WorldWideScience

Sample records for cortical pyramidal neurons

  1. Ephrin-B1 controls the columnar distribution of cortical pyramidal neurons by restricting their tangential migration.

    Science.gov (United States)

    Dimidschstein, Jordane; Passante, Lara; Dufour, Audrey; van den Ameele, Jelle; Tiberi, Luca; Hrechdakian, Tatyana; Adams, Ralf; Klein, Rüdiger; Lie, Dieter Chichung; Jossin, Yves; Vanderhaeghen, Pierre

    2013-09-18

    Neurons of the cerebral cortex are organized in layers and columns. Unlike laminar patterning, the mechanisms underlying columnar organization remain largely unexplored. Here, we show that ephrin-B1 plays a key role in this process through the control of nonradial steps of migration of pyramidal neurons. In vivo gain of function of ephrin-B1 resulted in a reduction of tangential motility of pyramidal neurons, leading to abnormal neuronal clustering. Conversely, following genetic disruption of ephrin-B1, cortical neurons displayed a wider lateral dispersion, resulting in enlarged ontogenic columns. Dynamic analyses revealed that ephrin-B1 controls the lateral spread of pyramidal neurons by limiting neurite extension and tangential migration during the multipolar phase. Furthermore, we identified P-Rex1, a guanine-exchange factor for Rac3, as a downstream ephrin-B1 effector required to control migration during the multipolar phase. Our results demonstrate that ephrin-B1 inhibits nonradial migration of pyramidal neurons, thereby controlling the pattern of cortical columns.

  2. Regulation of action potential waveforms by axonal GABAA receptors in cortical pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Yang Xia

    Full Text Available GABAA receptors distributed in somatodendritic compartments play critical roles in regulating neuronal activities, including spike timing and firing pattern; however, the properties and functions of GABAA receptors at the axon are still poorly understood. By recording from the cut end (bleb of the main axon trunk of layer -5 pyramidal neurons in prefrontal cortical slices, we found that currents evoked by GABA iontophoresis could be blocked by picrotoxin, indicating the expression of GABAA receptors in axons. Stationary noise analysis revealed that single-channel properties of axonal GABAA receptors were similar to those of somatic receptors. Perforated patch recording with gramicidin revealed that the reversal potential of the GABA response was more negative than the resting membrane potential at the axon trunk, suggesting that GABA may hyperpolarize the axonal membrane potential. Further experiments demonstrated that the activation of axonal GABAA receptors regulated the amplitude and duration of action potentials (APs and decreased the AP-induced Ca2+ transients at the axon. Together, our results indicate that the waveform of axonal APs and the downstream Ca2+ signals are modulated by axonal GABAA receptors.

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

    Science.gov (United States)

    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.

  4. Dendritic Na(+) spikes enable cortical input to drive action potential output from hippocampal CA2 pyramidal neurons.

    Science.gov (United States)

    Sun, Qian; Srinivas, Kalyan V; Sotayo, Alaba; Siegelbaum, Steven A

    2014-01-01

    Synaptic inputs from different brain areas are often targeted to distinct regions of neuronal dendritic arbors. Inputs to proximal dendrites usually produce large somatic EPSPs that efficiently trigger action potential (AP) output, whereas inputs to distal dendrites are greatly attenuated and may largely modulate AP output. In contrast to most other cortical and hippocampal neurons, hippocampal CA2 pyramidal neurons show unusually strong excitation by their distal dendritic inputs from entorhinal cortex (EC). In this study, we demonstrate that the ability of these EC inputs to drive CA2 AP output requires the firing of local dendritic Na(+) spikes. Furthermore, we find that CA2 dendritic geometry contributes to the efficient coupling of dendritic Na(+) spikes to AP output. These results provide a striking example of how dendritic spikes enable direct cortical inputs to overcome unfavorable distal synaptic locale to trigger axonal AP output and thereby enable efficient cortico-hippocampal information flow.

  5. The influence of phospho-tau on dendritic spines of cortical pyramidal neurons in patients with Alzheimer’s disease

    Science.gov (United States)

    Merino-Serrais, Paula; Benavides-Piccione, Ruth; Blazquez-Llorca, Lidia; Kastanauskaite, Asta; Rábano, Alberto; Avila, Jesús

    2013-01-01

    The dendritic spines on pyramidal cells represent the main postsynaptic elements of cortical excitatory synapses and they are fundamental structures in memory, learning and cognition. In the present study, we used intracellular injections of Lucifer yellow in fixed tissue to analyse over 19 500 dendritic spines that were completely reconstructed in three dimensions along the length of the basal dendrites of pyramidal neurons in the parahippocampal cortex and CA1 of patients with Alzheimer’s disease. Following intracellular injection, sections were immunostained for anti-Lucifer yellow and with tau monoclonal antibodies AT8 and PHF-1, which recognize tau phosphorylated at Ser202/Thr205 and at Ser396/404, respectively. We observed that the diffuse accumulation of phospho-tau in a putative pre-tangle state did not induce changes in the dendrites of pyramidal neurons, whereas the presence of tau aggregates forming intraneuronal neurofibrillary tangles was associated with progressive alteration of dendritic spines (loss of dendritic spines and changes in their morphology) and dendrite atrophy, depending on the degree of tangle development. Thus, the presence of phospho-tau in neurons does not necessarily mean that they suffer severe and irreversible effects as thought previously but rather, the characteristic cognitive impairment in Alzheimer’s disease is likely to depend on the relative number of neurons that have well developed tangles. PMID:23715095

  6. Beyond laminar fate: toward a molecular classification of cortical projection/pyramidal neurons.

    NARCIS (Netherlands)

    Hevner, R.F.; Daza, R.A.; Rubenstein, J.L.; Stunnenberg, H.G.; Olavarria, J.F.; Englund, C.

    2003-01-01

    Cortical projection neurons exhibit diverse morphological, physiological, and molecular phenotypes, but it is unknown how many distinct types exist. Many projection cell phenotypes are associated with laminar fate (radial position), but each layer may also contain multiple types of projection cells.

  7. Delayed effects of corticosterone on slow after-hyperpolarization potentials in mouse hippocampal versus prefrontal cortical pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Anup G Pillai

    Full Text Available The rodent stress hormone corticosterone changes neuronal activity in a slow and persistent manner through transcriptional regulation. In the rat dorsal hippocampus, corticosterone enhances the amplitude of calcium-dependent potassium currents that cause a lingering slow after-hyperpolarization (sAHP at the end of depolarizing events. In this study we compared the putative region-dependency of the delayed effects of corticosterone (approximately 5 hrs after treatment on sAHP as well as other active and passive properties of layer 2/3 pyramidal neurons from three prefrontal areas, i.e. the lateral orbitofrontal, prelimbic and infralimbic cortex, with the hippocampus of adult mice. In agreement with previous studies, corticosterone increased sAHP amplitude in the dorsal hippocampus with depolarizing steps of increasing amplitude. However, in the lateral orbitofrontal, prelimbic and infralimbic cortices we did not observe any modifications of sAHP amplitude after corticosterone treatment. Properties of single action potentials or % ratio of the last spike interval with respect to the first spike interval, an indicator of accommodation in an action potential train, were not significantly affected by corticosterone in all brain regions examined. Lastly, corticosterone treatment did not induce any lasting changes in passive membrane properties of hippocampal or cortical neurons. Overall, the data indicate that corticosterone slowly and very persistently increases the sAHP amplitude in hippocampal pyramidal neurons, while this is not the case in the cortical regions examined. This implies that changes in excitability across brain regions reached by corticosterone may vary over a prolonged period of time after stress.

  8. Basal Dendritic Morphology of Cortical Pyramidal Neurons in Williams Syndrome: Prefrontal Cortex and Beyond

    Directory of Open Access Journals (Sweden)

    Branka Hrvoj-Mihic

    2017-08-01

    Full Text Available Williams syndrome (WS is a unique neurodevelopmental disorder with a specific behavioral and cognitive profile, which includes hyperaffiliative behavior, poor social judgment, and lack of social inhibition. Here we examined the morphology of basal dendrites on pyramidal neurons in the cortex of two rare adult subjects with WS. Specifically, we examined two areas in the prefrontal cortex (PFC—the frontal pole (Brodmann area 10 and the orbitofrontal cortex (Brodmann area 11—and three areas in the motor, sensory, and visual cortex (BA 4, BA 3-1-2, BA 18. The findings suggest that the morphology of basal dendrites on the pyramidal neurons is altered in the cortex of WS, with differences that were layer-specific, more prominent in PFC areas, and displayed an overall pattern of dendritic organization that differentiates WS from other disorders. In particular, and unlike what was expected based on typically developing brains, basal dendrites in the two PFC areas did not display longer and more branched dendrites compared to motor, sensory and visual areas. Moreover, dendritic branching, dendritic length, and the number of dendritic spines differed little within PFC and between the central executive region (BA 10 and BA 11 that is part of the orbitofrontal region involved into emotional processing. In contrast, the relationship between the degree of neuronal branching in supra- versus infra-granular layers was spared in WS. Although this study utilized tissue held in formalin for a prolonged period of time and the number of neurons available for analysis was limited, our findings indicate that WS cortex, similar to that in other neurodevelopmental disorders such as Down syndrome, Rett syndrome, Fragile X, and idiopathic autism, has altered morphology of basal dendrites on pyramidal neurons, which appears more prominent in selected areas of the PFC. Results were examined from developmental perspectives and discussed in the context of other

  9. Basal Dendritic Morphology of Cortical Pyramidal Neurons in Williams Syndrome: Prefrontal Cortex and Beyond.

    Science.gov (United States)

    Hrvoj-Mihic, Branka; Hanson, Kari L; Lew, Caroline H; Stefanacci, Lisa; Jacobs, Bob; Bellugi, Ursula; Semendeferi, Katerina

    2017-01-01

    Williams syndrome (WS) is a unique neurodevelopmental disorder with a specific behavioral and cognitive profile, which includes hyperaffiliative behavior, poor social judgment, and lack of social inhibition. Here we examined the morphology of basal dendrites on pyramidal neurons in the cortex of two rare adult subjects with WS. Specifically, we examined two areas in the prefrontal cortex (PFC)-the frontal pole (Brodmann area 10) and the orbitofrontal cortex (Brodmann area 11)-and three areas in the motor, sensory, and visual cortex (BA 4, BA 3-1-2, BA 18). The findings suggest that the morphology of basal dendrites on the pyramidal neurons is altered in the cortex of WS, with differences that were layer-specific, more prominent in PFC areas, and displayed an overall pattern of dendritic organization that differentiates WS from other disorders. In particular, and unlike what was expected based on typically developing brains, basal dendrites in the two PFC areas did not display longer and more branched dendrites compared to motor, sensory and visual areas. Moreover, dendritic branching, dendritic length, and the number of dendritic spines differed little within PFC and between the central executive region (BA 10) and BA 11 that is part of the orbitofrontal region involved into emotional processing. In contrast, the relationship between the degree of neuronal branching in supra- versus infra-granular layers was spared in WS. Although this study utilized tissue held in formalin for a prolonged period of time and the number of neurons available for analysis was limited, our findings indicate that WS cortex, similar to that in other neurodevelopmental disorders such as Down syndrome, Rett syndrome, Fragile X, and idiopathic autism, has altered morphology of basal dendrites on pyramidal neurons, which appears more prominent in selected areas of the PFC. Results were examined from developmental perspectives and discussed in the context of other neurodevelopmental disorders

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

    Science.gov (United States)

    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 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

  11. Dynamic FoxG1 expression coordinates the integration of multipolar pyramidal neuron precursors into the cortical plate.

    Science.gov (United States)

    Miyoshi, Goichi; Fishell, Gord

    2012-06-21

    Pyramidal cells of the cerebral cortex are born in the ventricular zone and migrate through the intermediate zone to enter into the cortical plate. In the intermediate zone, these migrating precursors move tangentially and initiate the extension of their axons by transiently adopting a characteristic multipolar morphology. We observe that expression of the forkhead transcription factor FoxG1 is dynamically regulated during this transitional period. By utilizing conditional genetic strategies, we show that the downregulation of FoxG1 at the beginning of the multipolar cell phase induces Unc5D expression, the timing of which ultimately determines the laminar identity of pyramidal neurons. In addition, we demonstrate that the re-expression of FoxG1 is required for cells to transit out of the multipolar cell phase and to enter into the cortical plate. Thus, the dynamic expression of FoxG1 during migration within the intermediate zone is essential for the proper assembly of the cerebral cortex.

  12. Dysregulated Expression of Neuregulin-1 by Cortical Pyramidal Neurons Disrupts Synaptic Plasticity

    Directory of Open Access Journals (Sweden)

    Amit Agarwal

    2014-08-01

    Full Text Available Neuregulin-1 (NRG1 gene variants are associated with increased genetic risk for schizophrenia. It is unclear whether risk haplotypes cause elevated or decreased expression of NRG1 in the brains of schizophrenia patients, given that both findings have been reported from autopsy studies. To study NRG1 functions in vivo, we generated mouse mutants with reduced and elevated NRG1 levels and analyzed the impact on cortical functions. Loss of NRG1 from cortical projection neurons resulted in increased inhibitory neurotransmission, reduced synaptic plasticity, and hypoactivity. Neuronal overexpression of cysteine-rich domain (CRD-NRG1, the major brain isoform, caused unbalanced excitatory-inhibitory neurotransmission, reduced synaptic plasticity, abnormal spine growth, altered steady-state levels of synaptic plasticity-related proteins, and impaired sensorimotor gating. We conclude that an “optimal” level of NRG1 signaling balances excitatory and inhibitory neurotransmission in the cortex. Our data provide a potential pathomechanism for impaired synaptic plasticity and suggest that human NRG1 risk haplotypes exert a gain-of-function effect.

  13. Distinct Physiological Effects of Dopamine D4 Receptors on Prefrontal Cortical Pyramidal Neurons and Fast-Spiking Interneurons.

    Science.gov (United States)

    Zhong, Ping; Yan, Zhen

    2016-01-01

    Dopamine D4 receptor (D4R), which is strongly linked to neuropsychiatric disorders, such as attention-deficit hyperactivity disorder and schizophrenia, is highly expressed in pyramidal neurons and GABAergic interneurons in prefrontal cortex (PFC). In this study, we examined the impact of D4R on the excitability of these 2 neuronal populations. We found that D4R activation decreased the frequency of spontaneous action potentials (sAPs) in PFC pyramidal neurons, whereas it induced a transient increase followed by a decrease of sAP frequency in PFC parvalbumin-positive (PV+) interneurons. D4R activation also induced distinct effects in both types of PFC neurons on spontaneous excitatory and inhibitory postsynaptic currents, which drive the generation of sAP. Moreover, dopamine substantially decreased sAP frequency in PFC pyramidal neurons, but markedly increased sAP frequency in PV+ interneurons, and both effects were partially mediated by D4R activation. In the phencyclidine model of schizophrenia, the decreasing effect of D4R on sAP frequency in both types of PFC neurons was attenuated, whereas the increasing effect of D4R on sAP in PV+ interneurons was intact. These results suggest that D4R activation elicits distinct effects on synaptically driven excitability in PFC projection neurons versus fast-spiking interneurons, which are differentially altered in neuropsychiatric disorder-related conditions.

  14. Micro RNA detection in long-term fixed tissue of cortical glutamatergic pyramidal neurons after targeted laser-capture neuroanatomical microdissection.

    Science.gov (United States)

    Herai, Roberto R; Stefanacci, Lisa; Hrvoj-Mihic, Branka; Chailangkarn, Thanathom; Hanson, Kari; Semendeferi, Katerina; Muotri, Alysson R

    2014-09-30

    Formalin fixation (FF) is the standard and most common method for preserving postmortem brain tissue. FF stabilizes cellular morphology and tissue architecture, and can be used to study the distinct morphologic and genetic signatures of different cell types. Although the procedure involved in FF degrades messenger RNA over time, an alternative approach is to use small RNAs (sRNAs) for genetic analysis associated with cell morphology. Although genetic analysis is carried out on fresh or frozen tissue, there is limited availability or impossibility on targeting specific cell populations, respectively. The goal of this study is to detect miRNA and other classes of sRNA stored in formalin or in paraffin embedded for over decades. Two brain samples, one formed by a mixed population of cortical and subcortical cells, and one formed by pyramidal shaped cells collected by laser-capture microdissection, were subjected to sRNA sequencing. Performing bioinformatics analysis over the sequenced sRNA from brain tissue, we detected several classes of sRNA, such as miRNAs that play key roles in brain neurodevelopmental and maintenance pathways, and hsa-mir-155 expression in neurons. Comparison with existing method: Our method is the first to combine the approaches for: laser-capture of pyramidal neurons from long-term formalin-fixed brain; extract sRNA from laser-captured pyramidal neurons; apply a suite of bioinformatics tools to detect miRNA and other classes of sRNAs on sequenced samples having high levels of RNA degradation. This is the first study to show that sRNA can be rescued from laser-captured FF pyramidal neurons. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Cortical overexpression of neuronal calcium sensor-1 induces functional plasticity in spinal cord following unilateral pyramidal tract injury in rat.

    Directory of Open Access Journals (Sweden)

    Ping K Yip

    Full Text Available 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.

  16. Brain-derived neurotrophic factor-mediated retrograde signaling required for the induction of long-term potentiation at inhibitory synapses of visual cortical pyramidal neurons.

    Science.gov (United States)

    Inagaki, Tsuyoshi; Begum, Tahamina; Reza, Faruque; Horibe, Shoko; Inaba, Mie; Yoshimura, Yumiko; Komatsu, Yukio

    2008-06-01

    High-frequency stimulation (HFS) induces long-term potentiation (LTP) at inhibitory synapses of layer 5 pyramidal neurons in developing rat visual cortex. This LTP requires postsynaptic Ca2+ rise for induction, while the maintenance mechanism is present at the presynaptic site, suggesting presynaptic LTP expression and the necessity of retrograde signaling. We investigated whether the supposed signal is mediated by brain-derived neurotrophic factor (BDNF), which is expressed in pyramidal neurons but not inhibitory interneurons. LTP did not occur when HFS was applied in the presence of the Trk receptor tyrosine kinase inhibitor K252a in the perfusion medium. HFS produced LTP when bath application of K252a was started after HFS or when K252a was loaded into postsynaptic cells. LTP did not occur in the presence of TrkB-IgG scavenging BDNF or function-blocking anti-BDNF antibody in the medium. In cells loaded with the Ca2+ chelator BAPTA, the addition of BDNF to the medium enabled HFS to induce LTP without affecting baseline synaptic transmission. These results suggest that BDNF released from postsynaptic cells activates presynaptic TrkB, leading to LTP. Because BDNF, expressed activity dependently, regulates the maturation of cortical inhibition, inhibitory LTP may contribute to this developmental process, and hence experience-dependent functional maturation of visual cortex.

  17. The origin of cortical neurons

    Directory of Open Access Journals (Sweden)

    J.G. Parnavelas

    2002-12-01

    Full Text Available Neurons of the mammalian cerebral cortex comprise two broad classes: pyramidal neurons, which project to distant targets, and the inhibitory nonpyramidal cells, the cortical interneurons. Pyramidal neurons are generated in the germinal ventricular zone, which lines the lateral ventricles, and migrate along the processes of radial glial cells to their positions in the developing cortex in an `inside-out' sequence. The GABA-containing nonpyramidal cells originate for the most part in the ganglionic eminence, the primordium of the basal ganglia in the ventral telencephalon. These cells follow tangential migratory routes to enter the cortex and are in close association with the corticofugal axonal system. Once they enter the cortex, they move towards the ventricular zone, possibly to obtain positional information, before they migrate radially in the direction of the pial surface to take up their positions in the developing cortex. The mechanisms that guide interneurons throughout these long and complex migratory routes are currently under investigation.

  18. Homeostatic responses by surviving cortical pyramidal cells in neurodegenerative tauopathy.

    Science.gov (United States)

    Crimins, Johanna L; Rocher, Anne B; Peters, Alan; Shultz, Penny; Lewis, Jada; Luebke, Jennifer I

    2011-11-01

    Cortical neuron death is prevalent by 9 months in rTg(tau(P301L))4510 tau mutant mice (TG) and surviving pyramidal cells exhibit dendritic regression and spine loss. We used whole-cell patch-clamp recordings to investigate the impact of these marked structural changes on spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and sIPSCs) of layer 3 pyramidal cells in frontal cortical slices from behaviorally characterized TG and non-transgenic (NT) mice at this age. Frontal lobe function of TG mice was intact following a short delay interval but impaired following a long delay interval in an object recognition test, and cortical atrophy and cell loss were pronounced. Surviving TG cells had significantly reduced dendritic diameters, total spine density, and mushroom spines, yet sEPSCs were increased and sIPSCs were unchanged in frequency. Thus, despite significant regressive structural changes, synaptic responses were not reduced in TG cells, indicating that homeostatic compensatory mechanisms occur during progressive tauopathy. Consistent with this idea, surviving TG cells were more intrinsically excitable than NT cells, and exhibited sprouting of filopodia and axonal boutons. Moreover, the neuropil in TG mice showed an increased density of asymmetric synapses, although their mean size was reduced. Taken together, these data indicate that during progressive tauopathy, cortical pyramidal cells compensate for loss of afferent input by increased excitability and establishment of new synapses. These compensatory homeostatic mechanisms may play an important role in slowing the progression of neuronal network dysfunction during neurodegenerative tauopathies.

  19. Pyramidal Cells in Prefrontal Cortex of Primates: Marked Differences in Neuronal Structure Among Species

    Science.gov (United States)

    Elston, Guy N.; Benavides-Piccione, Ruth; Elston, Alejandra; Manger, Paul R.; DeFelipe, Javier

    2010-01-01

    The most ubiquitous neuron in the cerebral cortex, the pyramidal cell, is characterized by markedly different dendritic structure among different cortical areas. The complex pyramidal cell phenotype in granular prefrontal cortex (gPFC) of higher primates endows specific biophysical properties and patterns of connectivity, which differ from those in other cortical regions. However, within the gPFC, data have been sampled from only a select few cortical areas. The gPFC of species such as human and macaque monkey includes more than 10 cortical areas. It remains unknown as to what degree pyramidal cell structure may vary among these cortical areas. Here we undertook a survey of pyramidal cells in the dorsolateral, medial, and orbital gPFC of cercopithecid primates. We found marked heterogeneity in pyramidal cell structure within and between these regions. Moreover, trends for gradients in neuronal complexity varied among species. As the structure of neurons determines their computational abilities, memory storage capacity and connectivity, we propose that these specializations in the pyramidal cell phenotype are an important determinant of species-specific executive cortical functions in primates. PMID:21347276

  20. Serotonin modulation of cortical neurons and networks

    Directory of Open Access Journals (Sweden)

    Pau eCelada

    2013-04-01

    Full Text Available 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

  1. Brief dopaminergic stimulations produce transient physiological changes in prefrontal pyramidal neurons.

    Science.gov (United States)

    Moore, Anna R; Zhou, Wen-Liang; Potapenko, Evgeniy S; Kim, Eun-Ji; Antic, Srdjan D

    2011-01-25

    In response to food reward and other pertinent events, midbrain dopaminergic neurons fire short bursts of action potentials causing a phasic release of dopamine in the prefrontal cortex (rapid and transient increases in cortical dopamine concentration). Here we apply short (2s) iontophoretic pulses of glutamate, GABA, dopamine and dopaminergic agonists locally, onto layer 5 pyramidal neurons in brain slices of the rat medial prefrontal cortex (PFC). Unlike glutamate and GABA, brief dopaminergic pulses had negligible effects on the resting membrane potential. However, dopamine altered action potential firing in an extremely rapid (iontophoresis current artifact. Our present data imply that one population of PFC pyramidal neurons receiving direct synaptic contacts from midbrain dopaminergic neurons would stall during the 0.5s of the phasic dopamine burst. The spillover dopamine, on the other hand, would act as a positive stimulator of cortical excitability (30% increase) to all D2-receptor carrying pyramidal cells, for the next 40s.

  2. Sensory deprivation differentially impacts the dendritic development of pyramidal versus non-pyramidal neurons in layer 6 of mouse barrel cortex.

    Science.gov (United States)

    Chen, Chia-Chien; Tam, Danny; Brumberg, Joshua C

    2012-04-01

    Early postnatal sensory experience can have profound impacts on the structure and function of cortical circuits affecting behavior. Using the mouse whisker-to-barrel system we chronically deprived animals of normal sensory experience by bilaterally trimming their whiskers every other day from birth for the first postnatal month. Brain tissue was then processed for Golgi staining and neurons in layer 6 of barrel cortex were reconstructed in three dimensions. Dendritic and somatic parameters were compared between sensory-deprived and normal sensory experience groups. Results demonstrated that layer 6 non-pyramidal neurons in the chronically deprived group showed an expansion of their dendritic arbors. The pyramidal cells responded to sensory deprivation with increased somatic size and basilar dendritic arborization but overall decreased apical dendritic parameters. In sum, sensory deprivation impacted on the neuronal architecture of pyramidal and non-pyramidal neurons in layer 6, which may provide a substrate for observed physiological and behavioral changes resulting from whisker trimming.

  3. Alterations of neocortical pyramidal neurons: turning points in the genesis of mental retardation

    Directory of Open Access Journals (Sweden)

    Alberto eGranato

    2014-08-01

    Full Text Available Pyramidal neurons represent the majority of neocortical cells and their involvement in cognitive functions is decisive. Therefore, they are the most obvious target of developmental disorders characterized by mental retardation. Genetic and non-genetic forms of intellectual disability share a few basic pathogenetic signatures that result in the anomalous function of pyramidal neurons. Here we review the key mechanisms impairing these neurons and their participation in the cortical network, with special focus on experimental models of fetal exposure to alcohol. Due to the heterogeneity of pyramidal neurons, some alterations affect selectively a given cell population, which may also differ depending on the considered pathology. These specific features open new possibilities for the interpretation of cognitive defects observed in mental retardation syndromes, as well as for novel therapeutic interventions.

  4. Turtle Dorsal Cortex Pyramidal Neurons Comprise Two Distinct Cell Types with Indistinguishable Visual Responses.

    Directory of Open Access Journals (Sweden)

    Thomas Crockett

    Full Text Available A detailed inventory of the constituent pieces in cerebral cortex is considered essential to understand the principles underlying cortical signal processing. Specifically, the search for pyramidal neuron subtypes is partly motivated by the hypothesis that a subtype-specific division of labor could create a rich substrate for computation. On the other hand, the extreme integration of individual neurons into the collective cortical circuit promotes the hypothesis that cellular individuality represents a smaller computational role within the context of the larger network. These competing hypotheses raise the important question to what extent the computational function of a neuron is determined by its individual type or by its circuit connections. We created electrophysiological profiles from pyramidal neurons within the sole cellular layer of turtle visual cortex by measuring responses to current injection using whole-cell recordings. A blind clustering algorithm applied to these data revealed the presence of two principle types of pyramidal neurons. Brief diffuse light flashes triggered membrane potential fluctuations in those same cortical neurons. The apparently network driven variability of the visual responses concealed the existence of subtypes. In conclusion, our results support the notion that the importance of diverse intrinsic physiological properties is minimized when neurons are embedded in a synaptic recurrent network.

  5. BDNF has opposite effects on the quantal amplitude of pyramidal neuron and interneuron excitatory synapses.

    Science.gov (United States)

    Rutherford, L C; Nelson, S B; Turrigiano, G G

    1998-09-01

    Recently, we have identified a novel form of synaptic plasticity that acts to stabilize neocortical firing rates by scaling the quantal amplitude of AMPA-mediated synaptic inputs up or down as a function of neuronal activity. Here, we show that the effects of activity blockade on quantal amplitude are mediated through the neurotrophin brain-derived neurotrophic factor (BDNF). Exogenous BDNF prevented, and a TrkB-IgG fusion protein reproduced, the effects of activity blockade on pyramidal quantal amplitude. BDNF had opposite effects on pyramidal neuron and interneuron quantal amplitudes and modified the ratio of pyramidal neuron to interneuron firing rates. These data demonstrate a novel role for BDNF in the homeostatic regulation of excitatory synaptic strengths and in the maintenance of the balance of cortical excitation and inhibition.

  6. Dendritic potassium channels in hippocampal pyramidal neurons.

    Science.gov (United States)

    Johnston, D; Hoffman, D A; Magee, J C; Poolos, N P; Watanabe, S; Colbert, C M; Migliore, M

    2000-05-15

    Potassium channels located in the dendrites of hippocampal CA1 pyramidal neurons control the shape and amplitude of back-propagating action potentials, the amplitude of excitatory postsynaptic potentials and dendritic excitability. Non-uniform gradients in the distribution of potassium channels in the dendrites make the dendritic electrical properties markedly different from those found in the soma. For example, the influence of a fast, calcium-dependent potassium current on action potential repolarization is progressively reduced in the first 150 micrometer of the apical dendrites, so that action potentials recorded farther than 200 micrometer from the soma have no fast after-hyperpolarization and are wider than those in the soma. The peak amplitude of back-propagating action potentials is also progressively reduced in the dendrites because of the increasing density of a transient potassium channel with distance from the soma. The activation of this channel can be reduced by the activity of a number of protein kinases as well as by prior depolarization. The depolarization from excitatory postsynaptic potentials (EPSPs) can inactivate these A-type K+ channels and thus lead to an increase in the amplitude of dendritic action potentials, provided the EPSP and the action potentials occur within the appropriate time window. This time window could be in the order of 15 ms and may play a role in long-term potentiation induced by pairing EPSPs and back-propagating action potentials.

  7. Dense and overlapping innervation of pyramidal neurons by neocortical chandelier cells

    Science.gov (United States)

    Inan, Melis; Blázquez-Llorca, Lidia; Merchán-Perez, Angel; Anderson, Stewart A.; DeFelipe, Javier; Yuste, Rafael

    2013-01-01

    Chandelier (or axo-axonic) cells are a distinct group of GABAergic interneurons that innervate the axon initial segments of pyramidal cells and thus could have an important role controlling the activity of cortical circuits. To understand their connectivity we labeled upper layers chandelier cells (ChCs) from mouse neocortex with a genetic strategy and studied how their axons contact local populations of pyramidal neurons, using immunohistochemical detection of axon initial segments. We studied ChCs located in the border of layers 1 and 2 from primary somatosensory cortex and find that practically all ChC axon terminals contact axon initial segments with an average of 3–5 boutons per cartridge. By measuring the number of putative synapses in initial segments we estimate that each pyramidal neuron is innervated, on average, by at least 4 ChCs. Additionally, each individual ChC contacts 35–50% of pyramidal neurons within its axonal arbor, with pockets of high innervation density. Finally, we find that ChC axons seems to have a conserved innervation pattern at different postnatal ages (P18–90), with only relatively small lateral expansions of their arbor and increases in the total number of their cartridges during the developmental period analyzed. We conclude that ChCs innervate neighboring pyramidal neurons in a dense and overlapping manner, an innervation pattern which could enable ChCs exert a widespread influence on their local circuits. PMID:23365230

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

    Science.gov (United States)

    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

  9. Responses to Gamma-Aminobutyric Acid of Rat Visual Cortical Neurons in Tissue Slices

    Science.gov (United States)

    1986-04-01

    Neurol. 234: 242-263. Peters, A. and Proskauer, c. C. (1980) Synaptic relationships between a multipolar stellate cell and a pyramidal neuron in rat...APR 1986 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Responses to Gamma-Aminobutyric Acid of Rat Visual Cortical Neurons in...AIR FORCE MEDICAL CENTER Title of Thesis: Responses to Gamma-Aminobutyric Acid of Rat Visual Cortical Neurons in Tissue Slices Name of Candidate

  10. Mitochondrial DNA copy numbers in pyramidal neurons are decreased and mitochondrial biogenesis transcriptome signaling is disrupted in Alzheimer's disease hippocampi.

    Science.gov (United States)

    Rice, Ann C; Keeney, Paula M; Algarzae, Norah K; Ladd, Amy C; Thomas, Ravindar R; Bennett, James P

    2014-01-01

    Alzheimer's disease (AD) is the major cause of adult-onset dementia and is characterized in its pre-diagnostic stage by reduced cerebral cortical glucose metabolism and in later stages by reduced cortical oxygen uptake, implying reduced mitochondrial respiration. Using quantitative PCR we determined the mitochondrial DNA (mtDNA) gene copy numbers from multiple groups of 15 or 20 pyramidal neurons, GFAP(+) astrocytes and dentate granule neurons isolated using laser capture microdissection, and the relative expression of mitochondrial biogenesis (mitobiogenesis) genes in hippocampi from 10 AD and 9 control (CTL) cases. AD pyramidal but not dentate granule neurons had significantly reduced mtDNA copy numbers compared to CTL neurons. Pyramidal neuron mtDNA copy numbers in CTL, but not AD, positively correlated with cDNA levels of multiple mitobiogenesis genes. In CTL, but not in AD, hippocampal cDNA levels of PGC1α were positively correlated with multiple downstream mitobiogenesis factors. Mitochondrial DNA copy numbers in pyramidal neurons did not correlate with hippocampal Aβ1-42 levels. After 48 h exposure of H9 human neural stem cells to the neurotoxic fragment Aβ25-35, mtDNA copy numbers were not significantly altered. In summary, AD postmortem hippocampal pyramidal neurons have reduced mtDNA copy numbers. Mitochondrial biogenesis pathway signaling relationships are disrupted in AD, but are mostly preserved in CTL. Our findings implicate complex alterations of mitochondria-host cell relationships in AD.

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

    Science.gov (United States)

    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 interneurons (16%, p 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.

  12. Morphology and ontogeny of rat perirhinal cortical neurons.

    Science.gov (United States)

    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.

  13. Morphometric characteristics of Neuropeptide Y immunoreactive neurons of human cortical amygdaloid nucleus

    Directory of Open Access Journals (Sweden)

    Mališ Miloš

    2008-01-01

    Full Text Available Introduction Cortical amygdaloid nucleus belongs to the corticomedial part of the amygdaloid complex. In this nucleus there are neurons that produce neuropetide Y. This peptide has important roles in sleeping, learning, memory, gastrointestinal regulation, anxiety, epilepsy, alcoholism and depression. Material and methods We investigated morphometric characteristics (numbers of primary dendrites, longer and shorter diameters of cell bodies and maximal radius of dendritic arborization of NPY immunoreactive neurons of human cortical amygdaloid nucleus on 6 male adult human brains, aged 46 to 77 years, by immunohistochemical avidin-biotin technique. Results Our investigation has shown that in this nucleus there is a moderate number of NPY immunoreactive neurons. 67% of found neurons were nonpyramidal, while 33% were pyramidal. Among the nonpyramidal neurons the dominant groups were multipolar neurons (41% - of which 25% were multipolar irregular, and 16% multipolar oval. Among the pyramidal neurons the dominant groups were the neurons with triangular shape of cell body (21%. All found NPY immunoreactive neurons (pyramidal and nonpyramidal altogether had intervals of values of numbers of primary dendrites 2 to 6, longer diameters of cell bodies 13 to 38 µm, shorter diameters of cell bodies 9 to 20 µm and maximal radius of dendritic arborization 50 to 340 µm. More than a half of investigated neurons (57% had 3 primary dendrites. Discussion and conclusion The other researchers did not find such percentage of pyramidal immunoreactive neurons in this amygdaloid nucleus. If we compare our results with the results of the ather researchers we can conclude that all pyramidal NPY immunoreactive neurons found in this human amygdaloid nucleus belong to the class I of neurons, and that all nonpyramidal NPY immunoreactive neurons belong to the class II of neurons described by other researchers. We suppose that all found pyramidal neurons were projectional.

  14. PyramidalExplorer: A New Interactive Tool to Explore Morpho-Functional Relations of Human Pyramidal Neurons.

    Science.gov (United States)

    Toharia, Pablo; Robles, Oscar D; Fernaud-Espinosa, Isabel; Makarova, Julia; Galindo, Sergio E; Rodriguez, Angel; Pastor, Luis; Herreras, Oscar; DeFelipe, Javier; Benavides-Piccione, Ruth

    2015-01-01

    This work presents PyramidalExplorer, a new tool to interactively explore and reveal the detailed organization of the microanatomy of pyramidal neurons with functionally related models. It consists of a set of functionalities that allow possible regional differences in the pyramidal cell architecture to be interactively discovered by combining quantitative morphological information about the structure of the cell with implemented functional models. The key contribution of this tool is the morpho-functional oriented design that allows the user to navigate within the 3D dataset, filter and perform Content-Based Retrieval operations. As a case study, we present a human pyramidal neuron with over 9000 dendritic spines in its apical and basal dendritic trees. Using PyramidalExplorer, we were able to find unexpected differential morphological attributes of dendritic spines in particular compartments of the neuron, revealing new aspects of the morpho-functional organization of the pyramidal neuron.

  15. Control of cortical neuronal migration by glutamate and GABA

    Directory of Open Access Journals (Sweden)

    Heiko J Luhmann

    2015-01-01

    Full Text Available 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.

  16. Cholinergic Neurons Excite Cortically Projecting Basal Forebrain GABAergic Neurons

    Science.gov (United States)

    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

  17. NK-3 receptor activation depolarizes and induces an after-depolarization in pyramidal neurons in gerbil cingulate cortex

    DEFF Research Database (Denmark)

    Rekling, Jens C

    2004-01-01

    The involvement of tachykinins in cortical function is poorly understood. To study the actions of neurokinin-3 (NK3) receptor activation in frontal cortex, whole cell patch clamp recordings were performed from pyramidal neurons in slices of cingulate cortex from juvenile gerbils. Senktide (500n......M), a selective NK3 receptor agonist, induced a transient increase in spontaneous EPSPs in layer V pyramidal neurons, accompanied by a small depolarization ( approximately 4 mV). EPSPs during senktide had a larger amplitude and faster 10-90% rise time than during control. Senktide induced a transient...... depolarization in layer II/III pyramidal neurons, which often reached threshold for spikes. The depolarization ( approximately 6 mV) persisted in TTX, and was accompanied by an increase in input resistance. Senktide also transiently induced a slow after-depolarization, which appeared following a depolarizing...

  18. Fractal dimension of apical dendritic arborization differs in the superficial and the deep pyramidal neurons of the rat cerebral neocortex.

    Science.gov (United States)

    Puškaš, Nela; Zaletel, Ivan; Stefanović, Bratislav D; Ristanović, Dušan

    2015-03-04

    Pyramidal neurons of the mammalian cerebral cortex have specific structure and pattern of organization that involves the presence of apical dendrite. Morphology of the apical dendrite is well-known, but quantification of its complexity still remains open. Fractal analysis has proved to be a valuable method for analyzing the complexity of dendrite morphology. The aim of this study was to establish the fractal dimension of apical dendrite arborization of pyramidal neurons in distinct neocortical laminae by using the modified box-counting method. A total of thirty, Golgi impregnated neurons from the rat brain were analyzed: 15 superficial (cell bodies located within lamina II-III), and 15 deep pyramidal neurons (cell bodies situated within lamina V-VI). Analysis of topological parameters of apical dendrite arborization showed no statistical differences except in total dendritic length (p=0.02), indicating considerable homogeneity between the two groups of neurons. On the other hand, average fractal dimension of apical dendrite was 1.33±0.06 for the superficial and 1.24±0.04 for the deep cortical neurons, showing statistically significant difference between these two groups (pfractal dimension values, apical dendrites of the superficial pyramidal neurons tend to show higher structural complexity compared to the deep ones.

  19. Functional changes in piriform cortex pyramidal neurons in the chronic methamphetamine-treated rat.

    Science.gov (United States)

    Hori, Nobuaki; Kadota, Tomoko; Akaike, Norio

    2015-01-01

    Chronic treatment of rats with methamphetamine (MAP) causes a range of functional changes to the central nervous system (CNS), including a toxicity that is widespread throughout the brain (Frost and Cadet 2000; Fasihpour et al. 2013). In this report, we examined the effect of chronic MAP treatment on pyramidal neurons of the rat piriform cortex, an area involved in sensory processing, associative learning and a model system for studies on synaptic plasticity. MAP treatment significantly depolarized the membrane potential and decreased neuronal input resistance. Furthermore, the voltage-dependence of both AMPA and NMDA responses was disturbed by chronic MAP treatment, and the extent of long-term potentiation (LTP) was decreased. Morphological changes of MAP-treated rat pyramidal neurons were observed as blebbing of the dendrite trees. The changes we observed represent detrimental effects on the function of piriform cortical neurons further illustrating deficits in synaptic plasticity extend beyond the hippocampus. These changes may contribute to behavioural deficits in chronic MAP-treated animals.

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

    Science.gov (United States)

    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.

  1. Simple method for evaluation of planum temporale pyramidal neurons shrinkage in postmortem tissue of Alzheimer disease patients.

    Science.gov (United States)

    Kutová, Martina; Mrzílková, Jana; Kirdajová, Denisa; Řípová, Daniela; Zach, Petr

    2014-01-01

    We measured the length of the pyramidal neurons in the cortical layer III in four subregions of the planum temporale (transitions into superior temporal gyrus, Heschl's gyrus, insular cortex, and Sylvian fissure) in control group and Alzheimer disease patients. Our hypothesis was that overall length of the pyramidal neurons would be smaller in the Alzheimer disease group compared to controls and also there would be right-left asymmetry in both the control and Alzheimer disease groups. We found pyramidal neuron length asymmetry only in controls--in the transition into the Sylvian fissure--and the rest of the subregions in the control group and Alzheimer disease patients did not show size difference. However, control-Alzheimer disease group pyramidal neuron length comparison revealed (a) no length difference in superior temporal gyrus transition area, (b) reversal of asymmetry in the insular transition area with left insular transition significantly shorter in the Alzheimer disease group compared to the control group, (c) both right and left Heschl's gyrus transitions significantly shorter in the Alzheimer disease group compared to the control group, and (d) right Sylvian fissure transition significantly shorter in the Alzheimer disease group compared to the control group. This neuronal length measurement method could supplement already existing neuropathological criteria for postmortem Alzheimer disease diagnostics.

  2. Extrasynaptic glutamate receptor activation as cellular bases for dynamic range compression in pyramidal neurons

    Directory of Open Access Journals (Sweden)

    Katerina D Oikonomou

    2012-08-01

    Full Text Available Repetitive synaptic stimulation overcomes the ability of astrocytic processes to clear glutamate from the extracellular space, allowing some dendritic segments to become submerged in a pool of glutamate. This dynamic arrangement activates extrasynaptic NMDA receptors located on dendritic shafts. We used voltage-sensitive and calcium-sensitive dyes to probe dendritic function in this glutamate-rich location. An excess of glutamate in the extrasynaptic space was achieved either by repetitive synaptic stimulation or by glutamate iontophoresis onto the dendrites of pyramidal neurons. Two successive activations of synaptic inputs produced a typical NMDA spike, whereas five successive synaptic inputs produced characteristic plateau potentials, reminiscent of cortical UP states. While NMDA spikes were coupled with brief calcium transients highly restricted to the glutamate input site, the dendritic plateau potentials were accompanied by calcium influx along the entire dendritic branch. Once initiated, the glutamate-mediated dendritic plateau potentials could not be interrupted by negative voltage pulses. Activation of extrasynaptic NMDA receptors in cellular compartments void of spines is sufficient to initiate and support plateau potentials. The only requirement for sustained depolarizing events is a surplus of free glutamate near a group of extrasynaptic receptors. Highly nonlinear dendritic spikes (plateau potentials are summed in a highly sublinear fashion at the soma, revealing the cellular bases of signal compression in cortical circuits. Extrasynaptic NMDA receptors provide pyramidal neurons with a function analogous to a dynamic range compression in audio engineering. They limit or reduce the volume of loud sounds (i.e. strong glut. inputs and amplify quiet sounds (i.e. glutamatergic inputs that barely cross the dendritic threshold for local spike initiation. Our data also explain why consecutive cortical UP states have uniform amplitudes in a

  3. Cdk5 is required for multipolar-to-bipolar transition during radial neuronal migration and proper dendrite development of pyramidal neurons in the cerebral cortex.

    Science.gov (United States)

    Ohshima, Toshio; Hirasawa, Motoyuki; Tabata, Hidenori; Mutoh, Tetsuji; Adachi, Tomoko; Suzuki, Hiromi; Saruta, Keiko; Iwasato, Takuji; Itohara, Shigeyoshi; Hashimoto, Mistuhiro; Nakajima, Kazunori; Ogawa, Masaharu; Kulkarni, Ashok B; Mikoshiba, Katsuhiko

    2007-06-01

    The mammalian cerebral cortex consists of six layers that are generated via coordinated neuronal migration during the embryonic period. Recent studies identified specific phases of radial migration of cortical neurons. After the final division, neurons transform from a multipolar to a bipolar shape within the subventricular zone-intermediate zone (SVZ-IZ) and then migrate along radial glial fibres. Mice lacking Cdk5 exhibit abnormal corticogenesis owing to neuronal migration defects. When we introduced GFP into migrating neurons at E14.5 by in utero electroporation, we observed migrating neurons in wild-type but not in Cdk5(-/-) embryos after 3-4 days. Introduction of the dominant-negative form of Cdk5 into the wild-type migrating neurons confirmed specific impairment of the multipolar-to-bipolar transition within the SVZ-IZ in a cell-autonomous manner. Cortex-specific Cdk5 conditional knockout mice showed inverted layering of the cerebral cortex and the layer V and callosal neurons, but not layer VI neurons, had severely impaired dendritic morphology. The amount of the dendritic protein Map2 was decreased in the cerebral cortex of Cdk5-deficient mice, and the axonal trajectory of cortical neurons within the cortex was also abnormal. These results indicate that Cdk5 is required for proper multipolar-to-bipolar transition, and a deficiency of Cdk5 results in abnormal morphology of pyramidal neurons. In addition, proper radial neuronal migration generates an inside-out pattern of cerebral cortex formation and normal axonal trajectories of cortical pyramidal neurons.

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

    Directory of Open Access Journals (Sweden)

    Hyeon Seo

    Full Text Available 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.

  5. Alterations of neocortical pyramidal neurons: turning points in the genesis of mental retardation.

    Science.gov (United States)

    Granato, Alberto; De Giorgio, Andrea

    2014-01-01

    Pyramidal neurons (PNs) represent the majority of neocortical cells and their involvement in cognitive functions is decisive. Therefore, they are the most obvious target of developmental disorders characterized by mental retardation. Genetic and non-genetic forms of intellectual disability share a few basic pathogenetic signatures that result in the anomalous function of PNs. Here, we review the key mechanisms impairing these neurons and their participation in the cortical network, with special focus on experimental models of fetal exposure to alcohol. Due to the heterogeneity of PNs, some alterations affect selectively a given cell population, which may also differ depending on the considered pathology. These specific features open new possibilities for the interpretation of cognitive defects observed in mental retardation syndromes, as well as for novel therapeutic interventions.

  6. Anterior cingulate pyramidal neurons display altered dendritic branching in depressed suicides.

    Science.gov (United States)

    Hercher, Christa; Canetti, Lilian; Turecki, Gustavo; Mechawar, Naguib

    2010-04-01

    It is hypothesized that mood disorders are accompanied by altered wiring and plasticity in key limbic brain regions such as the anterior cingulate cortex (ACC). To test this hypothesis at the cellular level, we analyzed basilar dendritic arborizations extended by layer VI pyramidal neurons in silver-impregnated postmortem ACC samples from well-characterized depressed suicide subjects (n=12) and matched sudden-death controls (n=7). One cm(3) tissue blocks were stained using a Golgi preparation, cut on a microtome, and mounted on slides. Basilar dendritic arbors from 195 neurons were reconstructed, and the number, length, and diameter of branches were determined at each branch order. The size and number of spines borne by these branches were also assessed. Third-order branches were significantly reduced in number (24% fewer; p=0.00262) in depressed suicides compared to controls. The size and average length of these branches, as well as their number of spines/length were unaltered. On average, for each pyramidal neuron analyzed in depressed subjects, the fewer third-order branches resulted in a significant reduction in branch length (28% shorter; p=0.00976) at this branch order. These results provide the first evidence of altered cortical dendritic branching in mood disorders. Given that proximal dendritic branches grow during perinatal development, and that they are generally less plastic at maturity than distal segments, we speculate that these differences in dendritic branching may reflect a biological predisposition to depression and suicide.

  7. Intrinsic oscillations of neocortex generated by layer 5 pyramidal neurons.

    Science.gov (United States)

    Silva, L R; Amitai, Y; Connors, B W

    1991-01-25

    Rhythmic activity in the neocortex varies with different behavioral and pathological states and in some cases may encode sensory information. However, the neural mechanisms of these oscillations are largely unknown. Many pyramidal neurons in layer 5 of the neocortex showed prolonged, 5- to 12-hertz rhythmic firing patterns at threshold. Rhythmic firing was due to intrinsic membrane properties, sodium conductances were essential for rhythmicity, and calcium-dependent conductances strongly modified rhythmicity. Isolated slices of neocortex generated epochs of 4- to 10-hertz synchronized activity when N-methyl-D-aspartate receptor-mediated channels were facilitated. Layer 5 was both necessary and sufficient to produce these synchronized oscillations. Thus, synaptic networks of intrinsically rhythmic neurons in layer 5 may generate or promote certain synchronized oscillations of the neocortex.

  8. Intrinsic Oscillations of Neocortex Generated by Layer 5 Pyramidal Neurons

    Science.gov (United States)

    Silva, Laurie R.; Amitai, Yael; Connors, Barry W.

    1991-01-01

    Rhythmic activity in the neocortex varies with different behavioral and pathological states and in some cases may encode sensory information. However, the neural mechanisms of these oscillations are largely unknown. Many pyramidal neurons in layer 5 of the neocortex showed prolonged, 5- to 12-hertz rhythmic firing patterns at threshold. Rhythmic firing was due to intrinsic membrane properties, sodium conductances were essential for rhythmicity, and calcium-dependent conductances strongly modified rhythmicity. Isolated slices of neocortex generated epochs of 4- to 10-hertz synchronized activity when N-methyl-D-aspartate receptor-mediated channels were facilitated. Layer 5 was both necessary and sufficient to produce these synchronized oscillations. Thus, synaptic networks of intrinsically rhythmic neurons in layer 5 may generate or promote certain synchronized oscillations of the neocortex.

  9. Dendritic spine density of prefrontal layer 6 pyramidal neurons in relation to apical dendrite sculpting by nicotinic acetylcholine receptors

    Directory of Open Access Journals (Sweden)

    Lily eKang

    2015-10-01

    Full Text Available Prefrontal layer 6 (L6 pyramidal neurons play an important role in the adult control of attention, facilitated by their strong activation by nicotinic acetylcholine receptors. These neurons in mouse association cortex are distinctive morphologically when compared to L6 neurons in primary cortical regions. Roughly equal proportions of the prefrontal L6 neurons have apical dendrites that are long (reaching to the pial surface versus short (terminating in the deep layers, as in primary cortical regions. This distinct prefrontal morphological pattern is established in the post-juvenile period and appears dependent on nicotinic receptors. Here, we examine dendritic spine densities in these two subgroups of prefrontal L6 pyramidal neurons under control conditions as well as after perturbation of nicotinic acetylcholine receptors. In control mice, the long neurons have significantly greater apical and basal dendritic spine density compared to the short neurons. Furthermore, manipulations of nicotinic receptors (chrna5 deletion or chronic developmental nicotine exposure have distinct effects on these two subgroups of L6 neurons: apical spine density is significantly reduced in long neurons, and basal spine density is significantly increased in short neurons. These changes appear dependent on the α5 nicotinic subunit encoded by chrna5. Overall, the two subgroups of prefrontal L6 neurons appear positioned to integrate information either across cortex (long neurons or within the deep layers (short neurons, and nicotinic perturbations differently alter spine density within each subgroup. Such changes have ramifications for adult executive function and possibly also for the morphological vulnerability of prefrontal cortex to subsequent stress exposure.

