steriade, M

    1996-01-01

    1. The fluctuations during various phases of the slow sleep oscillation (< 1 Hz) in synaptic responsiveness of motor cortical (Cx), thalamic reticular (RE) and thalamocortical (TC) neurones were investigated intracellularly in cats under ketamine-xylazine anaesthesia. Orthodromic responses to stimuli applied to brachium conjunctivum (BC) axons and corticothalamic pathways were studied. The phases of slow oscillation consist of a long-hyperpolarized, followed by a sharp depth-negative EEG deflection and a series of faster waves that are associated with the depolarization of Cx and RE neurones, while TC cells display a sequence of IPSPs within the spindle frequency. 2. BC-evoked bisynaptic excitatory postsynaptic potentials (EPSPs) in Cx and RE neurones were drastically reduced in amplitude during the long-lasting hyperpolarization and the early part of the depolarizing phase. By contrast, the BC-evoked monosynaptic EPSPs of TC cells were not diminished during the depth-positive EEG wave, but the hyperpolarization during this phase of the slow oscillation prevented TC neurones transferring prethalamic signals to the cortex. 3. At variance with the diminished bisynaptic EPSPs evoked in response to BC stimuli during the long-lasting hyperpolarization, Cx-evoked monosynaptic EPSPs in Cx cells increased linearly with hyperpolarization during this phase of the slow oscillation. Similarly, the amplitudes of Cx-evoked EPSPs in RE and TC cells were not diminished during the long-lasting hyperpolarization. 4. The diminished responsiveness of Cx and RE neurones to prethalamic volleys during the long-lasting hyperpolarization is attributed to gating processes at the level of TC cells that, because of their hyperpolarization, do not transfer prethalamic information to further relays. PMID:8814620

  18. Potential protection of green tea polyphenols against 1800 MHz electromagnetic radiation-induced injury on rat cortical neurons.

    PubMed

    Liu, Mei-Li; Wen, Jian-Qiang; Fan, Yu-Bo

    2011-10-01

    Radiofrequency electromagnetic fields (EMF) are harmful to public health, but the certain anti-irradiation mechanism is not clear yet. The present study was performed to investigate the possible protective effects of green tea polyphenols against electromagnetic radiation-induced injury in the cultured rat cortical neurons. In this study, green tea polyphenols were used in the cultured cortical neurons exposed to 1800 MHz EMFs by the mobile phone. We found that the mobile phone irradiation for 24 h induced marked neuronal cell death in the MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl-tetrazolium bromide) and TUNEL (TdT mediated biotin-dUTP nicked-end labeling) assay, and protective effects of green tea polyphenols on the injured cortical neurons were demonstrated by testing the content of Bcl-2 Assaciated X protein (Bax) in the immunoprecipitation assay and Western blot assay. In our study results, the mobile phone irradiation-induced increases in the content of active Bax were inhibited significantly by green tea polyphenols, while the contents of total Bax had no marked changes after the treatment of green tea polyphenols. Our results suggested a neuroprotective effect of green tea polyphenols against the mobile phone irradiation-induced injury on the cultured rat cortical neurons.

  19. A role for cortical nNOS/NK1 neurons in coupling homeostatic sleep drive to EEG slow wave activity.

    PubMed

    Morairty, Stephen R; Dittrich, Lars; Pasumarthi, Ravi K; Valladao, Daniel; Heiss, Jaime E; Gerashchenko, Dmitry; Kilduff, Thomas S

    2013-12-10

    Although the neural circuitry underlying homeostatic sleep regulation is little understood, cortical neurons immunoreactive for neuronal nitric oxide synthase (nNOS) and the neurokinin-1 receptor (NK1) have been proposed to be involved in this physiological process. By systematically manipulating the durations of sleep deprivation and subsequent recovery sleep, we show that activation of cortical nNOS/NK1 neurons is directly related to non-rapid eye movement (NREM) sleep time, NREM bout duration, and EEG δ power during NREM sleep, an index of preexisting homeostatic sleep drive. Conversely, nNOS knockout mice show reduced NREM sleep time, shorter NREM bouts, and decreased power in the low δ range during NREM sleep, despite constitutively elevated sleep drive. Cortical NK1 neurons are still activated in response to sleep deprivation in these mice but, in the absence of nNOS, they are unable to up-regulate NREM δ power appropriately. These findings support the hypothesis that cortical nNOS/NK1 neurons translate homeostatic sleep drive into up-regulation of NREM δ power through an NO-dependent mechanism.

  20. Resveratrol attenuates cortical neuron activity: roles of large conductance calcium-activated potassium channels and voltage-gated sodium channels.

    PubMed

    Wang, Ya-Jean; Chan, Ming-Huan; Chen, Linyi; Wu, Sheng-Nan; Chen, Hwei-Hisen

    2016-05-21

    Resveratrol, a phytoalexin found in grapes and red wine, exhibits diverse pharmacological activities. However, relatively little is known about whether resveratrol modulates the ion channels in cortical neurons. The large-conductance calcium-activated potassium channels (BKCa) and voltage-gated sodium channels were expressed in cortical neurons and play important roles in regulation of neuronal excitability. The present study aimed to determine the effects of resveratrol on BKCa currents and voltage-gated sodium currents in cortical neurons. Resveratrol concentration-dependently increased the current amplitude and the opening activity of BKCa channels, but suppressed the amplitude of voltage-gated sodium currents. Similar to the BKCa channel opener NS1619, resveratrol decreased the firing rate of action potentials. In addition, the enhancing effects of BKCa channel blockers tetraethylammonium (TEA) and paxilline on action potential firing were sensitive to resveratrol. Our results indicated that the attenuation of action potential firing rate by resveratrol might be mediated through opening the BKCa channels and closing the voltage-gated sodium channels. As BKCa channels and sodium channels are critical molecular determinants for seizure generation, our findings suggest that regulation of these two channels in cortical neurons probably makes a considerable contribution to the antiseizure activity of resveratrol.