  10. Dendritic Properties Control Energy Efficiency of Action Potentials in Cortical Pyramidal Cells

    Directory of Open Access Journals (Sweden)

    Guosheng Yi

    2017-09-01

    Full Text Available Neural computation is performed by transforming input signals into sequences of action potentials (APs, which is metabolically expensive and limited by the energy available to the brain. The metabolic efficiency of single AP has important consequences for the computational power of the cell, which is determined by its biophysical properties and morphologies. Here we adopt biophysically-based two-compartment models to investigate how dendrites affect energy efficiency of APs in cortical pyramidal neurons. We measure the Na+ entry during the spike and examine how it is efficiently used for generating AP depolarization. We show that increasing the proportion of dendritic area or coupling conductance between two chambers decreases Na+ entry efficiency of somatic AP. Activating inward Ca2+ current in dendrites results in dendritic spike, which increases AP efficiency. Activating Ca2+-activated outward K+ current in dendrites, however, decreases Na+ entry efficiency. We demonstrate that the active and passive dendrites take effects by altering the overlap between Na+ influx and internal current flowing from soma to dendrite. We explain a fundamental link between dendritic properties and AP efficiency, which is essential to interpret how neural computation consumes metabolic energy and how biophysics and morphologies contribute to such consumption.

  11. Dendritic Target Region-Specific Formation of Synapses Between Excitatory Layer 4 Neurons and Layer 6 Pyramidal Cells.

    Science.gov (United States)

    Qi, Guanxiao; Feldmeyer, Dirk

    2016-04-01

    Excitatory connections between neocortical layer 4 (L4) and L6 are part of the corticothalamic feedback microcircuitry. Here we studied the intracortical element of this feedback loop, the L4 spiny neuron-to-L6 pyramidal cell connection. We found that the distribution of synapses onto both putative corticothalamic (CT) and corticocortical (CC) L6 pyramidal cells (PCs) depends on the presynaptic L4 neuron type but is independent of the postsynaptic L6 PC type. L4 spiny stellate cells establish synapses on distal apical tuft dendrites of L6 PCs and elicit slow unitary excitatory postsynaptic potentials (uEPSPs) in L6 somata. In contrast, the majority of L4 star pyramidal neurons target basal and proximal apical oblique dendrites of L6 PCs and show fast uEPSPs. Compartmental modeling suggests that the slow uEPSP time course is primarily the result of dendritic filtering. This suggests that the dendritic target specificity of the 2 L4 spiny neuron types is due to their different axonal projection patterns across cortical layers. The preferential dendritic targeting by different L4 neuron types may facilitate the generation of dendritic Ca(2+) or Na(+) action potentials in L6 PCs; this could play a role in synaptic gain modulation in the corticothalamic pathway.

  12. Potential Synaptic Connectivity of Different Neurons onto Pyramidal Cells in a 3D Reconstruction of the Rat Hippocampus

    Directory of Open Access Journals (Sweden)

    Deepak eRopireddy

    2011-07-01

    Full Text Available Most existing connectomic data and ongoing efforts focus either on individual synapses (e.g. with electron microscopy or on regional connectivity (tract tracing. An individual pyramidal cell extends thousands of synapses over macroscopic distances (~cm. The contrasting requirements of high resolution and large field of view make it too challenging to acquire the entire synaptic connectivity for even a single typical cortical neuron. Light microscopy can image whole neuronal arbors and resolve dendritic branches. Analyzing connectivity in terms of close spatial appositions between axons and dendrites could thus bridge the opposite scales, from synaptic level to whole systems. In the mammalian cortex, structural plasticity of spines and boutons makes these ‘potential synapses’ functionally relevant to learning capability and memory capacity. To date, however, potential synapses have only been mapped in the surrounding of a neuron and relative to its local orientation rather than in a system-level anatomical reference. Here we overcome this limitation by estimating the potential connectivity of different neurons embedded into a detailed 3D reconstruction of the rat hippocampus. Axonal and dendritic trees were oriented with respect to hippocampal cytoarchitecture according to longitudinal and transversal curvatures. We report the potential connectivity onto pyramidal cell dendrites from the axons of a dentate granule cell, three CA3 pyramidal cells, one CA2 pyramidal cell, and 13 CA3b interneurons. The numbers, densities, and distributions of potential synapses were analyzed in each sub-region (e.g. CA3 vs. CA1, layer (e.g. oriens vs. radiatum, and septo-temporal location (e.g. dorsal vs. ventral. The overall ratio between the numbers of actual and potential synapses was ~0.20 for the granule and CA3 pyramidal cells. All potential connectivity patterns are strikingly dependent on the anatomical location of both pre-synaptic and post

  13. Housing under the pyramid reduces susceptibility of hippocampal CA3 pyramidal neurons to prenatal stress in the developing rat offspring.

    Science.gov (United States)

    Murthy, Krishna Dilip; George, Mitchel Constance; Ramasamy, Perumal; Mustapha, Zainal Arifin

    2013-12-01

    Mother-offspring interaction begins before birth. The foetus is particularly vulnerable to environmental insults and stress. The body responds by releasing excess of the stress hormone cortisol, which acts on glucocorticoid receptors. Hippocampus in the brain is rich in glucocorticoid receptors and therefore susceptible to stress. The stress effects are reduced when the animals are placed under a model wooden pyramid. The present study was to first explore the effects of prenatal restraint-stress on the plasma corticosterone levels and the dendritic arborisation of CA3 pyramidal neurons in the hippocampus of the offspring. Further, to test whether the pyramid environment would alter these effects, as housing under a pyramid is known to reduce the stress effects, pregnant Sprague Dawley rats were restrained for 9 h per day from gestation day 7 until parturition in a wire-mesh restrainer. Plasma corticosterone levels were found to be significantly increased. In addition, there was a significant reduction in the apical and the basal total dendritic branching points and intersections of the CA3 hippocampal pyramidal neurons. The results thus suggest that, housing in the pyramid dramatically reduces prenatal stress effects in rats.

  14. Quantitative analysis of basal dendritic tree of layer III pyramidal neurons in different areas of adult human frontal cortex.

    Science.gov (United States)

    Zeba, Martina; Jovanov-Milosević, Natasa; Petanjek, Zdravko

    2008-01-01

    Large long projecting (cortico-cortical) layer IIIc pyramidal neurons were recently disclosed to be in the basis of cognitive processing in primates. Therefore, we quantitatively examined the basal dendritic morphology of these neurons by using rapid Golgi and Golgi Cox impregnation methods among three distinct Brodmann areas (BA) of an adult human frontal cortex: the primary motor BA4 and the associative magnopyramidal BA9 from left hemisphere and the Broca's speech BA45 from both hemispheres. There was no statistically significant difference in basal dendritic length or complexity, as dendritic spine number or their density between analyzed BA's. In addition, we analyzed each of these BA's immunocytochemically for distribution of SMI-32, a marker of largest long distance projecting neurons. Within layer IIIc, the highest density of SMI-32 immunopositive pyramidal neurons was observed in associative BA9, while in primary BA4 they were sparse. Taken together, these data suggest that an increase in the complexity of cortico-cortical network within human frontal areas of different functional order may be principally based on the increase in density of large, SMI-32 immunopositive layer IIIc neurons, rather than by further increase in complexity of their dendritic tree and synaptic network.

  15. High-Degree Neurons Feed Cortical Computations.

    Directory of Open Access Journals (Sweden)

    Nicholas M Timme

    2016-05-01

    Full Text Available 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

  16. Effect of mescaline on single cortical neurones.

    Science.gov (United States)

    Bradshaw, C M; Roberts, M H; Szabadi, E

    1971-12-01

    The effects of mescaline upon single cortical neurones were studied, using the microiontophoretic technique. Mescaline elicited excitatory and depressant responses similar to those evoked by noradrenaline (NA) and 5-hydroxytryptamine (5-HI). The responses to NA and mescaline were usually in the same direction, the neurone being either excited by both drugs or depressed by both drugs. The correlation between the effects of mescaline and 5-HT, however, was less consistent. The beta-adrenoceptor blocking agent MJ-1999 and the 5-HT antagonist methysergide were both effective in antagonizing mescaline responses.

  17. Loss of sensory input increases the intrinsic excitability of layer 5 pyramidal neurons in rat barrel cortex.

    Science.gov (United States)

    Breton, Jean-Didier; Stuart, Greg J

    2009-11-01

    Development of the cortical map is experience dependent, with different critical periods in different cortical layers. Previous work in rodent barrel cortex indicates that sensory deprivation leads to changes in synaptic transmission and plasticity in layer 2/3 and 4. Here, we studied the impact of sensory deprivation on the intrinsic properties of layer 5 pyramidal neurons located in rat barrel cortex using simultaneous somatic and dendritic recording. Sensory deprivation was achieved by clipping all the whiskers on one side of the snout. Loss of sensory input did not change somatic active and resting membrane properties, and did not influence dendritic action potential (AP) backpropagation. In contrast, sensory deprivation led to an increase in the percentage of layer 5 pyramidal neurons showing burst firing. This was associated with a reduction in the threshold for generation of dendritic calcium spikes during high-frequency AP trains. Cell-attached recordings were used to assess changes in the properties and expression of dendritic HCN channels. These experiments indicated that sensory deprivation caused a decrease in HCN channel density in distal regions of the apical dendrite. To assess the contribution of HCN down-regulation on the observed increase in dendritic excitability following sensory deprivation, we investigated the impact of blocking HCN channels. Block of HCN channels removed differences in dendritic calcium electrogenesis between control and deprived neurons. In conclusion, these observations indicate that sensory loss leads to increased dendritic excitability of cortical layer 5 pyramidal neurons. Furthermore, they suggest that increased dendritic calcium electrogenesis following sensory deprivation is mediated in part via down-regulation of dendritic HCN channels.

  18. Active dendrites support efficient initiation of dendritic spikes in hippocampal CA3 pyramidal neurons

    OpenAIRE

    Kim, Sooyun; Guzman, Segundo J.; Hu, Hua; Jonas, Peter

    2012-01-01

    CA3 pyramidal neurons are important for memory formation and pattern completion in the hippocampal network. It is generally thought that proximal synapses from the mossy fibers activate these neurons most efficiently, whereas distal inputs from the perforant path have a weaker modulatory influence. We used confocally targeted patch-clamp recording from dendrites and axons to map the activation of rat CA3 pyramidal neurons at the subcellular level. Our results reveal two distinct dendritic dom...

  19. Properties of persistent postnatal cortical subplate neurons.

    Science.gov (United States)

    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.

  20. Effect of Anatomically Realistic Full-Head Model on Activation of Cortical Neurons in Subdural Cortical Stimulation—A Computational Study

    Science.gov (United States)

    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.

  1. Enhanced Ras activity in pyramidal neurons induces cellular hypertrophy and changes in afferent and intrinsic connectivity in synRas mice.

    Science.gov (United States)

    Gärtner, Ulrich; Alpár, Alán; Seeger, Gudrun; Heumann, Rolf; Arendt, Thomas

    2004-05-01

    Neurotrophic actions are critically controlled and transmitted to cellular responses by the small G protein Ras which is therefore essential for normal functioning and plasticity of the nervous system. The present study summarises findings of recent studies on morphological changes in the neocortex of synRas mice expressing Val12-Ha-Ras in vivo under the control of the rat synapsin I promoter. In the here reported model (introduced by Heumann et al. [J. Cell Biol. 151 (2000) 1537]), transgenic Val12-Ha-Ras expression is confined to the pyramidal cell population and starts postnatally at a time, when neurons are postmitotic and their developmental maturation has been basically completed. Expression of Val12-Ha-Ras results in a significant enlargement of pyramidal neurons. Size, complexity and spine density of dendritic trees are increased, which leads, finally, to cortical expansion. However, the main morphological design principles of 'transgenic' pyramidal cells remain preserved. In addition to somato-dendritic changes, expression of Val12-Ha-Ras in pyramidal cells induces augmented axon calibres and upregulates the establishment of efferent boutons. Despite the enlargement of cortical size, the overall density of terminals representing intra- or interhemispheric, specific and non-specific afferents is unchanged or even higher in transgenic mice suggesting a significant increase in the total afferent input to the neocortex. Although interneurons do not express the transgene and are therefore excluded from direct, intrinsic Val12-Ha-Ras effects, they respond with morphological adaptations to structural changes. Thus, dendritic arbours of interneurons are extended to follow the cortical expansion and basket cells establish a denser inhibitory innervation of 'transgenic' pyramidal cells perikarya. It is concluded that expression of Val12-Ha-Ras in pyramidal neurons results in remodelling of neocortical structuring which strongly implicates a crucial involvement of

  2. Stellate and pyramidal neurons in goldfish telencephalon respond differently to anoxia and GABA receptor inhibition.

    Science.gov (United States)

    Hossein-Javaheri, Nariman; Wilkie, Michael P; Lado, Wudu E; Buck, Leslie T

    2017-02-15

    With oxygen deprivation, the mammalian brain undergoes hyper-activity and neuronal death while this does not occur in the anoxia-tolerant goldfish (Carassius auratus). Anoxic survival of the goldfish may rely on neuromodulatory mechanisms to suppress neuronal hyper-excitability. As γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain, we decided to investigate its potential role in suppressing the electrical activity of goldfish telencephalic neurons. Utilizing whole-cell patch-clamp recording, we recorded the electrical activities of both excitatory (pyramidal) and inhibitory (stellate) neurons. With anoxia, membrane potential (Vm) depolarized in both cell types from -72.2 mV to -57.7 mV and from -64.5 mV to -46.8 mV in pyramidal and stellate neurons, respectively. While pyramidal cells remained mostly quiescent, action potential frequency (APf) of the stellate neurons increased 68-fold. Furthermore, the GABAA receptor reversal potential (E-GABA) was determined using the gramicidin perforated-patch-clamp method and found to be depolarizing in pyramidal (-53.8 mV) and stellate neurons (-42.1 mV). Although GABA was depolarizing, pyramidal neurons remained quiescent as EGABA was below the action potential threshold (-36 mV pyramidal and -38 mV stellate neurons). Inhibition of GABAA receptors with gabazine reversed the anoxia-mediated response. While GABAB receptor inhibition alone did not affect the anoxic response, co-antagonism of GABAA and GABAB receptors (gabazine and CGP-55848) led to the generation of seizure-like activities in both neuron types. We conclude that with anoxia, Vm depolarizes towards EGABA which increases APf in stellate neurons and decreases APf in pyramidal neurons, and that GABA plays an important role in the anoxia tolerance of goldfish brain. © 2017. Published by The Company of Biologists Ltd.

  3. Location-dependent excitatory synaptic interactions in pyramidal neuron dendrites.

    Directory of Open Access Journals (Sweden)

    Bardia F Behabadi

    Full Text Available Neocortical pyramidal neurons (PNs receive thousands of excitatory synaptic contacts on their basal dendrites. Some act as classical driver inputs while others are thought to modulate PN responses based on sensory or behavioral context, but the biophysical mechanisms that mediate classical-contextual interactions in these dendrites remain poorly understood. We hypothesized that if two excitatory pathways bias their synaptic projections towards proximal vs. distal ends of the basal branches, the very different local spike thresholds and attenuation factors for inputs near and far from the soma might provide the basis for a classical-contextual functional asymmetry. Supporting this possibility, we found both in compartmental models and electrophysiological recordings in brain slices that the responses of basal dendrites to spatially separated inputs are indeed strongly asymmetric. Distal excitation lowers the local spike threshold for more proximal inputs, while having little effect on peak responses at the soma. In contrast, proximal excitation lowers the threshold, but also substantially increases the gain of distally-driven responses. Our findings support the view that PN basal dendrites possess significant analog computing capabilities, and suggest that the diverse forms of nonlinear response modulation seen in the neocortex, including uni-modal, cross-modal, and attentional effects, could depend in part on pathway-specific biases in the spatial distribution of excitatory synaptic contacts onto PN basal dendritic arbors.

  4. Acetaminophen induces apoptosis in rat cortical neurons.

    Directory of Open Access Journals (Sweden)

    Inmaculada Posadas

    Full Text Available BACKGROUND: Acetaminophen (AAP is widely prescribed for treatment of mild pain and fever in western countries. It is generally considered a safe drug and the most frequently reported adverse effect associated with acetaminophen is hepatotoxicity, which generally occurs after acute overdose. During AAP overdose, encephalopathy might develop and contribute to morbidity and mortality. Our hypothesis is that AAP causes direct neuronal toxicity contributing to the general AAP toxicity syndrome. METHODOLOGY/PRINCIPAL FINDINGS: We report that AAP causes direct toxicity on rat cortical neurons both in vitro and in vivo as measured by LDH release. We have found that AAP causes concentration-dependent neuronal death in vitro at concentrations (1 and 2 mM that are reached in human plasma during AAP overdose, and that are also reached in the cerebrospinal fluid of rats for 3 hours following i.p injection of AAP doses (250 and 500 mg/kg that are below those required to induce acute hepatic failure in rats. AAP also increases both neuronal cytochrome P450 isoform CYP2E1 enzymatic activity and protein levels as determined by Western blot, leading to neuronal death through mitochondrial-mediated mechanisms that involve cytochrome c release and caspase 3 activation. In addition, in vivo experiments show that i.p. AAP (250 and 500 mg/kg injection induces neuronal death in the rat cortex as measured by TUNEL, validating the in vitro data. CONCLUSIONS/SIGNIFICANCE: The data presented here establish, for the first time, a direct neurotoxic action by AAP both in vivo and in vitro in rats at doses below those required to produce hepatotoxicity and suggest that this neurotoxicity might be involved in the general toxic syndrome observed during patient APP overdose and, possibly, also when AAP doses in the upper dosing schedule are used, especially if other risk factors (moderate drinking, fasting, nutritional impairment are present.

  5. Increased Synaptic Excitation and Abnormal Dendritic Structure of Prefrontal Cortex Layer V Pyramidal Neurons following Prolonged Binge-Like Consumption of Ethanol

    Science.gov (United States)

    Klenowski, Paul M.; Fogarty, Matthew J.; Shariff, Masroor; Belmer, Arnauld

    2016-01-01

    Abstract Long-term alcohol use causes a multitude of neurochemical changes in cortical regions that facilitate the transition to dependence. Therefore, we used a model of long-term, binge-like ethanol consumption in rats to determine the effects on morphology and synaptic physiology of medial prefrontal cortex (mPFC) layer V pyramidal neurons. Following 10 weeks of ethanol consumption, we recorded synaptic currents from mPFC neurons and used neurobiotin filling to analyze their morphology. We then compared these data to measurements obtained from age-matched, water-drinking control rats. We found that long-term ethanol consumption caused a significant increase in total dendrite arbor length of mPFC layer V pyramidal neurons. Dendritic restructuring was primarily observed in basal dendrite arbors, with mPFC neurons from animals engaged in long-term ethanol drinking having significantly larger and more complex basal arbors compared with controls. These changes were accompanied by significantly increased total spine densities and spontaneous postsynaptic excitatory current frequency, suggesting that long-term binge-like ethanol consumption enhances basal excitatory synaptic transmission in mPFC layer V pyramidal neurons. Our results provide insights into the morphological and functional changes in mPFC layer V pyramidal neuronal physiology following prolonged exposure to ethanol and support changes in mPFC activity during the development of alcohol dependence. PMID:28032119

  6. Early establishment of multiple release site connectivity between interneurons and pyramidal neurons in the developing hippocampus.

    Science.gov (United States)

    Groc, Laurent; Gustafsson, Bengt; Hanse, Eric

    2003-05-01

    The strength of the synaptic transmission between two neurons critically depends on the number of release sites connecting the neurons. Here we examine the development of connectivity between gamma-aminobutyric acid (GABA)ergic interneurons and CA1 pyramidal neurons in the hippocampus. GABAergic postsynaptic currents (PSCs) were recorded in whole-cell voltage-clamped CA1 pyramidal neurons. By comparing spontaneous and miniature (action potential-independent) GABAergic PSCs, we found that multiple release site connectivity is established already at the first postnatal day and that the degree of connectivity remains unaltered into adulthood. During the same time there is a dramatic increase in the number of GABAergic synapses on each pyramidal neuron as indicated by the increase in frequency of miniature GABAergic PSCs. These results indicate that during development a given interneuron contacts an increasing number of target pyramidal neurons but with the same multiple release site connectivity. It has been shown previously that the connectivity between CA3 and CA1 pyramidal neurons is initially restricted to one release site, and develops gradually. The present result thus suggests different mechanisms to govern the maturation of excitatory and inhibitory synaptic transmissions.

  7. Morphology cluster and prediction of growth of human brain pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    Chao Yu; Zengxin Han; Wencong Zeng; Shenquan Liu

    2012-01-01

    Predicting neuron growth is valuable to understand the morphology of neurons, thus it is helpful in the research of neuron classification. This study sought to propose a new method of predicting the growth of human neurons using 1 907 sets of data in human brain pyramidal neurons obtained from the website of NeuroMorpho.Org. First, we analyzed neurons in a morphology field and used an expectation-maximization algorithm to specify the neurons into six clusters. Second, naive Bayes classifier was used to verify the accuracy of the expectation-maximization algorithm. Experiment results proved that the cluster groups here were efficient and feasible. Finally, a new method to rank the six expectation-maximization algorithm clustered classes was used in predicting the growth of human pyramidal neurons.

  8. Three-dimensional Quantification of Dendritic Spines from Pyramidal Neurons Derived from Human Induced Pluripotent Stem Cells.

    Science.gov (United States)

    Gouder, Laura; Tinevez, Jean-Yves; Goubran-Botros, Hany; Benchoua, Alexandra; Bourgeron, Thomas; Cloëz-Tayarani, Isabelle

    2015-10-10

    Dendritic spines are small protrusions that correspond to the post-synaptic compartments of excitatory synapses in the central nervous system. They are distributed along the dendrites. Their morphology is largely dependent on neuronal activity, and they are dynamic. Dendritic spines express glutamatergic receptors (AMPA and NMDA receptors) on their surface and at the levels of postsynaptic densities. Each spine allows the neuron to control its state and local activity independently. Spine morphologies have been extensively studied in glutamatergic pyramidal cells of the brain cortex, using both in vivo approaches and neuronal cultures obtained from rodent tissues. Neuropathological conditions can be associated to altered spine induction and maturation, as shown in rodent cultured neurons and one-dimensional quantitative analysis (1). The present study describes a protocol for the 3D quantitative analysis of spine morphologies using human cortical neurons derived from neural stem cells (late cortical progenitors). These cells were initially obtained from induced pluripotent stem cells. This protocol allows the analysis of spine morphologies at different culture periods, and with possible comparison between induced pluripotent stem cells obtained from control individuals with those obtained from patients with psychiatric diseases.

  9. Modulation of NMDA and AMPA-mediated synaptic transmission by CB1 receptors in frontal cortical pyramidal cells.

    Science.gov (United States)

    Li, Qiang; Yan, Haidun; Wilson, Wilkie A; Swartzwelder, H Scott

    2010-06-25

    Although the endogenous cannabinoid system modulates a variety of physiological and pharmacological processes, the specific role of cannabinoid CB1 receptors in the modulation of glutamatergic neurotransmission and neural plasticity is not well understood. Using whole-cell patch clamp recording techniques, evoked or spontaneous excitatory postsynaptic currents (eEPSCs or sEPSCs) were recorded from visualized, layer II/III pyramidal cells in frontal cortical slices from rat brain. Bath application of the CB1 receptor agonist, WIN 55212-2 (WIN), reduced the amplitude of NMDA receptor-mediated EPSCs in a concentration-dependent manner. When co-applied with the specific CB1 antagonists, AM251 or AM281, WIN did not suppress NMDA receptor-mediated EPSCs. WIN also reduced the amplitude of evoked AMPA receptor-mediated EPSCs, an effect that was also reversed by AM251. Both the frequency and amplitude of spontaneous AMPA receptor-mediated EPSCs were significantly reduced by WIN. In contrast, WIN reduced the frequency, but not the amplitude of miniature EPSCs, suggesting that the suppression of glutamatergic activity by CB1 receptors in the frontal neocortex is mediated by a presynaptic mechanism. Taken together, these data indicate a critical role for endocannabinoid signaling in the regulation of excitatory synaptic transmission in frontal neocortex, and suggest a possible neuronal mechanism whereby THC regulates cortical function.

  10. Thrombin modulates persistent sodium current in CA1 pyramidal neurons of young and adult rat hippocampus.

    Science.gov (United States)

    Lunko, O O; Isaev, D S; Krishtal, O O; Isaeva, E V

    2015-01-01

    Serine protease thrombin, a key factor of blood coagulation, participates in many neuronal processes important for normal brain functioning and during pathological conditions involving abnormal neuronal synchronization, neurodegeneration and inflammation. Our previous study on CA3 pyramidal neurons showed that application ofthrombin through the activation of specific protease-activated receptor 1 (PAR1) produces a significant hyperpolarizing shift of the activation of the TTX-sensitive persistent voltage-gated Na+ current (I(Nap)) thereby affecting membrane potential and seizure threshold at the network level. It was shown that PAR1 is also expressed in CA1 area of hippocampus and can be implicated in neuronal damage in this area after status epilepticus. The aim of the present study was to evaluate the effect of thrombin on I(NaP) in CA1 pyramidal neurons from adult and young rats. Using whole cell patch-clamp technique we demonstrate that thrombin application results in the hyperpolarization shift of I(NaP) activation as well as increase in the I(NaP) amplitude in both age groups. We have found that I(NaP) in pyramidal neurons of hippocampal CA 1 region is more vulnerable to the thrombin action than I(NaP) in pyramidal neurons of hippocampal CA3 region. We have also found that the immature hippocampus is more sensitive to thrombin action which emphasizes the contribution of thrombin-dependent pathway to the regulation of neuronal activity in immature brain.

  11. De novo expression of the neurokinin 1 receptor in spinal lamina I pyramidal neurons in polyarthritis.

    Science.gov (United States)

    Almarestani, L; Waters, S M; Krause, J E; Bennett, G J; Ribeiro-da-Silva, A

    2009-05-20

    Spinal lamina I (LI) neurons play a major role in the transmission and integration of pain-related information that is relayed to higher centers. Alterations in the excitability of these neurons influence chronic pain development, and expression of the neurokinin 1 receptor (NK-1r) is thought to play a major role in such changes. Novel expression of NK-1r may underlie hyperexcitability in new populations of LI neurons. LI projection neurons can be classified morphologically into fusiform, pyramidal, and multipolar cells, differing in their functional properties, with the pyramidal type being nonnociceptive. In agreement with this, we have shown that spinoparabrachial pyramidal neurons seldom express NK-1r, in contrast with the other two cell types. In this study we investigated in the rat the long-term changes in NK-1r expression by spinoparabrachial LI neurons following the unilateral injection in the hindpaw plantar surface of complete Freund's adjuvant (CFA). Cholera toxin subunit B (CTb) was injected unilaterally into the parabrachial nucleus. Our results revealed that, ipsilaterally, pyramidal neurons were seldom immunoreactive for NK-1r both in saline-injected and in CFA-injected rats, up to 10 days post-CFA. However, a considerable number of pyramidal cells were immunoreactive for NK-1r at 15, 21, and 30 days post-CFA. Our data raise the possibility -- which needs to be confirmed by electrophysiology -- that most LI projection neurons of the pyramidal type are likely nonnociceptive in naive animals but might become nociceptive following the development of arthritis.

  12. Intermediate Progenitor Cohorts Differentially Generate Cortical Layers and Require Tbr2 for Timely Acquisition of Neuronal Subtype Identity.

    Science.gov (United States)

    Mihalas, Anca B; Elsen, Gina E; Bedogni, Francesco; Daza, Ray A M; Ramos-Laguna, Kevyn A; Arnold, Sebastian J; Hevner, Robert F

    2016-06-28

    Intermediate progenitors (IPs) amplify the production of pyramidal neurons, but their role in selective genesis of cortical layers or neuronal subtypes remains unclear. Using genetic lineage tracing in mice, we find that IPs destined to produce upper cortical layers first appear early in corticogenesis, by embryonic day 11.5. During later corticogenesis, IP laminar fates are progressively limited to upper layers. We examined the role of Tbr2, an IP-specific transcription factor, in laminar fate regulation using Tbr2 conditional mutant mice. Upon Tbr2 inactivation, fewer neurons were produced by immediate differentiation and laminar fates were shifted upward. Genesis of subventricular mitoses was, however, not reduced in the context of a Tbr2-null cortex. Instead, neuronal and laminar differentiation were disrupted and delayed. Our findings indicate that upper-layer genesis depends on IPs from many stages of corticogenesis and that Tbr2 regulates the tempo of laminar fate implementation for all cortical layers.

  13. Intermediate Progenitor Cohorts Differentially Generate Cortical Layers and Require Tbr2 for Timely Acquisition of Neuronal Subtype Identity

    Directory of Open Access Journals (Sweden)

    Anca B. Mihalas

    2016-06-01

    Full Text Available Intermediate progenitors (IPs amplify the production of pyramidal neurons, but their role in selective genesis of cortical layers or neuronal subtypes remains unclear. Using genetic lineage tracing in mice, we find that IPs destined to produce upper cortical layers first appear early in corticogenesis, by embryonic day 11.5. During later corticogenesis, IP laminar fates are progressively limited to upper layers. We examined the role of Tbr2, an IP-specific transcription factor, in laminar fate regulation using Tbr2 conditional mutant mice. Upon Tbr2 inactivation, fewer neurons were produced by immediate differentiation and laminar fates were shifted upward. Genesis of subventricular mitoses was, however, not reduced in the context of a Tbr2-null cortex. Instead, neuronal and laminar differentiation were disrupted and delayed. Our findings indicate that upper-layer genesis depends on IPs from many stages of corticogenesis and that Tbr2 regulates the tempo of laminar fate implementation for all cortical layers.

  14. Pyramidal cells make specific connections onto smooth (GABAergic neurons in mouse visual cortex.

    Directory of Open Access Journals (Sweden)

    Rita Bopp

    2014-08-01

    Full Text Available One of the hallmarks of neocortical circuits is the predominance of recurrent excitation between pyramidal neurons, which is balanced by recurrent inhibition from smooth GABAergic neurons. It has been previously described that in layer 2/3 of primary visual cortex (V1 of cat and monkey, pyramidal cells filled with horseradish peroxidase connect approximately in proportion to the spiny (excitatory, 95% and 81%, respectively and smooth (GABAergic, 5% and 19%, respectively dendrites found in the neuropil. By contrast, a recent ultrastructural study of V1 in a single mouse found that smooth neurons formed 51% of the targets of the superficial layer pyramidal cells. This suggests that either the neuropil of this particular mouse V1 had a dramatically different composition to that of V1 in cat and monkey, or that smooth neurons were specifically targeted by the pyramidal cells in that mouse. We tested these hypotheses by examining similar cells filled with biocytin in a sample of five mice. We found that the average composition of the neuropil in V1 of these mice was similar to that described for cat and monkey V1, but that the superficial layer pyramidal cells do form proportionately more synapses with smooth dendrites than the equivalent neurons in cat or monkey. These distributions may underlie the distinct differences in functional architecture of V1 between rodent and higher mammals.

  15. Stearic acid protects primary cultured cortical neurons against oxidative stress

    Institute of Scientific and Technical Information of China (English)

    Ze-jian WANG; Cui-ling LIANG; Guang-mei LI; Cai-yi YU; Ming YIN

    2007-01-01

    Aim: To observe the effects of stearic acid against oxidative stress in primary cultured cortical neurons. Methods: Cortical neurons were exposed to glutamate,hydrogen peroxide (H202), or NaN3 insult in the presence or absence of stearic acid. Cell viability of cortical neurons was determined by MTT assay and LDH release. Endogenous antioxidant enzymes activity[superoxide dismutases (SOD),glutathione peroxidase (GSH-Px), and catalase (CAT)] and lipid peroxidation in cultured cortical neurons were evaluated using commercial kits. {3-[1(p-chloro-benzyl)-5-(isopropyl)-3-t-butylthiondol-2-yl]-2,2-dimethylpropanoic acid, Na}[MK886; 5 pmol/L; a noncompetitive inhibitor of proliferator-activated receptor(PPAR)α], bisphenol A diglycidyl ether (BADGE; 100 μmol/L; an antagonist of PPARγ), and cycloheximide (CHX; 30 μmol/L, an inhibitor of protein synthesis)were tested for their effects on the neuroprotection afforded by stearic acid.Western blotting was used to determine the PPARγ protein level in cortical neurons.Results: Stearic acid dose-dependently protected cortical neurons against glutamate or H202 injury and increased glutamate uptake in cultured neurons.This protection was concomitant to the inhibition of lipid peroxidation and to the promotion activity of Cu/Zn SOD and CAT in cultured cortical neurons. Its neuroprotective effects were completely blocked by BADGE and CHX. After incubation with H2O2 for 24 h, the expression of the PPARγ protein decreased significantly (P<0.05), and the inhibitory effect of H2O2 on the expression of PPARγ can be attenuated by stearic acid. Conclusion: Stearic acid can protect cortical neurons against oxidative stress by boosting the internal antioxidant enzymes.Its neuroprotective effect may be mainly mediated by the activation of PPARγ and new protein synthesis in cortical neurons.

  16. Decreased pyramidal neuron size in Brodmann areas 44 and 45 in patients with autism.

    Science.gov (United States)

    Jacot-Descombes, Sarah; Uppal, Neha; Wicinski, Bridget; Santos, Micaela; Schmeidler, James; Giannakopoulos, Panteleimon; Heinsen, Helmut; Heinsein, Helmut; Schmitz, Christoph; Hof, Patrick R

    2012-07-01

    Autism is a neurodevelopmental disorder characterized by deficits in social interaction and social communication, as well as by the presence of repetitive and stereotyped behaviors and interests. Brodmann areas 44 and 45 in the inferior frontal cortex, which are involved in language processing, imitation function, and sociality processing networks, have been implicated in this complex disorder. Using a stereologic approach, this study aims to explore the presence of neuropathological differences in areas 44 and 45 in patients with autism compared to age- and hemisphere-matched controls. Based on previous evidence in the fusiform gyrus, we expected to find a decrease in the number and size of pyramidal neurons as well as an increase in volume of layers III, V, and VI in patients with autism. We observed significantly smaller pyramidal neurons in patients with autism compared to controls, although there was no difference in pyramidal neuron numbers or layer volumes. The reduced pyramidal neuron size suggests that a certain degree of dysfunction of areas 44 and 45 plays a role in the pathology of autism. Our results also support previous studies that have shown specific cellular neuropathology in autism with regionally specific reduction in neuron size, and provide further evidence for the possible involvement of the mirror neuron system, as well as impairment of neuronal networks relevant to communication and social behaviors, in this disorder.

  17. Layer- and column-specific knockout of NMDA receptors in pyramidal neurons of the mouse barrel cortex.

    Directory of Open Access Journals (Sweden)

    Rachel Aronoff

    2007-11-01

    Full Text Available Viral vectors injected into the mouse brain offer the possibility for localized genetic modifications in a highly controlled manner. Lentivector injection into mouse neocortex transduces cells within a diameter of approximately 200µm, which closely matches the lateral scale of a column in barrel cortex. The depth and volume of the injection determines which cortical layer is transduced. Furthermore, transduced gene expression from the lentivector can be limited to predominantly pyramidal neurons by using a 1.3kb fragment of the αCaMKII promoter. This technique therefore allows genetic manipulation of a specific cell type in defined columns and layers of the neocortex. By expressing Cre recombinase from such a lentivector in gene-targeted mice carrying a floxed gene, highly specific genetic lesions can be induced. Here, we demonstrate the utility of this approach by specifically knocking out NMDA receptors (NMDARs in pyramidal neurons in the somatosensory barrel cortex of gene-targeted mice carrying floxed NMDAR 1 genes. Neurons transduced with lentivector encoding GFP and Cre recombinase exhibit not only reductions in NMDAR 1 mRNA levels, but reduced NMDAR-dependent currents and pairing-induced synaptic potentiation. This technique for knockout of NMDARs in a cell type, column- and layer-specific manner in the mouse somatosensory cortex may help further our understanding of the functional roles of NMDARs in vivo during sensory perception and learning.

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

    Science.gov (United States)

    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

  19. Ginkgolides protects cultured cortical neurons against excitotoxic and oxidative insults

    Institute of Scientific and Technical Information of China (English)

    ZHANGYu-Yang; YUQing-Hai; YOUSong; SHENGLi

    2004-01-01

    AIM: The neurotoxicity of glutamate is associated with neurological disorders including hypoxic-ischaemic brain injury. Studies using cultured cortical neurons have demonstrated that exposure to glutamate produced delayed degeneration of mature neurons. Oxygen free radicals generated during injury have been postulated to be a major cause of neuronal cell

  20. The changing roles of neurons in the cortical subplate

    Directory of Open Access Journals (Sweden)

    Michael J Friedlander

    2009-08-01

    Full Text Available Neurons may serve different functions over the course of an organism’s life. Recent evidence suggests that cortical subplate neurons including those that reside in the white matter may perform longitudinal multi-tasking at different stages of development. These cells play a key role in early cortical development in coordinating thalamocortical reciprocal innervation. At later stages of development, they become integrated within the cortical microcircuitry. This type of longitudinal multi-tasking can enhance the capacity for information processing by populations of cells serving different functions over the lifespan. Subplate cells are initially derived when cells from the ventricular zone underlying the cortex migrate to the cortical preplate that is subsequently split by the differentiating neurons of the cortical plate with some neurons locating in the marginal zone and others settling below in the subplate (SP. While the cortical plate neurons form most of the cortical layers (layers 2-6, the marginal zone neurons form layer 1 and the SP neurons become interstitial cells of the white matter as well as forming a compact sublayer along the bottom of layer 6. After serving as transient innervation targets for thalamocortical axons, most of these cells die and layer 4 neurons become innervated by thalamic axons. However, 10-20% survives, remaining into adulthood along the bottom of layer 6 and as a scattered population of interstitial neurons in the white matter. Surviving subplate cells’ axons project throughout the overlying laminae, reaching layer 1 and issuing axon collaterals within white matter and in lower layer 6. This suggests that they participate in local synaptic networks, as well. Moreover, they receive excitatory and inhibitory synaptic inputs, potentially monitoring outputs from axon collaterals of cortical efferents, from cortical afferents and/or from each other. We explore our understanding of the functional connectivity of

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

    Science.gov (United States)

    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.

  2. Modelling the Somatic Electrical Response of Hippocampal Pyramidal Neurons

    Science.gov (United States)

    1989-09-01

    non-linear, time-varying conductances in the soma, including those that underly three putative sodium currents , (IN.-tr,, INa-tail, and INa-rep), a...for excitation and propagation of the nerve impulse. Biophysics Journal. 6:, 1966. [12] C. French and P. Gage. A threshold sodium current in pyramidal

  3. Spiking patterns of neocortical L5 pyramidal neurons in vitro change with temperature

    Directory of Open Access Journals (Sweden)

    Tristan eHedrick

    2011-01-01

    Full Text Available A subset of pyramidal neurons in layer 5 of the mammalian neocortex can fire action potentials in brief, high-frequency bursts while others fire spikes at regularly-spaced intervals. Here we show that individual layer 5 pyramidal neurons in acute slices from mouse primary motor cortex can adopt both regular and burst spiking patterns. During constant current injection at the soma, neurons displayed a regular firing pattern at 36-37 °C, but switched to burst spiking patterns upon cooling the slice to 24-26 °C. This change in firing pattern was reversible and repeatable and was independent of the somatic resting membrane potential. Hence these spiking patterns are not inherent to discrete populations of pyramidal neurons and are more interchangeable than previously thought. Burst spiking in these neurons is the result of electrical interactions between the soma and distal apical dendritic tree. Presumably the interactions between soma and distal dendrite are temperature-sensitive, suggesting that the manner in which layer 5 pyramidal neurons translate synaptic input into an output spiking pattern is fundamentally altered at sub-physiological temperatures.

  4. Chemical interactions with pyramidal neurons in layer 5 of the cerebral cortex: control of pain and anxiety.

    Science.gov (United States)

    Adams, J D

    2009-01-01

    Pyramidal neurons in layer 5 of the cerebral cortex are involved in learning and memory and have complex connections with other neurons through a very large array of dendrites. These dendrites can switch between long term depression and long term potentiation depending on global summation of various inputs. The plasticity of the input into pyramidal neurons makes the neuronal output variable. Many interneurons in the cerebral cortex and distant neurons in other brain regions are involved in providing input to pyramidal neurons. All of these neurons and interneurons have neurotransmitters that act through receptors to provide input to pyramidal neurons. Serotonin is one of the important neurotransmitters involved with pyramidal neurons and has been implicated in psychosis, psychedelic states and what are called sacred dreams. This review will discuss the various chemicals and receptors that are important with pyramidal neurons including opioids, nicotine, scopolamine, psilocybin, LSD, mescaline, ergot alkaloids, salvinorin A, ergine and other compounds that interact with opioid, nicotinic, muscarinic and serotonergic receptors. The natural compounds provide clues to structure activity relationships with the receptors. It has been postulated that each receptor in the body has a natural agonist and antagonist, in addition to the normal neurotransmitters. It is common for natural antagonists and agonists to be peptides. Various possible peptide structures will be proposed for natural antagonists and agonists at each receptor. Natural antagonists and agonists may provide new ways to explore the functions of pyramidal neurons in normal health and pain management.

  5. EFFECTS OF GLUTAMATE ON SODIUM CHANNEL IN ACUTELY DISSOCIATED HIPPOCAMPAL CA1 PYRAMIDAL NEURONS OF RATS

    Institute of Scientific and Technical Information of China (English)

    高宾丽; 伍国锋; 杨艳; 刘智飞; 曾晓荣

    2011-01-01

    Objective To observe the effects of glutamate on sodium channel in acutely dissociated hippocampal CA1 pyramidal neurons of rats.Methods Voltage-dependent sodium currents (INa) in acutely dissociated hippocampal CA1 pyramidal neurons of neonate rats were recorded by whole-cell patchclamp of the brain slice technique when a series of doses of glutamate (100-1000μmol/L) were applied.Results Different concentrations of glutamate could inhibit INa,and higher concentration of glutamate affected greater inhibitio...

  6. Steady-state dynamics and experience-dependent plasticity of dendritic spines of layer 4/5a pyramidal neurons in somatosensory cortex

    Directory of Open Access Journals (Sweden)

    Amaya Miquelajauregui

    2014-04-01

    Full Text Available The steady state dynamics and experience-dependent plasticity of dendritic spines of layer (L 2/3 and L5B cortical pyramidal neurons have recently been assessed using in vivo two-photon microscopy (Trachtenberg et al., 2002; Zuo et al., 2005; Holtmaat et al., 2006. In contrast, not much is known about spine dynamics in L4/5a neurons, regarded as direct recipients of thalamocortical input (Constantinople and Bruno, 2013. In the adult mouse somatosensory cortex (SCx, the transcription factor Ebf2 is enriched in excitatory neurons of L4/5a, including pyramidal neurons. We assessed the molecular and electrophysiological properties of these neurons as well as the morphology of their apical tufts (Scholl analysis and cortical outputs (optogenetics within the SCx. To test the hypothesis that L4/5a pyramidal neurons play an important role in sensory processing (given their key laminar position; soma depth ~450-480 µm, we successfully labeled them in Ebf2-Cre mice with EGFP by expressing recombinant rAAV vectors in utero. Using longitudinal in vivo two-photon microscopy through a craniotomy (Mostany and Portera-Cailliau, 2008, we repeatedly imaged spines in apical dendritic tufts of L4/5a neurons under basal conditions and after sensory deprivation. Under steady-state conditions in adults, the morphology of the apical tufts and the mean spine density were stable at 0.39 ± 0.05 spines/μm (comparable to L5B, Mostany et al., 2011. Interestingly, spine elimination increases 4-8 days after sensory deprivation, probably due to input loss. This suggests that Ebf2+ L4/5a neurons could be involved in early steps of processing of thalamocortical information.

  7. More sensitivity of cortical GABAergic neurons than glutamatergic neurons in response to acidosis.

    Science.gov (United States)

    Liu, Hua; Li, Fang; Wang, Chunyan; Su, Zhiqiang

    2016-05-25

    Acidosis impairs brain functions. Neuron-specific mechanisms underlying acidosis-induced brain dysfunction remain elusive. We studied the sensitivity of cortical GABAergic neurons and glutamatergic neurons to acidosis by whole-cell recording in brain slices. The acidification to the neurons was induced by perfusing artificial cerebral spinal fluid with lower pH. This acidification impairs excitability and synaptic transmission in the glutamatergic and GABAergic neurons. Acidosis impairs spiking capacity in the GABAergic neurons more than in the glutamatergic neurons. Acidosis also strengthens glutamatergic synaptic transmission and attenuates GABAergic synaptic transmission on the GABAergic neurons more than the glutamatergic neurons, which results in the functional impairment of these GABAergic neurons. This acidosis-induced dysfunction predominantly in the cortical GABAergic neurons drives the homeostasis of neuronal networks toward overexcitation and exacerbates neuronal impairment.

  8. Relating normalization to neuronal populations across cortical areas.

    Science.gov (United States)

    Ruff, Douglas A; Alberts, Joshua J; Cohen, Marlene R

    2016-09-01

    Normalization, which divisively scales neuronal responses to multiple stimuli, is thought to underlie many sensory, motor, and cognitive processes. In every study where it has been investigated, neurons measured in the same brain area under identical conditions exhibit a range of normalization, ranging from suppression by nonpreferred stimuli (strong normalization) to additive responses to combinations of stimuli (no normalization). Normalization has been hypothesized to arise from interactions between neuronal populations, either in the same or different brain areas, but current models of normalization are not mechanistic and focus on trial-averaged responses. To gain insight into the mechanisms underlying normalization, we examined interactions between neurons that exhibit different degrees of normalization. We recorded from multiple neurons in three cortical areas while rhesus monkeys viewed superimposed drifting gratings. We found that neurons showing strong normalization shared less trial-to-trial variability with other neurons in the same cortical area and more variability with neurons in other cortical areas than did units with weak normalization. Furthermore, the cortical organization of normalization was not random: neurons recorded on nearby electrodes tended to exhibit similar amounts of normalization. Together, our results suggest that normalization reflects a neuron's role in its local network and that modulatory factors like normalization share the topographic organization typical of sensory tuning properties.

  9. Characterization of intrinsic properties of cingulate pyramidal neurons in adult mice after nerve injury

    Directory of Open Access Journals (Sweden)

    Chen Tao

    2009-12-01

    Full Text Available Abstract The anterior cingulate cortex (ACC is important for cognitive and sensory functions including memory and chronic pain. Glutamatergic excitatory synaptic transmission undergo long-term potentiation in ACC pyramidal cells after peripheral injury. Less information is available for the possible long-term changes in neuronal action potentials or intrinsic properties. In the present study, we characterized cingulate pyramidal cells in the layer II/III of the ACC in adult mice. We then examined possible long-term changes in intrinsic properties of the ACC pyramidal cells after peripheral nerve injury. In the control mice, we found that there are three major types of pyramidal cells according to their action potential firing pattern: (i regular spiking (RS cells (24.7%, intrinsic bursting (IB cells (30.9%, and intermediate (IM cells (44.4%. In a state of neuropathic pain, the population distribution (RS: 21.3%; IB: 31.2%; IM: 47.5% and the single action potential properties of these three groups were indistinguishable from those in control mice. However, for repetitive action potentials, IM cells from neuropathic pain animals showed higher initial firing frequency with no change for the properties of RS and IB neurons from neuropathic pain mice. The present results provide the first evidence that, in addition to synaptic potentiation reported previously, peripheral nerve injury produces long-term plastic changes in the action potentials of cingulate pyramidal neurons in a cell type-specific manner.

  10. Anatomy and Physiology of the Thick-tufted Layer 5 Pyramidal Neuron

    Directory of Open Access Journals (Sweden)

    Srikanth eRamaswamy

    2015-06-01

    Full Text Available The thick-tufted layer 5 (TTL5 pyramidal neuron is one of the most extensively studied neuron types in the mammalian neocortex and has become a benchmark for understanding information processing in excitatory neurons. By virtue of having the widest local axonal and dendritic arborization, the TTL5 neuron encompasses various local neocortical neurons and thereby defines the dimensions of neocortical microcircuitry. The TTL5 neuron integrates input across all neocortical layers and is the principal output pathway funneling information flow to subcortical structures. Several studies over the past decades have investigated the anatomy, physiology, synaptology, and pathophysiology of the TTL5 neuron. This review summarizes key discoveries and identifies potential avenues of research to facilitate an integrated and unifying understanding on the role of a central neuron in the neocortex.

  11. The neocortex of cetartiodactyls. II. Neuronal morphology of the visual and motor cortices in the giraffe (Giraffa camelopardalis).

    Science.gov (United States)

    Jacobs, Bob; Harland, Tessa; Kennedy, Deborah; Schall, Matthew; Wicinski, Bridget; Butti, Camilla; Hof, Patrick R; Sherwood, Chet C; Manger, Paul R

    2015-09-01

    The present quantitative study extends our investigation of cetartiodactyls by exploring the neuronal morphology in the giraffe (Giraffa camelopardalis) neocortex. Here, we investigate giraffe primary visual and motor cortices from perfusion-fixed brains of three subadults stained with a modified rapid Golgi technique. Neurons (n = 244) were quantified on a computer-assisted microscopy system. Qualitatively, the giraffe neocortex contained an array of complex spiny neurons that included both "typical" pyramidal neuron morphology and "atypical" spiny neurons in terms of morphology and/or orientation. In general, the neocortex exhibited a vertical columnar organization of apical dendrites. Although there was no significant quantitative difference in dendritic complexity for pyramidal neurons between primary visual (n = 78) and motor cortices (n = 65), there was a significant difference in dendritic spine density (motor cortex > visual cortex). The morphology of aspiny neurons in giraffes appeared to be similar to that of other eutherian mammals. For cross-species comparison of neuron morphology, giraffe pyramidal neurons were compared to those quantified with the same methodology in African elephants and some cetaceans (e.g., bottlenose dolphin, minke whale, humpback whale). Across species, the giraffe (and cetaceans) exhibited less widely bifurcating apical dendrites compared to elephants. Quantitative dendritic measures revealed that the elephant and humpback whale had more extensive dendrites than giraffes, whereas the minke whale and bottlenose dolphin had less extensive dendritic arbors. Spine measures were highest in the giraffe, perhaps due to the high quality, perfusion fixation. The neuronal morphology in giraffe neocortex is thus generally consistent with what is known about other cetartiodactyls.