  1. AP-1 Transcription Factors Mediate BDNF-Positive Feedback Loop in Cortical Neurons.

    PubMed

    Tuvikene, Jürgen; Pruunsild, Priit; Orav, Ester; Esvald, Eli-Eelika; Timmusk, Tõnis

    2016-01-27

    Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, regulates both survival and differentiation of several neuronal populations in the nervous system during development, as well as synaptic plasticity in the adult brain. BDNF exerts its biological functions through its receptor TrkB. Although the regulation of BDNF transcription by neuronal activity has been widely studied, little is known about TrkB signaling-dependent expression of BDNF. Using rat primary cortical neuron cultures, we show that the BDNF gene is a subject to an extensive autoregulatory loop, where TrkB signaling upregulates the expression of all major BDNF transcripts, mainly through activating MAPK pathways. Investigating the mechanisms behind this autoregulation, we found that AP-1 transcription factors, comprising Jun and Fos family members, participate in the induction of BDNF exon I, III, and VI transcripts. AP-1 transcription factors directly upregulate the expression of exon I transcripts by binding two novel AP-1 cis-elements in promoter I. Moreover, our results show that the effect of AP-1 proteins on the activity of rat BDNF promoters III and VI is indirect, because AP-1 proteins were not detected to bind the respective promoter regions by chromatin immunoprecipitation (ChIP). Collectively, we describe an extensive positive feedback system in BDNF regulation, adding a new layer to the elaborate control of BDNF gene expression. Here, we show for the first time that in rat primary cortical neurons the expression of all major BDNF transcripts (exon I, II, III, IV, VI, and IXa transcripts) is upregulated in response to TrkB signaling, and that AP-1 transcription factors participate in the induction of exon I, III, and VI transcripts. Moreover, we have described two novel functional AP-1 cis-elements in BDNF promoter I, responsible for the activation of the promoter in response to TrkB signaling. Our results indicate the existence of a positive feedback loop for

  2. Upregulation of transmitter release probability improves a conversion of synaptic analogue signals into neuronal digital spikes

    PubMed Central

    2012-01-01

    Action potentials at the neurons and graded signals at the synapses are primary codes in the brain. In terms of their functional interaction, the studies were focused on the influence of presynaptic spike patterns on synaptic activities. How the synapse dynamics quantitatively regulates the encoding of postsynaptic digital spikes remains unclear. We investigated this question at unitary glutamatergic synapses on cortical GABAergic neurons, especially the quantitative influences of release probability on synapse dynamics and neuronal encoding. Glutamate release probability and synaptic strength are proportionally upregulated by presynaptic sequential spikes. The upregulation of release probability and the efficiency of probability-driven synaptic facilitation are strengthened by elevating presynaptic spike frequency and Ca2+. The upregulation of release probability improves spike capacity and timing precision at postsynaptic neuron. These results suggest that the upregulation of presynaptic glutamate release facilitates a conversion of synaptic analogue signals into digital spikes in postsynaptic neurons, i.e., a functional compatibility between presynaptic and postsynaptic partners. PMID:22852823

  3. Characterization of energy and neurotransmitter metabolism in cortical glutamatergic neurons derived from human induced pluripotent stem cells: A novel approach to study metabolism in human neurons.

    PubMed

    Aldana, Blanca I; Zhang, Yu; Lihme, Maria Fog; Bak, Lasse K; Nielsen, Jørgen E; Holst, Bjørn; Hyttel, Poul; Freude, Kristine K; Waagepetersen, Helle S

    2017-02-24

    Alterations in the cellular metabolic machinery of the brain are associated with neurodegenerative disorders such as Alzheimer's disease. Novel human cellular disease models are essential in order to study underlying disease mechanisms. In the present study, we characterized major metabolic pathways in neurons derived from human induced pluripotent stem cells (hiPSC). With this aim, cultures of hiPSC-derived neurons were incubated with [U-(13)C]glucose, [U-(13)C]glutamate or [U-(13)C]glutamine. Isotopic labeling in metabolites was determined using gas chromatography coupled to mass spectrometry, and cellular amino acid content was quantified by high-performance liquid chromatography. Additionally, we evaluated mitochondrial function using real-time assessment of oxygen consumption via the Seahorse XF(e)96 Analyzer. Moreover, in order to validate the hiPSC-derived neurons as a model system, a metabolic profiling was performed in parallel in primary neuronal cultures of mouse cerebral cortex and cerebellum. These serve as well-established models of GABAergic and glutamatergic neurons, respectively. The hiPSC-derived neurons were previously characterized as being forebrain-specific cortical glutamatergic neurons. However, a comparable preparation of predominantly mouse cortical glutamatergic neurons is not available. We found a higher glycolytic capacity in hiPSC-derived neurons compared to mouse neurons and a substantial oxidative metabolism through the mitochondrial tricarboxylic acid (TCA) cycle. This finding is supported by the extracellular acidification and oxygen consumption rates measured in the cultured human neurons. [U-(13)C]Glutamate and [U-(13)C]glutamine were found to be efficient energy substrates for the neuronal cultures originating from both mice and humans. Interestingly, isotopic labeling in metabolites from [U-(13)C]glutamate was higher than that from [U-(13)C]glutamine. Although the metabolic profile of hiPSC-derived neurons in vitro was