  12. Pyramidal neurons of the prefrontal cortex in post-stroke, vascular and other ageing-related dementias.

    Science.gov (United States)

    Foster, Vincent; Oakley, Arthur E; Slade, Janet Y; Hall, Roslyn; Polvikoski, Tuomo M; Burke, Matthew; Thomas, Alan J; Khundakar, Ahmad; Allan, Louise M; Kalaria, Raj N

    2014-09-01

    Dementia associated with cerebrovascular disease is common. It has been reported that ∼30% of elderly patients who survive stroke develop delayed dementia (post-stroke dementia), with most cases being diagnosed as vascular dementia. The pathological substrates associated with post-stroke or vascular dementia are poorly understood, particularly those associated with executive dysfunction. Three separate yet interconnecting circuits control executive function within the frontal lobe involving the dorsolateral prefrontal cortex, anterior cingulate cortex and the orbitofrontal cortex. We used stereological methods, along with immunohistological and related cell morphometric analysis, to examine densities and volumes of pyramidal neurons of the dorsolateral prefrontal cortex, anterior cingulate cortex and orbitofrontal cortex in the frontal lobe from a total of 90 elderly subjects (age range 71-98 years). Post-mortem brain tissues from post-stroke dementia and post-stroke patients with no dementia were derived from our prospective Cognitive Function After Stroke study. We also examined, in parallel, samples from ageing controls and similar age subjects pathologically diagnosed with Alzheimer's disease, mixed Alzheimer's disease and vascular dementia, and vascular dementia. We found pyramidal cell volumes in layers III and V in the dorsolateral prefrontal cortex of post-stroke and vascular dementia and, of mixed and Alzheimer's disease subjects to be reduced by 30-40% compared to post-stroke patients with no dementia and controls. There were no significant changes in neuronal volumes in either the anterior cingulate or orbitofrontal cortices. Remarkably, pyramidal neurons within the orbitofrontal cortex were also found to be smaller in size when compared to those in the other two neocortical regions. To relate the cell changes to cognitive function, we noted significant correlations between neuronal volumes and total CAMCOG, orientation and memory scores and clinical

  13. Accelerated dendritic development of rat cortical pyramidal cells and interneurons after biolistic transfection with BDNF and NT4/5.

    Science.gov (United States)

    Wirth, Marcus J; Brun, Annika; Grabert, Jochen; Patz, Silke; Wahle, Petra

    2003-12-01

    Neurotrophins are candidate molecules for regulating dendritogenesis. We report here on dendritic growth of rat visual cortex pyramidal and interneurons overexpressing 'brain-derived neurotrophic factor' BDNF and 'neurotrophin 4/5' NT4/5. Neurons in organotypic cultures were transfected with plasmids encoding either 'enhanced green fluorescent protein' EGFP, BDNF/EGFP or NT4/5/EGFP either at the day of birth with analysis at 5 days in vitro, or at 5 days in vitro with analysis at 10 days in vitro. In pyramidal neurons, both TrkB ligands increased dendritic length and number of segments without affecting maximum branch order and number of primary dendrites. In the early time window, only infragranular neurons were responsive. Neurons in layers II/III became responsive to NT4/5, but not BDNF, during the later time window. BDNF and NT4/5 transfectants at 10 days in vitro had still significantly shorter dendrites than adult pyramidal neurons, suggesting a massive growth spurt after 10 days in vitro. However, segment numbers were already in the range of adult neurons. Although this suggested a role for BDNF, long-term activity-deprived, and thus BDNF-deprived, pyramidal cells developed a dendritic complexity not different from neurons in active cultures except for higher spine densities on neurons of layers II/III and VI. Neutralization of endogenous NT4/5 causes shorter and less branched dendrites at 10 days in vitro suggesting an essential role for NT4/5. Neutralization of BDNF had no effect. Transfected multipolar interneurons became identifiable during the second time window. Both TrkB ligands significantly increased number of segments and branch order towards the adult state with little effects on dendritic length. The results suggested that early in development BDNF and NT4/5 probably accelerate dendritogenesis in an autocrine fashion. In particular, branch formation was advanced towards the adult pattern in pyramidal cells and interneurons.

  14. Zbtb20-Induced CA1 Pyramidal Neuron Development and Area Enlargement in the Cerebral Midline Cortex of Mice

    DEFF Research Database (Denmark)

    Nielsen, Jakob V; Blom, Jonas B; Noraberg, Jens

    2010-01-01

    Expression of the transcriptional repressor Zbtb20 is confined to the hippocampal primordium of the developing dorsal midline cortex in mice. Here, we show that misexpression of Zbtb20 converts projection neurons of the subiculum and postsubiculum (dorsal presubiculum) to CA1 pyramidal neurons...... that are innervated by Schaffer collateral projections in ectopic strata oriens and radiatum. The Zbtb20-transformed neurons express Bcl11B, Satb2, and Calbindin-D28k, which are markers of adult CA1 pyramidal neurons. Downregulation of Zbtb20 expression by RNA interference impairs the normal maturation of CA1...... pyramidal neurons resulting in deficiencies in Calbindin-D28k expression and in reduced apical dendritic arborizations in stratum lacunosum moleculare. Overall, the results show that Zbtb20 is required for various aspects of CA1 pyramidal neuron development such as the postnatal extension of apical...

  15. How cesium dialysis affects the passive properties of pyramidal neurons: implications for voltage clamp studies of persistent sodium current

    Energy Technology Data Exchange (ETDEWEB)

    Fleidervish, Ilya A; Libman, Lior [Koret School of Veterinary Medicine, Hebrew University of Jerusalem, PO Box 12, Rehovot 76100 (Israel)], E-mail: fleider@agri.huji.ac.il

    2008-03-15

    In order to accurately understand and model neuronal integration in the brain, we must know the biophysical properties of channels that are located far from the soma, in the axonal and dendritic membranes of central nerve cells. Reliable electrophysiological measurements in these regions are difficult to obtain, because the processes are too tiny to directly study with an electrode. One common strategy is to record with a somatic electrode that contains Cs{sup +}, to dialyze the intracellular space with this K{sup +} channel blocker, and thereby to render the neuron electrotonically compact. Does this work? Here, we combine the experimental and modeling techniques to determine the extent to which a whole-cell voltage clamp, established with a Cs{sup +}-containing pipette in the soma of a cortical pyramidal cell, attains adequate voltage control of distal neuronal processes. We focus on the low-voltage-activated, slowly inactivating 'persistent' Na{sup +} current (I{sub NaP}), that plays a crucial role in determining neuronal excitability and synaptic integration.

  16. How cesium dialysis affects the passive properties of pyramidal neurons: implications for voltage clamp studies of persistent sodium current

    Science.gov (United States)

    Fleidervish, Ilya A.; Libman, Lior

    2008-03-01

    In order to accurately understand and model neuronal integration in the brain, we must know the biophysical properties of channels that are located far from the soma, in the axonal and dendritic membranes of central nerve cells. Reliable electrophysiological measurements in these regions are difficult to obtain, because the processes are too tiny to directly study with an electrode. One common strategy is to record with a somatic electrode that contains Cs+, to dialyze the intracellular space with this K+ channel blocker, and thereby to render the neuron electrotonically compact. Does this work? Here, we combine the experimental and modeling techniques to determine the extent to which a whole-cell voltage clamp, established with a Cs+-containing pipette in the soma of a cortical pyramidal cell, attains adequate voltage control of distal neuronal processes. We focus on the low-voltage-activated, slowly inactivating 'persistent' Na+ current (INaP), that plays a crucial role in determining neuronal excitability and synaptic integration.

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

    Science.gov (United States)

    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.

  18. Electrophysiological actions of cyclosporin A and tacrolimus on rat hip-pocampal CA1 pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    Yong YU; Xue-qin CHEN; Yao-yuan CUI; Guo-yuan HU

    2007-01-01

    Aim: The aim of the present study was to investigate the electrophysiological actions of cyclosporin A (CsA) and tacrolimus (FK506) on neurons in the brain, and to elucidate the relevant mechanisms. Methods: Whole-cell current-clamp recording was made in CA1 pyramidal neurons in rat hippocampal slices; whole- cell voltage-clamp recording was made in dissociated hippocampal CA1 pyrami- dal neurons of rats. Results: CsA (100 μmol/L) and FKS06 (50 μmol/L) did not significantly alter the passive electrical properties of hippocampal CA1 pyramidal neurons, but slowed down the repolarizing phase of the action potential. CsA (10-100 μmol/L) selectively inhibited the delayed rectifier K~ current (IK,) in a concentration-dependent manner. CsA did not affect the kinetic properties of IK. Intracellular dialysis of CsA (100 μmol/L) had no effect on IK. The inhibition of IK by CsA (100/μmol/L) persisted under the low Ca2+ conditions that blocked the basal activity of calcineurin. Conclusion: CsA exerted calcineurin-independent inhibition on the IK in rat hippocampal pyramidal neurons. Taken together with our previous finding with FK506, it is conceivable that the spike broadening caused by the immunosuppressant drugs is due to direct inhibition on the IK.

  19. Layer 4 pyramidal neurons exhibit robust dendritic spine plasticity in vivo after input deprivation.

    Science.gov (United States)

    Miquelajauregui, Amaya; Kribakaran, Sahana; Mostany, Ricardo; Badaloni, Aurora; Consalez, G Giacomo; Portera-Cailliau, Carlos

    2015-05-06

    Pyramidal neurons in layers 2/3 and 5 of primary somatosensory cortex (S1) exhibit somewhat modest synaptic plasticity after whisker input deprivation. Whether neurons involved at earlier steps of sensory processing show more or less plasticity has not yet been examined. Here, we used longitudinal in vivo two-photon microscopy to investigate dendritic spine dynamics in apical tufts of GFP-expressing layer 4 (L4) pyramidal neurons of the vibrissal (barrel) S1 after unilateral whisker trimming. First, we characterize the molecular, anatomical, and electrophysiological properties of identified L4 neurons in Ebf2-Cre transgenic mice. Next, we show that input deprivation results in a substantial (∼50%) increase in the rate of dendritic spine loss, acutely (4-8 d) after whisker trimming. This robust synaptic plasticity in L4 suggests that primary thalamic recipient pyramidal neurons in S1 may be particularly sensitive to changes in sensory experience. Ebf2-Cre mice thus provide a useful tool for future assessment of initial steps of sensory processing in S1.

  20. Synaptic integration in tuft dendrites of layer 5 pyramidal neurons: a new unifying principle.

    Science.gov (United States)

    Larkum, Matthew E; Nevian, Thomas; Sandler, Maya; Polsky, Alon; Schiller, Jackie

    2009-08-07

    Tuft dendrites are the main target for feedback inputs innervating neocortical layer 5 pyramidal neurons, but their properties remain obscure. We report the existence of N-methyl-D-aspartate (NMDA) spikes in the fine distal tuft dendrites that otherwise did not support the initiation of calcium spikes. Both direct measurements and computer simulations showed that NMDA spikes are the dominant mechanism by which distal synaptic input leads to firing of the neuron and provide the substrate for complex parallel processing of top-down input arriving at the tuft. These data lead to a new unifying view of integration in pyramidal neurons in which all fine dendrites, basal and tuft, integrate inputs locally through the recruitment of NMDA receptor channels relative to the fixed apical calcium and axosomatic sodium integration points.

  1. Glutamate-bound NMDARs arising from in vivo-like network activity extend spatio-temporal integration in a L5 cortical pyramidal cell model.

    Directory of Open Access Journals (Sweden)

    Matteo Farinella

    2014-04-01

    Full Text Available In vivo, cortical pyramidal cells are bombarded by asynchronous synaptic input arising from ongoing network activity. However, little is known about how such 'background' synaptic input interacts with nonlinear dendritic mechanisms. We have modified an existing model of a layer 5 (L5 pyramidal cell to explore how dendritic integration in the apical dendritic tuft could be altered by the levels of network activity observed in vivo. Here we show that asynchronous background excitatory input increases neuronal gain and extends both temporal and spatial integration of stimulus-evoked synaptic input onto the dendritic tuft. Addition of fast and slow inhibitory synaptic conductances, with properties similar to those from dendritic targeting interneurons, that provided a 'balanced' background configuration, partially counteracted these effects, suggesting that inhibition can tune spatio-temporal integration in the tuft. Excitatory background input lowered the threshold for NMDA receptor-mediated dendritic spikes, extended their duration and increased the probability of additional regenerative events occurring in neighbouring branches. These effects were also observed in a passive model where all the non-synaptic voltage-gated conductances were removed. Our results show that glutamate-bound NMDA receptors arising from ongoing network activity can provide a powerful spatially distributed nonlinear dendritic conductance. This may enable L5 pyramidal cells to change their integrative properties as a function of local network activity, potentially allowing both clustered and spatially distributed synaptic inputs to be integrated over extended timescales.

  2. Changes in membrane properties of CA1 pyramidal neurons after transient forebrain ischemia in vivo.

    Science.gov (United States)

    Gao, T M; Pulsinelli, W A; Xu, Z C

    1999-03-01

    We have previously identified three distinct populations of CA1 pyramidal neurons after reperfusion based on differences in synaptic response, and named these late depolarizing postsynaptic potential neurons (enhanced synaptic transmission), non-late depolarizing postsynaptic potential and small excitatory postsynaptic neurons (depressed synaptic transmission). In the present study, spontaneous activity and membrane properties of CA1 neurons were examined up to 48 h following approximately 14 min ischemic depolarization using intracellular recording and staining techniques in vivo. In comparison with preischemic properties, the spontaneous firing rate and the spontaneous synaptic activity of CA1 neurons decreased significantly during reperfusion; spontaneous synaptic activity ceased completely 36-48 h after reperfusion, except for a low level of activity which persisted in non-late depolarizing postsynaptic potential neurons. Neuronal hyperactivity as indicated by increasing firing rate was never observed in the present study. The membrane input resistance and time constant decreased significantly in late depolarizing postsynaptic potential neurons at 24-48 h reperfusion. In contrast, similar changes were not observed in non-late depolarizing postsynaptic potential neurons. The rheobase, spike threshold and spike frequency adaptation in late depolarizing postsynaptic potential neurons increased progressively following reperfusion. Only a transient increase in rheobase and spike threshold was detected in non-late depolarizing postsynaptic potential neurons and spike frequency adaptation remained unchanged in these neurons. The amplitude of fast afterhyperpolarization increased in all neurons after reperfusion, with the smallest increment in non-late depolarizing postsynaptic potential neurons. Small excitatory postsynaptic potential neurons shared similar changes to those of late depolarizing postsynaptic potential neurons. These results suggest that the enhancement

  3. An in silico agent-based model demonstrates Reelin function in directing lamination of neurons during cortical development.

    Directory of Open Access Journals (Sweden)

    James R Caffrey

    Full Text Available The characteristic six-layered appearance of the neocortex arises from the correct positioning of pyramidal neurons during development and alterations in this process can cause intellectual disabilities and developmental delay. Malformations in cortical development arise when neurons either fail to migrate properly from the germinal zones or fail to cease migration in the correct laminar position within the cortical plate. The Reelin signalling pathway is vital for correct neuronal positioning as loss of Reelin leads to a partially inverted cortex. The precise biological function of Reelin remains controversial and debate surrounds its role as a chemoattractant or stop signal for migrating neurons. To investigate this further we developed an in silico agent-based model of cortical layer formation. Using this model we tested four biologically plausible hypotheses for neuron motility and four biologically plausible hypotheses for the loss of neuron motility (conversion from migration. A matrix of 16 combinations of motility and conversion rules was applied against the known structure of mouse cortical layers in the wild-type cortex, the Reelin-null mutant, the Dab1-null mutant and a conditional Dab1 mutant. Using this approach, many combinations of motility and conversion mechanisms can be rejected. For example, the model does not support Reelin acting as a repelling or as a stopping signal. In contrast, the study lends very strong support to the notion that the glycoprotein Reelin acts as a chemoattractant for neurons. Furthermore, the most viable proposition for the conversion mechanism is one in which conversion is affected by a motile neuron sensing in the near vicinity neurons that have already converted. Therefore, this model helps elucidate the function of Reelin during neuronal migration and cortical development.

  4. Distinctive transcriptome alterations of prefrontal pyramidal neurons in schizophrenia and schizoaffective disorder

    Science.gov (United States)

    Arion, Dominique; Corradi, John P.; Tang, Shaowu; Datta, Dibyadeep; Boothe, Franklyn; He, Aiqing; Cacace, Angela M.; Zaczek, Robert; Albright, Charles F.; Tseng, George; Lewis, David A.

    2014-01-01

    Schizophrenia is associated with alterations in working memory that reflect dysfunction of dorsolateral prefrontal cortex (DLPFC) circuitry. Working memory depends on the activity of excitatory pyramidal cells in DLPFC layer 3, and to a lesser extent in layer 5. Although many studies have profiled gene expression in DLPFC gray matter in schizophrenia, little is known about cell type-specific transcript expression in these two populations of pyramidal cells. We hypothesized that interrogating gene expression specifically in DLPFC layer 3 or 5 pyramidal cells would reveal new and/or more robust schizophrenia-associated differences that would provide new insights into the nature of pyramidal cell dysfunction in the illness. We also sought to determine the impact of other variables, such as a diagnosis of schizoaffective disorder or medication use at time of death, on the patterns of gene expression in pyramidal neurons. Individual pyramidal cells in DLPFC layers 3 or 5 were captured by laser microdissection from 36 subjects with schizophrenia or schizoaffective disorder and matched normal comparison subjects. The mRNA from cell collections was subjected to transcriptome profiling by microarray followed by qPCR validation. Expression of genes involved in mitochondrial (MT) or ubiquitin-proteasome system (UPS) functions were markedly down-regulated in the patient group (p values for MT-related and UPS-related pathways were <10−7 and <10−5 respectively). MT-related gene alterations were more prominent in layer 3 pyramidal cells, whereas UPS-related gene alterations were more prominent in layer 5 pyramidal cells. Many of these alterations were not present, or found to a lesser degree, in samples of DLPFC gray matter from the same subjects, suggesting that they are pyramidal cell-specific. Furthermore, these findings principally reflected alterations in the schizophrenia subjects, were not present or present to a lesser degree in the schizoaffective disorder subjects

  5. Loss of glutathione homeostasis associated with neuronal senescence facilitates TRPM2 channel activation in cultured hippocampal pyramidal neurons

    Directory of Open Access Journals (Sweden)

    Belrose Jillian C

    2012-04-01

    Full Text Available Abstract Background Glutathione (GSH plays an important role in neuronal oxidant defence. Depletion of cellular GSH is observed in neurodegenerative diseases and thereby contributes to the associated oxidative stress and Ca2+ dysregulation. Whether depletion of cellular GSH, associated with neuronal senescence, directly influences Ca2+ permeation pathways is not known. Transient receptor potential melastatin type 2 (TRPM2 is a Ca2+ permeable non-selective cation channel expressed in several cell types including hippocampal pyramidal neurons. Moreover, activation of TRPM2 during oxidative stress has been linked to cell death. Importantly, GSH has been reported to inhibit TRPM2 channels, suggesting they may directly contribute to Ca2+ dysregulation associated with neuronal senescence. Herein, we explore the relation between cellular GSH and TRPM2 channel activity in long-term cultures of hippocampal neurons. Results In whole-cell voltage-clamp recordings, we observe that TRPM2 current density increases in cultured pyramidal neurons over time in vitro. The observed increase in current density was prevented by treatment with NAC, a precursor to GSH synthesis. Conversely, treatment of cultures maintained for 2 weeks in vitro with L-BSO, which depletes GSH by inhibiting its synthesis, augments TRPM2 currents. Additionally, we demonstrate that GSH inhibits TRPM2 currents through a thiol-independent mechanism, and produces a 3.5-fold shift in the dose-response curve generated by ADPR, the intracellular agonist for TRPM2. Conclusion These results indicate that GSH plays a physiologically relevant role in the regulation of TRPM2 currents in hippocampal pyramidal neurons. This interaction may play an important role in aging and neurological diseases associated with depletion of GSH.

  6. Dopamine control of pyramidal neuron activity in the primary motor cortex via D2 receptors

    Directory of Open Access Journals (Sweden)

    Clément eVitrac

    2014-02-01

    Full Text Available The primary motor cortex (M1 is involved in fine voluntary movements control. Previous studies have shown the existence of a dopamine (DA innervation in M1 of rats and monkeys that could directly modulate M1 neuronal activity. However, none of these studies have described the precise distribution of DA terminals within M1 functional region nor have quantified the density of this innervation. Moreover, the precise role of DA on pyramidal neuron activity still remains unclear due to conflicting results from previous studies regarding D2 effects on M1 pyramidal neurons.In this study we assessed in mice the neuroanatomical characteristics of DA innervation in M1 using unbiased stereological quantification of dopamine transporter-immunostained fibers. We demonstrated for the first time in mice that DA innervates the deep layers of M1 targeting preferentially the forelimb representation area of M1. To address the functional role of the DA innervation on M1 neuronal activity, we performed electrophysiological recordings of single neurons activity in vivo and pharmacologically modulated D2 receptors activity. Local D2 receptors activation by quinpirole enhanced pyramidal neurons spike firing rate without changes in spike firing pattern. Altogether, these results indicate that DA innervation in M1 can increase neuronal activity through D2 receptors activation and suggest a potential contribution to the modulation of fine forelimb movement. Given the demonstrated role for DA in fine motor skill learning in M1, our results suggest that altered D2 modulation of M1 activity may be involved in the pathophysiology of movement disorders associated with disturbed DA homeostasis.

  7. De novo expression of neurokinin-1 receptors by spinoparabrachial lamina I pyramidal neurons following a peripheral nerve lesion.

    Science.gov (United States)

    Saeed, Abeer W; Ribeiro-da-Silva, Alfredo

    2013-06-01

    Lamina I of the spinal dorsal horn is a major site of integration and transmission to higher centers of nociceptive information from the periphery. One important primary afferent population that transmits such information to the spinal cord expresses substance P (SP). These fibers terminate in contact with lamina I projection neurons that express the SP receptor, also known as the neurokinin-1 receptor (NK-1r). Three types of lamina I projection neurons have been described: multipolar, fusiform, and pyramidal. Most neurons of the first two types are thought to be nociceptive and express the NK-1r, whereas most pyramidal neurons are nonnociceptive and do not express the NK-1r. In this immunocytochemical and behavioral study, we induced a neuropathic pain-like condition in the rat by means of a polyethylene cuff placed around in the sciatic nerve. We document that this lesion led to a de novo expression of NK-1r on pyramidal neurons as well as a significant increase in SP-immunoreactive innervation onto these neurons. These phenotypic changes were evident at the time of onset of neuropathic pain-related behavior. Additionally, we show that, after a noxious stimulus (intradermal capsaicin injection), these NK-1r on pyramidal neurons were internalized, providing evidence that these neurons become responsive to peripheral noxious stimulation. We suggest that the changes following nerve lesion in the phenotype and innervation pattern of pyramidal neurons are of significance for neuropathic pain and/or limb temperature regulation.

  8. On learning time delays between the spikes from different input neurons in a biophysical model of a pyramidal neuron.

    Science.gov (United States)

    Koutsou, Achilleas; Bugmann, Guido; Christodoulou, Chris

    2015-10-01

    Biological systems are able to recognise temporal sequences of stimuli or compute in the temporal domain. In this paper we are exploring whether a biophysical model of a pyramidal neuron can detect and learn systematic time delays between the spikes from different input neurons. In particular, we investigate whether it is possible to reinforce pairs of synapses separated by a dendritic propagation time delay corresponding to the arrival time difference of two spikes from two different input neurons. We examine two subthreshold learning approaches where the first relies on the backpropagation of EPSPs (excitatory postsynaptic potentials) and the second on the backpropagation of a somatic action potential, whose production is supported by a learning-enabling background current. The first approach does not provide a learning signal that sufficiently differentiates between synapses at different locations, while in the second approach, somatic spikes do not provide a reliable signal distinguishing arrival time differences of the order of the dendritic propagation time. It appears that the firing of pyramidal neurons shows little sensitivity to heterosynaptic spike arrival time differences of several milliseconds. This neuron is therefore unlikely to be able to learn to detect such differences.

  9. Selective neurofilament (SMI-32, FNP-7 and N200) expression in subpopulations of layer V pyramidal neurons in vivo and in vitro.

    Science.gov (United States)

    Voelker, Courtney C J; Garin, Nathalie; Taylor, Jeremy S H; Gähwiler, Beat H; Hornung, Jean-Pierre; Molnár, Zoltán

    2004-11-01

    There are two main types of layer V pyramidal neurons in rat cortex. Type I neurons have tufted apical dendrites extending into layer I, produce bursts of action potentials and project to subcortical targets (spinal cord, superior colliculus and pontine nuclei). Type II neurons have apical dendrites, which arborize in layers II-IV, do not produce bursts of action potentials and project to ipsilateral and contralateral cortex. The specific expression of different genes and proteins in these two distinct layer V neurons is unknown. To distinguish between distinct subpopulations, fluorescent microspheres were injected into subcortical targets (labeling type I neurons) or primary somatosensory cortex (labeling type II neurons) of adult rats. After transport, cortical sections were processed for immunohistochemistry using various antibodies. This study demonstrated that antigens recognized by SMI-32, N200 and FNP-7 antibodies were only expressed in subcortical (type I)--but not in contralateral (type II)--projecting neurons. NR1, NR2a/b, PLCbeta1, BDNF, NGF and TrkB antigens were highly expressed in all neuronal subpopulations examined. Organotypic culture experiments demonstrated that the development of neurofilament expression and laminar specificity does not depend on the presence of the subcortical targets. This study suggests specific markers for the subcortical projecting layer V neuron subpopulations.

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

    Science.gov (United States)

    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.

  11. Retinoic acid from the meninges regulates cortical neuron generation.

    Science.gov (United States)

    Siegenthaler, Julie A; Ashique, Amir M; Zarbalis, Konstantinos; Patterson, Katelin P; Hecht, Jonathan H; Kane, Maureen A; Folias, Alexandra E; Choe, Youngshik; May, Scott R; Kume, Tsutomu; Napoli, Joseph L; Peterson, Andrew S; Pleasure, Samuel J

    2009-10-30

    Extrinsic signals controlling generation of neocortical neurons during embryonic life have been difficult to identify. In this study we demonstrate that the dorsal forebrain meninges communicate with the adjacent radial glial endfeet and influence cortical development. We took advantage of Foxc1 mutant mice with defects in forebrain meningeal formation. Foxc1 dosage and loss of meninges correlated with a dramatic reduction in both neuron and intermediate progenitor production and elongation of the neuroepithelium. Several types of experiments demonstrate that retinoic acid (RA) is the key component of this secreted activity. In addition, Rdh10- and Raldh2-expressing cells in the dorsal meninges were either reduced or absent in the Foxc1 mutants, and Rdh10 mutants had a cortical phenotype similar to the Foxc1 null mutants. Lastly, in utero RA treatment rescued the cortical phenotype in Foxc1 mutants. These results establish RA as a potent, meningeal-derived cue required for successful corticogenesis.

  12. Intracellular activities related to in vitro hippocampal sharp waves are altered in CA3 pyramidal neurons of aged mice.

    Science.gov (United States)

    Moradi-Chameh, H; Peng, J; Wu, C; Zhang, L

    2014-09-26

    Pyramidal neurons in the hippocampal CA3 area interconnect intensively via recurrent axonal collaterals, and such CA3-to-CA3 recurrent circuitry plays important roles in the generation of hippocampal network activities. In particular, the CA3 circuitry is able to generate spontaneous sharp waves (SPWs) when examined in vitro. These in vitro SPWs are thought to result from the network activity of GABAergic inhibitory interneurons as SPW-correlating intracellular activities are featured with strong IPSPs in pyramidal neurons and EPSPs or spikes in GABAergic interneurons. In view of accumulating evidence indicating a decrease in subgroups of hippocampal GABAergic interneurons in aged animals, we test the hypothesis that the intracellular activities related to in vitro SPWs are altered in CA3 pyramidal neurons of aged mice. Hippocampal slices were prepared from adult and aged C57 black mice (ages 3-6 and 24-28months respectively). Population and single-cell activities were examined via extracellular and whole-cell patch-clamp recordings. CA3 SPW frequencies were not significantly different between the slices of adult and aged mice but SPW-correlating intracellular activities featured weaker IPSC components in aged CA3 pyramidal neurons compared to adult neurons. It was unlikely that this latter phenomenon was due to general impairments of GABAergic synapses in the aged CA3 circuitry as evoked IPSC responses and pharmacologically isolated IPSCs were observed in aged CA3 pyramidal neurons. In addition, aged CA3 pyramidal neurons displayed more positive resting potentials and had a higher propensity of burst firing than adult neurons. We postulate that alterations of GABAergic network activity may explain the reduced IPCS contributions to in vitro SPWs in aged CA3 pyramidal neurons. Overall, our present observations are supportive of the notion that excitability of hippocampal CA3 circuitry is increased in aged mice.

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

    Science.gov (United States)

    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

  14. Repetitive magnetic stimulation induces plasticity of excitatory postsynapses on proximal dendrites of cultured mouse CA1 pyramidal neurons.

    Science.gov (United States)

    Lenz, Maximilian; Platschek, Steffen; Priesemann, Viola; Becker, Denise; Willems, Laurent M; Ziemann, Ulf; Deller, Thomas; Müller-Dahlhaus, Florian; Jedlicka, Peter; Vlachos, Andreas

    2015-11-01

    Repetitive transcranial magnetic stimulation (rTMS) of the human brain can lead to long-lasting changes in cortical excitability. However, the cellular and molecular mechanisms which underlie rTMS-induced plasticity remain incompletely understood. Here, we used repetitive magnetic stimulation (rMS) of mouse entorhino-hippocampal slice cultures to study rMS-induced plasticity of excitatory postsynapses. By employing whole-cell patch-clamp recordings of CA1 pyramidal neurons, local electrical stimulations, immunostainings for the glutamate receptor subunit GluA1 and compartmental modeling, we found evidence for a preferential potentiation of excitatory synapses on proximal dendrites of CA1 neurons (2-4 h after stimulation). This rMS-induced synaptic potentiation required the activation of voltage-gated sodium channels, L-type voltage-gated calcium channels and N-methyl-D-aspartate-receptors. In view of these findings we propose a cellular model for the preferential strengthening of excitatory synapses on proximal dendrites following rMS in vitro, which is based on a cooperative effect of synaptic glutamatergic transmission and postsynaptic depolarization.

  15. The spatio-temporal characteristics of action potential initiation in layer 5 pyramidal neurons: a voltage imaging study.

    Science.gov (United States)

    Popovic, Marko A; Foust, Amanda J; McCormick, David A; Zecevic, Dejan

    2011-09-01

    The spatial pattern of Na(+) channel clustering in the axon initial segment (AIS) plays a critical role in tuning neuronal computations, and changes in Na(+) channel distribution have been shown to mediate novel forms of neuronal plasticity in the axon. However, immunocytochemical data on channel distribution may not directly predict spatio-temporal characteristics of action potential initiation, and prior electrophysiological measures are either indirect (extracellular) or lack sufficient spatial resolution (intracellular) to directly characterize the spike trigger zone (TZ). We took advantage of a critical methodological improvement in the high sensitivity membrane potential imaging (V(m) imaging) technique to directly determine the location and length of the spike TZ as defined in functional terms. The results show that in mature axons of mouse cortical layer 5 pyramidal cells, action potentials initiate in a region ∼20 μm in length centred between 20 and 40 μm from the soma. From this region, the AP depolarizing wave invades initial nodes of Ranvier within a fraction of a millisecond and propagates in a saltatory fashion into axonal collaterals without failure at all physiologically relevant frequencies. We further demonstrate that, in contrast to the saltatory conduction in mature axons, AP propagation is non-saltatory (monotonic) in immature axons prior to myelination.

  16. File list: ALL.Neu.50.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Neu.50.AllAg.Cortical_neuron mm9 All antigens Neural Cortical neuron SRX914998,...1057051 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Neu.50.AllAg.Cortical_neuron.bed ...

  17. File list: InP.Neu.50.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Neu.50.AllAg.Cortical_neuron mm9 Input control Neural Cortical neuron SRX804268...76,SRX671651,SRX671655 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Neu.50.AllAg.Cortical_neuron.bed ...

  18. File list: ALL.Neu.20.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Neu.20.AllAg.Cortical_neuron mm9 All antigens Neural Cortical neuron SRX914998,...1057051 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Neu.20.AllAg.Cortical_neuron.bed ...

  19. File list: InP.Neu.20.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Neu.20.AllAg.Cortical_neuron mm9 Input control Neural Cortical neuron SRX671659...76,SRX671651,SRX671655 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Neu.20.AllAg.Cortical_neuron.bed ...

  20. File list: Pol.Neu.20.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Neu.20.AllAg.Cortical_neuron mm9 RNA polymerase Neural Cortical neuron SRX75929...5,SRX759296,SRX217735,SRX759294,SRX759293,SRX217736 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Neu.20.AllAg.Cortical_neuron.bed ...

  1. File list: Oth.Neu.10.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Neu.10.AllAg.Cortical_neuron mm9 TFs and others Neural Cortical neuron SRX80425...3,SRX1057051 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.Neu.10.AllAg.Cortical_neuron.bed ...

  2. File list: InP.Neu.10.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Neu.10.AllAg.Cortical_neuron mm9 Input control Neural Cortical neuron SRX671669...47,SRX671651,SRX671674 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Neu.10.AllAg.Cortical_neuron.bed ...

  3. File list: His.Neu.50.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Neu.50.AllAg.Cortical_neuron mm9 Histone Neural Cortical neuron SRX671649,SRX67...759268,SRX759267,SRX759263,SRX759264,SRX759273,SRX759262,SRX759259,SRX759261,SRX759272 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/His.Neu.50.AllAg.Cortical_neuron.bed ...

  4. File list: Pol.Neu.05.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Neu.05.AllAg.Cortical_neuron mm9 RNA polymerase Neural Cortical neuron SRX21773...5,SRX217736,SRX759296,SRX759293,SRX759294,SRX759295 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Neu.05.AllAg.Cortical_neuron.bed ...

  5. File list: His.Neu.20.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Neu.20.AllAg.Cortical_neuron mm9 Histone Neural Cortical neuron SRX671649,SRX67...759260,SRX759258,SRX759267,SRX759262,SRX759259,SRX759261,SRX759263,SRX759264,SRX759272 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/His.Neu.20.AllAg.Cortical_neuron.bed ...

  6. File list: ALL.Neu.05.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Neu.05.AllAg.Cortical_neuron mm9 All antigens Neural Cortical neuron SRX217735,...1057043 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Neu.05.AllAg.Cortical_neuron.bed ...

  7. File list: InP.Neu.05.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Neu.05.AllAg.Cortical_neuron mm9 Input control Neural Cortical neuron SRX671676...74,SRX671672,SRX671651 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/InP.Neu.05.AllAg.Cortical_neuron.bed ...

  8. File list: His.Neu.05.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Neu.05.AllAg.Cortical_neuron mm9 Histone Neural Cortical neuron SRX671646,SRX10...759263,SRX759264,SRX759260,SRX759261,SRX759256,SRX759258,SRX759259,SRX759262,SRX759272 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/His.Neu.05.AllAg.Cortical_neuron.bed ...

  9. File list: Pol.Neu.10.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Neu.10.AllAg.Cortical_neuron mm9 RNA polymerase Neural Cortical neuron SRX21773...5,SRX759296,SRX217736,SRX759295,SRX759293,SRX759294 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Neu.10.AllAg.Cortical_neuron.bed ...

  10. File list: His.Neu.10.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Neu.10.AllAg.Cortical_neuron mm9 Histone Neural Cortical neuron SRX1057033,SRX6...759261,SRX759255,SRX759258,SRX759262,SRX759257,SRX759259,SRX759272,SRX759267,SRX759264 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/His.Neu.10.AllAg.Cortical_neuron.bed ...

  11. File list: Pol.Neu.50.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Neu.50.AllAg.Cortical_neuron mm9 RNA polymerase Neural Cortical neuron SRX75929...5,SRX759296,SRX759293,SRX759294,SRX217735,SRX217736 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Pol.Neu.50.AllAg.Cortical_neuron.bed ...

  12. File list: Oth.Neu.20.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Neu.20.AllAg.Cortical_neuron mm9 TFs and others Neural Cortical neuron SRX67167...3,SRX1057051 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.Neu.20.AllAg.Cortical_neuron.bed ...

  13. File list: ALL.Neu.10.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Neu.10.AllAg.Cortical_neuron mm9 All antigens Neural Cortical neuron SRX217735,...1057051 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/ALL.Neu.10.AllAg.Cortical_neuron.bed ...

  14. File list: Oth.Neu.05.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Neu.05.AllAg.Cortical_neuron mm9 TFs and others Neural Cortical neuron SRX67166...1,SRX1057043 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.Neu.05.AllAg.Cortical_neuron.bed ...

  15. File list: Oth.Neu.50.AllAg.Cortical_neuron [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Neu.50.AllAg.Cortical_neuron mm9 TFs and others Neural Cortical neuron SRX67167...3,SRX1057051 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.Neu.50.AllAg.Cortical_neuron.bed ...

  16. Thalamocortical input onto layer 5 pyramidal neurons measured using quantitative large-scale array tomography

    Directory of Open Access Journals (Sweden)

    Jong-Cheol eRah

    2013-11-01

    Full Text Available The subcellular locations of synapses on pyramidal neurons strongly influences dendritic integration and synaptic plasticity. Despite this, there is little quantitative data on spatial distributions of specific types of synaptic input. Here we use array tomography (AT, a high-resolution optical microscopy method, to examine thalamocortical (TC input onto layer 5 pyramidal neurons. We first verified the ability of AT to identify synapses using parallel electron microscopic analysis of TC synapses in layer 4. We then use large-scale AT to measure TC synapse distribution on L5 pyramdial neurons in a 1.00 x 0.83 x 0.21 mm^3 volume of mouse somatosensory cortex. We found that TC synapses primarily target basal dendrites in layer 5, but also make a considerable input to proximal apical dendrites in L4, consistent with previous work. Our analysis further suggests that TC inputs are biased towards certain branches and, within branches, synapses show significant clustering with an excess of TC synapse nearest neighbors within 5-15 μm compared to a random distribution. Thus, we show that AT is a sensitive and quantitative method to map specific types of synaptic input on the dendrites of entire neurons. We anticipate that this technique will be of wide utility for mapping functionally-relevant anatomical connectivity in neural circuits.

  17. Pituitary adenylate cyclase-activating polypeptide (PACAP) inhibits the slow afterhyperpolarizing current sIAHP in CA1 pyramidal neurons by activating multiple signaling pathways.

    Science.gov (United States)

    Taylor, Ruth D T; Madsen, Marita Grønning; Krause, Michael; Sampedro-Castañeda, Marisol; Stocker, Martin; Pedarzani, Paola

    2014-01-01

    The slow afterhyperpolarizing current (sIAHP ) is a calcium-dependent potassium current that underlies the late phase of spike frequency adaptation in hippocampal and neocortical neurons. sIAHP is a well-known target of modulation by several neurotransmitters acting via the cyclic AMP (cAMP) and protein kinase A (PKA)-dependent pathway. The neuropeptide pituitary adenylate cyclase activating peptide (PACAP) and its receptors are present in the hippocampal formation. In this study we have investigated the effect of PACAP on the sIAHP and the signal transduction pathway used to modulate intrinsic excitability of hippocampal pyramidal neurons. We show that PACAP inhibits the sIAHP , resulting in a decrease of spike frequency adaptation, in rat CA1 pyramidal cells. The suppression of sIAHP by PACAP is mediated by PAC1 and VPAC1 receptors. Inhibition of PKA reduced the effect of PACAP on sIAHP, suggesting that PACAP exerts part of its inhibitory effect on sIAHP by increasing cAMP and activating PKA. The suppression of sIAHP by PACAP was also strongly hindered by the inhibition of p38 MAP kinase (p38 MAPK). Concomitant inhibition of PKA and p38 MAPK indicates that these two kinases act in a sequential manner in the same pathway leading to the suppression of sIAHP. Conversely, protein kinase C is not part of the signal transduction pathway used by PACAP to inhibit sIAHP in CA1 neurons. Our results show that PACAP enhances the excitability of CA1 pyramidal neurons by inhibiting the sIAHP through the activation of multiple signaling pathways, most prominently cAMP/PKA and p38 MAPK. Our findings disclose a novel modulatory action of p38 MAPK on intrinsic excitability and the sIAHP, underscoring the role of this current as a neuromodulatory hub regulated by multiple protein kinases in cortical neurons.

  18. Coordinated scaling of cortical and cerebellar numbers of neurons

    Directory of Open Access Journals (Sweden)

    Suzana Herculano-Houzel

    2010-03-01

    Full Text Available 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 4 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.

  19. Membrane Potential Dynamics of CA1 Pyramidal Neurons during Hippocampal Ripples in Awake Mice.

    Science.gov (United States)

    Hulse, Brad K; Moreaux, Laurent C; Lubenov, Evgueniy V; Siapas, Athanassios G

    2016-02-17

    Ripples are high-frequency oscillations associated with population bursts in area CA1 of the hippocampus that play a prominent role in theories of memory consolidation. While spiking during ripples has been extensively studied, our understanding of the subthreshold behavior of hippocampal neurons during these events remains incomplete. Here, we combine in vivo whole-cell and multisite extracellular recordings to characterize the membrane potential dynamics of identified CA1 pyramidal neurons during ripples. We find that the subthreshold depolarization during ripples is uncorrelated with the net excitatory input to CA1, while the post-ripple hyperpolarization varies proportionately. This clarifies the circuit mechanism keeping most neurons silent during ripples. On a finer timescale, the phase delay between intracellular and extracellular ripple oscillations varies systematically with membrane potential. Such smoothly varying delays are inconsistent with models of intracellular ripple generation involving perisomatic inhibition alone. Instead, they suggest that ripple-frequency excitation leading inhibition shapes intracellular ripple oscillations.

  20. Endogenous polyamines regulate cortical neuronal excitability by blocking voltage-gated Na+ channels.

    Science.gov (United States)

    Fleidervish, Ilya A; Libman, Lior; Katz, Efrat; Gutnick, Michael J

    2008-12-02

    Because the excitable properties of neurons in the neocortex depend on the characteristics of voltage-gated Na(+) channels, factors which regulate those characteristics can fundamentally modify the dynamics of cortical circuits. Here, we report on a novel neuromodulatory mechanism that links the availability of Na(+) channels to metabolism of polyamines (PAs) in the cerebral cortex. Using single channel and whole-cell recordings, we found that products of PA metabolism, the ubiquitous aliphatic polycations spermine and spermidine, are endogenous blockers of Na(+) channels in layer 5 pyramidal cells. Because the blockade is activity-dependent, it is particularly effective against Na(+) channels which fail to inactivate rapidly and thus underlie the persistent Na(+) current. At the level of the local cortical circuit, pharmacological depletion of PAs led to increased spontaneous spiking and periods of hypersynchronous discharge. Our data suggest that changes in PA levels, whether associated with normal brain states or pathological conditions, profoundly modify Na(+) channel availability and thereby shape the integrative behavior of single neurons and neocortical circuits.

  1. Ammonia inhibits long-term potentiation via neurosteroid synthesis in hippocampal pyramidal neurons.

    Science.gov (United States)

    Izumi, Y; Svrakic, N; O'Dell, K; Zorumski, C F

    2013-03-13

    Neurosteroids are a class of endogenous steroids synthesized in the brain that are believed to be involved in the pathogenesis of neuropsychiatric disorders and memory impairment. Ammonia impairs long-term potentiation (LTP), a synaptic model of learning, in the hippocampus, a brain region involved in memory acquisition. Although mechanisms underlying ammonia-mediated LTP inhibition are not fully understood, we previously found that the activation of N-methyl-d-aspartate receptors (NMDARs) is important. Based on this, we hypothesize that metabolic stressors, including hyperammonemia, promote untimely NMDAR activation and result in neural adaptations that include the synthesis of allopregnanolone (alloP) and other GABA-potentiating neurosteroids that dampen neuronal activity and impair LTP and memory formation. Using an antibody against 5α-reduced neurosteroids, we found that 100 μM ammonia acutely enhanced neurosteroid immunostaining in pyramidal neurons in the CA1 region of rat hippocampal slices. The enhanced staining was blocked by finasteride, a selective inhibitor of 5α-reductase, a key enzyme required for alloP synthesis. Finasteride also overcame LTP inhibition by 100 μM ammonia, as did picrotoxin, an inhibitor of GABA-A receptors. These results indicate that GABA-enhancing neurosteroids, synthesized locally within pyramidal neurons, contribute significantly to ammonia-mediated synaptic dysfunction. These results suggest that the manipulation of neurosteroid synthesis could provide a strategy to improve cognitive function in individuals with hyperammonemia.

  2. Characterization of postsynaptic calcium signals in the pyramidal neurons of anterior cingulate cortex.

    Science.gov (United States)

    Li, Xu-Hui; Song, Qian; Chen, Tao; Zhuo, Min

    2017-01-01

    Calcium signaling is critical for synaptic transmission and plasticity. N-methyl-D-aspartic acid (NMDA) receptors play a key role in synaptic potentiation in the anterior cingulate cortex. Most previous studies of calcium signaling focus on hippocampal neurons, little is known about the activity-induced calcium signals in the anterior cingulate cortex. In the present study, we show that NMDA receptor-mediated postsynaptic calcium signals induced by different synaptic stimulation in anterior cingulate cortex pyramidal neurons. Single and multi-action potentials evoked significant suprathreshold Ca(2+) increases in somas and spines. Both NMDA receptors and voltage-gated calcium channels contributed to this increase. Postsynaptic Ca(2+)signals were induced by puff-application of glutamate, and a NMDA receptor antagonist AP5 blocked these signals in both somas and spines. Finally, long-term potentiation inducing protocols triggered postsynaptic Ca(2+) influx, and these influx were NMDA receptor dependent. Our results provide the first study of calcium signals in the anterior cingulate cortex and demonstrate that NMDA receptors play important roles in postsynaptic calcium signals in anterior cingulate cortex pyramidal neurons.

  3. Effects of calcium spikes in the layer 5 pyramidal neuron on coincidence detection and activity propagation

    Directory of Open Access Journals (Sweden)

    Yansong Chua

    2016-07-01

    Full Text Available The role of dendritic spiking mechanisms in neural processing is so far poorly understood. To investigate the role of calcium spikes in the functional properties of the single neuron and recurrent networks, we investigated a three compartment neuron model of the layer 5 pyramidal neuron with calcium dynamics in the distal compartment. By performing single neuron simulations with noisy synaptic input and occasional large coincident input at either just the distal compartment or at both somatic and distal compartments, we show that the presence of calcium spikes confers a substantial advantage for coincidence detection in the former case and a lesser advantage in the latter. We further show that the experimentally observed critical frequency phenomenon is not exhibited by a neuron receiving realistically noisy synaptic input, and so is unlikely to be a necessary component of coincidence detection. We next investigate the effect of calcium spikes in propagation of spiking activities in a feed-forward network embedded in a balanced recurrent network. The excitatory neurons in the network are again connected to either just the distal, or both somatic and distal compartments. With purely distal connectivity, activity propagation is stable and distinguishable for a large range of recurrent synaptic strengths if the feed-forward connections are sufficiently strong, but propagation does not occur in the absence of calcium spikes. When connections are made to both the somatic and the distal compartments, activity propagation is achieved for neurons with active calcium dynamics at a much smaller number of neurons per pool, compared to a network of passive neurons, but quickly becomes unstable as the strength of recurrent synapses increases. Activity propagation at higher scaling factors can be stabilized by increasing network inhibition or introducing short term depression in the excitatory synapses, but the signal to noise ration remains low. Our results

  4. Persistent sodium current drives conditional pacemaking in CA1 pyramidal neurons under muscarinic stimulation.

    Science.gov (United States)

    Yamada-Hanff, Jason; Bean, Bruce P

    2013-09-18

    Hippocampal CA1 pyramidal neurons are normally quiescent but can fire spontaneously when stimulated by muscarinic agonists. In brain slice recordings from mouse CA1 pyramidal neurons, we examined the ionic basis of this activity using interleaved current-clamp and voltage-clamp experiments. Both in control and after muscarinic stimulation, the steady-state current-voltage curve was dominated by inward TTX-sensitive persistent sodium current (I(NaP)) that activated near -75 mV and increased steeply with depolarization. In control, total membrane current was net outward (hyperpolarizing) near -70 mV so that cells had a stable resting potential. Muscarinic stimulation activated a small nonselective cation current so that total membrane current near -70 mV shifted to become barely net inward (depolarizing). The small depolarization triggers regenerative activation of I(NaP), which then depolarizes the cell from -70 mV to spike threshold. We quantified the relative contributions of I(NaP), hyperpolarization-activated cation current (I(h)), and calcium current to pacemaking by using the cell's own firing as a voltage command along with specific blockers. TTX-sensitive sodium current was substantial throughout the entire interspike interval, increasing as the membrane potential approached threshold, while both Ih and calcium current were minimal. Thus, spontaneous activity is driven primarily by activation of I(NaP) in a positive feedback loop starting near -70 mV and providing increasing inward current to threshold. These results show that the pacemaking "engine" from I(NaP) is an inherent property of CA1 pyramidal neurons that can be engaged or disengaged by small shifts in net membrane current near -70 mV, as by muscarinic stimulation.

  5. Broadband Macroscopic Cortical Oscillations Emerge from Intrinsic Neuronal Response Failures

    Directory of Open Access Journals (Sweden)

    Amir eGoldental

    2015-10-01

    Full Text Available Broadband spontaneous macroscopic neural oscillations are rhythmic cortical firing which was extensively examined during the last century, however, their possible origination is still controversial. In this work we show how macroscopic oscillations emerge in solely excitatory random networks and without topological constraints. We experimentally and theoretically show that these oscillations stem from the counterintuitive underlying mechanism - the intrinsic stochastic neuronal response failures. These neuronal response failures, which are characterized by short-term memory, lead to cooperation among neurons, resulting in sub- or several- Hertz macroscopic oscillations which coexist with high frequency gamma oscillations. A quantitative interplay between the statistical network properties and the emerging oscillations is supported by simulations of large networks based on single-neuron in-vitro experiments and a Langevin equation describing the network dynamics. Results call for the examination of these oscillations in the presence of inhibition and external drives.

  6. Action potential modulation in CA1 pyramidal neuron axons facilitates OLM interneuron activation in recurrent inhibitory microcircuits of rat hippocampus.