  4. Effect of Anatomically Realistic Full-Head Model on Activation of Cortical Neurons in Subdural Cortical Stimulation—A Computational Study

    PubMed Central

    Seo, Hyeon; Kim, Donghyeon; Jun, Sung Chan

    2016-01-01

    Electrical brain stimulation (EBS) is an emerging therapy for the treatment of neurological disorders, and computational modeling studies of EBS have been used to determine the optimal parameters for highly cost-effective electrotherapy. Recent notable growth in computing capability has enabled researchers to consider an anatomically realistic head model that represents the full head and complex geometry of the brain rather than the previous simplified partial head model (extruded slab) that represents only the precentral gyrus. In this work, subdural cortical stimulation (SuCS) was found to offer a better understanding of the differential activation of cortical neurons in the anatomically realistic full-head model than in the simplified partial-head models. We observed that layer 3 pyramidal neurons had comparable stimulation thresholds in both head models, while layer 5 pyramidal neurons showed a notable discrepancy between the models; in particular, layer 5 pyramidal neurons demonstrated asymmetry in the thresholds and action potential initiation sites in the anatomically realistic full-head model. Overall, the anatomically realistic full-head model may offer a better understanding of layer 5 pyramidal neuronal responses. Accordingly, the effects of using the realistic full-head model in SuCS are compelling in computational modeling studies, even though this modeling requires substantially more effort. PMID:27273817

  5. Effect of Anatomically Realistic Full-Head Model on Activation of Cortical Neurons in Subdural Cortical Stimulation-A Computational Study.

    PubMed

    Seo, Hyeon; Kim, Donghyeon; Jun, Sung Chan

    2016-06-07

    Electrical brain stimulation (EBS) is an emerging therapy for the treatment of neurological disorders, and computational modeling studies of EBS have been used to determine the optimal parameters for highly cost-effective electrotherapy. Recent notable growth in computing capability has enabled researchers to consider an anatomically realistic head model that represents the full head and complex geometry of the brain rather than the previous simplified partial head model (extruded slab) that represents only the precentral gyrus. In this work, subdural cortical stimulation (SuCS) was found to offer a better understanding of the differential activation of cortical neurons in the anatomically realistic full-head model than in the simplified partial-head models. We observed that layer 3 pyramidal neurons had comparable stimulation thresholds in both head models, while layer 5 pyramidal neurons showed a notable discrepancy between the models; in particular, layer 5 pyramidal neurons demonstrated asymmetry in the thresholds and action potential initiation sites in the anatomically realistic full-head model. Overall, the anatomically realistic full-head model may offer a better understanding of layer 5 pyramidal neuronal responses. Accordingly, the effects of using the realistic full-head model in SuCS are compelling in computational modeling studies, even though this modeling requires substantially more effort.

  6. Effect of Anatomically Realistic Full-Head Model on Activation of Cortical Neurons in Subdural Cortical Stimulation—A Computational Study

    NASA Astrophysics Data System (ADS)

    Seo, Hyeon; Kim, Donghyeon; Jun, Sung Chan

    2016-06-01

    Electrical brain stimulation (EBS) is an emerging therapy for the treatment of neurological disorders, and computational modeling studies of EBS have been used to determine the optimal parameters for highly cost-effective electrotherapy. Recent notable growth in computing capability has enabled researchers to consider an anatomically realistic head model that represents the full head and complex geometry of the brain rather than the previous simplified partial head model (extruded slab) that represents only the precentral gyrus. In this work, subdural cortical stimulation (SuCS) was found to offer a better understanding of the differential activation of cortical neurons in the anatomically realistic full-head model than in the simplified partial-head models. We observed that layer 3 pyramidal neurons had comparable stimulation thresholds in both head models, while layer 5 pyramidal neurons showed a notable discrepancy between the models; in particular, layer 5 pyramidal neurons demonstrated asymmetry in the thresholds and action potential initiation sites in the anatomically realistic full-head model. Overall, the anatomically realistic full-head model may offer a better understanding of layer 5 pyramidal neuronal responses. Accordingly, the effects of using the realistic full-head model in SuCS are compelling in computational modeling studies, even though this modeling requires substantially more effort.

  7. Cultured Cortical Neurons Can Perform Blind Source Separation According to the Free-Energy Principle

    PubMed Central

    Isomura, Takuya; Kotani, Kiyoshi; Jimbo, Yasuhiko

    2015-01-01

    Blind source separation is the computation underlying the cocktail party effect––a partygoer can distinguish a particular talker’s voice from the ambient noise. Early studies indicated that the brain might use blind source separation as a signal processing strategy for sensory perception and numerous mathematical models have been proposed; however, it remains unclear how the neural networks extract particular sources from a complex mixture of inputs. We discovered that neurons in cultures of dissociated rat cortical cells could learn to represent particular sources while filtering out other signals. Specifically, the distinct classes of neurons in the culture learned to respond to the distinct sources after repeating training stimulation. Moreover, the neural network structures changed to reduce free energy, as predicted by the free-energy principle, a candidate unified theory of learning and memory, and by Jaynes’ principle of maximum entropy. This implicit learning can only be explained by some form of Hebbian plasticity. These results are the first in vitro (as opposed to in silico) demonstration of neural networks performing blind source separation, and the first formal demonstration of neuronal self-organization under the free energy principle. PMID:26690814