    Directory of Open Access Journals (Sweden)

    Sooyun Kim

    Full Text Available Oriens-lacunosum moleculare (O-LM interneurons in the CA1 region of the hippocampus play a key role in feedback inhibition and in the control of network activity. However, how these cells are efficiently activated in the network remains unclear. To address this question, I performed recordings from CA1 pyramidal neuron axons, the presynaptic fibers that provide feedback innervation of these interneurons. Two forms of axonal action potential (AP modulation were identified. First, repetitive stimulation resulted in activity-dependent AP broadening. Broadening showed fast onset, with marked changes in AP shape following a single AP. Second, tonic depolarization in CA1 pyramidal neuron somata induced AP broadening in the axon, and depolarization-induced broadening summated with activity-dependent broadening. Outside-out patch recordings from CA1 pyramidal neuron axons revealed a high density of α-dendrotoxin (α-DTX-sensitive, inactivating K+ channels, suggesting that K+ channel inactivation mechanistically contributes to AP broadening. To examine the functional consequences of axonal AP modulation for synaptic transmission, I performed paired recordings between synaptically connected CA1 pyramidal neurons and O-LM interneurons. CA1 pyramidal neuron-O-LM interneuron excitatory postsynaptic currents (EPSCs showed facilitation during both repetitive stimulation and tonic depolarization of the presynaptic neuron. Both effects were mimicked and occluded by α-DTX, suggesting that they were mediated by K+ channel inactivation. Therefore, axonal AP modulation can greatly facilitate the activation of O-LM interneurons. In conclusion, modulation of AP shape in CA1 pyramidal neuron axons substantially enhances the efficacy of principal neuron-interneuron synapses, promoting the activation of O-LM interneurons in recurrent inhibitory microcircuits.

  7. Action potential modulation in CA1 pyramidal neuron axons facilitates OLM interneuron activation in recurrent inhibitory microcircuits of rat hippocampus.

    Science.gov (United States)

    Kim, Sooyun

    2014-01-01

    Oriens-lacunosum moleculare (O-LM) interneurons in the CA1 region of the hippocampus play a key role in feedback inhibition and in the control of network activity. However, how these cells are efficiently activated in the network remains unclear. To address this question, I performed recordings from CA1 pyramidal neuron axons, the presynaptic fibers that provide feedback innervation of these interneurons. Two forms of axonal action potential (AP) modulation were identified. First, repetitive stimulation resulted in activity-dependent AP broadening. Broadening showed fast onset, with marked changes in AP shape following a single AP. Second, tonic depolarization in CA1 pyramidal neuron somata induced AP broadening in the axon, and depolarization-induced broadening summated with activity-dependent broadening. Outside-out patch recordings from CA1 pyramidal neuron axons revealed a high density of α-dendrotoxin (α-DTX)-sensitive, inactivating K+ channels, suggesting that K+ channel inactivation mechanistically contributes to AP broadening. To examine the functional consequences of axonal AP modulation for synaptic transmission, I performed paired recordings between synaptically connected CA1 pyramidal neurons and O-LM interneurons. CA1 pyramidal neuron-O-LM interneuron excitatory postsynaptic currents (EPSCs) showed facilitation during both repetitive stimulation and tonic depolarization of the presynaptic neuron. Both effects were mimicked and occluded by α-DTX, suggesting that they were mediated by K+ channel inactivation. Therefore, axonal AP modulation can greatly facilitate the activation of O-LM interneurons. In conclusion, modulation of AP shape in CA1 pyramidal neuron axons substantially enhances the efficacy of principal neuron-interneuron synapses, promoting the activation of O-LM interneurons in recurrent inhibitory microcircuits.

  8. High- and low-conductance NMDA receptors are present in layer 4 spiny stellate and layer 2/3 pyramidal neurons of mouse barrel cortex.

    Science.gov (United States)

    Scheppach, Christian

    2016-12-01

    N-Methyl-D-aspartate (NMDA) receptors are ion channels activated by the neurotransmitter glutamate in the mammalian brain and are important in synaptic function and plasticity, but are also found in extrasynaptic locations and influence neuronal excitability. There are different NMDA receptor subtypes which differ in their single-channel conductance. Recently, synaptic plasticity has been studied in the mouse barrel cortex, the primary sensory cortex for input from the animal's whiskers. Pharmacological data imply the presence of low-conductance NMDA receptors in spiny stellate neurons of cortical layer 4, but of high-conductance NMDA receptors in pyramidal neurons of layer 2/3. Here, to obtain complementary electrophysiological information on the functional NMDA receptors expressed in layer 4 and layer 2/3 neurons, single NMDA receptor currents were recorded with the patch-clamp method. Both cell types were found to contain high-conductance as well as low-conductance NMDA receptors. The results are consistent with the reported pharmacological data on synaptic plasticity, and with previous claims of a prominent role of low-conductance NMDA receptors in layer 4 spiny stellate neurons, including broad integration, amplification and distribution of excitation within the barrel in response to whisker stimulation, as well as modulation of excitability by ambient glutamate. However, layer 4 cells also expressed high-conductance NMDA receptors. The presence of low-conductance NMDA receptors in layer 2/3 pyramidal neurons suggests that some of these functions may be shared with layer 4 spiny stellate neurons.

  9. Cortical neuronal mechanisms of sleep homeostasis.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  11. Entorhinal cortical innervation of parvalbumin-containing neurons (Basket and Chandelier cells) in the rat Ammon's horn.

    Science.gov (United States)

    Kiss, J; Buzsaki, G; Morrow, J S; Glantz, S B; Leranth, C

    1996-01-01

    Physiological data suggest that in the CA1-CA3 hippocampal areas of rats, entorhinal cortical efferents directly influence the activity of interneurons, in addition to pyramidal cells. To verify this hypothesis, the following experiments were performed: 1) light microscopic double-immunostaining for parvalbumin and the anterograde tracer Phaseolus vulgaris-leucoagglutinin injected into the entorhinal cortex; 2) light and electron microscopic analysis of cleaved spectrin-immunostained (i.e., degenerating axons and boutons) hippocampal sections following entorhinal cortex lesion; and 3) an electron microscopic study of parvalbumin-immunostained hippocampal sections after entorhinal cortex lesion. The results demonstrate that in the stratum lacunosum-moleculare of the CA1 and CA3 regions, entorhinal cortical axons form asymmetric synaptic contacts on parvalbumin-containing dendritic shafts. In the stratum lacunosum-moleculare, parvalbumin-immunoreactive dendrites represent processes of GABAergic, inhibitory basket and chandelier cells; these interneurons innervate the perisomatic area and axon initial segments of pyramidal cells, respectively. A feed-forward activation of these neurons by the entorhinal input may explain the strong, short-latency inhibition of pyramidal cells.

  12. Opto-current-clamp actuation of cortical neurons using a strategically designed channelrhodopsin.

    Directory of Open Access Journals (Sweden)

    Lei Wen

    Full Text Available BACKGROUND: Optogenetic manipulation of a neuronal network enables one to reveal how high-order functions emerge in the central nervous system. One of the Chlamydomonas rhodopsins, channelrhodopsin-1 (ChR1, has several advantages over channelrhodopsin-2 (ChR2 in terms of the photocurrent kinetics. Improved temporal resolution would be expected by the optogenetics using the ChR1 variants with enhanced photocurrents. METHODOLOGY/PRINCIPAL FINDINGS: The photocurrent retardation of ChR1 was overcome by exchanging the sixth helix domain with its counterpart in ChR2 producing Channelrhodopsin-green receiver (ChRGR with further reform of the molecule. When the ChRGR photocurrent was measured from the expressing HEK293 cells under whole-cell patch clamp, it was preferentially activated by green light and has fast kinetics with minimal desensitization. With its kinetic advantages the use of ChRGR would enable one to inject a current into a neuron by the time course as predicted by the intensity of the shedding light (opto-current clamp. The ChRGR was also expressed in the motor cortical neurons of a mouse using Sindbis pseudovirion vectors. When an oscillatory LED light signal was applied sweeping through frequencies, it robustly evoked action potentials synchronized to the oscillatory light at 5-10 Hz in layer 5 pyramidal cells in the cortical slice. The ChRGR-expressing neurons were also driven in vivo with monitoring local field potentials (LFPs and the time-frequency energy distribution of the light-evoked response was investigated using wavelet analysis. The oscillatory light enhanced both the in-phase and out-phase responses of LFP at the preferential frequencies of 5-10 Hz. The spread of activity was evidenced by the fact that there were many c-Fos-immunoreactive neurons that were negative for ChRGR in a region of the motor cortex. CONCLUSIONS/SIGNIFICANCE: The opto-current-clamp study suggests that the depolarization of a small number of neurons

  13. IKCa channels are a critical determinant of the slow AHP in CA1 pyramidal neurons.

    Science.gov (United States)

    King, Brian; Rizwan, Arsalan P; Asmara, Hadhimulya; Heath, Norman C; Engbers, Jordan D T; Dykstra, Steven; Bartoletti, Theodore M; Hameed, Shahid; Zamponi, Gerald W; Turner, Ray W

    2015-04-14

    Control over the frequency and pattern of neuronal spike discharge depends on Ca2+-gated K+ channels that reduce cell excitability by hyperpolarizing the membrane potential. The Ca2+-dependent slow afterhyperpolarization (sAHP) is one of the most prominent inhibitory responses in the brain, with sAHP amplitude linked to a host of circuit and behavioral functions, yet the channel that underlies the sAHP has defied identification for decades. Here, we show that intermediate-conductance Ca2+-dependent K+ (IKCa) channels underlie the sAHP generated by trains of synaptic input or postsynaptic stimuli in CA1 hippocampal pyramidal cells. These findings are significant in providing a molecular identity for the sAHP of central neurons that will identify pharmacological tools capable of potentially modifying the several behavioral or disease states associated with the sAHP.

  14. Glia-derived ATP inversely regulates excitability of pyramidal and CCK-positive neurons

    Science.gov (United States)

    Tan, Zhibing; Liu, Yu; Xi, Wang; Lou, Hui-fang; Zhu, Liya; Guo, Zhifei; Mei, Lin; Duan, Shumin

    2017-01-01

    Astrocyte responds to neuronal activity with calcium waves and modulates synaptic transmission through the release of gliotransmitters. However, little is known about the direct effect of gliotransmitters on the excitability of neuronal networks beyond synapses. Here we show that selective stimulation of astrocytes expressing channelrhodopsin-2 in the CA1 area specifically increases the firing frequency of CCK-positive but not parvalbumin-positive interneurons and decreases the firing rate of pyramidal neurons, phenomena mimicked by exogenously applied ATP. Further evidences indicate that ATP-induced increase and decrease of excitability are caused, respectively, by P2Y1 receptor-mediated inhibition of a two-pore domain potassium channel and A1 receptor-mediated opening of a G-protein-coupled inwardly rectifying potassium channel. Moreover, the activation of ChR2-expressing astrocytes reduces the power of kainate-induced hippocampal ex vivo gamma oscillation. Thus, through distinct receptor subtypes coupled with different K+ channels, astrocyte-derived ATP differentially modulates the excitability of different types of neurons and efficiently controls the activity of neuronal network. PMID:28128211

  15. Transient increase in Zn2+ in hippocampal CA1 pyramidal neurons causes reversible memory deficit.

    Directory of Open Access Journals (Sweden)

    Atsushi Takeda

    Full Text Available The translocation of synaptic Zn(2+ to the cytosolic compartment has been studied to understand Zn(2+ neurotoxicity in neurological diseases. However, it is unknown whether the moderate increase in Zn(2+ in the cytosolic compartment affects memory processing in the hippocampus. In the present study, the moderate increase in cytosolic Zn(2+ in the hippocampus was induced with clioquinol (CQ, a zinc ionophore. Zn(2+ delivery by Zn-CQ transiently attenuated CA1 long-term potentiation (LTP in hippocampal slices prepared 2 h after i.p. injection of Zn-CQ into rats, when intracellular Zn(2+ levels was transiently increased in the CA1 pyramidal cell layer, followed by object recognition memory deficit. Object recognition memory was transiently impaired 30 min after injection of ZnCl(2 into the CA1, but not after injection into the dentate gyrus that did not significantly increase intracellular Zn(2+ in the granule cell layer of the dentate gyrus. Object recognition memory deficit may be linked to the preferential increase in Zn(2+ and/or the preferential vulnerability to Zn(2+ in CA1 pyramidal neurons. In the case of the cytosolic increase in endogenous Zn(2+ in the CA1 induced by 100 mM KCl, furthermore, object recognition memory was also transiently impaired, while ameliorated by co-injection of CaEDTA to block the increase in cytosolic Zn(2+. The present study indicates that the transient increase in cytosolic Zn(2+ in CA1 pyramidal neurons reversibly impairs object recognition memory.

  16. Metrifonate decreases sI(AHP) in CA1 pyramidal neurons in vitro.

    Science.gov (United States)

    Power, J M; Oh, M M; Disterhoft, J F

    2001-01-01

    Metrifonate, a cholinesterase inhibitor, has been shown to enhance learning in aging rabbits and rats, and to alleviate the cognitive deficits observed in Alzheimer's disease patients. We have previously determined that bath application of metrifonate reduces the spike frequency adaptation and postburst afterhyperpolarization (AHP) in rabbit CA1 pyramidal neurons in vitro using sharp electrode current-clamp recording. The postburst AHP and accommodation observed in current clamp are the result of four slow outward potassium currents (sI(AHP), I(AHP), I(M), and I(C)) and the hyperpolarization activated mixed cation current, I(h). We recorded from visually identified CA1 hippocampal pyramidal neurons in vitro using whole cell voltage-clamp technique to better isolate and characterize which component currents of the AHP are affected by metrifonate. We observed an age-related enhancement of the slow component of the AHP tail current (sI(AHP)), but not of the fast decaying component of the AHP tail current (I(AHP), I(M), and I(C)). Bath perfusion of metrifonate reduced sI(AHP) at concentrations that cause a reduction of the AHP and accommodation in current-clamp recordings, with no apparent reduction of I(AHP), I(M), and I(C). The functional consequences of metrifonate administration are apparently mediated solely through modulation of the sI(AHP).

  17. Dynamic Expression Patterns of Progenitor and Pyramidal Neuron Layer Markers in the Developing Human Hippocampus.

    Science.gov (United States)

    Cipriani, Sara; Nardelli, Jeannette; Verney, Catherine; Delezoide, Anne-Lise; Guimiot, Fabien; Gressens, Pierre; Adle-Biassette, Homa

    2016-03-01

    The molecular mechanisms underlying the formation of hippocampus are unknown in humans. To improve our knowledge of molecules that potentially regulate pyramidal neurogenesis and layering in various hippocampal fields, we investigated the expression of progenitor markers and cell fate molecules from gestational week (GW) 9 to GW 20. At GW 9, the progenitor cell compartment of the hippocampal formation mainly consisted of PAX6(+) cells in the ventricular zone. Between GW 9 and 11, a second germinal area, the subventricular zone (SVZ), was formed, as shown by TBR2 labeling. Postmitotic markers (TBR1, CTIP2, SATB2, and CUX1) might reflect the inside-out layering of the plate from GW 11 onwards. TBR1(+) neurons appeared in the deep plate, whereas CTIP2(+), SATB2(+), and CUX1(+) neurons occupied the upper layers. From GW 16, differences in layer segregation were observed between the ammonic and subicular plates. Moreover, an ammonic-to-subicular maturation gradient was observed in germinal/postmitotic areas. Taken together, these findings demonstrate for the first time the presence of an SVZ in the hippocampus of human fetuses and laminar differences in transcription factor expression in the pyramidal layer of the human ammonic and subicular plate, and provide new information to further investigate the connectivity of the hippocampal formation.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  20. A Modified Technique for Culturing Primary Fetal Rat Cortical Neurons

    Directory of Open Access Journals (Sweden)

    Sui-Yi Xu

    2012-01-01

    Full Text Available The study explored a modified primary culture system for fetal rat cortical neurons. Day E18 embryos from pregnant Sprague Dawley rats were microdissected under a stereoscope. To minimize enzymatic damage to the cultured neurons, we applied a sequential digestion protocol using papain and Dnase I. The resulting sifted cell suspension was seeded at a density of 50,000 cells per cm2 onto 0.1 mg/mL L-PLL-covered vessels. After a four-hour incubation in high-glucose Dulbecco’s Modified Eagle’s Medium (HG-DMEM to allow the neurons to adhere, the media was changed to neurobasal medium that was refreshed by changing half of the volume after three days followed by a complete medium change every week. The cells displayed progressively robust neurite extension, and nonneuronal-like cells could barely be detected by five days in vitro (DIV; cell growth was still substantial at 14 DIV. Neurons were identified by β-tubulin III immunofluorescence, and neuronal purity within the cultures was assessed at over 95% by both flow cytometry and by dark-field counting of β-tubulin III-positive cells. These results suggest that the protocol was successful and that the high purity of neurons in this system could be used as the basis for generating various cell models of neurological disease.

  1. Electrophysiological effects of SKF83959 on hippocampal CA1 pyramidal neurons: potential mechanisms for the drug's neuroprotective effects.

    Directory of Open Access Journals (Sweden)

    Hong-Yuan Chu

    Full Text Available Although the potent anti-parkinsonian action of the atypical D₁-like receptor agonist SKF83959 has been attributed to the selective activation of phosphoinositol(PI-linked D₁ receptor, whereas the mechanism underlying its potent neuroprotective effect is not fully understood. In the present study, the actions of SKF83959 on neuronal membrane potential and neuronal excitability were investigated in CA1 pyramidal neurons of rat hippocampal slices. SKF83959 (10-100 µM caused a concentration-dependent depolarization, associated with a reduction of input resistance in CA1 pyramidal neurons. The depolarization was blocked neither by antagonists for D₁, D₂, 5-HT(2A/2C receptors and α₁-adrenoceptor, nor by intracellular dialysis of GDP-β-S. However, the specific HCN channel blocker ZD7288 (10 µM antagonized both the depolarization and reduction of input resistance caused by SKF83959. In voltage-clamp experiments, SKF83959 (10-100 µM caused a concentration-dependent increase of Ih current in CA1 pyramidal neurons, which was independent of D₁ receptor activation. Moreover, SKF83959 (50 µM caused a 6 mV positive shift in the activation curve of Ih and significantly accelerated the activation of Ih current. In addition, SKF83959 also reduced the neuronal excitability of CA1 pyramidal neurons, which was manifested by the decrease in the number and amplitude of action potentials evoked by depolarizing currents, and by the increase of firing threshold and rhoebase current. The above results suggest that SKF83959 increased Ih current through a D₁ receptor-independent mechanism, which led to the depolarization of hippocampal CA1 pyramidal neurons. These findings provide a novel mechanism for the drug's neuroprotective effects, which may contributes to its therapeutic benefits in Parkinson's disease.

  2. Cytosolic phospholipase A(2) alpha mediates electrophysiologic responses of hippocampal pyramidal neurons to neurotoxic NMDA treatment.

    Science.gov (United States)

    Shen, Ying; Kishimoto, Koji; Linden, David J; Sapirstein, Adam

    2007-04-03

    The arachidonic acid-generating enzyme cytosolic phospholipase A(2) alpha (cPLA(2)alpha) has been implicated in the progression of excitotoxic neuronal injury. However, the mechanisms of cPLA(2)alpha toxicity have yet to be determined. Here, we used a model system exposing mouse hippocampal slices to NMDA as an excitotoxic injury, in combination with simultaneous patch-clamp recording and confocal Ca(2+) imaging of CA1 pyramidal neurons. NMDA treatment caused significantly greater injury in wild-type (WT) than in cPLA(2)alpha null CA1 neurons. Bath application of NMDA evoked a slow inward current in voltage-clamped neurons (composed of both NMDA receptor-mediated and other conductances) that was smaller in cPLA(2)alpha null than in WT slices. This was not due to down-regulation of NMDA receptor function because NMDA receptor-mediated currents were equivalent in each genotype following brief photolysis of caged glutamate. Current-clamp recordings were made during and following NMDA exposure by eliciting a single action potential with a brief current injection. After NMDA exposure, WT CA1 neurons developed a spike-evoked plateau potential and an increased spike-evoked dendritic Ca(2+) transient. These effects were absent in CA1 neurons from cPLA(2)alpha null mice and WT neurons treated with a cPLA(2)alpha inhibitor. The Ca-sensitive K-channel toxins, apamin and paxilline, caused spike broadening and Ca(2+) enhancement in WT and cPLA(2)alpha null slices. NMDA application in WT and arachidonate applied to cPLA(2)alpha null cells occluded the effects of apamin/paxilline. These results indicate that cPLA(2)alpha activity is required for development of aberrant electrophysiologic events triggered by NMDA receptor activation, in part through attenuation of K-channel function.

  3. Dense neuron clustering explains connectivity statistics in cortical microcircuits.

    Directory of Open Access Journals (Sweden)

    Vladimir V Klinshov

    Full Text Available 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.

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

    Directory of Open Access Journals (Sweden)

    George A. Ojemann

    2013-04-01

    Full Text Available 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.

  5. Effects of Calcium Spikes in the Layer 5 Pyramidal Neuron on Coincidence Detection and Activity Propagation.

    Science.gov (United States)

    Chua, Yansong; Morrison, Abigail

    2016-01-01

    The role of dendritic spiking mechanisms in neural processing is so far poorly understood. To investigate the role of calcium spikes in the functional properties of the single neuron and recurrent networks, we investigated a three compartment neuron model of the layer 5 pyramidal neuron with calcium dynamics in the distal compartment. By performing single neuron simulations with noisy synaptic input and occasional large coincident input at either just the distal compartment or at both somatic and distal compartments, we show that the presence of calcium spikes confers a substantial advantage for coincidence detection in the former case and a lesser advantage in the latter. We further show that the experimentally observed critical frequency phenomenon, in which action potentials triggered by stimuli near the soma above a certain frequency trigger a calcium spike at distal dendrites, leading to further somatic depolarization, is not exhibited by a neuron receiving realistically noisy synaptic input, and so is unlikely to be a necessary component of coincidence detection. We next investigate the effect of calcium spikes in propagation of spiking activities in a feed-forward network (FFN) embedded in a balanced recurrent network. The excitatory neurons in the network are again connected to either just the distal, or both somatic and distal compartments. With purely distal connectivity, activity propagation is stable and distinguishable for a large range of recurrent synaptic strengths if the feed-forward connections are sufficiently strong, but propagation does not occur in the absence of calcium spikes. When connections are made to both the somatic and the distal compartments, activity propagation is achieved for neurons with active calcium dynamics at a much smaller number of neurons per pool, compared to a network of passive neurons, but quickly becomes unstable as the strength of recurrent synapses increases. Activity propagation at higher scaling factors can be

  6. Effect of etomidate on voltage-dependent potassium currents in rat isolated hippocampal pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    TAN Hong-yu; SUN Li-na; WANG Xiao-liang; YE Tie-hu

    2010-01-01

    Background Previous studies demonstrated general anesthetics affect potassium ion channels, which may be one of the mechanisms of general anesthesia. Because the effect of etomidate on potassium channels in rat hippocampus which is involved in memory function has not been studied, we investigated the effects of etomidate on both delayed rectifier potassium current (I_((K(DR))) and transient outward potassium current (I_((K(A))) in acutely dissociated rat hippocampal pyramidal neurons.Methods Single rat hippocampal pyramidal neurons from male Wistar rats of 7-10 days were acutely dissociated by enzymatic digestion and mechanical dispersion according to the methods of Kay and Wong with slight modification. Voltage-clamp recordings were performed in the whole-cell patch clamp configuration. Currents were recorded with a List EPC-10 amplifier and data were stored in a computer using Pulse 8.5. Student's paired two-tail t test was used for data analysis. Results At the concentration of 100 μmol/L, etomidate significantly inhibited I_(K(DR)) by 49.2% at +40 mV when depolarized from -110 mV (P 0.05). The IC_(50) value of etomidate for blocking I_(K(DR)) was calculated as 5.4 μmol/L, with a Hill slope of 2.45. At the presence of 10 μmol/L etomidate, the V_(1/2) of activation curve was shifted from (17.3±1.5) mV to (10.7±9.9) mV (n=8, P <0.05), the V_(1/2) of inactivation curve was shifted from (-18.3±2.2) mV to (-45.3±9.4) mV (n=8, P <0.05). Etomidate 10 μmol/L shifted both the activation curve and inactivation curve of I_(K(DR)) to negative potential, but mainly affected the inactivation kinetics.Conclusions Etomidate potently inhibited I_(K(DR)) but not I_(K(A)) in rat hippocampal pyramidal neurons. I_(K(DR)) was inhibited by etomidate in a concentration-dependent manner, while I_(K(A)) remained unaffected.

  7. Activation of Ih and TTX-sensitive sodium current at subthreshold voltages during CA1 pyramidal neuron firing.

    Science.gov (United States)

    Yamada-Hanff, Jason; Bean, Bruce P

    2015-10-01

    We used dynamic clamp and action potential clamp techniques to explore how currents carried by tetrodotoxin-sensitive sodium channels and HCN channels (Ih) regulate the behavior of CA1 pyramidal neurons at resting and subthreshold voltages. Recording from rat CA1 pyramidal neurons in hippocampal slices, we found that the apparent input resistance and membrane time constant were strongly affected by both conductances, with Ih acting to decrease apparent input resistance and time constant and sodium current acting to increase both. We found that both Ih and sodium current were active during subthreshold summation of artificial excitatory postsynaptic potentials (EPSPs) generated by dynamic clamp, with Ih dominating at less depolarized voltages and sodium current at more depolarized voltages. Subthreshold sodium current-which amplifies EPSPs-was most effectively recruited by rapid voltage changes, while Ih-which blunts EPSPs-was maximal for slow voltage changes. The combined effect is to selectively amplify rapid EPSPs. We did similar experiments in mouse CA1 pyramidal neurons, doing voltage-clamp experiments using experimental records of action potential firing of CA1 neurons previously recorded in awake, behaving animals as command voltages to quantify flow of Ih and sodium current at subthreshold voltages. Subthreshold sodium current was larger and subthreshold Ih was smaller in mouse neurons than in rat neurons. Overall, the results show opposing effects of subthreshold sodium current and Ih in regulating subthreshold behavior of CA1 neurons, with subthreshold sodium current prominent in both rat and mouse CA1 pyramidal neurons and additional regulation by Ih in rat neurons.

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

    Science.gov (United States)

    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

  9. Repeated transcranial magnetic stimulation prevents kindling-induced changes in electrophysiological properties of rat hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Shojaei, A; Semnanian, S; Janahmadi, M; Moradi-Chameh, H; Firoozabadi, S M; Mirnajafi-Zadeh, J

    2014-11-01

    The mechanisms underlying antiepileptic or antiepileptogenic effects of repeated transcranial magnetic stimulation (rTMS) are poorly understood. In this study, we investigated the effect of rTMS applied during rapid amygdala kindling on some electrophysiological properties of hippocampal CA1 pyramidal neurons. Male Wistar rats were kindled by daily electrical stimulation of the basolateral amygdala in a semi-rapid manner (12 stimulations/day) until they achieved stage-5 seizure. One group (kindled+rTMS (KrTMS)) of animals received rTMS (1Hz for 4min) 5min after termination of daily kindling stimulations. Twenty four hours following the last kindling stimulation electrophysiological properties of hippocampal CA1 pyramidal neurons were investigated using whole-cell patch-clamp technique. Amygdala kindling significantly depolarized the resting membrane potential and increased the input resistance, spontaneous firing activity, number of evoked spikes and half-width of the first evoked spike. Kindling also decreased the first-spike latency and amplitude significantly. Application of rTMS during kindling somehow prevented the development of seizures and protected CA1 pyramidal neurons of hippocampus against deleterious effect of kindling on both passive and active neuronal electrophysiological properties. Interestingly, application of rTMS alone enhanced the excitability of CA1 pyramidal neurons significantly. Based on the results of our study, it may be suggested that rTMS exerts its anticonvulsant effect, in part, through preventing the amygdala kindling-induced changes in electrophysiological properties of hippocampal CA1 pyramidal neurons. It seems that rTMS exerts protective effects on the neural circuits involved in spreading the seizures from the focus to other parts of the brain.

  10. Synergistic regulation of glutamatergic transmission by serotonin and norepinephrine reuptake inhibitors in prefrontal cortical neurons.

    Science.gov (United States)

    Yuen, Eunice Y; Qin, Luye; Wei, Jing; Liu, Wenhua; Liu, Aiyi; Yan, Zhen

    2014-09-05

    The monoamine system in the prefrontal cortex has been implicated in various mental disorders and has been the major target of anxiolytics and antidepressants. Clinical studies show that serotonin and norepinephrine reuptake inhibitors (SNRIs) produce better therapeutic effects than single selective reuptake inhibitors, but the underlying mechanisms are largely unknown. Here, we found that low dose SNRIs, by acting on 5-HT(1A) and α2-adrenergic receptors, synergistically reduced AMPA receptor (AMPAR)-mediated excitatory postsynaptic currents and AMPAR surface expression in prefrontal cortex pyramidal neurons via a mechanism involving Rab5/dynamin-mediated endocytosis of AMPARs. The synergistic effect of SNRIs on AMPARs was blocked by inhibition of activator of G protein signaling 3, a G protein modulator that prevents reassociation of G(i) protein α subunit and prolongs the βγ-mediated signaling pathway. Moreover, the depression of AMPAR-mediated excitatory postsynaptic currents by SNRIs required p38 kinase activity, which was increased by 5-HT(1A) and α2-adrenergic receptor co-activation in an activator of G protein signaling 3-dependent manner. These results have revealed a potential mechanism for the synergy between the serotonin and norepinephrine systems in the regulation of glutamatergic transmission in cortical neurons.

  11. Probabilistic identification of cerebellar cortical neurones across species.

    Directory of Open Access Journals (Sweden)

    Gert Van Dijck

    Full Text Available 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

  12. Effects of lithium chloride on outward potassium currents in acutely isolated hippocampal CA1 pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chaofeng; DU Huizhi; YANG Pin

    2006-01-01

    Although lithium possesses neuroprotective functions, the molecular mechanism underlying its actions has not been fully elucidated. In the present paper, the effects of lithium chloride on voltage-dependent potassium currents in the CA1 pyramidal neurons acutely isolated from rat hippocampus were studied using the whole-cell patch-clamp technique. Depolarizing test pulses activated two components of outward potassium currents: a rapidly activating and inactivating component, IA and a delayed component, IK. Results showed that lithium chloride increased the amplitude of IA in a concentration-dependent manner. Half enhancement concentration (EC50) was 22.80±5.45 μmol·L-1. Lithium chloride of 25 μmol·L-1 shifted the steady-state activation curve and inactivation curve of IA to more negative potentials, but mainly affected the activation kinetics. The amplitude and the activation processes of IK were not affected by lithium chloride. The effects of lithium chloride on potassium channel appear to possess neuroprotective properties by Ca2+-lowing effects modulate neuronal excitability by activating IA in rat hippocampal neurons.

  13. Evidence that dendritic mitochondria negatively regulate dendritic branching in pyramidal neurons in the neocortex.

    Science.gov (United States)

    Kimura, Toshiya; Murakami, Fujio

    2014-05-14

    The precise branching patterns of dendritic arbors have a profound impact on information processing in individual neurons and the brain. These patterns are established by positive and negative regulation of the dendritic branching. Although the mechanisms for positive regulation have been extensively investigated, little is known about those for negative regulation. Here, we present evidence that mitochondria located in developing dendrites are involved in the negative regulation of dendritic branching. We visualized mitochondria in pyramidal neurons of the mouse neocortex during dendritic morphogenesis using in utero electroporation of a mitochondria-targeted fluorescent construct. We altered the mitochondrial distribution in vivo by overexpressing Mfn1, a mitochondrial shaping protein, or the Miro-binding domain of TRAK2 (TRAK2-MBD), a truncated form of a motor-adaptor protein. We found that dendritic mitochondria were preferentially targeted to the proximal portion of dendrites only during dendritic morphogenesis. Overexpression of Mfn1 or TRAK2-MBD depleted mitochondria from the dendrites, an effect that was accompanied by increased branching of the proximal portion of the dendrites. This dendritic abnormality cannot be accounted for by changes in the distribution of membrane trafficking organelles since the overexpression of Mfn1 did not alter the distributions of the endoplasmic reticulum, Golgi, or endosomes. Additionally, neither did these constructs impair neuronal viability or mitochondrial function. Therefore, our results suggest that dendritic mitochondria play a critical role in the establishment of the precise branching pattern of dendritic arbors by negatively affecting dendritic branching.

  14. ERK1/2 Activation Is Necessary for BDNF to Increase Dendritic Spine Density in Hippocampal CA1 Pyramidal Neurons

    Science.gov (United States)

    Alonso, Mariana; Medina, Jorge H.; Pozzo-Miller, Lucas

    2004-01-01

    Brain-derived neurotrophic factor (BDNF) is a potent modulator of synaptic transmission and plasticity in the CNS, acting both pre- and postsynaptically. We demonstrated recently that BDNF/TrkB signaling increases dendritic spine density in hippocampal CA1 pyramidal neurons. Here, we tested whether activation of the prominent ERK (MAPK) signaling…

  15. Phosphorylation of CRMP2 by Cdk5 Regulates Dendritic Spine Development of Cortical Neuron in the Mouse Hippocampus

    Directory of Open Access Journals (Sweden)

    Xiaohua Jin

    2016-01-01

    Full Text Available Proper density and morphology of dendritic spines are important for higher brain functions such as learning and memory. However, our knowledge about molecular mechanisms that regulate the development and maintenance of dendritic spines is limited. We recently reported that cyclin-dependent kinase 5 (Cdk5 is required for the development and maintenance of dendritic spines of cortical neurons in the mouse brain. Previous in vitro studies have suggested the involvement of Cdk5 substrates in the formation of dendritic spines; however, their role in spine development has not been tested in vivo. Here, we demonstrate that Cdk5 phosphorylates collapsin response mediator protein 2 (CRMP2 in the dendritic spines of cultured hippocampal neurons and in vivo in the mouse brain. When we eliminated CRMP2 phosphorylation in CRMP2KI/KI mice, the densities of dendritic spines significantly decreased in hippocampal CA1 pyramidal neurons in the mouse brain. These results indicate that phosphorylation of CRMP2 by Cdk5 is important for dendritic spine development in cortical neurons in the mouse hippocampus.

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

    Science.gov (United States)

    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.

  17. Order-based representation in random networks of cortical neurons.

    Directory of Open Access Journals (Sweden)

    Goded Shahaf

    2008-11-01

    Full Text Available 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.

  18. Low concentrations of the solvent dimethyl sulphoxide alter intrinsic excitability properties of cortical and hippocampal pyramidal cells.

    Directory of Open Access Journals (Sweden)

    Francesco Tamagnini

    Full Text Available Dimethylsulfoxide (DMSO is a widely used solvent in biology. It has many applications perhaps the most common of which is in aiding the preparation of drug solutions from hydrophobic chemical entities. Recent studies have suggested that this molecule may be able to induce apoptosis in neural tissues urging caution regarding its introduction into humans, for example as part of stem cell transplants. Here we have used in vitro electrophysiological methods applied to murine brain slices to examine whether a few hours treatment with 0.05% DMSO (a concentration regarded by many as innocuous alters intrinsic excitability properties of neurones. We investigated pyramidal neurones in two distinct brain regions, namely area CA1 of the hippocampus and layer 2 of perirhinal cortex. In the former there was no effect on resting potential but input resistance was decreased by DMSO pre-treatment. In line with this action potential count for any level of depolarizing current stimulus was reduced by ∼25% following DMSO treatment. Ih-mediated "sag" was also increased in CA1 pyramids and action potential waveform analysis demonstrated that DMSO treatment moved action potential threshold towards resting potential. In perirhinal cortex a decreased action potential output for various depolarizing current stimuli was also seen. In these cells action potential threshold was unaltered by DMSO but a significant increase in action potential width was apparent. These data indicate that pre-treatment with this widely employed solvent can elicit multifaceted neurophysiological changes in mammalian neurones at concentrations below those frequently encountered in the published literature.

  19. Pituitary adenylate cyclase-activating polypeptide (PACAP) inhibits the slow afterhyperpolarizing current sIAHP in CA1 pyramidal neurons by activating multiple signaling pathways

    Science.gov (United States)

    Taylor, Ruth DT; Madsen, Marita Grønning; Krause, Michael; Sampedro-Castañeda, Marisol; Stocker, Martin; Pedarzani, Paola

    2014-01-01

    The slow afterhyperpolarizing current (sIAHP) is a calcium-dependent potassium current that underlies the late phase of spike frequency adaptation in hippocampal and neocortical neurons. sIAHP is a well-known target of modulation by several neurotransmitters acting via the cyclic AMP (cAMP) and protein kinase A (PKA)-dependent pathway. The neuropeptide pituitary adenylate cyclase activating peptide (PACAP) and its receptors are present in the hippocampal formation. In this study we have investigated the effect of PACAP on the sIAHP and the signal transduction pathway used to modulate intrinsic excitability of hippocampal pyramidal neurons. We show that PACAP inhibits the sIAHP, resulting in a decrease of spike frequency adaptation, in rat CA1 pyramidal cells. The suppression of sIAHP by PACAP is mediated by PAC1 and VPAC1 receptors. Inhibition of PKA reduced the effect of PACAP on sIAHP, suggesting that PACAP exerts part of its inhibitory effect on sIAHP by increasing cAMP and activating PKA. The suppression of sIAHP by PACAP was also strongly hindered by the inhibition of p38 MAP kinase (p38 MAPK). Concomitant inhibition of PKA and p38 MAPK indicates that these two kinases act in a sequential manner in the same pathway leading to the suppression of sIAHP. Conversely, protein kinase C is not part of the signal transduction pathway used by PACAP to inhibit sIAHP in CA1 neurons. Our results show that PACAP enhances the excitability of CA1 pyramidal neurons by inhibiting the sIAHP through the activation of multiple signaling pathways, most prominently cAMP/PKA and p38 MAPK. Our findings disclose a novel modulatory action of p38 MAPK on intrinsic excitability and the sIAHP, underscoring the role of this current as a neuromodulatory hub regulated by multiple protein kinases in cortical neurons. © 2013 The Authors. Hippocampus Published by Wiley Periodicals, Inc. PMID:23996525

  20. Resurgent Na+ current in pyramidal neurones of rat perirhinal cortex: axonal location of channels and contribution to depolarizing drive during repetitive firing

    Science.gov (United States)

    Castelli, Loretta; Biella, Gerardo; Toselli, Mauro; Magistretti, Jacopo

    2007-01-01

    The perirhinal cortex (PRC) is a supra-modal cortical area that collects and integrates information originating from uni- and multi-modal neocortical regions and directed to the hippocampus. The mechanisms that underlie the specific excitable properties of the different PRC neuronal types are still largely unknown, and their elucidation may be important in understanding the integrative functions of PRC. In this study we investigated the expression and properties of resurgent Na+ current (INaR) in pyramidal neurones of rat PRC area 35 (layer II). Patch-clamp experiments in acute PRC slices were first carried out. A measurable INaR was expressed by a large majority of neurones (31 out of 35 cells). INaR appeared as an inward, slowly decaying current elicited upon step repolarization after depolarizations sufficient to induce nearly complete inactivation of the transient Na+ current (INaT). INaR had a peak amplitude of ∼2.5% that of INaT, and showed the typical biophysical properties also observed in other neuronal types (i.e. cerebellar Purkinje and granule cells), including a bell-shaped current–voltage relationship with a peak at approximately −40 mV, and a characteristic acceleration of activation and decay speed at potentials negative to −45 mV. Current-clamp experiments were then carried out in which repetitive action-potential discharge at various frequencies was induced with depolarizing current injection. The voltage signals thus obtained were then used as command waveforms for voltage-clamp recordings. These experiments showed that a Na+ current identifiable as INaR activates in the early interspike phase even at relatively high firing frequencies (20 Hz), thereby contributing to the depolarizing drive and possibly enhancing repetitive discharge. In acutely dissociated area 35 layer II neurones, as well as in nucleated patches from the same neurones, INaR was never observed, despite the presence of typical INaTs. Since in both preparations neuronal

  1. Synaptic conductances during interictal discharges in pyramidal neurons of rat entorhinal cortex

    Directory of Open Access Journals (Sweden)

    Dmitry V. Amakhin

    2016-10-01

    Full Text Available In epilepsy, the balance of excitation and inhibition underlying the basis of neural network activity shifts, resulting in neuronal network hyperexcitability and recurrent seizure-associated discharges. Mechanisms involved in ictal and interictal events are not fully understood, in particular, because of controversial data regarding the dynamics of excitatory and inhibitory synaptic conductances. In the present study, we estimated AMPAR-, NMDAR-, and GABAAR-mediated conductances during two distinct types of interictal discharge (IID in pyramidal neurons of rat entorhinal cortex in cortico-hippocampal slices. Repetitively emerging seizure-like events and IIDs were recorded in high extracellular potassium, 4-aminopyridine, and reduced magnesium-containing solution. An original procedure for estimating synaptic conductance during IIDs was based on the differences among the current-voltage characteristics of the synaptic components. The synaptic conductance dynamics obtained revealed that the first type of IID is determined by activity of GABAAR channels with depolarized reversal potential. The second type of IID is determined by the interplay between excitation and inhibition, with prominent early AMPAR and prolonged depolarized GABAAR and NMDAR-mediated components. The study then validated the contribution of these components to IIDs by intracellular pharmacological isolation. These data provide new insights into the mechanisms of seizures generation, development, and cessation.

  2. Persistent sodium current properties in hippocampal CA1 pyramidal neurons of young and adult rats.

    Science.gov (United States)

    Lunko, Oleksii; Isaev, Dmytro; Maximyuk, Oleksandr; Ivanchick, Gleb; Sydorenko, Vadym; Krishtal, Oleg; Isaeva, Elena

    2014-01-24

    Persistent tetrodotoxin-sensitive sodium current (INaP) plays an important role in cellular and neuronal network excitability in physiological conditions and under different pathological circumstances. However, developmental changes in INaP properties remain largely unclear. In the present study using whole cell patch clamp technique we evaluated INaP properties in CA1 hippocampal pyramidal neurons isolated from young (postnatal day (P) 12-16) and adult (P60-75) rats. We show that the INaP density is substantially larger in the adult group. Although INaP inactivation characteristics were found to be similar in both groups, voltage dependence of INaP activation is shifted to more negative membrane potentials (young: -48.6±0.5mV vs. adult: -52.4±0.2mV, p<0.01). Our data indicates the increase of INaP contribution in the basal membrane sodium conductivity in the mature hippocampus.

  3. Plasticity-dependent, full detonation at hippocampal mossy fiber–CA3 pyramidal neuron synapses

    Science.gov (United States)

    Vyleta, Nicholas P; Borges-Merjane, Carolina; Jonas, Peter

    2016-01-01

    Mossy fiber synapses on CA3 pyramidal cells are 'conditional detonators' that reliably discharge postsynaptic targets. The 'conditional' nature implies that burst activity in dentate gyrus granule cells is required for detonation. Whether single unitary excitatory postsynaptic potentials (EPSPs) trigger spikes in CA3 neurons remains unknown. Mossy fiber synapses exhibit both pronounced short-term facilitation and uniquely large post-tetanic potentiation (PTP). We tested whether PTP could convert mossy fiber synapses from subdetonator into detonator mode, using a recently developed method to selectively and noninvasively stimulate individual presynaptic terminals in rat brain slices. Unitary EPSPs failed to initiate a spike in CA3 neurons under control conditions, but reliably discharged them after induction of presynaptic short-term plasticity. Remarkably, PTP switched mossy fiber synapses into full detonators for tens of seconds. Plasticity-dependent detonation may be critical for efficient coding, storage, and recall of information in the granule cell–CA3 cell network. DOI: http://dx.doi.org/10.7554/eLife.17977.001 PMID:27780032

  4. Characterization of voltage-gated Ca(2+ conductances in layer 5 neocortical pyramidal neurons from rats.

    Directory of Open Access Journals (Sweden)

    Mara Almog

    Full Text Available Neuronal voltage-gated Ca(2+ channels are involved in electrical signalling and in converting these signals into cytoplasmic calcium changes. One important function of voltage-gated Ca(2+ channels is generating regenerative dendritic Ca(2+ spikes. However, the Ca(2+ dependent mechanisms used to create these spikes are only partially understood. To start investigating this mechanism, we set out to kinetically and pharmacologically identify the sub-types of somatic voltage-gated Ca(2+ channels in pyramidal neurons from layer 5 of rat somatosensory cortex, using the nucleated configuration of the patch-clamp technique. The activation kinetics of the total Ba(2+ current revealed conductance activation only at medium and high voltages suggesting that T-type calcium channels were not present in the patches. Steady-state inactivation protocols in combination with pharmacology revealed the expression of R-type channels. Furthermore, pharmacological experiments identified 5 voltage-gated Ca(2+ channel sub-types - L-, N-, R- and P/Q-type. Finally, the activation of the Ca(2+ conductances was examined using physiologically derived voltage-clamp protocols including a calcium spike protocol and a mock back-propagating action potential (mBPAP protocol. These experiments enable us to suggest the possible contribution of the five Ca(2+ channel sub-types to Ca(2+ current flow during activation under physiological conditions.

  5. Maternal mobile phone exposure alters intrinsic electrophysiological properties of CA1 pyramidal neurons in rat offspring.

    Science.gov (United States)

    Razavinasab, Moazamehosadat; Moazzami, Kasra; Shabani, Mohammad

    2016-06-01

    Some studies have shown that exposure to electromagnetic field (EMF) may result in structural damage to neurons. In this study, we have elucidated the alteration in the hippocampal function of offspring Wistar rats (n = 8 rats in each group) that were chronically exposed to mobile phones during their gestational period by applying behavioral, histological, and electrophysiological tests. Rats in the EMF group were exposed to 900 MHz pulsed-EMF irradiation for 6 h/day. Whole cell recordings in hippocampal pyramidal cells in the mobile phone groups did show a decrease in neuronal excitability. Mobile phone exposure was mostly associated with a decrease in the number of action potentials fired in spontaneous activity and in response to current injection in both male and female groups. There was an increase in the amplitude of the afterhyperpolarization (AHP) in mobile phone rats compared with the control. The results of the passive avoidance and Morris water maze assessment of learning and memory performance showed that phone exposure significantly altered learning acquisition and memory retention in male and female rats compared with the control rats. Light microscopy study of brain sections of the control and mobile phone-exposed rats showed normal morphology.Our results suggest that exposure to mobile phones adversely affects the cognitive performance of both female and male offspring rats using behavioral and electrophysiological techniques.

  6. Factors mediating powerful voltage attenuation along CA1 pyramidal neuron dendrites

    Science.gov (United States)

    Golding, Nace L; Mickus, Timothy J; Katz, Yael; Kath, William L; Spruston, Nelson

    2005-01-01

    We performed simultaneous patch-electrode recordings from the soma and apical dendrite of CA1 pyramidal neurons in hippocampal slices, in order to determine the degree of voltage attenuation along CA1 dendrites. Fifty per cent attenuation of steady-state somatic voltage changes occurred at a distance of 238 μm from the soma in control and 409 μm after blocking the hyperpolarization-activated (H) conductance. The morphology of three neurons was reconstructed and used to generate computer models, which were adjusted to fit the somatic and dendritic voltage responses. These models identify several factors contributing to the voltage attenuation along CA1 dendrites, including high axial cytoplasmic resistivity, low membrane resistivity, and large H conductance. In most cells the resting membrane conductances, including the H conductances, were larger in the dendrites than the soma. Simulations suggest that synaptic potentials attenuate enormously as they propagate from the dendrite to the soma, with greater than 100-fold attenuation for synapses on many small, distal dendrites. A prediction of this powerful EPSP attenuation is that distal synaptic inputs are likely only to be effective in the presence of conductance scaling, dendritic excitability, or both. PMID:16002454

  7. Ibuprofen augments bilirubin toxicity in rat cortical neuronal culture.

    Science.gov (United States)

    Berns, Monika; Toennessen, Margit; Koehne, Petra; Altmann, Rodica; Obladen, Michael

    2009-04-01

    Premature infants are at risk for bilirubin-associated brain damage. In cell cultures bilirubin causes neuronal apoptosis and necrosis. Ibuprofen is used to close the ductus arteriosus, and is often given when hyperbilirubinemia is at its maximum. Ibuprofen is known to interfere with bilirubin-albumin binding. We hypothesized that bilirubin toxicity to cultured rat embryonic cortical neurons is augmented by coincubation with ibuprofen. Incubation with ibuprofen above a concentration of 125 microg/mL reduced cell viability, measured by methylthiazole tetrazolium reduction, to 68% of controls (p < 0.05). Lactate dehydrogenase (LDH) release increased from 29 to 38% (p < 0.01). The vehicle solution did not affect cell viability. Coincubation with 10 microM unconjugated bilirubin (UCB)/human serum albumin in a molar ratio of 3:1 and 250 microg/mL ibuprofen caused additional loss of cell viability and increased LDH release (p < 0.01), DNA fragmentation, and activated caspase-3. Preincubation with the pan-caspase inhibitor z-val-ala-asp-fluoromethyl ketone abolished ibuprofen- and UCB-induced DNA fragmentation. The study demonstrates that bilirubin in low concentration of 10 microM reduces neuron viability and ibuprofen increases this effect. Apoptosis is the underlying cell death mechanism.

  8. The adaptation of spike backpropagation delays in cortical neurons

    Directory of Open Access Journals (Sweden)

    Yossi eBuskila

    2013-10-01

    Full Text Available We measured the action potential backpropagation delays in apical dendrites of layer 5 pyramidal neurons of the somatosensory cortex under different stimulation regimes that exclude synaptic involvement. These delays showed robust features and did not correlate to either transient change in the stimulus strength or low frequency stimulation of suprathreshold membrane oscillations. However, our results indicate that backpropagation delays correlate with high frequency (>10 Hz stimulation of membrane oscillations, and that persistent suprathreshold sinusoidal stimulation injected directly into the soma results in an increase of the backpropagation delay, suggesting an intrinsic adaptation of the bAP, which does not involve any synaptic modifications. Moreover, the calcium chelator BAPTA eliminated the alterations in the backpropagation delays, strengthening the hypothesis that increased calcium concentration in the dendrites modulates dendritic excitability and can impact the backpropagation velocity. These results emphasize the impact of dendritic excitability on bAP velocity along the dendritic tree, which affects the precision of the bAP arrival at the synapse during specific stimulus regimes, and is capable of shifting the extent and polarity of synaptic strength during suprathreshold synaptic processes such as STDP.

  9. Properties of bilateral spinocerebellar activation of cerebellar cortical neurons

    Directory of Open Access Journals (Sweden)

    Pontus eGeborek

    2014-10-01

    Full Text Available We aimed to explore the cerebellar cortical inputs from two spinocerebellar pathways, the spinal border cell-component of the ventral spinocerebellar tract (SBC-VSCT and the dorsal spinocerebellar tract (DSCT, respectively, in the sublobule C1 of the cerebellar posterior lobe. The two pathways were activated by electrical stimulation of the contralateral lateral funiculus (coLF and the ipsilateral LF (iLF at lower thoracic levels. Most granule cells in sublobule C1 did not respond at all but part of the granule cell population displayed high-intensity responses to either coLF or iLF stimulation. As a rule, Golgi cells and Purkinje cell simple spikes responded to input from both LFs, although Golgi cells could be more selective. In addition, a small population of granule cells responded to input from both the coLF and the iLF. However, in these cases, similarities in the temporal topography and magnitude of the responses suggested that the same axons were stimulated from the two LFs, i.e. that the axons of individual spinocerebellar neurons could be present in both funiculi. This was also confirmed for a population of spinal neurons located within known locations of SBC-VSCT neurons and dorsal horn DSCT neurons. We conclude that bilateral spinocerebellar responses can occur in cerebellar granule cells, but the VSCT and DSCT systems that provide the input can also be organized bilaterally. The implications for the traditional functional separation of VSCT and DSCT systems and the issue whether granule cells primarily integrate functionally similar information or not are discussed.