  8. Local signals from beyond the receptive fields of striate cortical neurons.

    PubMed

    Müller, James R; Metha, Andrew B; Krauskopf, John; Lennie, Peter

    2003-08-01

    We examined in anesthetized macaque how the responses of a striate cortical neuron to patterns inside the receptive field were altered by surrounding patterns outside it. The changes in a neuron's response brought about by a surround are immediate and transient: they arise with the same latency as the response to a stimulus within the receptive field (this argues for a source locally in striate cortex) and become less effective as soon as 27 ms later. Surround signals appeared to exert their influence through divisive interaction (normalization) with those arising in the receptive field. Surrounding patterns presented at orientations slightly oblique to the preferred orientation consistently deformed orientation tuning curves of complex (but not simple) cells, repelling the preferred orientation but without decreasing the discriminability of the preferred grating and ones at slightly oblique orientations. By reducing responsivity and changing the tuning of complex cells locally in stimulus space, surrounding patterns reduce the correlations among responses of neurons to a particular stimulus, thus reducing the redundancy of image representation.

  9. Continuum limit of discrete neuronal structures: is cortical tissue an "excitable" medium?

    PubMed

    Hemmen, J L van

    2004-12-01

    As a simple model of cortical tissue, we study a locally connected network of spiking neurons in the continuum limit of space and time. This is to be contrasted with the usual numerical simulations that discretize both of them. Refractoriness, noise, axonal delays, and the time course of excitatory and inhibitory postsynaptic potentials have been taken into account explicitly. We pose, and answer, the question of whether the continuum limit presents a full description of scenarios found numerically (the answer is no, not quite). In other words, can the numerics be reduced to a continuum description of a well-known type? As a corollary, we derive some classical results such as those of Wilson and Cowan (1973), thus indicating under what conditions they are valid. Furthermore, we show that spatially discrete objects may be fragile due to noise arising from the stochasticity of the individual neurons, whereas they are not once the continuum limit has been taken. This, then, resolves the above question. Finally, we indicate how one can directly incorporate orientation preference of the neurons.

  10. Known and unexpected constraints evoke different kinematic, muscle, and motor cortical neuron responses during locomotion.

    PubMed

    Stout, Erik E; Sirota, Mikhail G; Beloozerova, Irina N

    2015-11-01

    During navigation through complex natural environments, people and animals must adapt their movements when the environment changes. The neural mechanisms of such adaptations are poorly understood, especially with respect to constraints that are unexpected and must be adapted to quickly. In this study, we recorded forelimb-related kinematics, muscle activity, and the activity of motor cortical neurons in cats walking along a raised horizontal ladder, a complex locomotion task requiring accurate limb placement. One of the crosspieces was motorized, and displaced before the cat stepped on the ladder or at different points along the cat's progression over the ladder, either towards or away from the cat. We found that, when the crosspiece was displaced before the cat stepped onto the ladder, the kinematic modifications were complex and involved all forelimb joints. When the crosspiece displaced unexpectedly while the cat was on the ladder, the kinematic modifications were minimalistic and primarily involved distal joints. The activity of M. triceps and M. extensor digitorum communis differed based on the direction of displacement. Out of 151 neurons tested, 69% responded to at least one condition; however, neurons were significantly more likely to respond when crosspiece displacement was unexpected. Most often they responded during the swing phase. These results suggest that different neural mechanisms and motor control strategies are used to overcome constraints for locomotor movements depending on whether they are known or emerge unexpectedly.

  11. Reaction-diffusion waves in neuronal tissue and the window of cortical excitability

    NASA Astrophysics Data System (ADS)

    Dahlem, M. A.; Müller, S. C.

    2004-07-01

    Spreading depression (SD) is a dynamic wave phenomenon occurring in all gray matter regions of the central nervous systems (CNS). It is characterized by a sudden breakdown of neuronal activity and accompanied by a massive influx and efflux of ions across the membrane of neurons. The retina is a constituent of the CNS in which one can easily observe the dynamic behavior of the SD wave fronts, because SD changes the optical properties of the tissue. There is ample evidence that SD belongs to the self-organization processes due to the coupling of reaction with diffusion in excitable medium. It is assumed that the occurrence of SD is associated with some neurological symptoms of migraine with aura. A frequently reported aura symptom is a traveling visual blind region (scotoma) with a preceding figure of scintillating line segments. The characteristic form and development of the scotoma suggests that the underlying phenomenon is a wave propagating through the primary visual cortex, most likely the cortical spreading depression. In this article we discuss similarities between SD waves and the migraine aura on the basis of properties of reaction-diffusion waves known from other excitable media. In particular, the propagation velocities, the shape and the dynamics of the waves are compared with each other. We find that the assumption of the neuronal tissue to be in a state of only weak excitability explains some properties of the migraine aura, such as the confined appearance and its propagation with a stable velocity.

  12. Minimal Hodgkin-Huxley type models for different classes of cortical and thalamic neurons.

    PubMed

    Pospischil, Martin; Toledo-Rodriguez, Maria; Monier, Cyril; Piwkowska, Zuzanna; Bal, Thierry; Frégnac, Yves; Markram, Henry; Destexhe, Alain

    2008-11-01

    We review here the development of Hodgkin-Huxley (HH) type models of cerebral cortex and thalamic neurons for network simulations. The intrinsic electrophysiological properties of cortical neurons were analyzed from several preparations, and we selected the four most prominent electrophysiological classes of neurons. These four classes are "fast spiking", "regular spiking", "intrinsically bursting" and "low-threshold spike" cells. For each class, we fit "minimal" HH type models to experimental data. The models contain the minimal set of voltage-dependent currents to account for the data. To obtain models as generic as possible, we used data from different preparations in vivo and in vitro, such as rat somatosensory cortex and thalamus, guinea-pig visual and frontal cortex, ferret visual cortex, cat visual cortex and cat association cortex. For two cell classes, we used automatic fitting procedures applied to several cells, which revealed substantial cell-to-cell variability within each class. The selection of such cellular models constitutes a necessary step towards building network simulations of the thalamocortical system with realistic cellular dynamical properties.