  10. Slow Bursting Neurons of Mouse Cortical Layer 6b Are Depolarized by Hypocretin/Orexin and Major Transmitters of Arousal

    Science.gov (United States)

    Wenger Combremont, Anne-Laure; Bayer, Laurence; Dupré, Anouk; Mühlethaler, Michel; Serafin, Mauro

    2016-01-01

    Neurons firing spontaneously in bursts in the absence of synaptic transmission have been previously recorded in different layers of cortical brain slices. It has been suggested that such neurons could contribute to the generation of alternating UP and DOWN states, a pattern of activity seen during slow-wave sleep. Here, we show that in layer 6b (L6b), known from our previous studies to contain neurons highly responsive to the wake-promoting transmitter hypocretin/orexin (hcrt/orx), there is a set of neurons, endowed with distinct intrinsic properties, which displayed a strong propensity to fire spontaneously in rhythmic bursts. In response to small depolarizing steps, they responded with a delayed firing of action potentials which, upon higher depolarizing steps, invariably inactivated and were followed by a depolarized plateau potential and a depolarizing afterpotential. These cells also displayed a strong hyperpolarization-activated rectification compatible with the presence of an Ih current. Most L6b neurons with such properties were able to fire spontaneously in bursts. Their bursting activity was of intrinsic origin as it persisted not only in presence of blockers of ionotropic glutamatergic and GABAergic receptors but also in a condition of complete synaptic blockade. However, a small number of these neurons displayed a mix of intrinsic bursting and synaptically driven recurrent UP and DOWN states. Most of the bursting L6b neurons were depolarized and excited by hcrt/orx through a direct postsynaptic mechanism that led to tonic firing and eventually inactivation. Similarly, they were directly excited by noradrenaline, histamine, dopamine, and neurotensin. Finally, the intracellular injection of these cells with dye and their subsequent Neurolucida reconstruction indicated that they were spiny non-pyramidal neurons. These results lead us to suggest that the propensity for slow rhythmic bursting of this set of L6b neurons could be directly impeded by hcrt

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

    Science.gov (United States)

    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

  12. Neuronal networks and mediators of cortical neurovascular coupling responses in normal and altered brain states.

    Science.gov (United States)

    Lecrux, C; Hamel, E

    2016-10-05

    Brain imaging techniques that use vascular signals to map changes in neuronal activity, such as blood oxygenation level-dependent functional magnetic resonance imaging, rely on the spatial and temporal coupling between changes in neurophysiology and haemodynamics, known as 'neurovascular coupling (NVC)'. Accordingly, NVC responses, mapped by changes in brain haemodynamics, have been validated for different stimuli under physiological conditions. In the cerebral cortex, the networks of excitatory pyramidal cells and inhibitory interneurons generating the changes in neural activity and the key mediators that signal to the vascular unit have been identified for some incoming afferent pathways. The neural circuits recruited by whisker glutamatergic-, basal forebrain cholinergic- or locus coeruleus noradrenergic pathway stimulation were found to be highly specific and discriminative, particularly when comparing the two modulatory systems to the sensory response. However, it is largely unknown whether or not NVC is still reliable when brain states are altered or in disease conditions. This lack of knowledge is surprising since brain imaging is broadly used in humans and, ultimately, in conditions that deviate from baseline brain function. Using the whisker-to-barrel pathway as a model of NVC, we can interrogate the reliability of NVC under enhanced cholinergic or noradrenergic modulation of cortical circuits that alters brain states.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.

  13. Neuronal Sirt3 protects against excitotoxic injury in mouse cortical neuron culture.

    Directory of Open Access Journals (Sweden)

    Sun Hee Kim

    Full Text Available BACKGROUND: Sirtuins (Sirt, a family of nicotinamide adenine nucleotide (NAD dependent deacetylases, are implicated in energy metabolism and life span. Among the known Sirt isoforms (Sirt1-7, Sirt3 was identified as a stress responsive deacetylase recently shown to play a role in protecting cells under stress conditions. Here, we demonstrated the presence of Sirt3 in neurons, and characterized the role of Sirt3 in neuron survival under NMDA-induced excitotoxicity. METHODOLOGY/PRINCIPAL FINDINGS: To induce excitotoxic injury, we exposed primary cultured mouse cortical neurons to NMDA (30 µM. NMDA induced a rapid decrease of cytoplasmic NAD (but not mitochondrial NAD in neurons through poly (ADP-ribose polymerase-1 (PARP-1 activation. Mitochondrial Sirt3 was increased following PARP-1 mediated NAD depletion, which was reversed by either inhibition of PARP-1 or exogenous NAD. We found that massive reactive oxygen species (ROS produced under this NAD depleted condition mediated the increase in mitochondrial Sirt3. By transfecting primary neurons with a Sirt3 overexpressing plasmid or Sirt3 siRNA, we showed that Sirt3 is required for neuroprotection against excitotoxicity. CONCLUSIONS: This study demonstrated for the first time that mitochondrial Sirt3 acts as a prosurvival factor playing an essential role to protect neurons under excitotoxic injury.

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

    Science.gov (United States)

    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. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  15. Whole-cell recordings of voltage-gated Calcium, Potassium and Sodium currents in acutely isolated hippocampal pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    Shuyun Huang; Qing Cai; Weitian Liu; Xiaoling Wang; Tao Wang

    2009-01-01

    Objective:To record Calcium, Potassium and Sodium currents in acutely isolated hippocampal pyramidal neurons. Methods:Hip-pocampal CA3 neurons were freshly isolated by 1 mg protease/3 ml SES and mechanical trituration with polished pipettes of progressively smaller tip diameters. Patch clamp technique in whole-cell mode was employed to record voltage-gated channel currents. Results:The procedure dissociated hippocampal neurons, preserving apical dendrites and several basal dendrites, without impairing the electrical characteristics of the neurons. Whole-cell patch clamp configuration was successfully used to record voltage-gated Ca2+ currents, delayed rectifier K+ current and voltage-gated Na+ currents. Conclusion:Protease combined with mechanical trituration may be used for the dissociation of neurons from rat hippocampus. Voltage-gated channels currents could be recorded using a patch clamp technique.

  16. Single mechanically-gated cation channel currents can trigger action potentials in neocortical and hippocampal pyramidal neurons.

    Science.gov (United States)

    Nikolaev, Yury A; Dosen, Peter J; Laver, Derek R; van Helden, Dirk F; Hamill, Owen P

    2015-05-22

    The mammalian brain is a mechanosensitive organ that responds to different mechanical forces ranging from intrinsic forces implicated in brain morphogenesis to extrinsic forces that can cause concussion and traumatic brain injury. However, little is known of the mechanosensors that transduce these forces. In this study we use cell-attached patch recording to measure single mechanically-gated (MG) channel currents and their affects on spike activity in identified neurons in neonatal mouse brain slices. We demonstrate that both neocortical and hippocampal pyramidal neurons express stretch-activated MG cation channels that are activated by suctions of ~25mm Hg, have a single channel conductance for inward current of 50-70pS and show weak selectivity for alkali metal cations (i.e., Na(+)pyramidal neurons. Not all neuron types studied here expressed MG channel currents. In particular, locus coeruleus and cerebellar Purkinje neurons showed no detectable MG channel activity. Moreover their robust rhythmic spike activity was resistant to mechanical modulation. Our observation that a single MG channel current can trigger spiking predicates the need for reassessment of the long held view that the impulse output of central neurons depends only upon their intrinsic voltage-gated channels and/or their integrated synaptic input.

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

    Science.gov (United States)

    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.

  18. LTP is accompanied by an enhanced local excitability of pyramidal neuron dendrites.

    Science.gov (United States)

    Frick, Andreas; Magee, Jeffrey; Johnston, Daniel

    2004-02-01

    The propagation and integration of signals in the dendrites of pyramidal neurons is regulated, in part, by the distribution and biophysical properties of voltage-gated ion channels. It is thus possible that any modification of these channels in a specific part of the dendritic tree might locally alter these signaling processes. Using dendritic and somatic whole-cell recordings, combined with calcium imaging in rat hippocampal slices, we found that the induction of long-term potentiation (LTP) was accompanied by a local increase in dendritic excitability that was dependent on the activation of NMDA receptors. These changes favored the back-propagation of action potentials into this dendritic region with a subsequent boost in the Ca(2+) influx. Dendritic cell-attached patch recordings revealed a hyperpolarized shift in the inactivation curve of transient, A-type K(+) currents that can account for the enhanced excitability. These results suggest an important mechanism associated with LTP for shaping signal processing and controlling dendritic function.

  19. Extracellular calcium modulates persistent sodium current-dependent burst-firing in hippocampal pyramidal neurons.

    Science.gov (United States)

    Su, H; Alroy, G; Kirson, E D; Yaari, Y

    2001-06-15

    The generation of high-frequency spike bursts ("complex spikes"), either spontaneously or in response to depolarizing stimuli applied to the soma, is a notable feature in intracellular recordings from hippocampal CA1 pyramidal cells (PCs) in vivo. There is compelling evidence that the bursts are intrinsically generated by summation of large spike afterdepolarizations (ADPs). Using intracellular recordings in adult rat hippocampal slices, we show that intrinsic burst-firing in CA1 PCs is strongly dependent on the extracellular concentration of Ca(2+) ([Ca(2+)](o)). Thus, lowering [Ca(2+)](o) (by equimolar substitution with Mn(2+) or Mg(2+)) induced intrinsic bursting in nonbursters, whereas raising [Ca(2+)](o) suppressed intrinsic bursting in native bursters. The induction of intrinsic bursting by low [Ca(2+)](o) was associated with enlargement of the spike ADP. Low [Ca(2+)](o)-induced intrinsic bursts and their underlying ADPs were suppressed by drugs that reduce the persistent Na(+) current (I(NaP)), indicating that this current mediates the slow burst depolarization. Blocking Ca(2+)-activated K(+) currents with extracellular Ni(2+) or intracellular chelation of Ca(2+) did not induce intrinsic bursting. This and other evidence suggest that lowering [Ca(2+)](o) may induce intrinsic bursting by augmenting I(NaP). Because repetitive neuronal activity in the hippocampus is associated with marked decreases in [Ca(2+)](o), the regulation of intrinsic bursting by extracellular Ca(2+) may provide a mechanism for preferential recruitment of this firing mode during certain forms of hippocampal activation.

  20. Valproic acid inhibits TTX-resistant sodium currents in prefrontal cortex pyramidal neurons.

    Science.gov (United States)

    Szulczyk, Bartlomiej; Nurowska, Ewa

    2017-09-16

    Valproic acid is frequently prescribed and used to treat epilepsy, bipolar disorder and other conditions. However, the mechanism of action of valproic acid has not been fully elucidated. The aim of this study was to assess the influence of valproic acid (200 μM) on TTX-resistant sodium currents in mPFC pyramidal neurons. Valproic acid inhibited the maximal amplitude and did not change the activation parameters of TTX-resistant sodium currents. Moreover, valproic acid (2 μM and 200 μM) shifted the TTX-resistant sodium channel inactivation curve towards hyperpolarisation. In the presence of valproic acid, TTX-resistant sodium currents recovered from inactivation more slowly. Valproic acid did not influence the use-dependent blockade of TTX-resistant sodium currents. This study suggests that a potential new mechanism of the antiepileptic action of valproic acid is, among others, inhibition of TTX-resistant sodium currents. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Age-related dysfunctions of the autophagy lysosomal pathway in hippocampal pyramidal neurons under proteasome stress.

    Science.gov (United States)

    Gavilán, Elena; Pintado, Cristina; Gavilan, Maria P; Daza, Paula; Sánchez-Aguayo, Inmaculada; Castaño, Angélica; Ruano, Diego

    2015-05-01

    Autophagy plays a key role in the maintenance of cellular homeostasis, and autophagy deregulation gives rise to severe disorders. Many of the signaling pathways regulating autophagy under stress conditions are still poorly understood. Using a model of proteasome stress in rat hippocampus, we have characterized the functional crosstalk between the ubiquitin proteasome system and the autophagy-lysosome pathway, identifying also age-related modifications in the crosstalk between both proteolytic systems. Under proteasome inhibition, both autophagy activation and resolution were efficiently induced in young but not in aged rats, leading to restoration of protein homeostasis only in young pyramidal neurons. Importantly, proteasome stress inhibited glycogen synthase kinase-3β in young but activated in aged rats. This age-related difference could be because of a dysfunction in the signaling pathway of the insulin growth factor-1 under stress situations. Present data highlight the potential role of glycogen synthase kinase-3β in the coordination of both proteolytic systems under stress situation, representing a key molecular target to sort out this deleterious effect.

  2. THE KINETICS OF MULTIBRANCH INTEGRATION ON THE DENDRITIC ARBOR OF CA1 PYRAMIDAL NEURONS

    Directory of Open Access Journals (Sweden)

    Sunggu eYang

    2014-05-01

    Full Text Available The process by which synaptic inputs separated in time and space are integrated by the dendritic arbor to produce a sequence of action potentials is among the most fundamental signal transformations that takes place within the central nervous system. Some aspects of this complex process, such as integration at the level of individual dendritic branches, have been extensively studied. But other aspects, such as how inputs from multiple branches are combined, and the kinetics of that integration have not been systematically examined. Using a 3D digital holographic photolysis technique to overcome the challenges posed by the complexities of the 3D anatomy of the dendritic arbor of CA1 pyramidal neurons for conventional photolysis, we show that integration on a single dendrite is fundamentally different from that on multiple dendrites. Multibranch integration occurring at oblique and basal dendrites allows somatic action potential firing of the cell to faithfully follow the driving stimuli over a significantly wider frequency range than what is possible with single branch integration. However, multibranch integration requires greater input strength to drive the somatic action potentials. This tradeoff between sensitivity and kinetics may explain the puzzling report of the predominance of multibranch, rather than single branch, integration from in vivo recordings during presentation of visual stimuli.

  3. Action Potential Modulation in CA1 Pyramidal Neuron Axons Facilitates OLM Interneuron Activation in Recurrent Inhibitory Microcircuits of Rat Hippocampus

    OpenAIRE

    Sooyun Kim

    2014-01-01

    Oriens-lacunosum moleculare (O-LM) interneurons in the CA1 region of the hippocampus play a key role in feedback inhibition and in the control of network activity. However, how these cells are efficiently activated in the network remains unclear. To address this question, I performed recordings from CA1 pyramidal neuron axons, the presynaptic fibers that provide feedback innervation of these interneurons. Two forms of axonal action potential (AP) modulation were identified. First, repetitive ...

  4. Asymmetries in numerical density of pyramidal neurons in the fifth layer of the human posterior parietal cortex

    Directory of Open Access Journals (Sweden)

    Đukić-Macut Nataša

    2012-01-01

    Full Text Available Background/Aim. Both superior parietal lobule (SPL of dorsolateral hemispheric surface and precuneus (PEC of medial surface are the parts of posterior parietal cortex. The aim of this study was to determine the numerical density (NV of pyramidal neurons in the layer V of SPL and PEC and their potential differences. Methods. From 20 (40 hemispheres formaline fixed human brains (both sexes; 27- 65 years tissue blocks from SPL and PEC from the left and right hemisphere were used. According to their size the brains were divided into two groups, the group I with the larger left (15 brains and the group II with the larger right hemisphere (5 brains. Serial Nissl sections (5 μm of the left and right SPL and PEC were used for stereological estimation of NV of the layer V pyramidal neurons. Results. NV of pyramidal neurons in the layer V in the left SPL of brains with larger left hemispheres was significantly higher than in the left SPL of brains with larger right hemisphere. Comparing sides in brains with larger left hemisphere, the left SPL had higher NV than the right one, and then the left PEC, and the right SPL had significantly higher NV than the right PEC. Comparing sides in brains with the larger right hemisphere, the left SPL had significantly higher NV than left PEC, but the right SPL had significantly higher NV than left SPL and the right PEC. Conclusion. Generally, there is an inverse relationship of NV between the medial and lateral areas of the human posterior parietal cortex. The obtained values were different between the brains with larger left and right hemispheres, as well as between the SPL and PEC. In all the comparisons the left SPL had the highest values of NV of pyramidal neurons in the layer V (4771.80 mm-3, except in brains with the larger right hemisphere.

  5. Acute Modulation of Synaptic Plasticity of Pyramidal Neurons by Activin in Adult Hippocampus

    Directory of Open Access Journals (Sweden)

    Yoshitaka eHasegawa

    2014-06-01

    Full Text Available Activin A is known as a neuroprotective factor produced upon acute excitotoxic injury of the hippocampus (in pathological states. We attempt to reveal the role of activin as a neuromodulator in the adult male hippocampus under physiological conditions (in healthy states, which remains largely unknown. We showed endogenous/basal expression of activin in the hippocampal neurons. Localization of activin receptors in dendritic spines (= postsynapses was demonstrated by immunoelectron microscopy. The incubation of hippocampal acute slices with activin A (10 ng/mL, 0.4 nM for 2 h altered the density and morphology of spines in CA1 pyramidal neurons. The total spine density increased by 1.2-fold upon activin treatments. Activin selectively increased the density of large-head spines, without affecting middle-head and small-head spines. Blocking of Erk/MAPK, PKA or PKC prevented the activin-induced spinogenesis by reducing the density of large-head spines, independent of Smad-induced gene transcription which usually takes more than several hours. Incubation of acute slices with activin for 2 h induced the moderate early long-term potentiation (moderate LTP upon weak theta burst stimuli. This moderate LTP induction was blocked by follistatin, MAPK inhibitor (PD98059 and inhibitor of NR2B subunit of NMDA receptors (Ro25-6981. It should be noted that the weak theta burst stimuli alone cannot induce moderate LTP. These results suggest that MAPK-induced phosphorylation of NMDA receptors (including NR2B may play an important role for activin-induced moderate LTP. Taken together, the current results reveal interesting physiological roles of endogenous activin as a synaptic modulator in the adult hippocampus.

  6. Computational modeling reveals dendritic origins of GABA(A-mediated excitation in CA1 pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Naomi Lewin

    Full Text Available GABA is the key inhibitory neurotransmitter in the adult central nervous system, but in some circumstances can lead to a paradoxical excitation that has been causally implicated in diverse pathologies from endocrine stress responses to diseases of excitability including neuropathic pain and temporal lobe epilepsy. We undertook a computational modeling approach to determine plausible ionic mechanisms of GABA(A-dependent excitation in isolated post-synaptic CA1 hippocampal neurons because it may constitute a trigger for pathological synchronous epileptiform discharge. In particular, the interplay intracellular chloride accumulation via the GABA(A receptor and extracellular potassium accumulation via the K/Cl co-transporter KCC2 in promoting GABA(A-mediated excitation is complex. Experimentally it is difficult to determine the ionic mechanisms of depolarizing current since potassium transients are challenging to isolate pharmacologically and much GABA signaling occurs in small, difficult to measure, dendritic compartments. To address this problem and determine plausible ionic mechanisms of GABA(A-mediated excitation, we built a detailed biophysically realistic model of the CA1 pyramidal neuron that includes processes critical for ion homeostasis. Our results suggest that in dendritic compartments, but not in the somatic compartments, chloride buildup is sufficient to cause dramatic depolarization of the GABA(A reversal potential and dominating bicarbonate currents that provide a substantial current source to drive whole-cell depolarization. The model simulations predict that extracellular K(+ transients can augment GABA(A-mediated excitation, but not cause it. Our model also suggests the potential for GABA(A-mediated excitation to promote network synchrony depending on interneuron synapse location - excitatory positive-feedback can occur when interneurons synapse onto distal dendritic compartments, while interneurons projecting to the perisomatic

  7. Differential emotional experience induces elevated spine densities on basal dendrites of pyramidal neurons in the anterior cingulate cortex of Octodon degus.

    Science.gov (United States)

    Helmeke, C; Poeggel, G; Braun, K

    2001-01-01

    It appears likely that, in analogy to the synaptic development of sensory and motor cortices, which critically depends on sensory or motor stimulation (Rosenzweig and Bennett, 1996), the synaptic development of limbic cortical regions are modulated by early postnatal cognitive and emotional experiences. The very first postnatal experience, which takes place in a confined and stable familial environment, is the interaction of the newborn individual with the parents and siblings (Gray, 1958). The aim of this quantitative morphological study was to analyze the impact of different degrees of juvenile emotional experience on the synaptic development in a limbic cortical area, the dorsal anterior cingulate cortex, a region which is involved in the perception and regulation of emotions. We study the precocious trumpet-tailed rat (Octodon degus) as the animal model, because, like human babies, this species is born with functional visual and acoustic systems and the pups are therefore capable of detecting even subtle environmental changes immediately after birth (Reynolds and Wright, 1979; Poeggel and Braun, 1996; Braun et al., 2000; Ovtscharoff and Braun, 2001). The results demonstrate that already a subtle disturbance of the familial environment such as handling induced significantly elevated spine densities on the basal dendrites of layer III cortical pyramidal neurons. More severe disturbances of the emotional environment, such as periodic parental deprivation with or without subsequent chronic social isolation, resulted in an elevation of spine densities of similar magnitude as seen after handling and in addition, altered spine densities confined to specific dendritic segments were observed in these groups. These observations unveil the remarkable sensitivity of the dorsal anterior cingulate cortex towards environmental influences and behavioral experiences during phases of postnatal development. The behavioral consequences of these experience-induced synaptic changes

  8. Prenatal morphine exposure reduces pyramidal neurons in CA1, CA2 and CA3 subfields of mice hippocampus

    Directory of Open Access Journals (Sweden)

    Soraya Ghafari

    2014-03-01

    Full Text Available Objective(s:This study was carried out to evaluate the effect of maternal morphine exposure during gestational and lactation period on pyramidal neurons of hippocampus in 18 and 32 day mice offspring. Materials and Methods: Thirty female mice were randomly allocated into cases and controls. In case group, animals received morphinesulfate 10 mg/kg.body weight intraperitoneally during 7 days before mating, gestational period (GD 0-21, 18 and 32 days after delivery in the experimental groups. The control animals received an equivalent volume of normal saline. Cerebrum of six offsprings in each group was removed and stained with cresyl violet and a monoclonal antibody NeuN for immunohistochemical detection of surviving pyramidal neurons. Quantitative computer-assisted morphometric study was done on hippocampus. Results: The number of pyramidal neurons in CA1, CA2 and CA3 in treated groups was significantly reduced in postnatal day 18 and 32 (P18, P32 compared to control groups (P

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  12. Layer 5 Pyramidal Neurons' Dendritic Remodeling and Increased Microglial Density in Primary Motor Cortex in a Murine Model of Facial Paralysis.

    Science.gov (United States)

    Urrego, Diana; Troncoso, Julieta; Múnera, Alejandro

    2015-01-01

    This work was aimed at characterizing structural changes in primary motor cortex layer 5 pyramidal neurons and their relationship with microglial density induced by facial nerve lesion using a murine facial paralysis model. Adult transgenic mice, expressing green fluorescent protein in microglia and yellow fluorescent protein in projecting neurons, were submitted to either unilateral section of the facial nerve or sham surgery. Injured animals were sacrificed either 1 or 3 weeks after surgery. Two-photon excitation microscopy was then used for evaluating both layer 5 pyramidal neurons and microglia in vibrissal primary motor cortex (vM1). It was found that facial nerve lesion induced long-lasting changes in the dendritic morphology of vM1 layer 5 pyramidal neurons and in their surrounding microglia. Dendritic arborization of the pyramidal cells underwent overall shrinkage. Apical dendrites suffered transient shortening while basal dendrites displayed sustained shortening. Moreover, dendrites suffered transient spine pruning. Significantly higher microglial cell density was found surrounding vM1 layer 5 pyramidal neurons after facial nerve lesion with morphological bias towards the activated phenotype. These results suggest that facial nerve lesions elicit active dendrite remodeling due to pyramidal neuron and microglia interaction, which could be the pathophysiological underpinning of some neuropathic motor sequelae in humans.

  13. C3G regulates cortical neuron migration, preplate splitting and radial glial cell attachment.

    Science.gov (United States)

    Voss, Anne K; Britto, Joanne M; Dixon, Mathew P; Sheikh, Bilal N; Collin, Caitlin; Tan, Seong-Seng; Thomas, Tim

    2008-06-01

    Neuronal migration is integral to the development of the cerebral cortex and higher brain function. Cortical neuron migration defects lead to mental disorders such as lissencephaly and epilepsy. Interaction of neurons with their extracellular environment regulates cortical neuron migration through cell surface receptors. However, it is unclear how the signals from extracellular matrix proteins are transduced intracellularly. We report here that mouse embryos lacking the Ras family guanine nucleotide exchange factor, C3G (Rapgef1, Grf2), exhibit a cortical neuron migration defect resulting in a failure to split the preplate into marginal zone and subplate and a failure to form a cortical plate. C3G-deficient cortical neurons fail to migrate. Instead, they arrest in a multipolar state and accumulate below the preplate. The basement membrane is disrupted and radial glial processes are disorganised and lack attachment in C3G-deficient brains. C3G is activated in response to reelin in cortical neurons, which, in turn, leads to activation of the small GTPase Rap1. In C3G-deficient cells, Rap1 GTP loading in response to reelin stimulation is reduced. In conclusion, the Ras family regulator C3G is essential for two aspects of cortex development, namely radial glial attachment and neuronal migration.

  14. Hippocampal pyramidal neurons switch from a multipolar migration mode to a novel "climbing" migration mode during development.

    Science.gov (United States)

    Kitazawa, Ayako; Kubo, Ken-ichiro; Hayashi, Kanehiro; Matsunaga, Yuki; Ishii, Kazuhiro; Nakajima, Kazunori

    2014-01-22

    The hippocampus plays important roles in brain functions. Despite the importance of hippocampal functions, recent analyses of neuronal migration have mainly been performed on the cerebral neocortex, and the cellular mechanisms responsible for the formation of the hippocampus are not yet completely understood. Moreover, why a prolonged time is required for hippocampal neurons to complete their migration has been unexplainable for several decades. We analyzed the migratory profile of neurons in the developing mouse hippocampal CA1 region and found that the hippocampal pyramidal neurons generated near the ventricle became postmitotic multipolar cells and accumulated in the multipolar cell accumulation zone (MAZ) in the late stage of development. The hippocampal neurons passed through the pyramidal layer by a unique mode of migration. Their leading processes were highly branched and made contact with many radial fibers. Time-lapse imaging revealed that the migrating cells changed their scaffolds from the original radial fibers to other radial fibers, and as a result they proceed in a zigzag manner, with long intervals. The migrating cells in the hippocampus reminded us of "rock climbers" that instead of using their hands to pull up their bodies were using their leading processes to pull up their cell bodies. Because this mode of migration had never been described, we called it the "climbing" mode. The change from the "climbing" mode in the hippocampus to the "locomotion" mode in the neocortex may have contributed to the brain expansion during evolution.

  15. Blockade of Ca2+-permeable AMPA/kainate channels decreases oxygen-glucose deprivation-induced Zn2+ accumulation and neuronal loss in hippocampal pyramidal neurons.

    Science.gov (United States)

    Yin, Hong Z; Sensi, Stefano L; Ogoshi, Fumio; Weiss, John H

    2002-02-15

    Synaptic release of Zn2+ and its translocation into postsynaptic neurons probably contribute to neuronal injury after ischemia or epilepsy. Studies in cultured neurons have revealed that of the three major routes of divalent cation entry, NMDA channels, voltage-sensitive Ca2+ channels (VSCCs), and Ca2+-permeable AMPA/kainate (Ca-A/K) channels, Ca-A/K channels exhibit the highest permeability to exogenously applied Zn2+. However, routes through which synaptically released Zn2+ gains entry to postsynaptic neurons have not been characterized in vivo. To model ischemia-induced Zn2+ movement in a system approximating the in vivo situation, we subjected mouse hippocampal slice preparations to controlled periods of oxygen and glucose deprivation (OGD). Timm's staining revealed little reactive Zn2+ in CA1 and CA3 pyramidal neurons of slices exposed in the presence of O2 and glucose. However, 15 min of OGD resulted in marked labeling in both regions. Whereas strong Zn2+ labeling persisted if both the NMDA antagonist MK-801 and the VSCC blocker Gd3+ were present during OGD, the presence of either the Ca-A/K channel blocker 1-naphthyl acetyl spermine (NAS) or the extracellular Zn2+ chelator Ca2+ EDTA substantially decreased Zn2+ accumulation in pyramidal neurons of both subregions. In parallel experiments, slices were subjected to 5 min OGD exposures as described above, followed 4 hr later by staining with the cell-death marker propidium iodide. As in the Timm's staining experiments, substantial CA1 or CA3 pyramidal neuronal damage occurred despite the presence of MK-801 and Gd3+, whereas injury was decreased by NAS or by Ca2+ EDTA (in CA1).

  16. Tonic GABAA conductance decreases membrane time constant and increases EPSP-spike precision in hippocampal pyramidal neurons

    Directory of Open Access Journals (Sweden)

    Agnieszka I Wlodarczyk

    2013-12-01

    Full Text Available Because of a complex dendritic structure, pyramidal neurons have a large membrane surface relative to other cells and so a large electrical capacitance and a large membrane time constant (τm. This results in slow depolarizations in response to excitatory synaptic inputs, and consequently increased and variable action potential latencies, which may be computationally undesirable. Tonic activation of GABAA receptors increases membrane conductance and thus regulates neuronal excitability by shunting inhibition. In addition, tonic increases in membrane conductance decrease the membrane time constant (τm, and improve the temporal fidelity of neuronal firing. Here we performed whole-cell current clamp recordings from hippocampal CA1 pyramidal neurons and found that bath application of 10 µM GABA indeed decreases τm in these cells. GABA also decreased first spike latency and jitter (standard deviation of the latency produced by current injection of 2 rheobases (500 ms. However, when larger current injections (3-6 rheobases were used, GABA produced no significant effect on spike jitter, which was low. Using mathematical modelling we demonstrate that the tonic GABAA conductance decreases rise time, decay time and half-width of EPSPs in pyramidal neurons. A similar effect was observed on EPSP/IPSP pairs produced by stimulation of Schaffer collaterals: the EPSP part of the response became shorter after application of GABA. Consistent with the current injection data, a significant decrease in spike latency and jitter was obtained in cell attached recordings only at near-threshold stimulation (50% success rate, S50. When stimulation was increased to 2- or 3- times S50, GABA significantly affected neither spike latency nor spike jitter. Our results suggest that a decrease in τm associated with elevations in ambient GABA can improve EPSP-spike precision at near-threshold synaptic inputs.

  17. Tonic GABAA conductance decreases membrane time constant and increases EPSP-spike precision in hippocampal pyramidal neurons.

    Science.gov (United States)

    Wlodarczyk, Agnieszka I; Xu, Chun; Song, Inseon; Doronin, Maxim; Wu, Yu-Wei; Walker, Matthew C; Semyanov, Alexey

    2013-01-01

    Because of a complex dendritic structure, pyramidal neurons have a large membrane surface relative to other cells and so a large electrical capacitance and a large membrane time constant (τm). This results in slow depolarizations in response to excitatory synaptic inputs, and consequently increased and variable action potential latencies, which may be computationally undesirable. Tonic activation of GABAA receptors increases membrane conductance and thus regulates neuronal excitability by shunting inhibition. In addition, tonic increases in membrane conductance decrease the membrane time constant (τm), and improve the temporal fidelity of neuronal firing. Here we performed whole-cell current clamp recordings from hippocampal CA1 pyramidal neurons and found that bath application of 10μM GABA indeed decreases τm in these cells. GABA also decreased first spike latency and jitter (standard deviation of the latency) produced by current injection of 2 rheobases (500 ms). However, when larger current injections (3-6 rheobases) were used, GABA produced no significant effect on spike jitter, which was low. Using mathematical modeling we demonstrate that the tonic GABAA conductance decreases rise time, decay time and half-width of EPSPs in pyramidal neurons. A similar effect was observed on EPSP/IPSP pairs produced by stimulation of Schaffer collaterals: the EPSP part of the response became shorter after application of GABA. Consistent with the current injection data, a significant decrease in spike latency and jitter was obtained in cell attached recordings only at near-threshold stimulation (50% success rate, S50). When stimulation was increased to 2- or 3- times S50, GABA significantly affected neither spike latency nor spike jitter. Our results suggest that a decrease in τm associated with elevations in ambient GABA can improve EPSP-spike precision at near-threshold synaptic inputs.

  18. Development and maturation of embryonic cortical neurons grafted into the damaged adult motor cortex

    Directory of Open Access Journals (Sweden)

    Nissrine Ballout

    2016-08-01

    Full Text Available 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 two 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.

  19. Activation of functional α7-containing nAChRs in hippocampal CA1 pyramidal neurons by physiological levels of choline in the presence of PNU-120596.

    Directory of Open Access Journals (Sweden)

    Bopanna I Kalappa

    Full Text Available BACKGROUND: The level of expression of functional α7-containing nicotinic acetylcholine receptors (nAChRs in hippocampal CA1 pyramidal neurons is believed to be very low compared to hippocampal CA1 interneurons, and for many years this expression was largely overlooked. However, high densities of expression of functional α7-containing nAChRs in CA1 pyramidal neurons may not be necessary for triggering important cellular and network functions, especially if activation of α7-containing nAChRs occurs in the presence of positive allosteric modulators such as PNU-120596. METHODOLOGY/PRINCIPAL FINDINGS: An approach previously developed for α7-containing nAChRs expressed in tuberomammillary neurons was applied to investigate functional CA1 pyramidal α7-containing nAChRs using rat coronal hippocampal slices and patch-clamp electrophysiology. The majority (∼71% of tested CA1 pyramidal neurons expressed low densities of functional α7-containing nAChRs as evidenced by small whole-cell responses to choline, a selective endogenous agonist of α7 nAChRs. These responses were potentiated by PNU-120596, a novel positive allosteric modulator of α7 nAChRs. The density of functional α7-containing nAChRs expressed in CA1 pyramidal neurons (and thus, the normalized net effect of activation, i.e., response net charge per unit of membrane capacitance per unit of time was estimated to be ∼5% of the density observed in CA1 interneurons. The results of this study demonstrate that despite low levels of expression of functional pyramidal α7-containing nAChRs, physiological levels of choline (∼10 µM are sufficient to activate these receptors and transiently depolarize and even excite CA1 pyramidal neurons in the presence of PNU-120596. The observed effects are possible because in the presence of 10 µM choline and 1-5 µM PNU-120596, a single opening of an individual pyramidal α7-containing nAChR ion channel appears to transiently depolarize (∼4 mV the

  20. Neurochemical, morphologic, and laminar characterization of cortical projection neurons in the cingulate motor areas of the macaque monkey

    Science.gov (United States)

    Nimchinsky, E. A.; Hof, P. R.; Young, W. G.; Morrison, J. H.; Bloom, F. E. (Principal Investigator)

    1996-01-01

    The primate cingulate gyrus contains multiple cortical areas that can be distinguished by several neurochemical features, including the distribution of neurofilament protein-enriched pyramidal neurons. In addition, connectivity and functional properties indicate that there are multiple motor areas in the cortex lining the cingulate sulcus. These motor areas were targeted for analysis of potential interactions among regional specialization, connectivity, and cellular characteristics such as neurochemical profile and morphology. Specifically, intracortical injections of retrogradely transported dyes and intracellular injection were combined with immunocytochemistry to investigate neurons projecting from the cingulate motor areas to the putative forelimb region of the primary motor cortex, area M1. Two separate groups of neurons projecting to area M1 emanated from the cingulate sulcus, one anterior and one posterior, both of which furnished commissural and ipsilateral connections with area M1. The primary difference between the two populations was laminar origin, with the anterior projection originating largely in deep layers, and the posterior projection taking origin equally in superficial and deep layers. With regard to cellular morphology, the anterior projection exhibited more morphologic diversity than the posterior projection. Commissural projections from both anterior and posterior fields originated largely in layer VI. Neurofilament protein distribution was a reliable tool for localizing the two projections and for discriminating between them. Comparable proportions of the two sets of projection neurons contained neurofilament protein, although the density and distribution of the total population of neurofilament protein-enriched neurons was very different in the two subareas of origin. Within a projection, the participating neurons exhibited a high degree of morphologic heterogeneity, and no correlation was observed between somatodendritic morphology and

  1. Euchromatin histone methyltransferase 1 regulates cortical neuronal network development

    Science.gov (United States)

    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

  2. Changes in neuronal excitability by activated microglia: Differential Na+ current up-regulation in pyramid-shaped and bipolar neurons by TNF-α and IL-18

    Directory of Open Access Journals (Sweden)

    Lars eKlapal

    2016-03-01

    Full Text Available Microglia are activated during pathological events in the brain and are capable of releasing various types of inflammatory cytokines. Here we demonstrate that the addition of 5% microglia activated by 1 µg/ml lipopolysaccharides (LPS to hippocampal cultures up-regulates Na+ current densities (INavD of bipolar as well as pyramid-shaped neurons, thereby increasing their excitability. Deactivation of microglia by the addition of 10 ng/ml transforming growth factor-β (TGF-β decreases INavD below control levels suggesting that the residual activated microglial cells influence neuronal excitability in control cultures. Preincubation of hippocampal cultures with 10 ng/ml tumor necrosis factor-α (TNF-α, a major cytokine released by activated microglia, up-regulated INavD significantly by ~30% in bipolar cells, whereas in pyramid-shaped cells the up-regulation only reached an increase of ~14%. Incubation of the cultures with antibodies against either TNF-receptor 1 or 2 blocked the up-regulation of INavD in bipolar cells, whereas in pyramid-shaped cells increases in INavD were exclusively blocked by antibodies against TNF-receptor 2, suggesting that both cell types respond differently to TNF-α exposure. Since additional cytokines, such as interleukin-18 (IL-18, are released from activated microglia we tested potential effects of IL-18 on INavD in both cell types. Exposure to 5-10 ng/ml IL-18 for 4 days increased INavD in both pyramid-shaped as well as bipolar neurons, albeit the dose-response curves were shifted to lower concentrations in bipolar cells. Our results suggest that by secretion of cytokines microglial cells up-regulate Na+ current densities in bipolar and pyramid-shaped neurons to some extent differentially. Depending on the exact cytokine composition and concentration released this could change the balance between the activity of inhibitory bipolar and excitatory pyramid-shaped cells. Since bipolar cells show a larger up-regulation of

  3. Changes in Neuronal Excitability by Activated Microglia: Differential Na(+) Current Upregulation in Pyramid-Shaped and Bipolar Neurons by TNF-α and IL-18.

    Science.gov (United States)

    Klapal, Lars; Igelhorst, Birte A; Dietzel-Meyer, Irmgard D

    2016-01-01

    Microglia are activated during pathological events in the brain and are capable of releasing various types of inflammatory cytokines. Here, we demonstrate that the addition of 5% microglia activated by 1 μg/ml lipopolysaccharides (LPS) to hippocampal cultures upregulates Na(+) current densities (INavD) of bipolar as well as pyramid-shaped neurons, thereby increasing their excitability. Deactivation of microglia by the addition of 10 ng/ml transforming growth factor-β (TGF-β) decreases INavD below control levels suggesting that the residual activated microglial cells influence neuronal excitability in control cultures. Preincubation of hippocampal cultures with 10 ng/ml tumor necrosis factor-α (TNF-α), a major cytokine released by activated microglia, upregulated INavD significantly by ~30% in bipolar cells, whereas in pyramid-shaped cells, the upregulation only reached an increase of ~14%. Incubation of the cultures with antibodies against either TNF-receptor 1 or 2 blocked the upregulation of INavD in bipolar cells, whereas in pyramid-shaped cells, increases in INavD were exclusively blocked by antibodies against TNF-receptor 2, suggesting that both cell types respond differently to TNF-α exposure. Since additional cytokines, such as interleukin-18 (IL-18), are released from activated microglia, we tested potential effects of IL-18 on INavD in both cell types. Exposure to 5-10 ng/ml IL-18 for 4 days increased INavD in both pyramid-shaped as well as bipolar neurons, albeit the dose-response curves were shifted to lower concentrations in bipolar cells. Our results suggest that by secretion of cytokines, microglial cells upregulate Na(+) current densities in bipolar and pyramid-shaped neurons to some extent differentially. Depending on the exact cytokine composition and concentration released, this could change the balance between the activity of inhibitory bipolar and excitatory pyramid-shaped cells. Since bipolar cells show a larger upregulation of

  4. Convergence of entorhinal and CA3 inputs onto pyramidal neurons and interneurons in hippocampal area CA1--an anatomical study in the rat.

    Science.gov (United States)

    Kajiwara, Riichi; Wouterlood, Floris G; Sah, Anupam; Boekel, Amber J; Baks-te Bulte, Luciënne T G; Witter, Menno P

    2008-01-01

    The entorhinal cortex (EC) conveys information to hippocampal field CA1 either directly by way of projections from principal neurons in layer III, or indirectly by axons from layer II via the dentate gyrus, CA3, and Schaffer collaterals. These two pathways differentially influence activity in CA1, yet conclusive evidence is lacking whether and to what extent they converge onto single CA1 neurons. Presently we studied such convergence. Different neuroanatomical tracers injected into layer III of EC and into CA3, respectively, tagged simultaneously the direct entorhino-hippocampal fibers and the indirect innervation of CA1 neurons by Schaffer collaterals. In slices of fixed brains we intracellularly filled CA1 pyramidal cells and interneurons in stratum lacunosum-moleculare (LM) and stratum radiatum (SR). Sections of these slices were scanned in a confocal laser scanning microscope. 3D-reconstruction was used to determine whether boutons of the labeled input fibers were in contact with the intracellularly filled neurons. We analyzed 12 pyramidal neurons and 21 interneurons. Perforant path innervation to pyramidal neurons in our material was observed to be denser than that from CA3. All pyramidal neurons and 17 of the interneurons received contacts of both perforant pathway and Schaffer input on their dendrites and cell bodies. Four interneurons, which were completely embedded in LM, received only labeled perforant pathway input. Thus, we found convergence of both projection systems on single CA1 pyramidal and interneurons with dendrites that access the layers where perforant pathway fibers and Schaffer collaterals end.

  5. Adenosine actions on CA1 pyramidal neurones in rat hippocampal slices.

    Science.gov (United States)

    Greene, R W; Haas, H L

    1985-09-01

    Intracellular recordings with a bridge amplifier of CA1 pyramidal neurones in vitro were employed to study the mechanisms of action of exogenously applied adenosine in the hippocampal slice preparation of the rat. Adenosine enhanced the calcium-dependent, long-duration after-hyperpolarization (a.h.p.) at least in part by a reduction in the rate of decay of the a.h.p. Both the reduced rate of decay and that of the control can be described with a single exponential. Antagonism of the calcium-dependent potassium current (and as a result, the a.h.p.) by bath application of CdCl2 or intracellular injection of EGTA (ethyleneglycolbis-(beta-aminoethyl ether)N,N'-tetraacetic acid) did not reduce the adenosine-evoked hyperpolarization or decrease in input resistance. Similarly, TEA (tetraethylammonium), which antagonizes both the voltage- and calcium-sensitive, delayed, outward rectification, had no effect on the adenosine-evoked changes in resting membrane properties. Adenosine did not affect the early, transient, outward rectification. During exposure to 4-aminopyridine (4-AP) in concentrations sufficient to antagonize this early rectification, the changes in resting membrane properties evoked by adenosine were unaffected. We conclude that the enhancement of the a.h.p. and accommodation by adenosine may be mediated by a change in the regulation of intracellular calcium. However, the mechanism responsible for the hyperpolarization and decrease in input resistance evoked by adenosine is both calcium and voltage insensitive. Thus, it appears distinct from that mediating the enhancement of the a.h.p. and accommodation.

  6. The electrical activity of hippocampal pyramidal neuron is subjected to descending control by the brain orexin/hypocretin system.

    Science.gov (United States)

    Riahi, Esmail; Arezoomandan, Reza; Fatahi, Zahra; Haghparast, Abbas

    2015-03-01

    The hippocampus receives sparse orexinergic innervation from the lateral hypothalamus and expresses a high level of orexin receptor. The function of orexin receptor in the regulation of hippocampal neural activity has never been investigated. In this study, in vivo single unit recording was performed in urethane-anesthetized rats. After 15 min of baseline recording from pyramidal neuron within the CA1 region of the dorsal hippocampus, i.c.v. injection of orexin-A 0.5 nmol, SB334867 400 nmol, a selective orexin receptor 1 antagonist, saline, or DMSO, or microinjection of carbachol 250 nmol or saline into the ipsilateral lateral hypothalamus were performed using a Hamilton microsyringe, and the spontaneous firing activity continued to be recorded for 25 min. Results showed that orexin administration into the lateral cerebral ventricle excited 6 out of 8 neurons and inhibited 1 neuron. Chemical stimulation of the lateral hypothalamus by carbachol excited 9 out of 13 hippocampal neurons and inhibited 3 neurons. On the other hand, i.c.v. injection of the SB334867, caused reductions in the firing activity of 6 out of 10 neurons and increases in 4 additional neurons. It seems that orexin neurotransmission in the hippocampus mostly elicits an excitatory response, whereas blockade of orexin receptor has an inhibitory effect. Further studies need to be done to elucidate the underlying mechanism of orexin action on hippocampal neurons.

  7. Protective effects of berberine against amyloid beta-induced toxicity in cultured rat cortical neurons

    Institute of Scientific and Technical Information of China (English)

    Jing Wang; Yanjun Zhang; Shuai Du; Mixia Zhang

    2011-01-01

    Berberine, a major constituent of Coptidis rhizoma, exhibits neural protective effects. The present study analyzed the potential protective effect of berberine against amyloid G-induced cytotoxicity in rat cerebral cortical neurons. Alzheimer's disease cell models were treated with 0.5 and 2 μmol/Lberberine for 36 hours to inhibit amyloid G-induced toxicity. Methyl thiazolyl tetrazolium assay and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining results showed that berberine significantly increased cell viability and reduced cell apoptosis in primary cultured rat cortical neurons. In addition, western blot analysis revealed a protective effect of berberine against amyloid β-induced toxicity in cultured cortical neurons, which coincided with significantly decreased abnormal up-regulation of activated caspase-3. These results showed that berberine exhibited a protective effect against amyloid 13-induced cytotoxicity in cultured rat cortical neurons.

  8. Characterization of age-dependent and progressive cortical neuronal degeneration in presenilin conditional mutant mice.

    Directory of Open Access Journals (Sweden)

    Mary Wines-Samuelson

    Full Text Available Presenilins are the major causative genes of familial Alzheimer's disease (AD. Our previous study has demonstrated essential roles of presenilins in memory and neuronal survival. Here, we explore further how loss of presenilins results in age-related, progressive neurodegeneration in the adult cerebral cortex, where the pathogenesis of AD occurs. To circumvent the requirement of presenilins for embryonic development, we used presenilin conditional double knockout (Psen cDKO mice, in which presenilin inactivation is restricted temporally and spatially to excitatory neurons of the postnatal forebrain beginning at 4 weeks of age. Increases in the number of degenerating (Fluoro-Jade B+, 7.6-fold and apoptotic (TUNEL+, 7.4-fold neurons, which represent approximately 0.1% of all cortical neurons, were first detected at 2 months of age when there is still no significant loss of cortical neurons and volume in Psen cDKO mice. By 4 months of age, significant loss of cortical neurons (approximately 9% and gliosis was found in Psen cDKO mice. The apoptotic cell death is associated with caspase activation, as shown by increased numbers of cells immunoreactive for active caspases 9 and 3 in the Psen cDKO cortex. The vulnerability of cortical neurons to loss of presenilins is region-specific with cortical neurons in the lateral cortex most susceptible. Compared to the neocortex, the increase in apoptotic cell death and the extent of neurodegeneration are less dramatic in the Psen cDKO hippocampus, possibly in part due to increased neurogenesis in the aging dentate gyrus. Neurodegeneration is also accompanied with mitochondrial defects, as indicated by reduced mitochondrial density and altered mitochondrial size distribution in aging Psen cortical neurons. Together, our findings show that loss of presenilins in cortical neurons causes apoptotic cell death occurring in a very small percentage of neurons, which accumulates over time and leads to substantial loss

  9. The establishment of GABAergic and glutamatergic synapses on CA1 pyramidal neurons is sequential and correlates with the development of the apical dendrite.

    Science.gov (United States)

    Tyzio, R; Represa, A; Jorquera, I; Ben-Ari, Y; Gozlan, H; Aniksztejn, L

    1999-12-01

    We have performed a morphofunctional analysis of CA1 pyramidal neurons at birth to examine the sequence of formation of GABAergic and glutamatergic postsynaptic currents (PSCs) and to determine their relation to the dendritic arborization of pyramidal neurons. We report that at birth pyramidal neurons are heterogeneous. Three stages of development can be identified: (1) the majority of the neurons (80%) have small somata, an anlage of apical dendrite, and neither spontaneous nor evoked PSCs; (2) 10% of the neurons have a small apical dendrite restricted to the stratum radiatum and PSCs mediated only by GABA(A) receptors; and (3) 10% of the neurons have an apical dendrite that reaches the stratum lacunosum moleculare and PSCs mediated both by GABA(A) and glutamate receptors. These three groups of pyramidal neurons can be differentiated by their capacitance (C(m) = 17.9 +/- 0.8; 30.2 +/- 1.6; 43.2 +/- 3.0 pF, respectively). At birth, the synaptic markers synapsin-1 and synaptophysin labeling are present in dendritic layers but not in the stratum pyramidale, suggesting that GABAergic peridendritic synapses are established before perisomatic ones. The present observations demonstrate that GABAergic and glutamatergic synapses are established sequentially with GABAergic synapses being established first most likely on the apical dendrites of the principal neurons. We propose that different sets of conditions are required for the establishment of functional GABA and glutamate synapses, the latter necessitating more developed neurons that have apical dendrites that reach the lacunosum moleculare region.

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

    Science.gov (United States)

    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.

  11. Neuronal Dystroglycan Is Necessary for Formation and Maintenance of Functional CCK-Positive Basket Cell Terminals on Pyramidal Cells.