  13. Cultured Cortical Neurons Can Perform Blind Source Separation According to the Free-Energy Principle.

    PubMed

    Isomura, Takuya; Kotani, Kiyoshi; Jimbo, Yasuhiko

    2015-12-01

    Blind source separation is the computation underlying the cocktail party effect--a partygoer can distinguish a particular talker's voice from the ambient noise. Early studies indicated that the brain might use blind source separation as a signal processing strategy for sensory perception and numerous mathematical models have been proposed; however, it remains unclear how the neural networks extract particular sources from a complex mixture of inputs. We discovered that neurons in cultures of dissociated rat cortical cells could learn to represent particular sources while filtering out other signals. Specifically, the distinct classes of neurons in the culture learned to respond to the distinct sources after repeating training stimulation. Moreover, the neural network structures changed to reduce free energy, as predicted by the free-energy principle, a candidate unified theory of learning and memory, and by Jaynes' principle of maximum entropy. This implicit learning can only be explained by some form of Hebbian plasticity. These results are the first in vitro (as opposed to in silico) demonstration of neural networks performing blind source separation, and the first formal demonstration of neuronal self-organization under the free energy principle.

  14. Green Tea Polyphenols Attenuated Glutamate Excitotoxicity via Antioxidative and Antiapoptotic Pathway in the Primary Cultured Cortical Neurons.

    PubMed

    Cong, Lin; Cao, Chang; Cheng, Yong; Qin, Xiao-Yan

    2016-01-01

    Green tea polyphenols are a natural product which has antioxidative and antiapoptotic effects. It has been shown that glutamate excitotoxicity induced oxidative stress is linked to neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. In this study we explored the neuroprotective effect of green teen polyphenols against glutamate excitotoxicity in the primary cultured cortical neurons. We found that green tea polyphenols protected against glutamate induced neurotoxicity in the cortical neurons as measured by MTT and TUNEL assays. Green tea polyphenols were then showed to inhibit the glutamate induced ROS release and SOD activity reduction in the neurons. Furthermore, our results demonstrated that green tea polyphenols restored the dysfunction of mitochondrial pro- or antiapoptotic proteins Bax, Bcl-2, and caspase-3 caused by glutamate. Interestingly, the neuroprotective effect of green tea polyphenols was abrogated when the neurons were incubated with siBcl-2. Taken together, these results demonstrated that green tea polyphenols protected against glutamate excitotoxicity through antioxidative and antiapoptotic pathways.

  15. Preservation of Neuronal Number Despite Age-Related Cortical Brain Atrophy In Elderly Subjects Without Alzheimer Disease

    PubMed Central

    Freeman, Stefanie H.; Kandel, Ruth; Cruz, Luis; Rozkalne, Anete; Newell, Kathy; Frosch, Matthew P.; Hedley-Whyte, E. Tessa; Locascio, Joseph J.; Lipsitz, Lewis; Hyman, Bradley T.

    2009-01-01

    Cerebral volume loss has long been associated with normal aging but whether this is due to aging itself or to age-related diseases including incipient Alzheimer disease (AD) is uncertain. To understand the changes that occur in the aging brain, we examined the cerebral cortex of 27 normal individuals ranging in age from 56 to 103 years. None fulfilled the criteria for the neuropathological diagnosis of AD or other neurodegenerative disease. Seventeen of the elderly participants had cognitive testing an average of 6.7 months prior to death. We used quantitative approaches to analyze cortical thickness, neuronal number, and density. Frontal and temporal neocortical regions had clear evidence of cortical thinning with age but total neuronal numbers in frontal and temporal neocortical regions remained relatively constant over a 50-year age range. These data suggest that loss of neuronal and dendritic architecture, rather than loss of neurons, underlies neocortical volume loss with increasing age in the absence of AD. PMID:19018241

  16. Oxygen flux reduces Cux1 positive neurons and cortical growth in a gestational rodent model of growth restriction.

    PubMed

    Fletcher, Elaine; Wade, Jean; Georgala, Petrina A; Gillespie, Trudi L; Price, David J; Pilley, Elizabeth; Becher, Julie-Clare

    2017-03-01

    The mammalian cerebral cortex forms in an inside-out manner, establishing deep cortical layers before superficial layers and is regulated by transcription factors which influence cell differentiation. Preterm birth interrupts the trajectory of normal neurodevelopment and adverse perinatal exposures have been implicated in cortical injury. We hypothesise that growth restriction (GR) and fluctuating hyperoxia (ΔO2) impair cortical laminar development. Sprague-Dawley rats received 18% (non-restricted, NR) or 9% (growth restricted, GR) protein diet from E15-P7. Litters were reared in air or fluctuating hyperoxia (circa 10kPa) from P0 to P7. Cortical laminae were stained and measured. Neuronal subtypes were quantified using immunofluorescence for subtype-specific transcription factors (Satb2, Cux1, Ctip2, Tbr1). ΔO2 did not affect brain weight at P7 but reduced cortical thickness in both NR (p<0.05) and GR groups (p<0.001). ΔO2 resulted in superficial cortical thinning in both groups and in the deep layers of GR pups (p<0.001). Cell density was preserved. ΔO2 did not affect proportions of callosal, corticothalamic and corticospinal neurons but resulted in a reduction of neurons expressing Cux1 (p<0.01) implicated in dendritic branching and synapse formation. Postnatal ΔO2, a modifiable factor in neonatal care, impairs cortical development in a rodent model with preferential disadvantage to superficial neurons. Copyright © 2016 Elsevier GmbH. All rights reserved.

  17. Preconditioning of cortical neurons by oxygen-glucose deprivation: tolerance induction through abbreviated neurotoxic signaling.

    PubMed

    Tauskela, Joseph S; Brunette, Eric; Monette, Robert; Comas, Tanya; Morley, Paul

    2003-10-01

    Transient exposure of rat cortical cultures to nonlethal oxygen-glucose deprivation (OGD preconditioning) induces tolerance to otherwise lethal oxygen-glucose deprivation (OGD) or N-methyl-D-aspartate 24 h later. This study evaluates the role of cytosolic and mitochondrial Ca2+-dependent cellular signaling. Mechanistic findings are placed in context with other models of ischemic preconditioning or known neurotoxic pathways within cortical neurons. Tolerance to otherwise lethal OGD is suppressed by performing OGD preconditioning in the presence of the broad-scope catalytic antioxidants Mn(III)tetra(4-carboxyphenyl)porphyrin (MnTBAP) or Zn(II)tetra(4-carboxyphenyl)porphyrin [Zn(II)TBAP], but not by a less active analog, Mn(III)tetra(4-sulfonatophenyl)porphyrin, or a potent superoxide scavenger, Mn(III)tetra(N-ethyl-2-pyridyl)porphyrin chloride. Inhibitors of adenosine A1 receptors, nitric oxide synthase, mitogen-activated protein kinase, and poly(ADP-ribose) polymerase fail to suppress OGD preconditioning despite possible links with reactive oxygen species in other models of ischemic preconditioning. Preconditioning is suppressed by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), which has been ascribed elsewhere to inhibition of superoxide transport to the cytosol through mitochondrial anion channels. However, although it induces mitochondrial Ca2+ uptake, neuronal preconditioning is largely insensitive to mitochondrial uncoupling with carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone or 2,4-dinitrophenol. Un-couplers will prevent production of mitochondrial reactive oxygen species, implying nonmitochondrial targets by MnTBAP, Zn(II)TBAP, and DIDS. Emphasizing the importance of an increase in cytosolic Ca2+ during preconditioning, a Ca2+/calmodulin-dependent protein kinase II inhibitor, KN-62, suppresses development of subsequent tolerance. Summarizing, only those cellular transduction pathways that have the potential to be neurotoxic may be activated by

  18. CNTF-ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through upregulating L-type calcium channel activity.

    PubMed

    Sun, Meiqun; Liu, Hongli; Xu, Huanbai; Wang, Hongtao; Wang, Xiaojing

    2016-09-01

    A specialized culture medium termed ciliary neurotrophic factor-treated astrocyte-conditioned medium (CNTF-ACM) allows investigators to assess the peripheral effects of CNTF-induced activated astrocytes upon cultured neurons. CNTF-ACM has been shown to upregulate neuronal L-type calcium channel current activity, which has been previously linked to changes in mitochondrial respiration and oxidative stress. Therefore, the aim of this study was to evaluate CNTF-ACM's effects upon mitochondrial respiration and oxidative stress in rat cortical neurons. Cortical neurons, CNTF-ACM, and untreated control astrocyte-conditioned medium (UC-ACM) were prepared from neonatal Sprague-Dawley rat cortical tissue. Neurons were cultured in either CNTF-ACM or UC-ACM for a 48-h period. Changes in the following parameters before and after treatment with the L-type calcium channel blocker isradipine were assessed: (i) intracellular calcium levels, (ii) mitochondrial membrane potential (ΔΨm), (iii) oxygen consumption rate (OCR) and adenosine triphosphate (ATP) formation, (iv) intracellular nitric oxide (NO) levels, (v) mitochondrial reactive oxygen species (ROS) production, and (vi) susceptibility to the mitochondrial complex I toxin rotenone. CNTF-ACM neurons displayed the following significant changes relative to UC-ACM neurons: (i) increased intracellular calcium levels (p < 0.05), (ii) elevation in ΔΨm (p < 0.05), (iii) increased OCR and ATP formation (p < 0.05), (iv) increased intracellular NO levels (p < 0.05), (v) increased mitochondrial ROS production (p < 0.05), and (vi) increased susceptibility to rotenone (p < 0.05). Treatment with isradipine was able to partially rescue these negative effects of CNTF-ACM (p < 0.05). CNTF-ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through elevating L-type calcium channel activity.

  19. Transition from Initial Hypoactivity to Hyperactivity in Cortical Layer V Pyramidal Neurons after Traumatic Brain Injury In Vivo.

    PubMed

    Ping, Xingjie; Jin, Xiaoming

    2016-02-15

    Traumatic brain injury (TBI) often results in structural damage and a loss of neurons that is commonly accompanied by early changes in neuronal electrical activity. Loss of neuronal activity has been hypothesized to contribute to post-traumatic epileptogenesis through the regulation of homeostatic plasticity. The existence of activity loss in cortical neurons after TBI and its subsequent transition into hyperactivity over time is not well characterized, however, particularly in models of TBI in vivo. In the current study, changes in neuronal activity in the primary motor cortex after moderate controlled cortical impact (CCI) in mice were studied using a single-unit recording technique in vivo. Recordings were made at different time points after CCI from cortical layer V pyramidal neurons that were within 1-2 mm from the anterior edge of the injured foci. Within 1-4 h after CCI, the frequency of spontaneous single-unit activity depressed significantly, with the mean firing frequency decreasing from 2.59 ± 0.18 Hz in the sham group to 1.05 ± 0.20 Hz of the injured group. The firing frequencies recovered to the normal level at 1 day and 7 days post-CCI, but became significantly higher at 3 days and 14 days post-CCI. The results suggest that TBI caused initial loss of activity in neurons of the perilesional cortical region, which was followed by compensatory recovery and enhancement of activity. These time-dependent changes in neuronal activity may contribute to the development of hyperexcitability through homeostatic activity regulation.