    Science.gov (United States)

    Früh, Simon; Romanos, Jennifer; Panzanelli, Patrizia; Bürgisser, Daniela; Tyagarajan, Shiva K; Campbell, Kevin P; Santello, Mirko; Fritschy, Jean-Marc

    2016-10-05

    Distinct types of GABAergic interneurons target different subcellular domains of pyramidal cells, thereby shaping pyramidal cell activity patterns. Whether the presynaptic heterogeneity of GABAergic innervation is mirrored by specific postsynaptic factors is largely unexplored. Here we show that dystroglycan, a protein responsible for the majority of congenital muscular dystrophies when dysfunctional, has a function at postsynaptic sites restricted to a subset of GABAergic interneurons. Conditional deletion of Dag1, encoding dystroglycan, in pyramidal cells caused loss of CCK-positive basket cell terminals in hippocampus and neocortex. PV-positive basket cell terminals were unaffected in mutant mice, demonstrating interneuron subtype-specific function of dystroglycan. Loss of dystroglycan in pyramidal cells had little influence on clustering of other GABAergic postsynaptic proteins and of glutamatergic synaptic proteins. CCK-positive terminals were not established at P21 in the absence of dystroglycan and were markedly reduced when dystroglycan was ablated in adult mice, suggesting a role for dystroglycan in both formation and maintenance of CCK-positive terminals. The necessity of neuronal dystroglycan for functional innervation by CCK-positive basket cell axon terminals was confirmed by reduced frequency of inhibitory events in pyramidal cells of dystroglycan-deficient mice and further corroborated by the inefficiency of carbachol to increase IPSC frequency in these cells. Finally, neurexin binding seems dispensable for dystroglycan function because knock-in mice expressing binding-deficient T190M dystroglycan displayed normal CCK-positive terminals. Together, we describe a novel function of dystroglycan in interneuron subtype-specific trans-synaptic signaling, revealing correlation of presynaptic and postsynaptic molecular diversity.

  12. Slow cortical rhythms: from single-neuron electrophysiology to whole-brain imaging in vivo

    NARCIS (Netherlands)

    Olcese, U.; Faraguna, U.

    2015-01-01

    The slow cortical oscillation is the major brain rhythm occurring during sleep, and has been the object of thorough investigation for over thirty years. Despite all these efforts, the function and the neuronal mechanisms behind slow cortical rhythms remain only partially understood. In this review

  13. Slow cortical rhythms: from single-neuron electrophysiology to whole-brain imaging in vivo

    NARCIS (Netherlands)

    U. Olcese; U. Faraguna

    2015-01-01

    The slow cortical oscillation is the major brain rhythm occurring during sleep, and has been the object of thorough investigation for over thirty years. Despite all these efforts, the function and the neuronal mechanisms behind slow cortical rhythms remain only partially understood. In this review w

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  16. The rostral migratory stream generates hippocampal CA1 pyramidal-like neurons in a novel organotypic slice co-culture model

    Directory of Open Access Journals (Sweden)

    Ilyas Singec

    2015-10-01

    Full Text Available The mouse subventricular zone (SVZ generates large numbers of neuroblasts, which migrate in a distinct pathway, the rostral migratory stream (RMS, and replace specific interneurons in the olfactory bulb (OB. Here, we introduce an organotypic slice culture model that directly connects the RMS to the hippocampus as a new destination. RMS neuroblasts widely populate the hippocampus and undergo cellular differentiation. We demonstrate that RMS cells give rise to various neuronal subtypes and, surprisingly, to CA1 pyramidal neurons. Pyramidal neurons are typically generated before birth and are lost in various neurological disorders. Hence, this unique slice culture model enables us to investigate their postnatal genesis under defined in vitro conditions from the RMS, an unanticipated source for hippocampal pyramidal neurons.

  17. Bilaminar co-culture of primary rat cortical neurons and glia.

    Science.gov (United States)

    Shimizu, Saori; Abt, Anna; Meucci, Olimpia

    2011-11-12

    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 interactions(1). 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 methods(1-3). Neurons can be easily separated from the glial layer at any time during culture and used for different experimental applications ranging from electrophysiology(4), cellular and molecular biology(5-8), biochemistry(5), imaging and microscopy(4,6,7,9,10). The primary neurons extend axons and dendrites to form functional synapses(11), a process which is not observed in neuronal cell lines, although some

  18. The protective role of ascorbic acid on hippocampal CA1 pyramidal neurons in a rat model of maternal lead exposure.

    Science.gov (United States)

    Sepehri, Hamid; Ganji, Farzaneh

    2016-07-01

    Oxidative stress is a major pathogenic mechanism of lead neurotoxicity. The antioxidant ascorbic acid protects hippocampal pyramidal neurons against cell death during congenital lead exposure; however, critical functions like synaptic transmission, integration, and plasticity depend on preservation of dendritic and somal morphology. This study was designed to examine if ascorbic acid also protects neuronal morphology during developmental lead exposure. Timed pregnant rats were divided into four treatment groups: (1) control, (2) 100mg/kg ascorbic acid once a day via gavage, (3) 0.05% lead acetate in drinking water, and (4) 0.05% lead+100mg/kg oral ascorbic acid. Brains of eight male pups (P25) per treatment group were processed for Golgi staining. Changes in hippocampal CA1 pyramidal neurons' somal size were estimated by cross-sectional area and changes in dendritic arborization by Sholl's analysis. One-way ANOVA was used to compare results among treatment groups. Lead-exposed pups exhibited a significant decrease in somal size compared to controls (Pascorbic acid. Sholl's analysis revealed a significant increase in apical dendritic branch points near cell body (PAscorbic acid significantly but only partially reversed the somal and dendritic damage caused by developmental lead exposure. Oxidative stress thus contributes to lead neurotoxicity but other pathogenic mechanisms are also involved.

  19. Prolonged enhancement and depression of synaptic transmission in CA1 pyramidal neurons induced by transient forebrain ischemia in vivo.

    Science.gov (United States)

    Gao, T M; Pulsinelli, W A; Xu, Z C

    1998-11-01

    Evoked postsynaptic potentials of CA1 pyramidal neurons in rat hippocampus were studied during 48 h after severe ischemic insult using in vivo intracellular recording and staining techniques. Postischemic CA1 neurons displayed one of three distinct response patterns following contralateral commissural stimulation. At early recirculation times (0-12 h) approximately 50% of neurons exhibited, in addition to the initial excitatory postsynaptic potential, a late depolarizing postsynaptic potential lasting for more than 100 ms. Application of dizocilpine maleate reduced the amplitude of late depolarizing postsynaptic potential by 60%. Other CA1 neurons recorded in this interval failed to develop late depolarizing postsynaptic potentials but showed a modest blunting of initial excitatory postsynaptic potentials (non-late depolarizing postsynaptic potential neuron). The proportion of recorded neurons with late depolarizing postsynaptic potential characteristics increased to more than 70% during 13-24 h after reperfusion. Beyond 24 h reperfusion, approximately 20% of CA neurons exhibited very small excitatory postsynaptic potentials even with maximal stimulus intensity. The slope of the initial excitatory postsynaptic potentials in late depolarizing postsynaptic potential neurons increased to approximately 150% of control values up to 12 h after reperfusion indicating a prolonged enhancement of synaptic transmission. In contrast, the slope of the initial excitatory postsynaptic potentials in non-late depolarizing postsynaptic potential neurons decreased to less than 50% of preischemic values up to 24 h after reperfusion indicating a prolonged depression of synaptic transmission. More late depolarizing postsynaptic potential neurons were located in the medial portion of CA1 zone where neurons are more vulnerable to ischemia whereas more non-late depolarizing postsynaptic potential neurons were located in the lateral portion of CA1 zone where neurons are more resistant to

  20. Kv2 channel regulation of action potential repolarization and firing patterns in superior cervical ganglion neurons and hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Liu, Pin W; Bean, Bruce P

    2014-04-02

    Kv2 family "delayed-rectifier" potassium channels are widely expressed in mammalian neurons. Kv2 channels activate relatively slowly and their contribution to action potential repolarization under physiological conditions has been unclear. We explored the function of Kv2 channels using a Kv2-selective blocker, Guangxitoxin-1E (GxTX-1E). Using acutely isolated neurons, mixed voltage-clamp and current-clamp experiments were done at 37°C to study the physiological kinetics of channel gating and action potentials. In both rat superior cervical ganglion (SCG) neurons and mouse hippocampal CA1 pyramidal neurons, 100 nm GxTX-1E produced near-saturating block of a component of current typically constituting ∼60-80% of the total delayed-rectifier current. GxTX-1E also reduced A-type potassium current (IA), but much more weakly. In SCG neurons, 100 nm GxTX-1E broadened spikes and voltage clamp experiments using action potential waveforms showed that Kv2 channels carry ∼55% of the total outward current during action potential repolarization despite activating relatively late in the spike. In CA1 neurons, 100 nm GxTX-1E broadened spikes evoked from -70 mV, but not -80 mV, likely reflecting a greater role of Kv2 when other potassium channels were partially inactivated at -70 mV. In both CA1 and SCG neurons, inhibition of Kv2 channels produced dramatic depolarization of interspike voltages during repetitive firing. In CA1 neurons and some SCG neurons, this was associated with increased initial firing frequency. In all neurons, inhibition of Kv2 channels depressed maintained firing because neurons entered depolarization block more readily. Therefore, Kv2 channels can either decrease or increase neuronal excitability depending on the time scale of excitation.

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

    Science.gov (United States)

    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 (pATF-2 group after 24hours (30%), have been significant lower (pATF-2 in embryonic cortical neurons following DNA damage.

  2. Latency dependent development of related firing patterns of cultured cortical neurons

    NARCIS (Netherlands)

    le Feber, Jakob; van Pelt, Jaap; Rutten, Wim

    Networks of cortical neurons were grown over multi electrode arrays to enable simultaneous measurement of signals from multiple neurons. We described functional connectivity in these networks by relationships be¬tween individual electrodes, based on conditional firing probabilities. In this study we

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  6. Activation of CRH receptor type 1 expressed on glutamatergic neurons increases excitability of CA1 pyramidal neurons by the modulation of voltage-gated ion channels

    Directory of Open Access Journals (Sweden)

    Stephan eKratzer

    2013-07-01

    Full Text Available Corticotropin-releasing hormone (CRH plays an important role in a substantial number of patients with stress-related mental disorders, such as anxiety disorders and depression. CRH has been shown to increase neuronal excitability in the hippocampus, but the underlying mechanisms are poorly understood. The effects of CRH on neuronal excitability were investigated in acute hippocampal brain slices. Population spikes (PS and field excitatory postsynaptic potentials (fEPSP were evoked by stimulating Schaffer-collaterals and recorded simultaneously from the somatic and dendritic region of CA1 pyramidal neurons. CRH was found to increase PS amplitudes (mean  Standard error of the mean; 231.8  31.2% of control; n=10 while neither affecting fEPSPs (104.3 ± 4.2%; n=10 nor long-term potentiation (LTP. However, when Schaffer-collaterals were excited via action potentials (APs generated by stimulation of CA3 pyramidal neurons, CRH increased fEPSP amplitudes (119.8 ± 3.6%; n=8 and the magnitude of LTP in the CA1 region. Experiments in slices from transgenic mice revealed that the effect on PS amplitude is mediated exclusively by CRH receptor 1 (CRHR1 expressed on glutamatergic neurons. The effects of CRH on PS were dependent on phosphatase-2B, L- and T-type calcium channels and voltage-gated potassium channels but independent on intracellular Ca2+-elevation. In patch-clamp experiments, CRH increased the frequency and decay times of APs and decreased currents through A-type and delayed-rectifier potassium channels. These results suggest that CRH does not affect synaptic transmission per se, but modulates voltage-gated ion currents important for the generation of APs and hence elevates by this route overall neuronal activity.

  7. Selective retrograde transport of D-aspartate in spinal interneurons and cortical neurons of rats

    Energy Technology Data Exchange (ETDEWEB)

    Rustioni, A.; Cuenod, M. (Zurich Univ. (Switzerland))

    1982-03-18

    Retrograde labeling of neuronal elements in the brain and spinal cord has been investigated by autoradiographic techniques following injections of D-(/sup 3/H)aspartate (asp), (/sup 3/H)..gamma..-aminobutyric acid (GABA) or horseradish peroxidase (HRP) in the medulla and spinal cord of rats. Twenty-four hours after D-(/sup 3/H)asp injections focused upon the cuneate nucleus, autoradiographic labeling is present over fibers in the pyramidal tract, internal capsule and over layer V pyramids in the forelimb representation of the sensorimotor cortex. After (/sup 3/H)GABA injections in the same nucleus no labeling attributable to retrograde translocation can be detected in spinal segments, brain stem or cortex. Conversely, injections of 30% HRP in the cuneate nucleus label neurons in several brain stem nuclei, in spinal gray and in layer V of the sensorimotor cortex. D-(/sup 3/H)Asp injections focused on the dorsal horn at cervical segments label a fraction of perikarya of the substantia gelatinosa and a sparser population of larger neurons in laminae IV to VI for a distance of 3-5 segments above and below the injection point. No brain stem neuronal perikarya appear labeled following spinal injections of D-(/sup 3/H)asp although autoradiographic grains overlie pyramidal tract fibers on the side contralateral to the injection.

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

    Science.gov (United States)

    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.

  9. Responses of CA1 pyramidal neurons in rat hippocampus to transient forebrain ischemia: an in vivo intracellular recording study.

    Science.gov (United States)

    Xu, Z C; Pulsinelli, W A

    1994-04-25

    The electrophysiological responses of CA1 pyramidal neurons to 5 min forebrain ischemia were studied with intracellular recording and staining techniques in vivo. The baseline membrane potential rapidly depolarized to approximately -20 mV about 3 min after the onset of ischemia and began to repolarize 1-3 min after recirculation. The amplitude of this ischemic depolarization (ID) was related directly to the severity of ischemia and its latency of onset was inversely related to brain temperature. Spontaneous synaptic activity ceased shortly after ischemia onset while the evoke synaptic potentials lasted until shortly before the onset of ID. Inhibitory postsynaptic potentials (IPSPs) disappeared earlier than excitatory postsynaptic potentials (EPSPs) and the membrane input resistance of CA1 neurons increased after the onset of ischemia.

  10. Age- and location-dependent differences in store depletion-induced h-channel plasticity in hippocampal pyramidal neurons.

    Science.gov (United States)

    Clemens, Ann M; Johnston, Daniel

    2014-03-01

    Disruptions of endoplasmic reticulum (ER) Ca(2+) homeostasis are heavily linked to neuronal pathology. Depletion of ER Ca(2+) stores can result in cellular dysfunction and potentially cell death, although adaptive processes exist to aid in survival. We examined the age and region dependence of one postulated, adaptive response to ER store-depletion (SD), hyperpolarization-activated cation-nonspecific (h)-channel plasticity in neurons of the dorsal and ventral hippocampus (DHC and VHC, respectively) from adolescent and adult rats. With the use of whole-cell patch-clamp recordings from the soma and dendrites of CA1 pyramidal neurons, we observed a change in h-sensitive measurements in response to SD, induced by treatment with cyclopiazonic acid, a sarcoplasmic reticulum/ER Ca(2+)-ATPase blocker. We found that whereas DHC and VHC neurons in adolescent animals respond to SD with a perisomatic expression of SD h plasticity, adult animals express SD h plasticity with a dendritic and somatodendritic locus of plasticity in DHC and VHC neurons, respectively. Furthermore, SD h plasticity in adults was dependent on membrane potential and on the activation of L-type voltage-gated Ca(2+) channels. These results suggest that cellular responses to the impairment of ER function, or ER stress, are dependent on brain region and age and that the differential expression of SD h plasticity could provide a neural basis for region- and age-dependent disease vulnerabilities.

  11. Occurrence of complement protein C3 in dying pyramidal neurons in rat hippocampus after systemic administration of kainic acid.

    Science.gov (United States)

    Morita, Hiroyuki; Suzuki, Katsuaki; Mori, Norio; Yasuhara, Osamu

    2006-11-27

    To evaluate the roles of complement in kainic acid (KA)-induced neuronal damages, the immunohistochemical localization of the complement protein C3 was examined in rat hippocampus after systemic KA injection. The immunoreactivity for C3 was found in glial cells in control rats, and such glial cells were increased in number after KA injection. Our confocal study showed that C3-positive glial cells were microglia. Three to seven days after KA, C3 immunoreactivity appeared in CA1 and CA3 pyramidal neurons. Double staining for C3 combined with the terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling showed that occurrence of C3 immunoreactivity in neurons coincided well with that of DNA fragmentation. Western blot analysis and RT-PCR experiments suggested local synthesis of C3 by brain cells. Our results suggest that C3 contributes greatly to neuronal death after systemic KA administration, and that microglia and neurons are the local source of C3 in KA-induced brain injury.

  12. Selective vulnerability of spinal and cortical motor neuron subpopulations in delta7 SMA mice.

    Science.gov (United States)

    d'Errico, Paolo; Boido, Marina; Piras, Antonio; Valsecchi, Valeria; De Amicis, Elena; Locatelli, Denise; Capra, Silvia; Vagni, Francesco; Vercelli, Alessandro; Battaglia, Giorgio

    2013-01-01

    Loss of the survival motor neuron gene (SMN1) is responsible for spinal muscular atrophy (SMA), the most common inherited cause of infant mortality. Even though the SMA phenotype is traditionally considered as related to spinal motor neuron loss, it remains debated whether the specific targeting of motor neurons could represent the best therapeutic option for the disease. We here investigated, using stereological quantification methods, the spinal cord and cerebral motor cortex of ∆7 SMA mice during development, to verify extent and selectivity of motor neuron loss. We found progressive post-natal loss of spinal motor neurons, already at pre-symptomatic stages, and a higher vulnerability of motor neurons innervating proximal and axial muscles. Larger motor neurons decreased in the course of disease, either for selective loss or specific developmental impairment. We also found a selective reduction of layer V pyramidal neurons associated with layer V gliosis in the cerebral motor cortex. Our data indicate that in the ∆7 SMA model SMN loss is critical for the spinal cord, particularly for specific motor neuron pools. Neuronal loss, however, is not selective for lower motor neurons. These data further suggest that SMA pathogenesis is likely more complex than previously anticipated. The better knowledge of SMA models might be instrumental in shaping better therapeutic options for affected patients.

  13. Downregulation of transient K+ channels in dendrites of hippocampal CA1 pyramidal neurons by activation of PKA and PKC.

    Science.gov (United States)

    Hoffman, D A; Johnston, D

    1998-05-15

    We have reported recently a high density of transient A-type K+ channels located in the distal dendrites of CA1 hippocampal pyramidal neurons and shown that these channels shape EPSPs, limit the back-propagation of action potentials, and prevent dendritic action potential initiation (). Because of the importance of these channels in dendritic signal propagation, their modulation by protein kinases would be of significant interest. We investigated the effects of activators of cAMP-dependent protein kinase (PKA) and the Ca2+-dependent phospholipid-sensitive protein kinase (PKC) on K+ channels in cell-attached patches from the distal dendrites of hippocampal CA1 pyramidal neurons. Inclusion of the membrane-permeant PKA activators 8-bromo-cAMP (8-br-cAMP) or forskolin in the dendritic patch pipette resulted in a depolarizing shift in the activation curve for the transient channels of approximately 15 mV. Activation of PKC by either of two phorbol esters also resulted in a 15 mV depolarizing shift of the activation curve. Neither PKA nor PKC activation affected the sustained or slowly inactivating component of the total outward current. This downregulation of transient K+ channels in the distal dendrites may be responsible for some of the frequently reported increases in cell excitability found after PKA and PKC activation. In support of this hypothesis, we found that activation of either PKA or PKC significantly increased the amplitude of back-propagating action potentials in distal dendrites.

  14. Hyperforin modulates dendritic spine morphology in hippocampal pyramidal neurons by activating Ca(2+) -permeable TRPC6 channels.

    Science.gov (United States)

    Leuner, Kristina; Li, Wei; Amaral, Michelle D; Rudolph, Stephanie; Calfa, Gaston; Schuwald, Anita M; Harteneck, Christian; Inoue, Takafumi; Pozzo-Miller, Lucas

    2013-01-01

    The standardized extract of the St. John's wort plant (Hypericum perforatum) is commonly used to treat mild to moderate depression. Its active constituent is hyperforin, a phloroglucinol derivative that reduces the reuptake of serotonin and norepinephrine by increasing intracellular Na(+) concentration through the activation of nonselective cationic TRPC6 channels. TRPC6 channels are also Ca(2+) -permeable, resulting in intracellular Ca(2+) elevations. Indeed, hyperforin activates TRPC6-mediated currents and Ca(2+) transients in rat PC12 cells, which induce their differentiation, mimicking the neurotrophic effect of nerve growth factor. Here, we show that hyperforin modulates dendritic spine morphology in CA1 and CA3 pyramidal neurons of hippocampal slice cultures through the activation of TRPC6 channels. Hyperforin also evoked intracellular Ca(2+) transients and depolarizing inward currents sensitive to the TRPC channel blocker La(3+) , thus resembling the actions of the neurotrophin brain-derived neurotrophic factor (BDNF) in hippocampal pyramidal neurons. These results suggest that the antidepressant actions of St. John's wort are mediated by a mechanism similar to that engaged by BDNF.

  15. β-Adrenergic receptor agonist increases voltage-gated Na(+) currents in medial prefrontal cortex pyramidal neurons.

    Science.gov (United States)

    Szulczyk, Bartlomiej

    2015-05-19

    The prefrontal cortex does not function properly in neuropsychiatric diseases and during chronic stress. The aim of this study was to test the effects of isoproterenol, a β-adrenergic receptor agonist, on the voltage-dependent fast-inactivating Na(+) currents in medial prefrontal cortex (mPFC) pyramidal neurons obtained from young rats. The recordings were performed in the cell-attached configuration. Isoproterenol (2μM) did not change the peak Na(+) current amplitude but shifted the IV curve of the Na(+) currents toward hyperpolarization. Pretreatment of the cells with the β-adrenergic antagonists propranolol and metoprolol abolished the effect of isoproterenol on the Na(+) currents, suggesting the involvement of β1-adrenergic receptors. The effect of β-adrenergic receptor stimulation on the sodium currents was dependent on kinase A and kinase C; the effect was diminished in the presence of the kinase A antagonist H-89 and the kinase C antagonist chelerythrine and abolished when the antagonists were coapplied. Moreover, isoproterenol depolarized the membrane potential recorded using the perforated-patch method, and this depolarization was abolished by cesium ions. Thus, in mPFC pyramidal neurons, stimulation of β-adrenergic receptors up-regulates the fast-inactivating voltage-gated Na(+) currents evoked by suprathreshold depolarizations.

  16. Spatio-temporal extension in site of origin for cortical calretinin neurons in primates

    Directory of Open Access Journals (Sweden)

    Ana eHladnik

    2014-06-01

    Full Text Available The vast majority of cortical GABAergic neurons can be defined by parvalbumin, somatostatin or calretinin expression. In most mammalians parvalbumin and somatostatin interneurons have constant proportions, each representing 5-7% of the total neuron number. In contrast, there is a 3 fold increase in the proportion of calretinin interneurons, which do not exceed 4% in rodents and reach 12% in higher order areas of primate cerebral cortex. In rodents almost all parvalbumin and somatostatin interneurons originate from the medial part of the subpallial proliferative structure, the ganglionic eminence (GE, while almost all calretinin interneurons originate from its caudal part. The spatial pattern of cortical GABAergic neurons origin from the GE is preserved in the monkey and human brain. However, it could be expected that the evolution is changing developmental rules to enable considerable expansion of calretinin interneuron population. During the early fetal period in primates cortical GABAergic neurons are almost entirely generated in the subpallium, as in rodents. Already at that time the primate caudal ganglionic eminence (CGE shows a relative increase in size and production of calretinin interneurons. During the second trimester of gestation, that is the main neurogenetic stage in primates without clear correlates found in rodents, the pallial production of cortical GABAergic neurons together with the extended persistence of the GE is observed. We propose that the CGE could be the main source of calretinin interneurons for the posterior and lateral cortical regions, but not for the frontal cortex. The associative granular frontal cortex represents around one third of the cortical surface and contains almost half of cortical calretinin interneurons. The majority of calretinin interneurons destined for the frontal cortex could be generated in the pallium, especially in the newly evolved outer subventricular zone that becomes the main pool of

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

    Science.gov (United States)

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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. Copyright © 2016. Published by Elsevier Ireland Ltd.

  20. Diminished perisomatic GABAergic terminals on cortical neurons adjacent to amyloid plaques

    Directory of Open Access Journals (Sweden)

    Virginia Garcia-Marin

    2009-11-01

    Full Text Available One of the main pathological hallmarks of Alzheimer’s disease (AD is the accumulation of plaques in the cerebral cortex, which may appear either in the neuropil or in direct association with neuronal somata. Since different axonal systems innervate the dendritic (mostly glutamatergic and perisomatic (mostly GABAergic regions of neurons, the accumulation of plaques in the neuropil or associated with the soma might produce different alterations to synaptic circuits. We have used a variety of conventional light, confocal and electron microscopy techniques to study their relationship with neuronal somata in the cerebral cortex from AD patients and APP/PS1 transgenic mice. The main finding was that the membrane surfaces of neurons (mainly pyramidal cells in contact with plaques lack GABAergic perisomatic synapses. Since these perisomatic synapses are thought to exert a strong influence on the output of pyramidal cells, their loss may lead to the hyperactivity of the neurons in contact with plaques. These results suggest that plaques modify circuits in a more selective manner than previously thought.

  1. Automated evolutionary optimization of ion channel conductances and kinetics in models of young and aged rhesus monkey pyramidal neurons.

    Science.gov (United States)

    Rumbell, Timothy H; Draguljić, Danel; Yadav, Aniruddha; Hof, Patrick R; Luebke, Jennifer I; Weaver, Christina M

    2016-08-01

    Conductance-based compartment modeling requires tuning of many parameters to fit the neuron model to target electrophysiological data. Automated parameter optimization via evolutionary algorithms (EAs) is a common approach to accomplish this task, using error functions to quantify differences between model and target. We present a three-stage EA optimization protocol for tuning ion channel conductances and kinetics in a generic neuron model with minimal manual intervention. We use the technique of Latin hypercube sampling in a new way, to choose weights for error functions automatically so that each function influences the parameter search to a similar degree. This protocol requires no specialized physiological data collection and is applicable to commonly-collected current clamp data and either single- or multi-objective optimization. We applied the protocol to two representative pyramidal neurons from layer 3 of the prefrontal cortex of rhesus monkeys, in which action potential firing rates are significantly higher in aged compared to young animals. Using an idealized dendritic topology and models with either 4 or 8 ion channels (10 or 23 free parameters respectively), we produced populations of parameter combinations fitting the target datasets in less than 80 hours of optimization each. Passive parameter differences between young and aged models were consistent with our prior results using simpler models and hand tuning. We analyzed parameter values among fits to a single neuron to facilitate refinement of the underlying model, and across fits to multiple neurons to show how our protocol will lead to predictions of parameter differences with aging in these neurons.

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

    Science.gov (United States)

    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.

  3. Guidance cue for cortical radial migration discovered

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ The regulatory mechanism for neuronal migration in the developing cortex is a major unsolved problem in developmental neurobiology. It is generally accepted that the migration of newborn pyramidal neurons from the ventricular zone toward upper cortical layers is guided by radial glial fibers in the developing cortex, and that the laminar structure of the cortex is formed through regulated attachment and detachment of migrating neurons with radial glial fibers.

  4. Disruption of Transient Serotonin Accumulation by Non-Serotonin-Producing Neurons Impairs Cortical Map Development

    Directory of Open Access Journals (Sweden)

    Xiaoning Chen

    2015-01-01

    Full Text Available Polymorphisms that alter serotonin transporter SERT expression and functionality increase the risks for autism and psychiatric traits. Here, we investigate how SERT controls serotonin signaling in developing CNS in mice. SERT is transiently expressed in specific sets of glutamatergic neurons and uptakes extrasynaptic serotonin during perinatal CNS development. We show that SERT expression in glutamatergic thalamocortical axons (TCAs dictates sensory map architecture. Knockout of SERT in TCAs causes lasting alterations in TCA patterning, spatial organizations of cortical neurons, and dendritic arborization in sensory cortex. Pharmacological reduction of serotonin synthesis during the first postnatal week rescues sensory maps in SERTGluΔ mice. Furthermore, knockdown of SERT expression in serotonin-producing neurons does not impair barrel maps. We propose that spatiotemporal SERT expression in non-serotonin-producing neurons represents a determinant in early life genetic programming of cortical circuits. Perturbing this SERT function could be involved in the origin of sensory and cognitive deficits associated with neurodevelopmental disorders.

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

    Science.gov (United States)

    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...

  6. Baicalein reverts L-valine-induced persistent sodium current up-modulation in primary cortical neurons.

    Science.gov (United States)

    Caioli, Silvia; Candelotti, Elena; Pedersen, Jens Z; Saba, Luana; Antonini, Alessia; Incerpi, Sandra; Zona, Cristina

    2016-04-01

    L-valine is a branched-chain amino acid (BCAA) largely used as dietary integrator by athletes and involved in some inherited rare diseases such as maple syrup urine disease. This pathology is caused by an altered BCAA metabolism with the accumulation of toxic keto acids in tissues and body fluids with consequent severe neurological symptoms. In animal models of BCAA accumulation, increased oxidative stress levels and lipid peroxidation have been reported. The aim of this study was to analyze both whether high BCAA concentrations in neurons induce reactive oxygen species (ROS) production and whether, by performing electrophysiological recordings, the neuronal functional properties are modified. Our results demonstrate that in primary cortical cultures, a high dose of valine increases ROS production and provokes neuronal hyperexcitability because the action potential frequencies and the persistent sodium current amplitudes increase significantly compared to non-treated neurons. Since Baicalein, a flavone obtained from the Scutellaria root, has been shown to act as a strong antioxidant with neuroprotective effects, we evaluated its possible antioxidant activity in primary cortical neurons chronically exposed to L-valine. The preincubation of cortical neurons with Baicalein prevents the ROS production and is able to revert both the neuronal hyperexcitability and the increase of the persistent sodium current, indicating a direct correlation between the ROS production and the altered physiological parameters. In conclusion, our data show that the electrophysiological alterations of cortical neurons elicited by high valine concentration are due to the increase in ROS production, suggesting much caution in the intake of BCAA dietary integrators.

  7. Cortical neurons immunoreactive for the potassium channel Kv3.1b subunit are predominantly surrounded by perineuronal nets presumed as a buffering system for cations.

    Science.gov (United States)

    Härtig, W; Derouiche, A; Welt, K; Brauer, K; Grosche, J; Mäder, M; Reichenbach, A; Brückner, G

    1999-09-18

    Perineuronal nets (PNs) are known as chondroitin sulphate-rich, lattice-like coatings of the extracellular matrix. In the cortex of mammalian species investigated so far, they were mainly found around GABAergic neurons, but to a lesser degree also around pyramidal cells. Previous investigations in the rat revealed similar distribution patterns of fast-firing neurons expressing both the Kv3.1b subunit of voltage-gated potassium channels and the calcium-binding protein parvalbumin. In the present study, triple fluorescence labelling was applied for the simultaneous demonstration of PNs with the N-acetylgalactosamine-specific Wisteria floribunda agglutinin (WFA), parvalbumin-immunoreactivity (ir) with a monoclonal antibody and of Kv3.1b-ir with several rabbit antibodies. Subsets of non-pyramidal neurons - enwrapped by PNs and expressing parvalbumin and Kv3.1b - were detected in the rat and monkey neocortex and hippocampus. In the rat, faintly stained PNs were additionally found around several layer II/III and V pyramidal cells immunonegative for Kv3.1b, but contacted by Kv3.1b-containing boutons. In the monkey, more intensely labelled PNs frequently occurred around pyramidal cells which themselves appeared to be Kv3. 1b-immunopositive. We also observed minor Kv3.1b-ir and parvalbumin-ir cortical cell populations which were devoid of PNs; occasionally, nets were detected around neurons lacking both immunoreactivities. By confocal laser scanning microscopy, Kv3.1b-ir and WFA-binding sites were found adjoining at the soma and proximal dendritic surface, while lectin-binding sites usually extended on more distal dendritic segments and the axon initial segments which failed to express detectable Kv3.1b-ir. This spatial relationship of both markers was also confirmed by combined WFA-gold labelling and Kv3.1b-immunoperoxidase staining at the electron microscopic level. The data are used for a critical examination of current hypotheses concerning the functional role of PNs

  8. Loss of Functional A-Type Potassium Channels in the Dendrites of CA1 Pyramidal Neurons from a Mouse Model of Fragile X Syndrome

    OpenAIRE

    Routh, Brandy N.; Johnston, Daniel; Brager, Darrin H.

    2013-01-01

    Despite the critical importance of voltage-gated ion channels in neurons, very little is known about their functional properties in Fragile X syndrome: the most common form of inherited cognitive impairment. Using three complementary approaches, we investigated the physiological role of A-type K+ currents (IKA) in hippocampal CA1 pyramidal neurons from fmr1-/y mice. Direct measurement of IKA using cell-attached patch-clamp recordings revealed that there was significantly less IKA in the dendr...

  9. Activity-Dependent Release of Endogenous BDNF From Mossy Fibers Evokes a TRPC3 Current and Ca2+ Elevations in CA3 Pyramidal Neurons

    OpenAIRE

    Yong LI; Calfa, Gaston; Inoue, Takafumi; Amaral, Michelle D.; Pozzo-Miller, Lucas

    2010-01-01

    Multiple studies have demonstrated that brain-derived neurotrophic factor (BDNF) is a potent modulator of neuronal structure and function in the hippocampus. However, the majority of studies to date have relied on the application of recombinant BDNF. We herein report that endogenous BDNF, released via theta burst stimulation of mossy fibers (MF), elicits a slowly developing cationic current and intracellular Ca2+ elevations in CA3 pyramidal neurons with the same pharmacological profile of the...

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

    Directory of Open Access Journals (Sweden)

    Gefei Wang

    2016-01-01

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

    Science.gov (United States)

    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

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

    Institute of Scientific and Technical Information of China (English)

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

    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 microg-lial conditioned medium, peak INMDA in neurons increased. These effects of lipopolysaccharide were suppressed by neuropeptide Y. After addition of the neuropeptide Y Y1 receptor antago-nist 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 excitotoxic-ity, thereby protecting neurons.

  13. Selective shunting of the NMDA EPSP component by the slow afterhyperpolarization in rat CA1 pyramidal neurons.

    Science.gov (United States)

    Fernández de Sevilla, David; Fuenzalida, Marco; Porto Pazos, Ana B; Buño, Washington

    2007-05-01

    Pyramidal neuron dendrites express voltage-gated conductances that control synaptic integration and plasticity, but the contribution of the Ca(2+)-activated K(+)-mediated currents to dendritic function is not well understood. Using dendritic and somatic recordings in rat hippocampal CA1 pyramidal neurons in vitro, we analyzed the changes induced by the slow Ca(2+)-activated K(+)-mediated afterhyperpolarization (sAHP) generated by bursts of action potentials on excitatory postsynaptic potentials (EPSPs) evoked at the apical dendrites by perforant path-Schaffer collateral stimulation. Both the amplitude and decay time constants of EPSPs (tau(EPSP)) were reduced by the sAHP in somatic recordings. In contrast, the dendritic EPSP amplitude remained unchanged, whereas tau(EPSP) was reduced. Temporal summation was reduced and spatial summation linearized by the sAHP. The amplitude of the isolated N-methyl-D-aspartate component of EPSPs (EPSP(NMDA)) was reduced, whereas tau(NMDA) was unaffected by the sAHP. In contrast, the sAHP did not modify the amplitude of the isolated EPSP(AMPA) but reduced tau(AMPA) both in dendritic and somatic recordings. These changes are attributable to a conductance increase that acted mainly via a selective "shunt" of EPSP(NMDA) because they were absent under voltage clamp, not present with imposed hyperpolarization simulating the sAHP, missing when the sAHP was inhibited with isoproterenol, and reduced under block of EPSP(NMDA). EPSPs generated at the basal dendrites were similarly modified by the sAHP, suggesting both a somatic and apical dendritic location of the sAHP channels. Therefore the sAHP may play a decisive role in the dendrites by regulating synaptic efficacy and temporal and spatial summation.

  14. Coupling (reduced Graphene Oxide to Mammalian Primary Cortical Neurons In Vitro

    Directory of Open Access Journals (Sweden)

    Antonina M. Monaco

    2015-08-01

    Full Text Available Neuronal nanoscale interfacing aims at identifying or designing nanostructured smart materials and validating their applications as novel biocompatible scaffolds with active properties for neuronal networks formation, nerve regeneration, and bidirectional biosignal coupling. Among several carbon-based nanomaterials, Graphene recently attracted great interest for biological applications, given its unique mechanical, optical, electronic properties, and its recent technological applications. Here we explore the use of Graphene Oxide (GO and reduced Graphene Oxide (rGO as biocompatible culture substrates for primary neuronal networks developing ex vivo. We quantitatively studied cytotoxicity and cellular viability as well as single-cell and network-level electrophysiological properties of neurons in vitro. Our results confirm previous reports, employing immortalized cell lines or pluripotent stem cells, and extend them to mammalian primary cortical neurons: GO and rGO are biocompatible substrates and do not alter neuronal excitable properties.

  15. Calcium-activated potassium conductances contribute to action potential repolarization at the soma but not the dendrites of hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Poolos, N P; Johnston, D

    1999-07-01

    Evidence is accumulating that voltage-gated channels are distributed nonuniformly throughout neurons and that this nonuniformity underlies regional differences in excitability within the single neuron. Previous reports have shown that Ca2+, Na+, A-type K+, and hyperpolarization-activated, mixed cation conductances have varying distributions in hippocampal CA1 pyramidal neurons, with significantly different densities in the apical dendrites compared with the soma. Another important channel mediates the large-conductance Ca2+-activated K+ current (IC), which is responsible in part for repolarization of the action potential (AP) and generation of the afterhyperpolarization that follows the AP recorded at the soma. We have investigated whether this current is activated by APs retrogradely propagating in the dendrites of hippocampal pyramidal neurons using whole-cell dendritic patch-clamp recording techniques. We found no IC activation by back-propagating APs in distal dendritic recordings. Dendritic APs activated IC only in the proximal dendrites, and this activation decayed within the first 100-150 micrometer of distance from the soma. The decay of IC in the proximal dendrites occurred despite AP amplitude, plus presumably AP-induced Ca2+ influx, that was comparable with that at the soma. Thus we conclude that IC activation by action potentials is nonuniform in the hippocampal pyramidal neuron, which may represent a further example of regional differences in neuronal excitability that are determined by the nonuniform distribution of voltage-gated channels in dendrites.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  18. Network bursts in cortical neuronal cultures: 'noise - versus pacemaker'- driven neural network simulations

    NARCIS (Netherlands)

    Gritsun, T.; Stegenga, J.; le Feber, Jakob; Rutten, Wim

    2009-01-01

    In this paper we address the issue of spontaneous bursting activity in cortical neuronal cultures and explain what might cause this collective behavior using computer simulations of two different neural network models. While the common approach to acivate a passive network is done by introducing

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

    Science.gov (United States)

    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…

  20. Long-term exposure of mice to nucleoside analogues disrupts mitochondrial DNA maintenance in cortical neurons.

    Directory of Open Access Journals (Sweden)

    Yulin Zhang

    Full Text Available Nucleoside analogue reverse transcriptase inhibitor (NRTI, an integral component of highly active antiretroviral therapy (HAART, was widely used to inhibit HIV replication. Long-term exposure to NRTIs can result in mitochondrial toxicity which manifests as lipoatrophy, lactic acidosis, cardiomyopathy and myopathy, as well as polyneuropathy. But the cerebral neurotoxicity of NRTIs is still not well known partly due to the restriction of blood-brain barrier (BBB and the complex microenvironment of the central nervous system (CNS. In this study, the Balb/c mice were administered 50 mg/kg stavudine (D4T, 100 mg/kg zidovudine (AZT, 50 mg/kg lamivudine (3TC or 50 mg/kg didanosine (DDI per day by intraperitoneal injection, five days per week for one or four months, and primary cortical neurons were cultured and exposed to 25 µM D4T, 50 µM AZT, 25 µM 3TC or 25 µM DDI for seven days. Then, single neuron was captured from mouse cerebral cortical tissues by laser capture microdissection. Mitochondrial DNA (mtDNA levels of the primary cultured cortical neurons, and captured neurons or glial cells, and the tissues of brains and livers and muscles were analyzed by relative quantitative real-time PCR. The data showed that mtDNA did not lose in both NRTIs exposed cultured neurons and one month NRTIs treated mouse brains. In four months NRTIs treated mice, brain mtDNA levels remained unchanged even if the mtDNA levels of liver (except for 3TC and muscle significantly decreased. However, mtDNA deletion was significantly higher in the captured neurons from mtDNA unchanged brains. These results suggest that long-term exposure to NRTIs can result in mtDNA deletion in mouse cortical neurons.

  1. Activation of pyramidal neurons in mouse medial prefrontal cortex enhances food seeking behavior while reducing impulsivity in the absence of an effect on food intake

    Directory of Open Access Journals (Sweden)

    Daniel McAllister Warthen

    2016-03-01

    Full Text Available The medial prefrontal cortex (mPFC is involved in a wide range of executive cognitive functions, including reward evaluation, decision-making, memory extinction, mood, and task switching. Manipulation of the mPFC has been shown to alter food intake and food reward valuation, but whether exclusive stimulation of mPFC pyramidal neurons, which form the principle output of the mPFC, is sufficient to mediate food rewarded instrumental behavior is unknown. We sought to determine the behavioral consequences of manipulating mPFC output by exciting pyramidal neurons in mouse mPFC during performance of a panel of behavioral assays, focusing on food reward. We found that increasing mPFC pyramidal cell output using Designer Receptors Exclusively Activated by Designer Drugs (DREADD enhanced performance in instrumental food reward assays that assess food seeking behavior, while sparing effects in affect and food intake. Specifically, activation of mPFC pyramidal neurons enhanced operant responding for food reward, reinstatement of palatable food seeking, and suppression of impulsive responding for food reward. Conversely, activation of mPFC pyramidal neurons had no effect on unconditioned food intake, social interaction, or behavior in an open field. Furthermore, we found that behavioral outcome is influenced by the degree of mPFC activation, with a low drive sufficient to enhance operant responding and a higher drive required to alter impulsivity. Additionally, we provide data demonstrating that DREADD stimulation involves a nitric oxide synthase dependent pathway, similar to endogenous muscarinic M3 receptor stimulation, a finding that provides novel mechanistic insight into an increasingly widespread method of remote neuronal control.

  2. Expression of 5-HT2A receptors in prefrontal cortex pyramidal neurons projecting to nucleus accumbens. Potential relevance for atypical antipsychotic action

    OpenAIRE

    Mocci, Giuseppe; Jiménez-Sánchez, Laura; Adell, Albert; Cortés, Roser; Artigas, Francesc

    2013-01-01

    The prefrontal cortex (PFC) is involved in higher brain functions altered in schizophrenia. Classical antipsychotic drugs modulate information processing in cortico-limbic circuits via dopamine D2 receptor blockade in nucleus accumbens (NAc) whereas atypical antipsychotic drugs preferentially target cortical serotonin (5-HT) receptors. The brain networks involved in the therapeutic action of atypical drugs are not fully understood. Previous work indicated that medial PFC (mPFC) pyramidal neur...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  5. Effects of the analgesic acetaminophen (Paracetamol) and its para-aminophenol metabolite on viability of mouse-cultured cortical neurons.

    Science.gov (United States)

    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.

  6. Necdin regulates p53 acetylation via Sirtuin1 to modulate DNA damage response in cortical neurons.

    Science.gov (United States)

    Hasegawa, Koichi; Yoshikawa, Kazuaki

    2008-08-27

    Sirtuin1 (Sirt1), a mammalian homolog of yeast Sir2, deacetylates the tumor suppressor protein p53 and attenuates p53-mediated cell death. Necdin, a p53-interacting protein expressed predominantly in postmitotic neurons, is a melanoma antigen family protein that promotes neuronal differentiation and survival. In mammals, the necdin gene (Ndn) is maternally imprinted, and mutant mice carrying mutated paternal Ndn show abnormalities of neuronal development. Here we report that necdin regulates the acetylation status of p53 via Sirt1 to suppress p53-dependent apoptosis in postmitotic neurons. Double-immunostaining analysis demonstrated that necdin colocalizes with Sirt1 in postmitotic neurons of mouse embryonic forebrain in vivo. Coimmunoprecipitation and in vitro binding analyses revealed that necdin interacts with both p53 and Sirt1 to potentiate Sirt1-mediated p53 deacetylation by facilitating their association. Primary cortical neurons prepared from paternal Ndn-deficient mice have high p53 acetylation levels and are sensitive to the DNA-damaging compounds camptothecin and hydrogen peroxide. Moreover, DNA transfection per se increases p53 acetylation and apoptosis in paternal Ndn-deficient neurons, whereas small interfering RNA-mediated p53 knockdown completely blocks these changes. However, Sirt1 knockdown increases both acetylated p53 level and apoptosis in wild-type neurons but fails to affect them in paternal Ndn-deficient neurons. In organotypic forebrain slice cultures treated with hydrogen peroxide, p53 is accumulated and colocalized with necdin and Sirt1 in cortical neurons. These results suggest that necdin downregulates p53 acetylation levels by forming a stable complex with p53 and Sirt1 to protect neurons from DNA damage-induced apoptosis.

  7. The role of extracellular conductivity profiles in compartmental models for neurons: particulars for layer 5 pyramidal cells.

    Science.gov (United States)

    Wang, Kai; Riera, Jorge; Enjieu-Kadji, Herve; Kawashima, Ryuta

    2013-07-01

    With the rapid increase in the number of technologies aimed at observing electric activity inside the brain, scientists have felt the urge to create proper links between intracellular- and extracellular-based experimental approaches. Biophysical models at both physical scales have been formalized under assumptions that impede the creation of such links. In this work, we address this issue by proposing a multicompartment model that allows the introduction of complex extracellular and intracellular resistivity profiles. This model accounts for the geometrical and electrotonic properties of any type of neuron through the combination of four devices: the integrator, the propagator, the 3D connector, and the collector. In particular, we applied this framework to model the tufted pyramidal cells of layer 5 (PCL5) in the neocortex. Our model was able to reproduce the decay and delay curves of backpropagating action potentials (APs) in this type of cell with better agreement with experimental data. We used the voltage drops of the extracellular resistances at each compartment to approximate the local field potentials generated by a PCL5 located in close proximity to linear microelectrode arrays. Based on the voltage drops produced by backpropagating APs, we were able to estimate the current multipolar moments generated by a PCL5. By adding external current sources in parallel to the extracellular resistances, we were able to create a sensitivity profile of PCL5 to electric current injections from nearby microelectrodes. In our model for PCL5, the kinetics and spatial profile of each ionic current were determined based on a literature survey, and the geometrical properties of these cells were evaluated experimentally. We concluded that the inclusion of the extracellular space in the compartmental models of neurons as an extra electrotonic medium is crucial for the accurate simulation of both the propagation of the electric potentials along the neuronal dendrites and the

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

    Science.gov (United States)

    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

  9. The Diversity of Cortical Inhibitory Synapses

    Directory of Open Access Journals (Sweden)

    Yoshiyuki eKubota

    2016-04-01

    Full Text Available The most typical and well known inhibitory action in the cortical microcircuit is a strong inhibition on the target neuron by axo-somatic synapses. However, it has become clear that synaptic inhibition in the cortex is much more diverse and complicated. Firstly, at least ten or more inhibitory non-pyramidal cell subtypes engage in diverse inhibitory functions to produce the elaborate activity characteristic of the different cortical states. Each distinct non-pyramidal cell subtype has its own independent inhibitory function. Secondly, the inhibitory synapses innervate different neuronal domains, such as axons, spines, dendrites and soma, and their IPSP size is not uniform. Thus cortical inhibition is highly complex, with a wide variety of anatomical and physiological modes. Moreover, the functional significance of the various inhibitory synapse innervation styles and their unique structural dynamic behaviors differ from those of excitatory synapses. In this review, we summarize our current understanding of the inhibitory mechanisms of the cortical microcircuit.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Tilo Schwalger

    2017-04-01

    Full Text Available 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.

  12. Development of Cortical GABAergic Neurons: Interplay of progenitor diversity and environmental factors on fate specification

    Directory of Open Access Journals (Sweden)

    Juliana Alves Brandão

    2015-04-01

    Full Text Available Cortical GABAergic interneurons constitute an extremely diverse population of cells organized in a well-defined topology of precisely interconnected cells. They play a crucial role regulating inhibitory-excitatory balance in brain circuits, gating sensory perception and regulating spike timing to brain oscillations during distinct behaviors. Dysfunctions in the establishment of proper inhibitory circuits have been associated to several brain disorders such as autism, epilepsy and schizophrenia. In the rodent adult cortex, inhibitory neurons are generated during the second gestational week from distinct progenitor lineages located in restricted domains of the ventral telencephalon. However, only recently, studies have revealed some of the mechanisms generating the heterogeneity of neuronal subtypes and their modes of integration in brain networks. Here we will discuss some the events involved in the production of cortical GABAergic neuron diversity with focus on the interaction between intrinsically driven genetic programs and environmental signals during development.

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

    Science.gov (United States)

    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.

  14. Neuregulin 3 Mediates Cortical Plate Invasion and Laminar Allocation of GABAergic Interneurons

    Directory of Open Access Journals (Sweden)

    Giorgia Bartolini

    2017-01-01

    Full Text Available Neural circuits in the cerebral cortex consist of excitatory pyramidal cells and inhibitory interneurons. These two main classes of cortical neurons follow largely different genetic programs, yet they assemble into highly specialized circuits during development following a very precise choreography. Previous studies have shown that signals produced by pyramidal cells influence the migration of cortical interneurons, but the molecular nature of these factors has remained elusive. Here, we identified Neuregulin 3 (Nrg3 as a chemoattractive factor expressed by developing pyramidal cells that guides the allocation of cortical interneurons in the developing cortical plate. Gain- and loss-of-function approaches reveal that Nrg3 modulates the migration of interneurons into the cortical plate in a process that is dependent on the tyrosine kinase receptor ErbB4. Perturbation of Nrg3 signaling in conditional mutants leads to abnormal lamination of cortical interneurons. Nrg3 is therefore a critical mediator in the assembly of cortical inhibitory circuits.

  15. Loss of functional A-type potassium channels in the dendrites of CA1 pyramidal neurons from a mouse model of fragile X syndrome.

    Science.gov (United States)

    Routh, Brandy N; Johnston, Daniel; Brager, Darrin H

    2013-12-11

    Despite the critical importance of voltage-gated ion channels in neurons, very little is known about their functional properties in Fragile X syndrome: the most common form of inherited cognitive impairment. Using three complementary approaches, we investigated the physiological role of A-type K(+) currents (I(KA)) in hippocampal CA1 pyramidal neurons from fmr1-/y mice. Direct measurement of I(KA) using cell-attached patch-clamp recordings revealed that there was significantly less I(KA) in the dendrites of CA1 neurons from fmr1-/y mice. Interestingly, the midpoint of activation for A-type K(+) channels was hyperpolarized for fmr1-/y neurons compared with wild-type, which might partially compensate for the lower current density. Because of the rapid time course for recovery from steady-state inactivation, the dendritic A-type K(+) current in CA1 neurons from both wild-type and fmr1-/y mice is likely mediated by K(V)4 containing channels. The net effect of the differences in I(KA) was that back-propagating action potentials had larger amplitudes producing greater calcium influx in the distal dendrites of fmr1-/y neurons. Furthermore, CA1 pyramidal neurons from fmr1-/y mice had a lower threshold for LTP induction. These data suggest that loss of I(KA) in hippocampal neurons may contribute to dendritic pathophysiology in Fragile X syndrome.

  16. Selective pharmacological modulation of pyramidal neurons and interneurons in the CA1 region of the rat hippocampus

    Directory of Open Access Journals (Sweden)

    Marzia eMartina

    2013-03-01

    Full Text Available The hippocampus is a complex network tightly regulated by interactions between excitatory and inhibitory neurons. In neurodegenerative disorders where cognitive functions such as learning and memory are impaired this excitation-inhibition balance may be altered. Interestingly, the uncompetitive NMDAR antagonist memantine, currently in clinical use for the treatment of Alzheimer’s disease (AD, may alter the excitation-inhibition balance in the hippocampus. However, the specific mechanism by which memantine exerts this action is not clear. To better elucidate the effect of memantine on hippocampal circuitry, we studied its pharmacology on NMDAR currents in both pyramidal cells (PCs and interneurons (Ints in the CA1 region of the hippocampus. Applying whole-cell patch-clamp methodology to acute rat hippocampal slices, we report that memantine antagonism is more robust in PCs than in Ints. Using specific NMDAR subunit antagonists, we determined that this selective antagonism of memantine is attributable to specific differences in the molecular make up of the NMDARs in excitatory and inhibitory neurons. These findings offer new insight into the mechanism of action and therapeutic potential of NMDA receptor pharmacology in modulating hippocampal excitability.

  17. Axonal action-potential initiation and Na+ channel densities in the soma and axon initial segment of subicular pyramidal neurons.

    Science.gov (United States)

    Colbert, C M; Johnston, D

    1996-11-01

    A long-standing hypothesis is that action potentials initiate first in the axon hillock/initial segment (AH-IS) region because of a locally high density of Na+ channels. We tested this idea in subicular pyramidal neurons by using patch-clamp recordings in hippocampal slices. Simultaneous recordings from the soma and IS confirmed that orthodromic action potentials initiated in the axon and then invaded the soma. However, blocking Na+ channels in the AH-IS with locally applied tetrodotoxin (TTX) did not raise the somatic threshold membrane potential for orthodromic spikes. TTX applied to the axon beyond the AH-IS (30-60 microm from the soma) raised the apparent somatic threshold by approximately 8 mV. We estimated the Na+ current density in the AH-IS and somatic membranes by using cell-attached patch-clamp recordings and found similar magnitudes (3-4 pA/microm2). Thus, the present results suggest that orthodromic action potentials initiate in the axon beyond the AH-IS and that the minimum threshold for spike initiation of the neuron is not determined by a high density of Na+ channels in the AH-IS region.

  18. Biphasic somatic A-type K channel downregulation mediates intrinsic plasticity in hippocampal CA1 pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Sung-Cherl Jung

    Full Text Available Since its original description, the induction of synaptic long-term potentiation (LTP has been known to be accompanied by a lasting increase in the intrinsic excitability (intrinsic plasticity of hippocampal neurons. Recent evidence shows that dendritic excitability can be enhanced by an activity-dependent decrease in the activity of A-type K(+ channels. In the present manuscript, we examined the role of A-type K(+ channels in regulating intrinsic excitability of CA1 pyramidal neurons of the hippocampus after synapse-specific LTP induction. In electrophysiological recordings we found that LTP induced a potentiation of excitability which was accompanied by a two-phased change in A-type K(+ channel activity recorded in nucleated patches from organotypic slices of rat hippocampus. Induction of LTP resulted in an immediate but short lasting hyperpolarization of the voltage-dependence of steady-state A-type K(+ channel inactivation along with a progressive, long-lasting decrease in peak A-current density. Blocking clathrin-mediated endocytosis prevented the A-current decrease and most measures of intrinsic plasticity. These results suggest that two temporally distinct but overlapping mechanisms of A-channel downregulation together contribute to the plasticity of intrinsic excitability. Finally we show that intrinsic plasticity resulted in a global enhancement of EPSP-spike coupling.

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

    Science.gov (United States)

    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.

  20. Cortical hypoexcitation defines neuronal responses in the immediate aftermath of traumatic brain injury.

    Directory of Open Access Journals (Sweden)

    Victoria Philippa Anne Johnstone

    Full Text Available 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.

  1. Activity-dependent structural plasticity after aversive experiences in amygdala and auditory cortex pyramidal neurons.

    Science.gov (United States)

    Gruene, Tina; Flick, Katelyn; Rendall, Sam; Cho, Jin Hyung; Gray, Jesse; Shansky, Rebecca

    2016-07-22

    The brain is highly plastic and undergoes changes in response to many experiences. Learning especially can induce structural remodeling of dendritic spines, which is thought to relate to memory formation. Classical Pavlovian fear conditioning (FC) traditionally pairs an auditory cue with an aversive footshock, and has been widely used to study neural processes underlying associative learning and memory. Past research has found dendritic spine changes after FC in several structures. But, due to heterogeneity of cells within brain structures and limitations of traditional neuroanatomical techniques, it is unclear if all cells included in analyses were actually active during learning processes, even if known circuits are isolated. In this study, we employed a novel approach to analyze structural plasticity explicitly in neurons activated by exposure to either cued or uncued footshocks. We used male and female Arc-dVenus transgenic mice, which express the Venus fluorophore driven by the activity-related Arc promoter, to identify neurons that were active during either scenario. We then targeted fluorescent microinjections to Arc+ and neighboring Arc- neurons in the basolateral area of the amygdala (BLA) and auditory association cortex (TeA). In both BLA and TeA, Arc+ neurons had reduced thin and mushroom spine densities compared to Arc- neurons. This effect was present in males and females alike and also in both cued and uncued shock groups. Overall, this study adds to our understanding of how neuronal activity affects structural plasticity, and represents a methodological advance in the ways we can directly relate structural changes to experience-related neural activity.

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

    Science.gov (United States)

    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 PLC-γ1 (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.

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

    Science.gov (United States)

    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.

  4. Homeostatic maintenance in excitability of tree shrew hippocampal CA3 pyramidal neurons after chronic stress

    NARCIS (Netherlands)

    Kole, MHP; Czeh, B; Fuchs, E

    2004-01-01

    The experience of chronic stress induces a reversible regression of hippocampal CA3 apical neuron dendrites. Although such postsynaptic membrane reduction will obviously diminish the possibility of synaptic input, the consequences for the functional membrane properties of these cells are not well un

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

    Directory of Open Access Journals (Sweden)

    Jia-jia Wu

    2016-01-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  7. Various tolerances to arsenic trioxide between human cortical neurons and leukemic cells

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jin; MENG Ran; SUI Xinhua; LI Wenbin; YANG Baofeng

    2006-01-01

    Arsenic trioxide (As2O3) is very effective for treatment of acute promyelocytic leukaemia (APL) but little can pass through the blood-brain-barrier (BBB),which limits its use in the prevention and treatment of central nervous system leukaemia (CNSL). Before creating a non-invasive method to help As2O3 's access, the safe and effective therapeutic concentration of As2O3 in the CNS ought to be known. The changes of apoptosis biomarkers, [Ca2+]i and PKC activity of both leukaemia cells and human cortical neurons, were monitored before and after being treated with As2O3 in vitro with laser confocal microscopy and Western blot. NSE concentration, the neuron invasive biomarker, was monitored by enzyme immunoassay (NSE-EIA). This study revealed that cortical neuron was more tolerable to As2O3 compared to NB4. 1.0 μmol / L As2O3 showed little influence on cortical neuron but effectively promoted apoptosis and induced differentiation of NB4.

  8. In vivo whole-cell patch-clamp recording of sensory synaptic responses of cingulate pyramidal neurons to noxious mechanical stimuli in adult mice

    Directory of Open Access Journals (Sweden)

    Descalzi Giannina

    2010-09-01

    Full Text Available Abstract The anterior cingulate cortex (ACC plays important roles in emotion, learning, memory and persistent pain. Our previous in vitro studies have demonstrated that pyramidal neurons in layer II/III of the adult mouse ACC can be characterized into three types: regular spiking (RS, intermediate (IM and intrinsic bursting (IB cells, according to their action potential (AP firing patterns. However, no in vivo information is available for the intrinsic properties and sensory responses of ACC neurons of adult mice. Here, we performed in vivo whole-cell patch-clamp recordings from pyramidal neurons in adult mice ACC under urethane anesthetized conditions. First, we classified the intrinsic properties and analyzed their slow oscillations. The population ratios of RS, IM and IB cells were 10, 62 and 28%, respectively. The mean spontaneous APs frequency of IB cells was significantly greater than those of RS and IM cells, while the slow oscillations were similar among ACC neurons. Peripheral noxious pinch stimuli induced evoked spike responses in all three types of ACC neurons. Interestingly, IB cells showed significantly greater firing frequencies than RS and IM cells. In contrast, non-noxious brush did not induce any significant response. Our studies provide the first in vivo characterization of ACC neurons in adult mice, and demonstrate that ACC neurons are indeed nociceptive. These findings support the critical roles of ACC in nociception, from mice to humans.

  9. Dopamine Inhibits High-Frequency Stimulation-Induced Long-Term Potentiation of Intrinsic Excitability in CA1 Hippocampal Pyramidal Neurons

    Directory of Open Access Journals (Sweden)

    Chun-ling Wei

    2012-09-01

    Full Text Available The efficiency of neural circuits is modified by changes not only in synaptic strength, but also in intrinsic excitability of neurons. In CA1 hippocampal pyramidal neurons, bidirectional changes in the intrinsic excitability are often presented after induction of synaptic long-term potentiation or depression. This plasticity of intrinsic excitability has been identified as a cellular correlate of learning. Besides, behavioral learning often involves action of reinforcement or rewarding mediated by dopamine (DA. Here, we examined how DA influences the intrinsic plasticity of CA1 hippocampal pyramidal neurons when high-frequency stimulation (HFS was applied to Schaffer collaterals. The results showed that DA inhibits the decrease in rheobase and increase in mean firing rate of pyramidal neurons induced by HFS, and that this inhibition was abolished by the D1-like receptor antagonist SCH23390 but not by the D2-like receptor antagonist sulpiride. The results suggest that DA inhibits the potentiation of excitability induced by presynaptic HFS, and that this inhibition depends on the activation of D1-like receptors.

  10. Effect of low frequency repetitive transcranial magnetic stimulation on kindling-induced changes in electrophysiological properties of rat CA1 pyramidal neurons.

    Science.gov (United States)

    Moradi Chameh, Homeira; Janahmadi, Mahyar; Semnanian, Saeed; Shojaei, Amir; Mirnajafi-Zadeh, Javad

    2015-05-01

    In this study, the effect of repetitive transcranial magnetic stimulation (rTMS) on the kindling induced changes in electrophysiological firing properties of hippocampal CA1 pyramidal neurons was investigated. Male Wistar rats were kindled by daily electrical stimulation of the basolateral amygdala in a semi-rapid manner (12 stimulations/day) until they achieved stage-5 seizure. One group (kindled+rTMS (KrTMS)) of animals received rTMS (240 pulses at 1 Hz) at 5 min after termination of daily kindling stimulations. Twenty-four hours following the last kindling stimulation electrophysiological properties of hippocampal CA1 pyramidal neurons were investigated using a whole-cell patch clamp technique, under current clamp condition. Amygdala kindling significantly decreased the adaptation index, post-afterhyperpolarization, rheobase current, utilization time, and delay to the first rebound spike. It also caused an increase in the voltage sag, number of rebound spikes and number of evoked action potential. Results of the present study revealed that application of rTMS following kindling stimulations had antiepileptogenic effects. In addition, application of rTMS prevented hyperexcitability of CA1 pyramidal neurons induced by kindling and conserved the normal neuronal firing.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  17. [The effect of enzymatic treatment using proteases on properties of persistent sodium current in CA1 pyramidal neurons of rat hippocampus].

    Science.gov (United States)

    Lun'ko, O O; Isaiev, D S; Maxymiuk, O P; Kryshtal', O O; Isaieva, O V

    2014-01-01

    We investigated the effect of proteases, widely used for neuron isolation in electrophysiological studies, on the amplitude and kinetic characteristics of persistent sodium current (I(NaP)) in hippocampal CA1 pyramidal neurons. Properties of I(NaP) were studied on neurons isolated by mechanical treatment (control group) and by mechanical and enzymatic treatment using pronase E (from Streptomyces griseus) or protease type XXIII (from Aspergillus oryzae). We show that in neurons isolated with pronase E kinetic of activation and density of I(NaP) was unaltered. Enzymatic treatment with protease type XXIII did not alter I(NaP) activation but result in significant decrease in I(NaP) density. Our data indicates that enzymatic treatment using pronase E for neuron isolation is preferable for investigation of I(NaP).

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

    Science.gov (United States)

    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.

  19. Crambescidin 816 induces calcium influx though glutamate receptors in primary cultures of cortical neurons

    Directory of Open Access Journals (Sweden)

    Víctor Martín Vázquez

    2014-06-01

    In summary, our data suggest that the cytotoxic effect of 10 μM Cramb816 in cortical neurons may be related to an increase in the cytosolic calcium concentration elicited by the toxin, which is shown to be mediated by glutamate receptor activation. Further studies analyzing the effect of glutamate receptor blockers on the cytotoxic effect of Cramb816 are needed to confirm this hypothesis.

  20. Sodium entry during action potentials of mammalian central neurons: incomplete inactivation and reduced metabolic efficiency in fast-spiking neurons

    OpenAIRE

    Carter, Brett C.; Bean, Bruce P.

    2009-01-01

    We measured the time course of sodium entry during action potentials of mouse central neurons at 37 °C to examine how efficiently sodium entry is coupled to depolarization. In cortical pyramidal neurons, sodium entry was nearly completely confined to the rising phase of the spike: only ~25% more sodium enters than the theoretical minimum necessary for spike depolarization. However, in fast-spiking GABAergic neurons (cerebellar Purkinje cells and cortical interneurons), twice as much sodium en...

  1. Translational profiling of stress-induced neuroplasticity in the CA3 pyramidal neurons of BDNF Val66Met mice.

    Science.gov (United States)

    Gray, J D; Rubin, T G; Kogan, J F; Marrocco, J; Weidmann, J; Lindkvist, S; Lee, F S; Schmidt, E F; McEwen, B S

    2016-12-13

    Genetic susceptibility and environmental factors (such as stress) can interact to affect the likelihood of developing a mood disorder. Stress-induced changes in the hippocampus have been implicated in mood disorders, and mutations in several genes have now been associated with increased risk, such as brain-derived neurotrophic factor (BDNF). The hippocampus has important anatomical subdivisions, and pyramidal neurons of the vulnerable CA3 region show significant remodeling after chronic stress, but the mechanisms underlying their unique plasticity remain unknown. This study characterizes stress-induced changes in the in vivo translating mRNA of this cell population using a CA3-specific enhanced green fluorescent protein (EGFP) reporter fused to the L10a large ribosomal subunit (EGFPL10a). RNA-sequencing after isolation of polysome-bound mRNAs allows for cell-type-specific, genome-wide characterization of translational changes after stress. The data demonstrate that acute and chronic stress produce unique translational profiles and that the stress history of the animal can alter future reactivity of CA3 neurons. CA3-specific EGFPL10a mice were then crossed to the stress-susceptible BDNF Val66Met mouse line to characterize how a known genetic susceptibility alters both baseline translational profiles and the reactivity of CA3 neurons to stress. Not only do Met allele carriers exhibit distinct levels of baseline translation in genes implicated in ion channel function and cytoskeletal regulation, but they also activate a stress response profile that is highly dissimilar from wild-type mice. Closer examination of genes implicated in the mechanisms of neuroplasticity, such as the NMDA and AMPA subunits and the BDNF pathway, reveal how wild-type mice upregulate many of these genes in response to stress, but Met allele carriers fail to do so. These profiles provide a roadmap of stress-induced changes in a genetically homogenous population of hippocampal neurons and

  2. MeCP2 mutation results in compartment-specific reductions in dendritic branching and spine density in layer 5 motor cortical neurons of YFP-H mice.

    Directory of Open Access Journals (Sweden)

    David P Stuss

    Full Text Available Rett Syndrome (RTT is a neurodevelopmental disorder predominantly caused by mutations in the X-linked gene MECP2. A primary feature of the syndrome is the impaired maturation and maintenance of excitatory synapses in the central nervous system (CNS. Different RTT mouse models have shown that particular Mecp2 mutations have highly variable effects on neuronal architecture. Distinguishing MeCP2 mutant cellular phenotypes therefore demands analysis of specific mutations in well-defined neuronal subpopulations. We examined a transgenically labeled subset of cortical neurons in YFP-H mice crossed with the Mecp2(tm1.1Jae mutant line. YFP(+ Layer 5 pyramidal neurons in the motor cortex of wildtype and hemizygous mutant male mice were examined for differences in dendrite morphology and spine density. Total basal dendritic length was decreased by 18.6% due to both shorter dendrites and reduced branching proximal to the soma. Tangential dendrite lengths in the apical tuft were reduced by up to 26.6%. Spine density was reduced by 47.4% in the apical tuft and 54.5% in secondary apical dendrites, but remained unaffected in primary apical and proximal basal dendrites. We also found that MeCP2 mutation reduced the number of YFP(+ cells in YFP-H mice by up to 72% in various cortical regions without affecting the intensity of YFP expression in individual cells. Our results support the view that the effects of MeCP2 mutation are highly context-dependent and cannot be generalized across mutation types and cell populations.

  3. Muscarinic Long-Term Enhancement of Tonic and Phasic GABAA Inhibition in Rat CA1 Pyramidal Neurons

    Science.gov (United States)

    Domínguez, Soledad; Fernández de Sevilla, David; Buño, Washington

    2016-01-01

    Acetylcholine (ACh) regulates network operation in the hippocampus by controlling excitation and inhibition in rat CA1 pyramidal neurons (PCs), the latter through gamma-aminobutyric acid type-A receptors (GABAARs). Although, the enhancing effects of ACh on GABAARs have been reported (Dominguez et al., 2014, 2015), its role in regulating tonic GABAA inhibition has not been explored in depth. Therefore, we aimed at determining the effects of the activation of ACh receptors on responses mediated by synaptic and extrasynaptic GABAARs. Here, we show that under blockade of ionotropic glutamate receptors ACh, acting through muscarinic type 1 receptors, paired with post-synaptic depolarization induced a long-term enhancement of tonic GABAA currents (tGABAA) and puff-evoked GABAA currents (pGABAA). ACh combined with depolarization also potentiated IPSCs (i.e., phasic inhibition) in the same PCs, without signs of interactions of synaptic responses with pGABAA and tGABAA, suggesting the contribution of two different GABAA receptor pools. The long-term enhancement of GABAA currents and IPSCs reduced the excitability of PCs, possibly regulating plasticity and learning in behaving animals. PMID:27833531

  4. Bidirectional Hebbian Plasticity Induced by Low-Frequency Stimulation in Basal Dendrites of Rat Barrel Cortex Layer 5 Pyramidal Neurons

    Science.gov (United States)

    Díez-García, Andrea; Barros-Zulaica, Natali; Núñez, Ángel; Buño, Washington; Fernández de Sevilla, David

    2017-01-01

    According to Hebb's original hypothesis (Hebb, 1949), synapses are reinforced when presynaptic activity triggers postsynaptic firing, resulting in long-term potentiation (LTP) of synaptic efficacy. Long-term depression (LTD) is a use-dependent decrease in synaptic strength that is thought to be due to synaptic input causing a weak postsynaptic effect. Although the mechanisms that mediate long-term synaptic plasticity have been investigated for at least three decades not all question have as yet been answered. Therefore, we aimed at determining the mechanisms that generate LTP or LTD with the simplest possible protocol. Low-frequency stimulation of basal dendrite inputs in Layer 5 pyramidal neurons of the rat barrel cortex induces LTP. This stimulation triggered an EPSP, an action potential (AP) burst, and a Ca2+ spike. The same stimulation induced LTD following manipulations that reduced the Ca2+ spike and Ca2+ signal or the AP burst. Low-frequency whisker deflections induced similar bidirectional plasticity of action potential evoked responses in anesthetized rats. These results suggest that both in vitro and in vivo similar mechanisms regulate the balance between LTP and LTD. This simple induction form of bidirectional hebbian plasticity could be present in the natural conditions to regulate the detection, flow, and storage of sensorimotor information. PMID:28203145

  5. Ablation of SNX6 leads to defects in synaptic function of CA1 pyramidal neurons and spatial memory

    Science.gov (United States)

    Niu, Yang; Dai, Zhonghua; Liu, Wenxue; Zhang, Cheng; Yang, Yanrui; Guo, Zhenzhen; Li, Xiaoyu; Xu, Chenchang; Huang, Xiahe; Wang, Yingchun; Shi, Yun S; Liu, Jia-Jia

    2017-01-01

    SNX6 is a ubiquitously expressed PX-BAR protein that plays important roles in retromer-mediated retrograde vesicular transport from endosomes. Here we report that CNS-specific Snx6 knockout mice exhibit deficits in spatial learning and memory, accompanied with loss of spines from distal dendrites of hippocampal CA1 pyramidal cells. SNX6 interacts with Homer1b/c, a postsynaptic scaffold protein crucial for the synaptic distribution of other postsynaptic density (PSD) proteins and structural integrity of dendritic spines. We show that SNX6 functions independently of retromer to regulate distribution of Homer1b/c in the dendritic shaft. We also find that Homer1b/c translocates from shaft to spines by protein diffusion, which does not require SNX6. Ablation of SNX6 causes reduced distribution of Homer1b/c in distal dendrites, decrease in surface levels of AMPAR and impaired AMPAR-mediated synaptic transmission. These findings reveal a physiological role of SNX6 in CNS excitatory neurons. DOI: http://dx.doi.org/10.7554/eLife.20991.001 PMID:28134614

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

    Directory of Open Access Journals (Sweden)

    José Joaquín Merino

    2014-02-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  8. The presence of cortical neurons in striatal-cortical co-cultures alters the effects of dopamine and BDNF on Medium Spiny Neuron dendritic development

    Directory of Open Access Journals (Sweden)

    Rachel D Penrod

    2015-07-01

    Full Text Available 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 in the co-culture further enhances MSN dendritic arborization and spine density, but the effects of dopamine 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.

  9. Neonatal Propofol and Etomidate Exposure Enhance Inhibitory Synaptic Transmission in Hippocampal Cornus Ammonis 1 Pyramidal Neurons

    Institute of Scientific and Technical Information of China (English)

    Jia-Qiang Zhang; Wan-Ying Xu; Chang-Qing Xu

    2016-01-01

    Background:Propofol and etomidate are the most important intravenous general anesthetics in the current clinical use and that mediate gamma-aminobutyric acid's (GABAergic) synaptic transmission.However,their long-term effects on GABAergic synaptic transmission induced by neonatal propofol or etomidate exposure remain unclear.We investigated the long-term GABAergic neurotransmission alterations,following neonatal propofol and etomidate administration.Methods:Sprague-Dawley rat pups at postnatal days 4 6 were underwent 6-h-long propofol-induced or 5-h-long etomidate-induced anesthesia.We performed whole-cell patch-clamp recording from pyramidal cells in the cornus ammonis 1 area of acute hippocampal slices of postnatal 80-90 days.Spontaneous and miniature inhibitory GABAergic currents (spontaneous inhibitory postsynaptic currents [sIPSCs] and miniature inhibitory postsynaptic currents [mIPSCs]) and their kinetic characters were measured.The glutamatergic tonic effect on inhibitory transmission and the effect of bumetanide on neonatal propofol exposure were also examined.Results:Neonatal propofol exposure significantly increased the frequency of mIPSCs (from 1.87 ± 0.35 Hz to 3.43 ± 0.51 Hz,P < 0.05) and did not affect the amplitude of mIPSCs and sIPSCs.Both propofol and etomidate slowed the decay time of mIPSCs kinetics (168.39 ± 27.91 ms and 267.02 ± 100.08 ms vs.68.18 ± 12.43 ms;P < 0.05).Bumetanide significantly blocked the frequency increase and reversed the kinetic alteration of mIPSCs induced by neonatal propofol exposure (3.01 ± 0.45 Hz and 94.30 ± 32.56 ms).Conclusions:Neonatal propofol and etomidate exposure has long-term effects on inhibitory GABAergic transmission.Propofol might act at pre-and post-synaptic GABA receptor A (GABAA) receptors within GABAergic synapses and impairs the glutamatergic tonic input to GABAergic synapses;etomidate might act at the postsynaptic site.

  10. Loss of nonphosphorylated neurofilament immunoreactivity in temporal cortical areas in Alzheimer's disease.

    Science.gov (United States)

    Thangavel, R; Sahu, S K; Van Hoesen, G W; Zaheer, A

    2009-05-05

    The distribution of immunoreactive neurons with nonphosphorylated neurofilament protein (SMI32) was studied in temporal cortical areas in normal subjects and in patients with Alzheimer's disease (AD). SMI32 immunopositive neurons were localized mainly in cortical layers II, III, V and VI, and were medium to large-sized pyramidal neurons. Patients with AD had prominent degeneration of SMI32 positive neurons in layers III and V of Brodmann areas 38, 36, 35 and 20; in layers II and IV of the entorhinal cortex (Brodmann area 28); and hippocampal neurons. Neurofibrillary tangles (NFTs) were stained with Thioflavin-S and with an antibody (AT8) against hyperphosphorylated tau. The NFT distribution was compared to that of the neuronal cytoskeletal marker SMI32 in these temporal cortical regions. The results showed that the loss of SMI32 immunoreactivity in temporal cortical regions of AD brain is paralleled by an increase in NFTs and AT8 immunoreactivity in neurons. The SMI32 immunoreactivity was drastically reduced in the cortical layers where tangle-bearing neurons are localized. A strong SMI32 immunoreactivity was observed in numerous neurons containing NFTs by double-immunolabeling with SMI32 and AT8. However, few neurons were labeled by AT8 and SMI32. These results suggest that the development of NFTs in some neurons results from some alteration in SMI32 expression, but does not account for all, particularly, early NFT-related changes. Also, there is a clear correlation of NFTs with selective population of pyramidal neurons in the temporal cortical areas and these pyramidal cells are specifically prone to formation of paired helical filaments. Furthermore, these pyramidal neurons might represent a significant portion of the neurons of origin of long corticocortical connection, and consequently contribute to the destruction of memory-related input to the hippocampal formation.

  11. The GLP-1 Receptor Agonist Exendin-4 and Diazepam Differentially Regulate GABAA Receptor-Mediated Tonic Currents in Rat Hippocampal CA3 Pyramidal Neurons.

    Directory of Open Access Journals (Sweden)

    Sergiy V Korol

    Full Text Available Glucagon-like peptide-1 (GLP-1 is a metabolic hormone that is secreted in a glucose-dependent manner and enhances insulin secretion. GLP-1 receptors are also found in the brain where their signalling affects neuronal activity. We have previously shown that the GLP-1 receptor agonists, GLP-1 and exendin-4 enhanced GABA-activated synaptic and tonic currents in rat hippocampal CA3 pyramidal neurons. The hippocampus is the centre for memory and learning and is important for cognition. Here we examined if exendin-4 similarly enhanced the GABA-activated currents in the presence of the benzodiazepine diazepam. In whole-cell recordings in rat brain slices, diazepam (1 μM, an allosteric positive modulator of GABAA receptors, alone enhanced the spontaneous inhibitory postsynaptic current (sIPSC amplitude and frequency by a factor of 1.3 and 1.6, respectively, and doubled the tonic GABAA current normally recorded in the CA3 pyramidal cells. Importantly, in the presence of exendin-4 (10 nM plus diazepam (1 μM, only the tonic but not the sIPSC currents transiently increased as compared to currents recorded in the presence of diazepam alone. The results suggest that exendin-4 potentiates a subpopulation of extrasynaptic GABAA receptors in the CA3 pyramidal neurons.

  12. Ongoing epileptiform activity in the post-ischemic hippocampus is associated with a permanent shift of the excitatory-inhibitory synaptic balance in CA3 pyramidal neurons.

    Science.gov (United States)

    Epsztein, Jérôme; Milh, Mathieu; Bihi, Rachid Id; Jorquera, Isabel; Ben-Ari, Yehezkel; Represa, Alfonso; Crépel, Valérie

    2006-06-28

    Ischemic strokes are often associated with late-onset epilepsy, but the underlying mechanisms are poorly understood. In the hippocampus, which is one of the regions most sensitive to ischemic challenge, global ischemia induces a complete loss of CA1 pyramidal neurons, whereas the resistant CA3 pyramidal neurons display a long-term hyperexcitability several months after the insult. The mechanisms of this long-term hyperexcitability remain unknown despite its clinical implication. Using chronic in vivo EEG recordings and in vitro field recordings in slices, we now report spontaneous interictal epileptiform discharges in the CA3 area of the hippocampus from post-ischemic rats several months after the insult. Whole-cell recordings from CA3 pyramidal neurons, revealed a permanent reduction in the frequency of spontaneous and miniature GABAergic IPSCs and a parallel increase in the frequency of spontaneous and miniature glutamatergic postsynaptic currents. Global ischemia also induced a dramatic loss of GABAergic interneurons and terminals together with an increase in glutamatergic terminals in the CA3 area of the hippocampus. Altogether, our results show a morpho-functional reorganization in the CA3 network several months after global ischemia, resulting in a net shift in the excitatory-inhibitory balance toward excitation that may constitute a substrate for the generation of epileptiform discharges in the post-ischemic hippocampus.

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

    Science.gov (United States)

    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 (pregenerating neurons exhibited distinct axonal dynamics, with a significant (pneuronal structural plasticity and defining the role of astrocyte reactivity in the response to trauma.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  16. Inhibitory control of linear and supralinear dendritic excitation in CA1 pyramidal neurons.

    Science.gov (United States)

    Müller, Christina; Beck, Heinz; Coulter, Douglas; Remy, Stefan

    2012-09-01

    The transformation of dendritic excitatory synaptic inputs to axonal action potential output is the fundamental computation performed by all principal neurons. We show that in the hippocampus this transformation is potently controlled by recurrent inhibitory microcircuits. However, excitatory input on highly excitable dendritic branches could resist inhibitory control by generating strong dendritic spikes and trigger precisely timed action potential output. Furthermore, we show that inhibition-sensitive branches can be transformed into inhibition-resistant, strongly spiking branches by intrinsic plasticity of branch excitability. In addition, we demonstrate that the inhibitory control of spatially defined dendritic excitation is strongly regulated by network activity patterns. Our findings suggest that dendritic spikes may serve to transform correlated branch input into reliable and temporally precise output even in the presence of inhibition.

  17. Kv4 potassium channel subunits control action potential repolarization and frequency-dependent broadening in rat hippocampal CA1 pyramidal neurones.

    Science.gov (United States)

    Kim, Jinhyun; Wei, Dong-Sheng; Hoffman, Dax A

    2005-11-15

    A-type potassium channels regulate neuronal firing frequency and the back-propagation of action potentials (APs) into dendrites of hippocampal CA1 pyramidal neurones. Recent molecular cloning studies have found several families of voltage-gated K(+) channel genes expressed in the mammalian brain. At present, information regarding the relationship between the protein products of these genes and the various neuronal functions performed by voltage-gated K(+) channels is lacking. Here we used a combination of molecular, electrophysiological and imaging techniques to show that one such gene, Kv4.2, controls AP half-width, frequency-dependent AP broadening and dendritic action potential propagation. Using a modified Sindbis virus, we expressed either the enhanced green fluorescence protein (EGFP)-tagged Kv4.2 or an EGFP-tagged dominant negative mutant of Kv4.2 (Kv4.2g(W362F)) in CA1 pyramidal neurones of organotypic slice cultures. Neurones expressing Kv4.2g(W362F) displayed broader action potentials with an increase in frequency-dependent AP broadening during a train compared with control neurones. In addition, Ca(2)(+) imaging of Kv4.2g(W362F) expressing dendrites revealed enhanced AP back-propagation compared to control neurones. Conversely, neurones expressing an increased A-type current through overexpression of Kv4.2 displayed narrower APs with less frequency dependent broadening and decreased dendritic propagation. These results point to Kv4.2 as the major contributor to the A-current in hippocampal CA1 neurones and suggest a prominent role for Kv4.2 in regulating AP shape and dendritic signalling. As Ca(2)(+) influx occurs primarily during AP repolarization, Kv4.2 activity can regulate cellular processes involving Ca(2)(+)-dependent second messenger cascades such as gene expression and synaptic plasticity.

  18. Visualization of cortical projection neurons with retrograde TET-off lentiviral vector.

    Directory of Open Access Journals (Sweden)

    Akiya Watakabe

    Full Text Available We are interested in identifying and characterizing various projection neurons that constitute the neocortical circuit. For this purpose, we developed a novel lentiviral vector that carries the tetracycline transactivator (tTA and the transgene under the TET Responsive Element promoter (TRE on a single backbone. By pseudotyping such a vector with modified rabies G-protein, we were able to express palmitoylated-GFP (palGFP or turboFP635 (RFP in corticothalamic, corticocortical, and corticopontine neurons of mice. The high-level expression of the transgene achieved by the TET-Off system enabled us to observe characteristic elaboration of neuronal processes for each cell type. At higher magnification, we were able to observe fine structures such as boutons and spines as well. We also injected our retrograde TET-Off vector to the marmoset cortex and proved that it can be used to label the long-distance cortical connectivity of millimeter scale. In conclusion, our novel retrograde tracer provides an attractive option to investigate the morphologies of identified cortical projection neurons of various species.

  19. Expression profile analysis of hippocampal CA1 pyramidal neurons in aged Ts65Dn mice, a model of Down syndrome (DS) and Alzheimer's disease (AD).

    Science.gov (United States)

    Alldred, Melissa J; Lee, Sang Han; Petkova, Eva; Ginsberg, Stephen D

    2015-09-01

    Down syndrome (DS) is caused by the triplication of human chromosome 21 (HSA21) and is the most common genetic cause of intellectual disability, with individuals having deficits in cognitive function including hippocampal learning and memory and neurodegeneration of cholinergic basal forebrain neurons, a pathological hallmark of Alzheimer's disease (AD). To date, the molecular underpinnings driving this pathology have not been elucidated. The Ts65Dn mouse is a segmental trisomy model of DS and like DS/AD pathology, displays age-related cognitive dysfunction and basal forebrain cholinergic neuron (BFCN) degeneration. To determine molecular and cellular changes important for elucidating mechanisms of neurodegeneration in DS/AD pathology, expression profiling studies were performed. Molecular fingerprinting of homogeneous populations of Cornu Ammonis 1 (CA1) pyramidal neurons was performed via laser capture microdissection followed by Terminal Continuation RNA amplification combined with custom-designed microarray analysis and subsequent validation of individual transcripts by qPCR and protein analysis via immunoblotting. Significant alterations were observed within CA1 pyramidal neurons of aged Ts65Dn mice compared to normal disomic (2N) littermates, notably in excitatory and inhibitory neurotransmission receptor families and neurotrophins, including brain-derived neurotrophic factor as well as several cognate neurotrophin receptors. Examining gene and protein expression levels after the onset of BFCN degeneration elucidated transcriptional and translational changes in neurons within a vulnerable circuit that may cause the AD-like pathology seen in DS as these individuals age, and provide rational targets for therapeutic interventions.

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

    Science.gov (United States)

    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.

  1. Effect of cholecystokinin-8 on in vitro cultured rat cortical neurons against apoptosis

    Institute of Scientific and Technical Information of China (English)

    Ying Liu; Jiangbao Zhou

    2006-01-01

    BACKGROUND: Cholecystokinin (CCK-8) can regulate the synthesis of NO, release of amino acid substance and suppress Ca2+ inflow. It is unknown about neuroprotection of CCK-8 on neuronal apoptosis and its relationship with nerve growth factor (NGF).OBJECTryE: To investigate the protective effect of CCK-8 on in vitro cultured rat cortical neurons against apoptosis induced by glutamate, and explore its effect on expression of NGF in the neurons during apoptosis.DESIGN: Randomized controlled experiment on the basis of cells.SETTING: Children's Research Institute Affiliated to Children Hospital of Chongqing Medical University.MATERIALS: Eighty SD rats of 1-day old; DMEM/F12 culture medium (Biochrom Company, Germany);Fetal bovine serum (TBD Company, Tianjin); CCK-8 (Sigma Company, USA). Glutamate (Bioengineering Company, Shanghai); TUNEL kit and NGF- in situ hybridization kit (Boster Bioengineering Company,Wuhan); anti-NGF polyclonal antibody (Santa-Cluz Company); NGF immunocytochemistry kit (Zhongshan Company, Beijing).METHODS: The experiments were carried out in Children's Research Institute Affiliated to Children Hospital of Chongqing Medical University from December 2004 to September 2005. Primary cultured cortical neurons from SD rats of 1-day oldwere incubated for 7 days. The cultured cells were divided randomly into 3 groups:experimental group, model group and control group. Neurons in experimental groups were added CCK-8 of 1 ×10-6, 1 ×10-7, 1 ×10-8 μ mol/L respectively, and then added 50 μmol/L glutamate solution a hour later. Neurons in model groups were treated with 50 μ mol/L glutamate solution. In the control group, cells were treated with normal medium. Apoptosis of cultured cortical neurons were observed by fluorescent microscope, the expression of NGF protein and mRNA were determined respectively by immunocytochemistry and in situ hybridization, and apoptosis of cortical neurons was detected with terminal deoxynucleotidyl transferase-mediated nick

  2. 17beta-estradiol benzoate decreases the AHP amplitude in CA1 pyramidal neurons.

    Science.gov (United States)

    Kumar, Ashok; Foster, Thomas C

    2002-08-01

    Disruption of Ca(2+) homeostasis is hypothesized to mediate several electrophysiological markers of brain aging. Recent evidence indicates that estradiol can rapidly alter Ca(2+)-dependent processes in neurons through nongenomic mechanisms. In the current study, electrophysiological effects of 17beta-estradiol benzoate (EB) on the Ca(2+)-activated afterhyperpolarization (AHP) were investigated using intracellular sharp electrode recording in hippocampal slices from ovariectomized Fischer 344 female rats. The AHP amplitude was enhanced in aged (22-24 mo) compared with young (5-8 mo) rats and direct application of EB (100 pM) reduced the AHP in aged rats. The age-related difference was due, in part, to the increased AHP amplitude of aged animals, since an EB-mediated decrease in the AHP could be observed in young rats when the extracellular Ca(2+) was elevated to increase the AHP amplitude. In aged rats, bath application of EB occluded the ability of the L-channel blocker, nifedipine (10 microM), to attenuate the AHP. The results support a role for EB in modifying hippocampal Ca(2+)-dependent processes in a manner diametrically opposite that observed during aging, possibly through L-channel inhibition.

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

    Science.gov (United States)

    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

  4. Electrophysiological changes of CA1 pyramidal neurons following transient forebrain ischemia: an in vivo intracellular recording and staining study.

    Science.gov (United States)

    Xu, Z C; Pulsinelli, W A

    1996-09-01

    1. Electrophysiological changes of CA1 pyramidal neurons in rat hippocampus were studied before, during 5 min forebrain ischemia, and after reperfusion using in vivo intracellular recording and staining techniques. 2. membrane input resistance of CA1 neurons decreased from 25.98 +/- 7.24 M omega (mean +/- SD, n = 42) before ischemia to 16.33 +/- 6.50 M omega shortly after the onset of ischemia (n = 6, P < 0.01). The input resistance fell to zero during ischemic depolarization and quickly returned to 24.42 +/- 10.36 M omega (n = 11) within 2 h after reperfusion. 3. The time constant of CA1 neurons decreased from 11.49 +/- 5.45 ms (n = 36) to 3.09 +/- 1.66 ms (n = 6, P < 0.01) during ischemia. The time constant remained significantly less than preischemic levels within 2 h after reperfusion (5.40 +/- 2.60 ms, n = 13, P < 0.01) and gradually returned to preischemic levels 4-5 h after reperfusion. 4. The spike height decreased from 91 +/- 10.35 mV (n = 45) before ischemia to 82 +/- 8.00 mV (n = 9, P < 0.05) within 2 h after reperfusion and fully returned to preischemic level 2-5 h after reperfusion. The spike width increased from 1.14 +/- 0.22 ms (n = 45) before ischemia to 1.36 +/- 0.22 ms (n = 9, P < 0.05) within 2 h after reperfusion and remained at this level 4-5 h after reperfusion. 5. The spike threshold significantly increased from -54 +/- 3.93 mV (n = 45) before ischemia to -49 +/- 5.04 mV (n = 8, P < 0.01) within 2 h after reperfusion. The rheobase increased accordingly from 0.34 +/- 0.16 nA (n = 41) to 0.73 +/- 0.26 nA (n = 6, P < 0.01). The spike threshold returned to control levels 4-5 h after reperfusion, while the rheobase was still significantly higher than control levels (0.50 +/- 0.21 nA, n = 16, P < 0.01). 6. The frequency of repetitive firing evoked by depolarizing current pulses was suppressed within 2 h after reperfusion (n = 6, P < 0.01). The spike frequency increased slightly 2-5 h after reperfusion but was still significantly below the control

  5. Homocysteine Aggravates Cortical Neural Cell Injury through Neuronal Autophagy Overactivation following Rat Cerebral Ischemia-Reperfusion

    Directory of Open Access Journals (Sweden)

    Yaqian Zhao

    2016-07-01

    Full Text Available Elevated homocysteine (Hcy levels have been reported to be involved in neurotoxicity after ischemic stroke. However, the underlying mechanisms remain incompletely understood to date. In the current study, we hypothesized that neuronal autophagy activation may be involved in the toxic effect of Hcy on cortical neurons following cerebral ischemia. Brain cell injury was determined by hematoxylin-eosin (HE staining and TdT-mediated dUTP Nick-End Labeling (TUNEL staining. The level and localization of autophagy were detected by transmission electron microscopy, western blot and immunofluorescence double labeling. The oxidative DNA damage was revealed by immunofluorescence of 8-Hydroxy-2′-deoxyguanosine (8-OHdG. Hcy treatment aggravated neuronal cell death, significantly increased the formation of autophagosomes and the expression of LC3B and Beclin-1 in the brain cortex after middle cerebral artery occlusion-reperfusion (MCAO. Immunofluorescence analysis of LC3B and Beclin-1 distribution indicated that their expression occurred mainly in neurons (NeuN-positive and hardly in astrocytes (GFAP-positive. 8-OHdG expression was also increased in the ischemic cortex of Hcy-treated animals. Conversely, LC3B and Beclin-1 overexpression and autophagosome accumulation caused by Hcy were partially blocked by the autophagy inhibitor 3-methyladenine (3-MA. Hcy administration enhanced neuronal autophagy, which contributes to cell death following cerebral ischemia. The oxidative damage-mediated autophagy may be a molecular mechanism underlying neuronal cell toxicity of elevated Hcy level.

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

    Science.gov (United States)

    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

  7. Lactate modulates the activity of primary cortical neurons through a receptor-mediated pathway.

    Directory of Open Access Journals (Sweden)

    Luigi Bozzo

    Full Text Available 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.

  8. Lactate modulates the activity of primary cortical neurons through a receptor-mediated pathway.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  13. Modulation of specific sensory cortical areas by segregated basal forebrain cholinergic neurons demonstrated by neuronal tracing and optogenetic stimulation in mice

    Directory of Open Access Journals (Sweden)

    Irene eChaves-Coira

    2016-04-01

    Full Text Available 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 and Fast Blue 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

  14. Modulation of Specific Sensory Cortical Areas by Segregated Basal Forebrain Cholinergic Neurons Demonstrated by Neuronal Tracing and Optogenetic Stimulation in Mice

    Science.gov (United States)

    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

  15. Acetylcholine modulates transient outward potassium channel in acutely isolated cerebral cortical neurons of rats

    Institute of Scientific and Technical Information of China (English)

    Lanwei Cui; Tao Sun; Lihui Qu; Yurong Li; Haixia Wen

    2009-01-01

    BACKGROUND:The neuronal transient outward potassium channel has been shown to be highly associated with acetylcholine.However,the influence of acetylcholine on the transient outward potassium current in cerebral cortical neurons remains poorly understood.OBJECTIVE:To investigate acetylcholine modulation on transient outward potassium current in rat parietal cortical neurons using the whole-cell patch-clamp technique.DESIGN,TIME AND SETTING:A neuroelectrophysiology study was performed at the Department of Physiology,Harbin Medical University between January 2005 and January 2006.MATERIALS:Wistar rats were provided by the Animal Research Center,the Second Hospital of Harbin Medical University;PC-IIC patch-clamp amplifier and IBBClamp data collection analysis system were provided by Huazhong University for Science and Technology,Wuhan,China;PP-83 microelectrode puller was purchased from Narrishage,Japan.METHODS:The parietal somatosensory cortical neurons were acutely dissociated,and the modulation of acetylcholine (0.1,1,10,100 μmol/L) on transient outward potassium channel was recorded using the whole-cell patch-clamp technique.MAIN OUTCOME MEASURES:Influence of acetylcholine on transient outward potassium current,potassium channel activation,and inactivation.RESULTS:The inhibitory effect of acetylcholine on transient outward potassium current was dose- and voltage-dependent (P<0.01).Acetylcholine was found to significantly affect the activation process of transient outward potassium current,i.e.,the activation curve of transient outward potassium current was left-shifted,while the inactivation curve was shifted to hyperpolarization.Acetylcholine significantly prolonged the time constant of recovery from inactivation of transient outward potassium current (P<0.01).CONCLUSION:These results suggest that acetylcholine inhibits transient outward potassium current by regulating activation and inactivation processes of the transient outward potassium channel.

  16. Cell Signaling Mechanisms by which Geniposide Regulates Insulin- Degrading Enzyme Expression in Primary Cortical Neurons.

    Science.gov (United States)

    Zhang, Yonglan; Xia, Zhining; Liu, Jianhui; Yin, Fei

    2015-01-01

    An increasing number of studies have demonstrated that insulin-degrading enzyme (IDE) plays an essential role in both the degradation and its activity of β-amyloid (Aβ). Therefore, the regulation of IDE expression and/or modification of IDE-dependent actions are two emerging strategies for the treatment of Alzheimer's disease (AD). We previously observed that geniposide, a novel agonist of glucagon-like peptide 1 receptor (GLP-1R), could attenuate Aβ-induced neurotoxicity by regulating the expression of IDE in primary cortical neurons. However, the signal transduction mechanisms underlying this effect were not elucidated. The present study, therefore examined and explored the cell signaling transduction and molecular mechanisms by which geniposide induces the expression of IDE in primary cortical neurons. The current study revealed that LY294002 (an inhibitor for phosphatidyl inositol 3-kinase, PI3K), PP1 (inhibitor for c-Src), GW9662 (antagonist for peroxisome proliferator-activated receptor γ, PPARγ), H89 (an inhibitor for protein kinase A, PKA) and AG1478 (an antagonist for epidermal growth factor receptor, EGFR) prohibited the up-regulation of IDE induced by geniposide in primary cortical neurons. Further, geniposide also enhanced the phosphorylation of PPARγ and accelerated the release of phosphorylated FoxO1 (forkhead box O1) from nuclear fraction to the cytosol. Moreover, geniposide directly activated the activity of IDE promoter in PC12 cells, which confirmed the presence of the GLP-1 receptor. Taken together, our findings reveal for the first time the cell signaling transduction pathway of geniposide regulating the expression of IDE in neurons.

  17. A new role for TIMP-1 in modulating neurite outgrowth and morphology of cortical neurons.

    Directory of Open Access Journals (Sweden)

    Adlane Ould-yahoui

    Full Text Available 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, betaIII-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.

  18. Schisandrin B protects rat cortical neurons against Abeta1-42-induced neurotoxicity.

    Science.gov (United States)

    Wang, Bin; Wang, Xue-Mei

    2009-07-01

    In the present study, we investigated the neuroprotective effects of schisandrin B on amyloid-beta1-42-induced toxicity and its potential mechanisms in rat cortical neuron cells. Amyloid beta1-42 significantly reduced cell viability and increased apoptosis. Pretreatment with schisandrin B prior to amyloid-beta1-42 exposure significantly elevated cell viability and reduced apoptosis. The anti-apoptotic effect of schisandrin B in rat cortical neurons was mediated by up-regulation of the anti-apoptotic protein Bcl-2 and down-regulation of the pro-apoptotic protein Bax. Schisandrin B also reduced the release of mitochondrial cytochrome c into cytosol and decreased caspase-9 and caspase-3 activities. Furthermore, schisandrin B increased activities of anti-oxidant reduced glutathione and decreased production of oxidative glutathione. Taken together, these results suggest that schisandrin B protected primary cultures of rat cortical cells against amyloid-beta1-42-induced neurotoxicity through anti-apoptosis involved in a mitochondria-mediated pathway and anti-oxidant action. Schisandrin B may represent a potential treatment strategy for Alzheimer's disease.

  19. CNTF-ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through upregulating L-type calcium channel activity.

    Science.gov (United States)

    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 ACM (p ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through elevating L-type calcium channel activity.

  20. Cortical excitatory neurons become protected from cell division during neurogenesis in an Rb family-dependent manner.

    Science.gov (United States)

    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.

  1. Effects of deprivation of oxygen or glucose on the neural activity in the guinea pig hippocampal slice--intracellular recording study of pyramidal neurons.

    Science.gov (United States)

    Takata, T; Okada, Y

    1995-06-12

    The block of synaptic transmission and neural activity during deprivation of oxygen or glucose has been simply attributed to the lack of energy due to the disorder of energy production. To clarify the interrelation between neural activity and energy metabolism during hypoxia or glucose deprivation, we studied the changes in ATP levels and electrical events of pyramidal neurons in the CA3 region and [Ca2+]i mobilization of the dendritic and cellular region of CA3 area, using guinea pig hippocampal slices. The studies of field potentials and intracellular recording from the pyramidal cell of CA3 area during hypoxia or glucose deprivation revealed that the cessation of synaptic activity and the depolarization of resting potential occurred earlier than during glucose deprivation while the increase of [Ca2+]i was slow during hypoxia but rapid during glucose deprivation although the ATP level of CA3 area was maintained at its original level for 20 min during both conditions. When glucose was replaced by lactate, ATP concentration was not reduced but the electrical activity decayed and [Ca2+]i increased with the similar time course as observed during lack of glucose, only. These results suggest that different mechanisms underlie the block of synaptic transmission in the CA3 pyramidal neurons during hypoxia and glucose deprivation and that lactate cannot substitute for glucose in the maintenance of neural activity.

  2. Near infrared radiation rescues mitochondrial dysfunction in cortical neurons after oxygen-glucose deprivation.

    Science.gov (United States)

    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.

  3. Functional and molecular differences between voltage-gated K+ channels of fast-spiking interneurons and pyramidal neurons of rat hippocampus.