  20. Differential Tiam1/Rac1 activation in hippocampal and cortical neurons mediates differential spine shrinkage in response to oxygen/glucose deprivation

    PubMed Central

    Blanco-Suárez, Elena; Fiuza, Maria; Liu, Xun; Chakkarapani, Elavazhagan; Hanley, Jonathan G

    2014-01-01

    Distinct neuronal populations show differential sensitivity to global ischemia, with hippocampal CA1 neurons showing greater vulnerability compared to cortical neurons. The mechanisms that underlie differential vulnerability are unclear, and we hypothesize that intrinsic differences in neuronal cell biology are involved. Dendritic spine morphology changes in response to ischemic insults in vivo, but cell type-specific differences and the molecular mechanisms leading to such morphologic changes are unexplored. To directly compare changes in spine size in response to oxygen/glucose deprivation (OGD) in cortical and hippocampal neurons, we used separate and equivalent cultures of each cell type. We show that cortical neurons exhibit significantly greater spine shrinkage compared to hippocampal neurons. Rac1 is a Rho-family GTPase that regulates the actin cytoskeleton and is involved in spine dynamics. We show that Rac1 and the Rac guanine nucleotide exchange factor (GEF) Tiam1 are differentially activated by OGD in hippocampal and cortical neurons. Hippocampal neurons express more Tiam1 than cortical neurons, and reducing Tiam1 expression in hippocampal neurons by shRNA enhances OGD-induced spine shrinkage. Tiam1 knockdown also reduces hippocampal neuronal vulnerability to OGD. This work defines fundamental differences in signalling pathways that regulate spine morphology in distinct neuronal populations that may have a role in the differential vulnerability to ischemia. PMID:25248834

  1. Differential Tiam1/Rac1 activation in hippocampal and cortical neurons mediates differential spine shrinkage in response to oxygen/glucose deprivation.

    PubMed

    Blanco-Suárez, Elena; Fiuza, Maria; Liu, Xun; Chakkarapani, Elavazhagan; Hanley, Jonathan G

    2014-12-01

    Distinct neuronal populations show differential sensitivity to global ischemia, with hippocampal CA1 neurons showing greater vulnerability compared to cortical neurons. The mechanisms that underlie differential vulnerability are unclear, and we hypothesize that intrinsic differences in neuronal cell biology are involved. Dendritic spine morphology changes in response to ischemic insults in vivo, but cell type-specific differences and the molecular mechanisms leading to such morphologic changes are unexplored. To directly compare changes in spine size in response to oxygen/glucose deprivation (OGD) in cortical and hippocampal neurons, we used separate and equivalent cultures of each cell type. We show that cortical neurons exhibit significantly greater spine shrinkage compared to hippocampal neurons. Rac1 is a Rho-family GTPase that regulates the actin cytoskeleton and is involved in spine dynamics. We show that Rac1 and the Rac guanine nucleotide exchange factor (GEF) Tiam1 are differentially activated by OGD in hippocampal and cortical neurons. Hippocampal neurons express more Tiam1 than cortical neurons, and reducing Tiam1 expression in hippocampal neurons by shRNA enhances OGD-induced spine shrinkage. Tiam1 knockdown also reduces hippocampal neuronal vulnerability to OGD. This work defines fundamental differences in signalling pathways that regulate spine morphology in distinct neuronal populations that may have a role in the differential vulnerability to ischemia.

  2. Incorporating Midbrain Adaptation to Mean Sound Level Improves Models of Auditory Cortical Processing

    PubMed Central

    Schoppe, Oliver; King, Andrew J.; Schnupp, Jan W.H.; Harper, Nicol S.

    2016-01-01

    Adaptation to stimulus statistics, such as the mean level and contrast of recently heard sounds, has been demonstrated at various levels of the auditory pathway. It allows the nervous system to operate over the wide range of intensities and contrasts found in the natural world. Yet current standard models of the response properties of auditory neurons do not incorporate such adaptation. Here we present a model of neural responses in the ferret auditory cortex (the IC Adaptation model), which takes into account adaptation to mean sound level at a lower level of processing: the inferior colliculus (IC). The model performs high-pass filtering with frequency-dependent time constants on the sound spectrogram, followed by half-wave rectification, and passes the output to a standard linear–nonlinear (LN) model. We find that the IC Adaptation model consistently predicts cortical responses better than the standard LN model for a range of synthetic and natural stimuli. The IC Adaptation model introduces no extra free parameters, so it improves predictions without sacrificing parsimony. Furthermore, the time constants of adaptation in the IC appear to be matched to the statistics of natural sounds, suggesting that neurons in the auditory midbrain predict the mean level of future sounds and adapt their responses appropriately. SIGNIFICANCE STATEMENT An ability to accurately predict how sensory neurons respond to novel stimuli is critical if we are to fully characterize their response properties. Attempts to model these responses have had a distinguished history, but it has proven difficult to improve their predictive power significantly beyond that of simple, mostly linear receptive field models. Here we show that auditory cortex receptive field models benefit from a nonlinear preprocessing stage that replicates known adaptation properties of the auditory midbrain. This improves their predictive power across a wide range of stimuli but keeps model complexity low as it

  3. Bcl11a (Ctip1) Controls Migration of Cortical Projection Neurons through Regulation of Sema3c.

    PubMed

    Wiegreffe, Christoph; Simon, Ruth; Peschkes, Katharina; Kling, Carolin; Strehle, Michael; Cheng, Jin; Srivatsa, Swathi; Liu, Pentao; Jenkins, Nancy A; Copeland, Neal G; Tarabykin, Victor; Britsch, Stefan

    2015-07-15

    During neocortical development, neurons undergo polarization, oriented migration, and layer-type-specific differentiation. The transcriptional programs underlying these processes are not completely understood. Here, we show that the transcription factor Bcl11a regulates polarity and migration of upper layer neurons. Bcl11a-deficient late-born neurons fail to correctly switch from multipolar to bipolar morphology, resulting in impaired radial migration. We show that the expression of Sema3c is increased in migrating Bcl11a-deficient neurons and that Bcl11a is a direct negative regulator of Sema3c transcription. In vivo gain-of-function and rescue experiments demonstrate that Sema3c is a major downstream effector of Bcl11a required for the cell polarity switch and for the migration of upper layer neurons. Our data uncover a novel Bcl11a/Sema3c-dependent regulatory pathway used by migrating cortical neurons.

  4. Changes in cortical and striatal neurons predict behavioral and electrophysiological abnormalities in a transgenic murine model of Huntington's disease.

    PubMed

    Laforet, G A; Sapp, E; Chase, K; McIntyre, C; Boyce, F M; Campbell, M; Cadigan, B A; Warzecki, L; Tagle, D A; Reddy, P H; Cepeda, C; Calvert, C R; Jokel, E S; Klapstein, G J; Ariano, M A; Levine, M S; DiFiglia, M; Aronin, N

    2001-12-01

    Neurons in Huntington's disease exhibit selective morphological and subcellular alterations in the striatum and cortex. The link between these neuronal changes and behavioral abnormalities is unclear. We investigated relationships between essential neuronal changes that predict motor impairment and possible involvement of the corticostriatal pathway in developing behavioral phenotypes. We therefore generated heterozygote mice expressing the N-terminal one-third of huntingtin with normal (CT18) or expanded (HD46, HD100) glutamine repeats. The HD mice exhibited motor deficits between 3 and 10 months. The age of onset depended on an expanded polyglutamine length; phenotype severity correlated with increasing age. Neuronal changes in the striatum (nuclear inclusions) preceded the onset of phenotype, whereas cortical changes, especially the accumulation of huntingtin in the nucleus and cytoplasm and the appearance of dysmorphic dendrites, predicted the onset and severity of behavioral deficits. Striatal neurons in the HD mice displayed altered responses to cortical stimulation and to activation by the excitotoxic agent NMDA. Application of NMDA increased intracellular Ca(2+) levels in HD100 neurons compared with wild-type neurons. Results suggest that motor deficits in Huntington's disease arise from cumulative morphological and physiological changes in neurons that impair corticostriatal circuitry.

  5. Differences in the strength of cortical and brainstem inputs to SSA and non-SSA neurons in the inferior colliculus

    PubMed Central

    Ayala, Yaneri A.; Udeh, Adanna; Dutta, Kelsey; Bishop, Deborah; Malmierca, Manuel S.; Oliver, Douglas L.

    2015-01-01

    In an ever changing auditory scene, change detection is an ongoing task performed by the auditory brain. Neurons in the midbrain and auditory cortex that exhibit stimulus-specific adaptation (SSA) may contribute to this process. Those neurons adapt to frequent sounds while retaining their excitability to rare sounds. Here, we test whether neurons exhibiting SSA and those without are part of the same networks in the inferior colliculus (IC). We recorded the responses to frequent and rare sounds and then marked the sites of these neurons with a retrograde tracer to correlate the source of projections with the physiological response. SSA neurons were confined to the non-lemniscal subdivisions and exhibited broad receptive fields, while the non-SSA were confined to the central nucleus and displayed narrow receptive fields. SSA neurons receive strong inputs from auditory cortical areas and very poor or even absent projections from the brainstem nuclei. On the contrary, the major sources of inputs to the neurons that lacked SSA were from the brainstem nuclei. These findings demonstrate that auditory cortical inputs are biased in favor of IC synaptic domains that are populated by SSA neurons enabling them to compare top-down signals with incoming sensory information from lower areas. PMID:25993334

  6. Differences in the strength of cortical and brainstem inputs to SSA and non-SSA neurons in the inferior colliculus.

    PubMed

    Ayala, Yaneri A; Udeh, Adanna; Dutta, Kelsey; Bishop, Deborah; Malmierca, Manuel S; Oliver, Douglas L

    2015-05-20

    In an ever changing auditory scene, change detection is an ongoing task performed by the auditory brain. Neurons in the midbrain and auditory cortex that exhibit stimulus-specific adaptation (SSA) may contribute to this process. Those neurons adapt to frequent sounds while retaining their excitability to rare sounds. Here, we test whether neurons exhibiting SSA and those without are part of the same networks in the inferior colliculus (IC). We recorded the responses to frequent and rare sounds and then marked the sites of these neurons with a retrograde tracer to correlate the source of projections with the physiological response. SSA neurons were confined to the non-lemniscal subdivisions and exhibited broad receptive fiel