    Science.gov (United States)

    Martina, M; Schultz, J H; Ehmke, H; Monyer, H; Jonas, P

    1998-10-15

    We have examined gating and pharmacological characteristics of somatic K+ channels in fast-spiking interneurons and regularly spiking principal neurons of hippocampal slices. In nucleated patches isolated from basket cells of the dentate gyrus, a fast delayed rectifier K+ current component that was highly sensitive to tetraethylammonium (TEA) and 4-aminopyridine (4-AP) (half-maximal inhibitory concentrations Kv3 (Kv3.1, Kv3.2) subunit transcripts were expressed in almost all (89%) of the interneurons but only in 17% of the pyramidal neurons. In contrast, Kv4 (Kv4.2, Kv4.3) subunit mRNAs were present in 87% of pyramidal neurons but only in 55% of interneurons. Selective block of fast delayed rectifier K+ channels, presumably assembled from Kv3 subunits, by 4-AP reduced substantially the action potential frequency in interneurons. These results indicate that the differential expression of Kv3 and Kv4 subunits shapes the action potential phenotypes of principal neurons and interneurons in the cortex.

  4. Silencing gamma-aminobutyric acid A receptor alpha 1 subunit expression and outward potassium current in developing cortical neurons

    Institute of Scientific and Technical Information of China (English)

    Tao Bo; Jiang Li; Jian Li; Xingfang Li; Kaihui Xing

    2011-01-01

    We used RNA interference (RNAi) to disrupt synthesis of the cortical neuronal γ-aminobutyric acid A receptor (GABAAR) α1 in rats during development, and measured outward K+ currents during neuronal electrical activity using whole-cell patch-clamp techniques. Three pairs of small interfering RNA (siRNA) for GABAAR α1 subunit were designed using OligoEngine RNAi software. This siRNA was found to effectively inhibited GABAAR α1 mRNA expression in cortical neuronal culture in vitro, but did not significantly affect neuronal survival. Outward K+ currents were decreased, indicating that GABAAR α1 subunits in developing neurons participate in neuronal function by regulating outward K+ current.

  5. Cortical regulation of dopamine depletion-induced dendritic spine loss in striatal medium spiny neurons.

    Science.gov (United States)

    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. Sub-millisecond firing synchrony of closely neighboring pyramidal neurons in hippocampal CA1 of rats during delayed non-matching to sample task

    Directory of Open Access Journals (Sweden)

    Susumu Takahashi

    2009-09-01

    Full Text Available Firing synchrony among neurons is thought to play functional roles in several brain regions. In theoretical analyses, firing synchrony among neurons within sub-millisecond precision is feasible to convey information. However, little is known about the occurrence and the functional significance of the sub-millisecond synchrony among closely neighboring neurons in the brain of behaving animals because of a technical issue: spikes simultaneously generated from closely neighboring neurons are overlapped in the extracellular space and are not easily separated. As described herein, using a unique spike sorting technique based on independent component analysis together with extracellular 12-channel multi-electrodes (dodecatrodes, we separated such overlapping spikes and investigated the firing synchrony among closely neighboring pyramidal neurons in the hippocampal CA1 of rats during a delayed non-matching to sample task. Results showed that closely neighboring pyramidal neurons in the hippocampal CA1 can co-fire with sub-millisecond precision. The synchrony generally co-occurred with the firing rate modulation in relation to both internal (retention and comparison and external (stimulus input and motor output events during the task. However, the synchrony occasionally occurred in relation to stimulus inputs even when rate modulation was clearly absent, suggesting that the synchrony is not simply accompanied with firing rate modulation and that the synchrony and the rate modulation might code similar information independently. We therefore conclude that the sub-millisecond firing synchrony in the hippocampus is an effective carrier for propagating information—as represented by the firing rate modulations—to downstream neurons.

  7. Interplay between kinesin-1 and cortical dynein during axonal outgrowth and microtubule organization in Drosophila neurons.

    Science.gov (United States)

    del Castillo, Urko; Winding, Michael; Lu, Wen; Gelfand, Vladimir I

    2015-12-28

    In this study, we investigated how microtubule motors organize microtubules in Drosophila neurons. We showed that, during the initial stages of axon outgrowth, microtubules display mixed polarity and minus-end-out microtubules push the tip of the axon, consistent with kinesin-1 driving outgrowth by sliding antiparallel microtubules. At later stages, the microtubule orientation in the axon switches from mixed to uniform polarity with plus-end-out. Dynein knockdown prevents this rearrangement and results in microtubules of mixed orientation in axons and accumulation of microtubule minus-ends at axon tips. Microtubule reorganization requires recruitment of dynein to the actin cortex, as actin depolymerization phenocopies dynein depletion, and direct recruitment of dynein to the membrane bypasses the actin requirement. Our results show that cortical dynein slides 'minus-end-out' microtubules from the axon, generating uniform microtubule arrays. We speculate that differences in microtubule orientation between axons and dendrites could be dictated by differential activity of cortical dynein.

  8. Dynamic changes in proprotein convertase 2 activity in cortical neurons after ischemia/reperfusion and oxygen-glucose deprivation

    Institute of Scientific and Technical Information of China (English)

    Shuqin Zhan; An Zhou; Chelsea Piper; Tao Yang

    2013-01-01

    In this study, a rat model of transient focal cerebral ischemia was established by performing 100 minutes of middle cerebral artery occlusion, and an in vitro model of experimental oxygen-glucose deprivation using cultured rat cortical neurons was established. Proprotein convertase 2 activity gradually decreased in the ischemic cortex with increasing duration of reperfusion. In cultured rat cortical neurons, the number of terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate-biotin nick end labeling-positive neurons significantly increased and proprotein convertase 2 activity also decreased gradually with increasing duration of oxygen-glucose deprivation. These experimental findings indicate that proprotein convertase 2 activity decreases in ischemic rat cortex after reperfusion, as well as in cultured rat cortical neurons after oxygen-glucose deprivation. These changes in enzyme activity may play an important pathological role in brain injury.

  9. Trans-anethole protects cortical neuronal cells against oxygen-glucose deprivation/reoxygenation.

    Science.gov (United States)

    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.

  10. 14,15-EET promotes mitochondrial biogenesis and protects cortical neurons against oxygen/glucose deprivation-induced apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lai; Chen, Man; Yuan, Lin; Xiang, Yuting [Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing (China); Zheng, Ruimao, E-mail: rmzheng@pku.edu.cn [Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing (China); Zhu, Shigong, E-mail: sgzhu@bjmu.edu.cn [Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing (China)

    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.

  11. CNTF-Treated Astrocyte Conditioned Medium Enhances Large-Conductance Calcium-Activated Potassium Channel Activity in Rat Cortical Neurons.

    Science.gov (United States)

    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 ACM produced a significant increase in BKα1 and BKβ3 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.

  12. Estimation of the effective orientation of the SHG source in primary cortical neurons

    OpenAIRE

    Psilodimitrakopoulos, Sotiris; Petegnief, Valérie; Soria, Guadalupe; Amat-Roldan, Ivan; Artigas, David; Planas, Anna M; Loza-Álvarez, Pablo

    2009-01-01

    In this paper we provide, for the first time to our knowledge, the effective orientation of the SHG source in cultured cortical neuronal processes in vitro. This is done by the use of the polarization sensitive second harmonic generation (PSHG) imaging microscopy technique. By performing a pixel-level resolution analysis we found that the SHG dipole source has a distribution of angles centered at θe =33.96°, with a bandwidth of ∆θe = 12.85°. This orientation can be related with the molecular...

  13. CNTF inhibits high voltage activated Ca2+ currents in fetal mouse cortical neurones

    DEFF Research Database (Denmark)

    Holm, Ninna R; Christophersen, Palle; Hounsgaard, Jørn;

    2002-01-01

    Neurotrophic factors yield neuroprotection by mechanisms that may be related to their effects as inhibitors of apoptosis as well as their effects on ion channels. The effect of ciliary neurotrophic factor (CNTF) on high-threshold voltage-activated Ca channels in cultured fetal mouse brain cortical...... neurones was investigated. Addition of CNTF into serum-free growth medium resulted in delayed reduction of the Ca2+ currents. The currents decreased to 50% after 4 h and stabilized at this level during incubation with CNTF for 48 h. Following removal of CNTF the inhibition was completely reversed after 18...

  14. Neuroprotective effects of L-carnitine against oxygenglucose deprivation in rat primary cortical neurons

    Directory of Open Access Journals (Sweden)

    Yu Jin Kim

    2012-07-01

    Full Text Available &lt;b&gt;Purpose:&lt;/b&gt; Hypoxic-ischemic encephalopathy is an important cause of neonatal mortality, as this brain injury disrupts normal mitochondrial respiratory activity. Carnitine plays an essential role in mitochondrial fatty acid transport and modulates excess acyl coenzyme A levels. In this study, we investigated whether treatment of primary cultures of rat cortical neurons with L-carnitine was able to prevent neurotoxicity resulting from oxygen-glucose deprivation (OGD. &lt;b&gt;Methods:&lt;/b&gt; Cortical neurons were prepared from Sprague-Dawley rat embryos. L-Carnitine was applied to cultures just prior to OGD and subsequent reoxygenation. The numbers of cells that stained with acridine orange (AO and propidium iodide (PI were counted, and lactate dehydrogenase (LDH activity and reactive oxygen species (ROS levels were measured. The 3-(4,5-dimethylthiazol-2-yl-2,5- diphenyltetrazolium bromide assay and the terminal uridine deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay were performed to evaluate the effect of L-carnitine (1 μM, 10 μM, and 100 μM on OGD-induced neurotoxicity. &lt;B&gt;Results:&lt;/b&gt; Treatment of primary cultures of rat cortical neurons with L-carnitine significantly reduced cell necrosis and prevented apoptosis after OGD. L-Carnitine application significantly reduced the number of cells that died, as assessed by the PI/AO ratio, and also reduced ROS release in the OGD groups treated with 10 μM and 100 μM of L-carnitine compared with the untreated OGD group (P&lt;0.05. The application of L-carnitine at 100 μM significantly decreased cytotoxicity, LDH release, and inhibited apoptosis compared to the untreated OGD group (P&lt;0.05. &lt;B&gt;Conclusion:&lt;/b&gt; L-Carnitine has neuroprotective benefits against OGD in rat primary cortical neurons in vitro.

  15. Muscarinic receptor activation determines the effects of store-operated Ca(2+)-entry on excitability and energy metabolism in pyramidal neurons.

    Science.gov (United States)

    Kann, Oliver; Taubenberger, Nando; Huchzermeyer, Christine; Papageorgiou, Ismini E; Benninger, Felix; Heinemann, Uwe; Kovács, Richard

    2012-01-01

    In various cell types, depletion of intracellular Ca(2+)-stores results in store-operated Ca(2+)-entry (SOCE) across the cellular membrane. However, the effects of SOCE on neuronal membrane excitability and mitochondrial functions in central neurons are not well defined. We investigated such cellular downstream effects in pyramidal neurons of rat organotypic hippocampal slice cultures by applying electrophysiological and fluorescence imaging techniques. We report that SOCE is associated with (i) elevations of Ca(2+)-concentration in individual neuronal mitochondria ([Ca(2+)](m)). In addition, SOCE can result in (ii) hyperpolarizing neuronal membrane currents, (iii) increase in extracellular K(+)-concentration ([K(+)](o)), (iv) mitochondrial membrane depolarization, and (v) changes in intracellular redox state (NAD(P)H and FAD fluorescence), the latter reflecting responses of energy metabolism. These additional downstream effects of SOCE required concomitant muscarinic receptor activation by carbachol or acetylcholine, and were suppressed by agonist washout or application of antagonist, atropine. We conclude that muscarinic receptor activation determines the downstream effects of SOCE on neuronal membrane excitability and energy metabolism. This mechanism might have significant impact on information processing and neurometabolic coupling in central neurons. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Combined chronic blockade of hyper-active L-type calcium channels and NMDA receptors ameliorates HIV-1 associated hyper-excitability of mPFC pyramidal neurons.

    Science.gov (United States)

    Khodr, Christina E; Chen, Lihua; Dave, Sonya; Al-Harthi, Lena; Hu, Xiu-Ti

    2016-10-01

    Human Immunodeficiency Virus type 1 (HIV-1) infection induces neurological and neuropsychological deficits, which are associated with dysregulation of the medial prefrontal cortex (mPFC) and other vulnerable brain regions. We evaluated the impact of HIV infection in the mPFC and the therapeutic potential of targeting over-active voltage-gated L-type Ca(2+) channels (L-channel) and NMDA receptors (NMDAR), as modeled in HIV-1 transgenic (Tg) rats. Whole-cell patch-clamp recording was used to assess the membrane properties and voltage-sensitive Ca(2+) potentials (Ca(2+) influx) in mPFC pyramidal neurons. Neurons from HIV-1 Tg rats displayed reduced rheobase, spike amplitude and inwardly-rectifying K(+) influx, increased numbers of action potentials, and a trend of aberrant firing compared to those from non-Tg control rats. Neuronal hyper-excitation was associated with abnormally-enhanced Ca(2+) influx (independent of NMDAR), which was eliminated by acute L-channel blockade. Combined chronic blockade of over-active L-channels and NMDARs with open-channel blockers abolished HIV effects on spiking, aberrant firing and Ca(2+) potential half-amplitude duration, though not the reduced inward rectification. In contrast, individual chronic blockade of over-active L-channels or NMDARs did not alleviate HIV-induced mPFC hyper-excitability. These studies demonstrate that HIV alters mPFC neuronal activity by dysregulating membrane excitability and Ca(2+) influx through the L-channels. This renders these neurons more susceptible and vulnerable to excitatory stimuli, and could contribute to HIV-associated neuropathogenesis. Combined targeting of over-active L-channels/NMDARs alleviates HIV-induced dysfunction of mPFC pyramidal neurons, emphasizing a potential novel therapeutic strategy that may effectively decrease HIV-induced Ca(2+) dysregulation in the mPFC.

  17. A comparison of 15 Hz sine on-line and off-line magnetic stimulation affecting the voltage-gated sodium channel currents of prefrontal cortex pyramidal neurons

    Science.gov (United States)

    Zheng, Yu; Dong, Lei; Gao, Yang; Dou, Jun-Rong; Li, Ze-yan

    2016-10-01

    Combined with the use of patch-clamp techniques, repetitive transcranial magnetic stimulation (rTMS) has proven to be a noninvasive neuromodulation tool that can inhibit or facilitate excitability of neurons after extensive research. The studies generally focused on the method: the neurons are first stimulated in an external standard magnetic exposure device, and then moved to the patch-clamp to record electrophysiological characteristics (off-line magnetic exposure). Despite its universality, real-time observation of the effects of magnetic stimulation on the neurons is more effective (on-line magnetic stimulation). In this study, we selected a standard exposure device for magnetic fields acting on mouse prefrontal cortex pyramidal neurons, and described a new method that a patch-clamp setup was modified to allow on-line magnetic stimulation. By comparing the off-line exposure and on-line stimulation of the same magnetic field intensity and frequency affecting the voltage-gated sodium channel currents, we succeeded in proving the feasibility of the new on-line stimulation device. We also demonstrated that the sodium channel currents of prefrontal cortex pyramidal neurons increased significantly under the 15 Hz sine 1 mT, and 2 mT off-line magnetic field exposure and under the 1 mT and 2 mT on-line magnetic stimulation, and the rate of acceleration was most significant on 2 mT on-line magnetic stimulation. This study described the development of a new on-line magnetic stimulator and successfully demonstrated its practicability for scientific stimulation of neurons.

  18. Tangentially migrating neurons assemble a primary cilium that promotes their reorientation to the cortical plate.

    Science.gov (United States)

    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.

  19. EFFECT OF MELATONIN AGAINST GLUTAMATE-INDUCED EXCITOTOXICITY ON CULTURED CEREBRAL CORTICAL NEURONS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective To research the effect of melatonin against glutamate excitotoxicity. Methods The model of glutamate-induced excitotoxic damage was built up in rat cerebral cortical cell culture. The effect of mela- tonin against excitotoxic injury was observed by determining the leakage rate of lactate dehydrogenase(LDH) from neurons. Results The leakage rate of LDH wasn't decreased markedly when cultures were exposed to melatonin be- fore, during or 6 h after glutamate treatment. The leakage rate of LDH was decreased significantly when melatonin was administered 0 h, 2 h or 4 h after the cultures were exposed to glutamate. The inhibitory function of melatonin on LDH leakage was most effective at 2 h and 4 h. Conclusion Melatonin has protective effects on neurons damaged by glutamate in a certain time limit.

  20. Cortical spreading depression in migraine-time to reconsider?

    Directory of Open Access Journals (Sweden)

    Alan J McComas

    2015-08-01

    Full Text Available New evidence concerning the pathophysiology of migraine has come from the results of therapeutic transcranial magnetic stimulation (tTMS. The instantaneous responses to single pulses applied during the aura or headache phase, together with a number of other observations, make it unlikely that cortical spreading depression is involved in migraine. tTMS is considered to act by abolishing abnormal impulse activity in cortical pyramidal neurons and a suggestion is made as to how this activity could arise.

  1. Neuronal morphology in the African elephant (Loxodonta africana) neocortex.

    Science.gov (United States)

    Jacobs, Bob; Lubs, Jessica; Hannan, Markus; Anderson, Kaeley; Butti, Camilla; Sherwood, Chet C; Hof, Patrick R; Manger, Paul R

    2011-01-01

    Virtually nothing is known about the morphology of cortical neurons in the elephant. To this end, the current study provides the first documentation of neuronal morphology in frontal and occipital regions of the African elephant (Loxodonta africana). Cortical tissue from the perfusion-fixed brains of two free-ranging African elephants was stained with a modified Golgi technique. Neurons of different types (N=75), with a focus on superficial (i.e., layers II-III) pyramidal neurons, were quantified on a computer-assisted microscopy system using Neurolucida software. Qualitatively, elephant neocortex exhibited large, complex spiny neurons, many of which differed in morphology/orientation from typical primate and rodent pyramidal neurons. Elephant cortex exhibited a V-shaped arrangement of bifurcating apical dendritic bundles. Quantitatively, the dendrites of superficial pyramidal neurons in elephant frontal cortex were more complex than in occipital cortex. In comparison to human supragranular pyramidal neurons, elephant superficial pyramidal neurons exhibited similar overall basilar dendritic length, but the dendritic segments tended to be longer in the elephant with less intricate branching. Finally, elephant aspiny interneurons appeared to be morphologically consistent with other eutherian mammals. The current results thus elaborate on the evolutionary roots of Afrotherian brain organization and highlight unique aspects of neural architecture in elephants.

  2. Elevated potassium elicits recurrent surges of large GABAA-receptor-mediated post-synaptic currents in hippocampal CA3 pyramidal neurons.

    Science.gov (United States)

    Shin, Damian Seung-Ho; Yu, Wilson; Sutton, Alex; Calos, Megan; Carlen, Peter Louis

    2011-03-01

    Previously, we found that rat hippocampal CA3 interneurons become hyperactive with increasing concentrations of extracellular K(+) up to 10 mM. However, it is unclear how this enhanced interneuronal activity affects pyramidal neurons. Here we voltage-clamped rat hippocampal CA3 pyramidal neurons in vitro at 0 mV to isolate γ-aminobutyric acid (GABA)-activated inhibitory post-synaptic currents (IPSCs) and measured these in artificial cerebrospinal fluid (aCSF) and with 10 mM K(+) bath perfusion. In aCSF, small IPSCs were present with amplitudes of 0.053 ± 0.007 nA and a frequency of 0.27 ± 0.14 Hz. With 10 mM K(+) perfusion, IPSCs increased greatly in frequency and amplitude, culminating in surge events with peak amplitudes of 0.56 ± 0.08 nA, that appeared and disappeared cyclically with durations lasting 2.02 ± 0.37 min repeatedly, up to 10 times over a 30-min bath perfusion of elevated K(+). These large IPSCs were GABA(A)-receptor mediated and did not involve significant desensitization of this receptor. Perfusion of a GABA transporter inhibitor (NO-711), glutamate receptor inhibitors CNQX and APV, or a gap junctional blocker (carbenoxolone) prevented the resurgence of large IPSCs. Pressure ejected sucrose resulted in the abolishment of subsequent surges. No elevated K(+)-mediated surges were observed in CA3 interneurons from the stratum oriens layer. In conclusion, these cyclic large IPSC events observable in CA3 pyramidal neurons in 10 mM KCl may be due to transient GABA depletion from continuously active interneuronal afferents.

  3. Golli Myelin Basic Proteins Modulate Voltage-Operated Ca(++) Influx and Development in Cortical and Hippocampal Neurons.

    Science.gov (United States)

    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

    Energy Technology Data Exchange (ETDEWEB)

    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

    Directory of Open Access Journals (Sweden)

    Chiaki eOhtaka-Maruyama

    2015-12-01

    Full Text Available Glutamatergic neurons of the mammalian cerebral cortex originate from the 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.

  6. Distinct regulation of activity-dependent transcription of immediate early genes in cultured rat cortical neurons.

    Science.gov (United States)

    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.

  7. Modeling the Formation Process of Grouping Stimuli Sets through Cortical Columns and Microcircuits to Feature Neurons

    Directory of Open Access Journals (Sweden)

    Frank Klefenz

    2013-01-01

    Full Text Available 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.

  8. A novel role for PTEN in the inhibition of neurite outgrowth by Myelin-associated glycoprotein in cortical neurons

    Science.gov (United States)

    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

  9. Low Concentrations of Alcohol Inhibit BDNF-Dependent GABAergic Plasticity via L-type Ca2+ channel Inhibition in Developing CA3 Hippocampal Pyramidal Neurons

    OpenAIRE

    Zucca, Stefano; Valenzuela, C. Fernando

    2010-01-01

    Fetal Alcohol Spectrum Disorder (FASD) is associated with learning and memory alterations that could be, in part, a consequence of hippocampal damage. The CA3 hippocampal subfield is one of the regions affected by ethanol (EtOH), including exposure during the 3rd trimester-equivalent (i.e. neonatal period in rats). However, the mechanism of action of EtOH is poorly understood. In CA3 pyramidal neurons from neonatal rats, dendritic BDNF release causes long-term potentiation of the frequency of...

  10. Basal forebrain neurons suppress amygdala kindling via cortical but not hippocampal cholinergic projections in rats.

    Science.gov (United States)

    Ferencz, I; Leanza, G; Nanobashvili, A; Kokaia, M; Lindvall, O

    2000-06-01

    Intraventricular administration of the immunotoxin 192 IgG-saporin in rats has been shown to cause a selective loss of cholinergic afferents to the hippocampus and cortical areas, and to facilitate seizure development in hippocampal kindling. Here we demonstrate that this lesion also accelerates seizure progression when kindling is induced by electrical stimulations in the amygdala. However, whereas intraventricular 192 IgG-saporin facilitated the development of the initial stages of hippocampal kindling, the same lesion promoted the late stages of amygdala kindling. To explore the role of various parts of the basal forebrain cholinergic system in amygdala kindling, selective lesions of the cholinergic projections to either hippocampus or cortex were produced by intraparenchymal injections of 192 IgG-saporin into medial septum/vertical limb of the diagonal band or nucleus basalis, respectively. Cholinergic denervation of the cortical regions caused acceleration of amygdala kindling closely resembling that observed after the more widespread lesion induced by intraventricular 192 IgG-saporin. In contrast, removal of the cholinergic input to the hippocampus had no effect on the development of amygdala kindling. These data indicate that basal forebrain cholinergic neurons suppress kindling elicited from amygdala, and that this dampening effect is mediated via cortical but not hippocampal projections.

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

    Science.gov (United States)

    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.

  12. Effects of the muscarinic antagonists pirenzepine and gallamine on spontaneous and evoked responses of rat cerebral cortical neurones.

    Science.gov (United States)

    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

  13. Neurites regrowth of cortical neurons by GSK3beta inhibition independently of Nogo receptor 1.

    Science.gov (United States)

    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.

  14. Calcium Dynamics in Basal Dendrites of Layer 5A and 5B Pyramidal Neurons Is Tuned to the Cell-Type Specific Physiological Action Potential Discharge

    Directory of Open Access Journals (Sweden)

    Patrik Krieger

    2017-07-01

    Full Text Available Layer 5 (L5 is a major neocortical output layer containing L5A slender-tufted (L5A-st and L5B thick-tufted (L5B-tt pyramidal neurons. These neuron types differ in their in vivo firing patterns, connectivity and dendritic morphology amongst other features, reflecting their specific functional role within the neocortical circuits. Here, we asked whether the active properties of the basal dendrites that receive the great majority of synaptic inputs within L5 differ between these two pyramidal neuron classes. To quantify their active properties, we measured the efficacy with which action potential (AP firing patterns backpropagate along the basal dendrites by measuring the accompanying calcium transients using two-photon laser scanning microscopy in rat somatosensory cortex slices. For these measurements we used both “artificial” three-AP patterns and more complex physiological AP patterns that were previously recorded in anesthetized rats in L5A-st and L5B-tt neurons in response to whisker stimulation. We show that AP patterns with relatively few APs (3APs evoke a calcium response in L5B-tt, but not L5A-st, that is dependent on the temporal pattern of the three APs. With more complex in vivo recorded AP patterns, the average calcium response was similar in the proximal dendrites but with a decay along dendrites (measured up to 100 μm of L5B-tt but not L5A-st neurons. Interestingly however, the whisker evoked AP patterns—although very different for the two cell types—evoke similar calcium responses. In conclusion, although the effectiveness with which different AP patterns evoke calcium transients vary between L5A-st and L5B-tt cell, the calcium influx appears to be tuned such that whisker-evoked calcium transients are within the same dynamic range for both cell types.

  15. Enhanced intrinsic excitability and EPSP-spike coupling accompany enriched environment-induced facilitation of LTP in hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Malik, Ruchi; Chattarji, Sumantra

    2012-03-01

    Environmental enrichment (EE) is a well-established paradigm for studying naturally occurring changes in synaptic efficacy in the hippocampus that underlie experience-induced modulation of learning and memory in rodents. Earlier research on the effects of EE on hippocampal plasticity focused on long-term potentiation (LTP). Whereas many of these studies investigated changes in synaptic weight, little is known about potential contributions of neuronal excitability to EE-induced plasticity. Here, using whole-cell recordings in hippocampal slices, we address this gap by analyzing the impact of EE on both synaptic plasticity and intrinsic excitability of hippocampal CA1 pyramidal neurons. Consistent with earlier reports, EE increased contextual fear memory and dendritic spine density on CA1 cells. Furthermore, EE facilitated LTP at Schaffer collateral inputs to CA1 pyramidal neurons. Analysis of the underlying causes for enhanced LTP shows EE to increase the frequency but not amplitude of miniature excitatory postsynaptic currents. However, presynaptic release probability, assayed using paired-pulse ratios and use-dependent block of N-methyl-d-aspartate receptor currents, was not affected. Furthermore, CA1 neurons fired more action potentials (APs) in response to somatic depolarization, as well as during the induction of LTP. EE also reduced spiking threshold and after-hyperpolarization amplitude. Strikingly, this EE-induced increase in excitability caused the same-sized excitatory postsynaptic potential to fire more APs. Together, these findings suggest that EE may enhance the capacity for plasticity in CA1 neurons, not only by strengthening synapses but also by enhancing their efficacy to fire spikes-and the two combine to act as an effective substrate for amplifying LTP.

  16. Self-organized two-state membrane potential transitions in a network of realistically modeled cortical neurons.

    Science.gov (United States)

    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.

  17. Cyclin-Dependent Kinase 5 Regulates Dendritic Spine Formation and Maintenance of Cortical Neuron in the Mouse Brain.

    Science.gov (United States)

    Mita, Naoki; He, Xiaojuan; Sasamoto, Kodai; Mishiba, Tomohide; Ohshima, Toshio

    2016-03-01

    Cyclin-dependent kinase 5 (Cdk5) activity is dependent on its association with 1 of 2 neuron-specific activators, p35 or p39. Cdk5 and its activators play an important role in brain development as well as higher functions like synaptic plasticity, learning, and memory. Reduction in p35 was reported in postmortem schizophrenia brain, in which reduced dendritic spine density was observed. Previous in vitro experiments have shown that Cdk5 is involved in dendritic spine formation, although in vivo evidence is limited. We examined dendritic spine formation in inducible-p35 conditional knockout (p35 cKO); p39 KO mice. When we deleted the p35 gene either during early postnatal days or at adult stage, we observed reduced spine densities of layer V neurons in the cerebral cortex and CA1 pyramidal neurons in the hippocampus. We further generated CA1-specific p35 conditional knockout (CA1-p35 cKO) mice and also CA1-p35 cKO; p39 KO mice in which have specific deletion of p35 in the CA1 region of hippocampus. We found a greater reduction in spine densities in CA1 pyramidal neurons in CA1-p35 cKO; p39 KO mice than in CA1-p35 cKO mice. These results indicate that dendritic spine formation and neuronal maintenance are dependent on Cdk5 activity.

  18. Female Mice Lacking Estrogen Receptor-α in Hypothalamic Proopiomelanocortin (POMC) Neurons Display Enhanced Estrogenic Response on Cortical Bone Mass.

    Science.gov (United States)

    Farman, H H; Windahl, S H; Westberg, L; Isaksson, H; Egecioglu, E; Schele, E; Ryberg, H; Jansson, J O; Tuukkanen, J; Koskela, A; Xie, S K; Hahner, L; Zehr, J; Clegg, D J; Lagerquist, M K; Ohlsson, C

    2016-08-01

    Estrogens are important regulators of bone mass and their effects are mainly mediated via estrogen receptor (ER)α. Central ERα exerts an inhibitory role on bone mass. ERα is highly expressed in the arcuate (ARC) and the ventromedial (VMN) nuclei in the hypothalamus. To test whether ERα in proopiomelanocortin (POMC) neurons, located in ARC, is involved in the regulation of bone mass, we used mice lacking ERα expression specifically in POMC neurons (POMC-ERα(-/-)). Female POMC-ERα(-/-) and control mice were ovariectomized (OVX) and treated with vehicle or estradiol (0.5 μg/d) for 6 weeks. As expected, estradiol treatment increased the cortical bone thickness in femur, the cortical bone mechanical strength in tibia and the trabecular bone volume fraction in both femur and vertebrae in OVX control mice. Importantly, the estrogenic responses were substantially increased in OVX POMC-ERα(-/-) mice compared with the estrogenic responses in OVX control mice for cortical bone thickness (+126 ± 34%, P mass, ERα was silenced using an adeno-associated viral vector. Silencing of ERα in hypothalamic VMN resulted in unchanged bone mass. In conclusion, mice lacking ERα in POMC neurons display enhanced estrogenic response on cortical bone mass and mechanical strength. We propose that the balance between inhibitory effects of central ERα activity in hypothalamic POMC neurons in ARC and stimulatory peripheral ERα-mediated effects in bone determines cortical bone mass in female mice.

  19. The dynamic brain: from spiking neurons to neural masses and cortical fields.

    Directory of Open Access Journals (Sweden)

    Gustavo Deco

    2008-08-01

    Full Text Available 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

  20. Tissue-type plasminogen activator induces synaptic vesicle endocytosis in cerebral cortical neurons.

    Science.gov (United States)

    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.

  1. Combined small-molecule inhibition accelerates the derivation of functional cortical neurons from human pluripotent stem cells.

    Science.gov (United States)

    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.

  2. Neuroprotective effects of human telomerase reverse transcriptase on beta-amyloid fragment 25-35-treated human embryonic cortical neurons

    Institute of Scientific and Technical Information of China (English)

    Lingping Kong; Lingzhi Wu; Jie Zhang; Yaping Liao; Huaqiao Wang

    2009-01-01

    BACKGROUND:Numerous current studies have suggested that human telomerase reverse transcriptase (hTERT) gene has neuroprotective effects and can inhibit apoptosis induced by various cytotoxic stresses;however,the mechanism of action remains unknown.OBJECTIVE:To evaluate the neuroprotective effects and possible mechanism of action of hTERT gene transfection in human embryonic cortical neurons treated with beta-amyloid fragment 25-35 (Aβ25-35).DESIGN,TIME AND SETTING:The randomized,controlled and molecular biological studies were performed at the Department of Anatomy and Brain Research,Zhongshan School of Medicine,Sun Yat-sen University,China,from September 2005 to June 2008.MATERIALS:AdEasy-1 Expression System was gifted by Professor Guoquan Gao from Sun Yat-Sen University,China.Human cortical neurons were derived from 12-20 week old aborted fetuses,obtained from the Guangzhou Maternal and Child Health Hospital,China.Mouse anti-Cdk5 and mouse anti-p16 monoclonal antibodies (Lab Vision,USA),and mouse anti-hTERT monoclonal antibody (Epitomics,USA),were used in this study.METHODS:(1) Recombinant adenovirus vectors,encoding hTERT (Ad-hTERT) and green fluorescent protein (Ad-GFP),were constructed using the AdEasy-1 Expression System.Human embryonic cortical neurons in the Ad-hTERT group were transfected with Ad-hTERT for 1-21 days.Likewise,human embryonic cortical neurons in the Ad-GFP group were transfected with Ad-GFP for 1-21 days.Human embryonic cortical neurons in the control group were cultured as normal.(2) Human embryonic cortical neurons in the Ad-hTERT group were treated with 10 μmol/L Aβ25-35 for 24 hours.Normal human embryonic cortical neurons treated with 10 μmol/L Aβ25-35 for 24 hours served as a model group.Human embryonic cortical neurons in the Ad-GFP and control groups were not treated with Aβ25-35.MAIN OUTCOME MEASURES:Expression of hTERT in human embryonic cortical neurons was evaluated by immunocytochemical staining and Western blot assay

  3. Curcumin protects microglia and primary rat cortical neurons against HIV-1 gp120-mediated inflammation and apoptosis.

    Directory of Open Access Journals (Sweden)

    Luyan Guo

    Full Text Available Curcumin is a molecule found in turmeric root that has anti-inflammatory, antioxidant, and anti-tumor properties and has been widely used as both an herbal drug and a food additive to treat or prevent neurodegenerative diseases. To explore whether curcumin is able to ameliorate HIV-1-associated neurotoxicity, we treated a murine microglial cell line (N9 and primary rat cortical neurons with curcumin in the presence or absence of neurotoxic HIV-1 gp120 (V3 loop protein. We found that HIV-1 gp120 profoundly induced N9 cells to produce reactive oxygen species (ROS, tumor necrosis factor-α (TNF-α and monocyte chemoattractant protein-1 (MCP-1. HIV-1 gp120 also induced apoptosis of primary rat cortical neurons. Curcumin exerted a powerful inhibitory effect against HIV-1 gp120-induced neuronal damage, reducing the production of ROS, TNF-α and MCP-1 by N9 cells and inhibiting apoptosis of primary rat cortical neurons. Curcumin may exert its biological activities through inhibition of the delayed rectification and transient outward potassium (K(+ current, as curcumin effectively reduced HIV-1 gp120-mediated elevation of the delayed rectification and transient outward K(+ channel current in neurons. We conclude that HIV-1 gp120 increases ROS, TNF-α and MCP-1 production in microglia, and induces cortical neuron apoptosis by affecting the delayed rectification and transient outward K(+ channel current. Curcumin reduces production of ROS and inflammatory mediators in HIV-1-gp120-stimulated microglia, and protects cortical neurons against HIV-1-mediated apoptosis, most likely through inhibition of HIV-1 gp120-induced elevation of the delayed rectification and transient outward K(+ current.

  4. Graded defragmentation of cortical neuronal firing during recovery of consciousness in rats.

    Science.gov (United States)

    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.

  5. Synaptic responsiveness of cortical and thalamic neurones during various phases of slow sleep oscillation in cat.

    Science.gov (United States)

    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

  6. Use of cortical neuronal networks for in vitro material biocompatibility testing.

    Science.gov (United States)

    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.

  7. Assortment of GABAergic plasticity in the cortical interneuron melting pot.

    Science.gov (United States)

    Méndez, Pablo; Bacci, Alberto

    2011-01-01

    Cortical structures of the adult mammalian brain are characterized by a spectacular diversity of inhibitory interneurons, which use GABA as neurotransmitter. GABAergic neurotransmission is fundamental for integrating and filtering incoming information and dictating postsynaptic neuronal spike timing, therefore providing a tight temporal code used by each neuron, or ensemble of neurons, to perform sophisticated computational operations. However, the heterogeneity of cortical GABAergic cells is associated to equally diverse properties governing intrinsic excitability as well as strength, dynamic range, spatial extent, anatomical localization, and molecular components of inhibitory synaptic connections that they form with pyramidal neurons. Recent studies showed that similarly to their excitatory (glutamatergic) counterparts, also inhibitory synapses can undergo activity-dependent changes in their strength. Here, some aspects related to plasticity and modulation of adult cortical and hippocampal GABAergic synaptic transmission will be reviewed, aiming at providing a fresh perspective towards the elucidation of the role played by specific cellular elements of cortical microcircuits during both physiological and pathological operations.

  8. Aluminum—induced apoptosis in cultured cortical neurons and its effects on SAPK/JNK signal transduction pathway

    Institute of Scientific and Technical Information of China (English)

    FuHJ; DongSZ

    2002-01-01

    Aluminum (Al) exposure and apoptotic cell death have been implicated in several neurodegenerative diseases.the mechanisms by which Al interacts with the nervous system are only partly understood.In this study,we used cultured cortical neurons to investigate the ability of Al to induce the apoptosis of neurons and to explore the role of SAPK/JNK signal transduction pathway on the apoptosis induced by Al.It was found that Al-induced degeneration of cortical neurons involved the DNA fragmentation characteristic of apoptosis.The rate of apoptosis increased significantly,which was measured by TdT-mediated dUTKP nick end labeling.Westerm blot analysis showed that SAPK/JNK activities of cortical neurons varied when the dose and exposure time of AlCl3 were different.Our study demonstrates that Al can induce the apoptosis of cortical neurons and SAPK/JNK signal transduction pathway may play a great role in the apoptosis.

  9. Potential protection of green tea polyphenols against 1800 MHz electromagnetic radiation-induced injury on rat cortical neurons.

    Science.gov (United States)

    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.

  10. Neuroprotection with metformin and thymoquinone against ethanol-induced apoptotic neurodegeneration in prenatal rat cortical neurons

    Directory of Open Access Journals (Sweden)

    Ullah Ikram

    2012-01-01

    Full Text Available Abstract Background Exposure to ethanol during early development triggers severe neuronal death by activating multiple stress pathways and causes neurological disorders, such as fetal alcohol effects or fetal alcohol syndrome. This study investigated the effect of ethanol on intracellular events that predispose developing neurons for apoptosis via calcium-mediated signaling. Although the underlying molecular mechanisms of ethanol neurotoxicity are not completely determined, mitochondrial dysfunction, altered calcium homeostasis and apoptosis-related proteins have been implicated in ethanol neurotoxicity. The present study was designed to evaluate the neuroprotective mechanisms of metformin (Met and thymoquinone (TQ during ethanol toxicity in rat prenatal cortical neurons at gestational day (GD 17.5. Results We found that Met and TQ, separately and synergistically, increased cell viability after ethanol (100 mM exposure for 12 hours and attenuated the elevation of cytosolic free calcium [Ca2+]c. Furthermore, Met and TQ maintained normal physiological mitochondrial transmembrane potential (ΔψM, which is typically lowered by ethanol exposure. Increased cytosolic free [Ca2+]c and lowered mitochondrial transmembrane potential after ethanol exposure significantly decreased the expression of a key anti-apoptotic protein (Bcl-2, increased expression of Bax, and stimulated the release of cytochrome-c from mitochondria. Met and TQ treatment inhibited the apoptotic cascade by increasing Bcl-2 expression. These compounds also repressed the activation of caspase-9 and caspase-3 and reduced the cleavage of PARP-1. Morphological conformation of cell death was assessed by TUNEL, Fluoro-Jade-B, and PI staining. These staining methods demonstrated more cell death after ethanol treatment, while Met, TQ or Met plus TQ prevented ethanol-induced apoptotic cell death. Conclusion These findings suggested that Met and TQ are strong protective agents against ethanol

  11. 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.

    Science.gov (United States)

    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

  12. Ion channel density and threshold dynamics of repetitive firing in a cortical neuron model.

    Science.gov (United States)

    Arhem, Peter; Blomberg, Clas

    2007-01-01

    Modifying the density and distribution of ion channels in a neuron (by natural up- and down-regulation, by pharmacological intervention or by spontaneous mutations) changes its activity pattern. In the present investigation, we analyze how the impulse patterns are regulated by the density of voltage-gated channels in a model neuron, based on voltage clamp measurements of hippocampal interneurons. At least three distinct oscillatory patterns, associated with three distinct regions in the Na-K channel density plane, were found. A stability analysis showed that the different regions are characterized by saddle-node, double-orbit, and Hopf bifurcation threshold dynamics, respectively. Single strongly graded action potentials occur in an area outside the oscillatory regions, but less graded action potentials occur together with repetitive firing over a considerable range of channel densities. The presently found relationship between channel densities and oscillatory behavior may be relevance for understanding principal spiking patterns of cortical neurons (regular firing and fast spiking). It may also be of relevance for understanding the action of pharmacological compounds on brain oscillatory activity.

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

    Directory of Open Access Journals (Sweden)

    Mark Aizenberg

    2015-12-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  15. Cultured Cortical Neurons Can Perform Blind Source Separation According to the Free-Energy Principle.

    Directory of Open Access Journals (Sweden)

    Takuya Isomura

    2015-12-01

    Full Text Available 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.

  16. Green Tea Polyphenols Attenuated Glutamate Excitotoxicity via Antioxidative and Antiapoptotic Pathway in the Primary Cultured Cortical Neurons.

    Science.gov (United States)

    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.

  17. Slow recovery from inactivation of Na+ channels underlies the activity-dependent attenuation of dendritic action potentials in hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Colbert, C M; Magee, J C; Hoffman, D A; Johnston, D

    1997-09-01

    Na+ action potentials propagate into the dendrites of pyramidal neurons driving an influx of Ca2+ that seems to be important for associative synaptic plasticity. During repetitive (10-50 Hz) firing, dendritic action potentials display a marked and prolonged voltage-dependent decrease in amplitude. Such a decrease is not apparent in somatic action potentials. We investigated the mechanisms of the different activity dependence of somatic and dendritic action potentials in CA1 pyramidal neurons of adult rats using whole-cell and cell-attached patch-clamp methods. There were three main findings. First, dendritic Na+ currents decreased in amplitude when repeatedly activated by brief (2 msec) depolarizations. Recovery was slow and voltage-dependent. Second, Na+ currents decreased much less in somatic than in dendritic patches. Third, although K+ currents remained constant during trains, K+ currents were necessary for dendritic action potential amplitude to decrease in whole-cell experiments. These results suggest that regional differences in Na+ and K+ channels determine the differences in the activity dependence of somatic and dendritic action potential amplitudes.

  18. Aβ induces acute depression of excitatory glutamatergic synaptic transmission through distinct phosphatase-dependent mechanisms in rat CA1 pyramidal neurons.

    Science.gov (United States)

    Yao, Wen; Zou, Hao-Jun; Sun, Da; Ren, Si-Qiang

    2013-06-17

    Beta-amyloid peptide (Aβ) has a causal role in the pathophysiology of Alzheimer's disease (AD). Recent studies indicate that Aβ can disrupt excitatory glutamatergic synaptic function at synaptic level. However, the underlying mechanisms remain obscure. In this study, we recorded evoked and spontaneous EPSCs in hippocampal CA1 pyramidal neurons via whole-cell voltage-clamping methods and found that 1 μM Aβ can induce acute depression of basal glutamatergic synaptic transmission through both presynaptic and postsynaptic dysfunction. Moreover, we also found that Aβ-induced both presynaptic and postsynaptic dysfunction can be reversed by the inhibitor of protein phosphatase 2B (PP2B), FK506, whereas only postsynaptic disruption can be ameliorated by the inhibitor of PP1/PP2A, Okadaic acid (OA). These results indicate that PP1/PP2A and PP2B have overlapping but not identical functions in Aβ-induced acute depression of excitatory glutamatergic synaptic transmission of hippocampal CA1 pyramidal neurons.

  19. Conditional ablation of neuroligin-1 in CA1 pyramidal neurons blocks LTP by a cell-autonomous NMDA receptor-independent mechanism

    Science.gov (United States)

    Jiang, Man; Polepalli, Jai; Chen, Lulu Y.; Zhang, Bo; Südhof, Thomas C.; Malenka, Robert C.

    2016-01-01

    Neuroligins are postsynaptic cell-adhesion molecules implicated in autism and other neuropsychiatric disorders. Despite extensive work, the role of neuroligins in synapse function and plasticity, especially NMDA receptor (NMDAR)-dependent LTP, remains unclear. To establish which synaptic functions unequivocally require neuroligins, we analyzed single and triple conditional knockout (cKO) mice for all three major neuroligin isoforms (NL1-NL3). We inactivated neuroligins by stereotactic viral expression of Cre-recombinase in hippocampal CA1 region pyramidal neurons at postnatal day 0 (P0) or day 21 (P21), and measured synaptic function, synaptic plasticity, and spine numbers in acute hippocampal slices 2–3 weeks later. Surprisingly, we find that ablation of neuroligins in newborn or juvenile mice only modestly impaired basal synaptic function in hippocampus, and caused no alteration in postsynaptic spine numbers. However, triple cKO of NL1-NL3 or single cKO of NL1 impaired NMDAR-mediated excitatory postsynaptic currents (NMDAR EPSCs), and abolished NMDAR-dependent LTP. Strikingly, the NL1 cKO also abolished LTP elicited by activation of L-type Ca2+-channels during blockade of NMDARs. These findings demonstrate that neuroligins are generally not essential for synapse formation in CA1 pyramidal neurons but shape synaptic properties and that NL1 specifically is required for LTP induced by postsynaptic Ca2+-elevations, a function which may contribute to the pathophysiological role of neuroligins in brain disorders. PMID:27217145

  20. Latent N-methyl-D-aspartate receptors in the recurrent excitatory pathway between hippocampal CA1 pyramidal neurons: Ca(2+)-dependent activation by blocking A1 adenosine receptors.

    Science.gov (United States)

    Klishin, A; Tsintsadze, T; Lozovaya, N; Krishtal, O

    1995-01-01

    When performed at increased external [Ca2+]/[Mg2+] ratio (2.5 mM/0.5 mM), temporary block of A1 adenosine receptors in hippocampus [by 8-cyclopentyltheophylline (CPT)] leads to a dramatic and irreversible change in the excitatory postsynaptic current (EPSC) evoked by Schaffer collateral/commissural (SCC) stimulation and recorded by in situ patch clamp in CA1 pyramidal neurons. The duration of the EPSC becomes stimulus dependent, increasing with increase in stimulus strength. The later occurring component of the EPSC is carried through N-methyl-D-aspartate (NMDA) receptor-operated channels but disappears under either the NMDA antagonist 2-amino-5-phosphonovaleric acid (APV) or the non-NMDA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). These findings indicate that the late component of the SCC-evoked EPSC is polysynaptic: predominantly non-NMDA receptor-mediated SCC inputs excite CA1 neurons that recurrently excite each other by predominantly NDMA receptor-mediated synapses. These recurrent connections are normally silent but become active after CPT treatment, leading to enhancement of the late component of the EPSC. The activity of these connections is maintained for at least 2 hr after CPT removal. When all functional NMDA receptors are blocked by dizocilpine maleate (MK-801), subsequent application of CPT leads to a partial reappearance of NMDA receptor-mediated EPSCs evoked by SCC stimulation, indicating that latent NMDA receptors are recruited. Altogether, these findings indicate the existence of a powerful system of NMDA receptor-mediated synaptic contacts in SCC input to hippocampal CA1 pyramidal neurons and probably also in reciprocal connections between these neurons, which in the usual preparation are kept latent by activity of A1 receptors. PMID:8618915

  1. Transcranial Direct Current Stimulation modulates cortical neuronal activity in Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Sara eMarceglia

    2016-03-01

    Full Text Available 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 7 subjects with probable AD (Mini-Mental State Examination, MMSE score >20. EEG (21 electrodes, 10-20 international system was recorded for 5 minutes with eyes closed before (baseline, t0 and 30 minutes 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

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

    Science.gov (United States)

    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

  3. Adenosine A1 receptor-mediated transactivation of the EGF receptor produces a neuroprotective effect on cortical neurons in vitro

    Institute of Scientific and Technical Information of China (English)

    Ke-qiang XIE; Li-min ZHANG; Yan CAO; Jun ZHU; Lin-yin FENG

    2009-01-01

    Aim:To understand the mechanism of the transactivation of the epidermal growth factor receptor (EGFR) mediated by the adenosine A1 receptor (A1R).Methods:Primary cultured rat cortical neurons subjected to oxygen-glucose deprivation (OGD) and HEK293/A1R cells were treated with the A1R-specific agonist N6-cyclopentyladenosine (CPA).Phospho-EGFR,Akt,and ERK1/2 were observed by Western blot.An interaction between EGFR and AIR was detected using immunoprecipitation and immunocytochemistry.Results:The A1R agonist CPA causes protein kinase B (Akt) activation and protects primary cortical neurons from oxygen-glucose deprivation (OGD) insult.A1R and EGFR co-localize in the membranes of neurons and form an immunocomplex.A1R stimulation induces significant EGFR phosphorylation via a P13K and Src kinase signaling pathway;this stimulation provides a neuroprotective effect in cortical neurons.CPA leads to sustained phosphorylation of extracellularly regulated kinases 1 and 2 (ERK1/2) in cortical neurons,but only to transient phosphorylation in HEK 293/A1R cells.The response to the AtR agonist is mediated primarily through EGFR trans-activation that is dependent on pertussis toxin (PTX)-sensitive G1 protein and metalloproteases in HEK 293/A1R.Conclusion:A1R-mediated EGFR transactivation confers a neuroprotective effect in primary cortical neurons.P13 kinase and Src kinase play pivotal roles in this response.

  4. Bcl11a (Ctip1) Controls Migration of Cortical Projection Neurons through Regulation of Sema3c.

    Science.gov (United States)

    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.

  5. Characterization of single voltage-gated Na+ and Ca2+ channels in apical dendrites of rat CA1 pyramidal neurons.

    Science.gov (United States)

    Magee, J C; Johnston, D

    1995-08-15

    1. We have used dendrite-attached patch-clamp techniques to record single Na+ and Ca2+ channel activity from the apical dendrites (up to 350 microns away from soma) of CA1 pyramidal neurons in rat hippocampal slices (ages: 2-8 weeks). 2. Na+ channels were found in every patch examined (range: 2 to > 20 channels per patch). Channel openings, which had a slope conductance of 15 +/- 0.3 pS (mean +/- S.E.M.), began with test commands to around -50 mV and consisted of both early transient channel activity and also later occurring prolonged openings of 5-15 ms. All Na+ channel activity was suppressed by inclusion of TTX (1 microM) in the recording pipette. 3. Ca2+ channel activity was recorded in about 80% of the patches examined (range: 1 to > 10 channels per patch). Several types of channel behaviour were observed in these patches. Single channel recordings in 110 mM BaCl2, revealed an approximately 10 pS channel of small unitary current amplitude (-0.5 pA at -20 mV). These channels began activating at relatively hyperpolarized potentials (-50 mV) and ensemble averages of this low voltage-activated (LVA) channel activity showed rapid inactivation. 4. A somewhat heterogeneous population of high voltage-activated, moderate conductance (HVAm; approximately 17 pS), Ca2+ channel activity was also encountered. These channels exhibited a relatively large unitary amplitude (-0.8 pA at 0 mV) and ensemble averages demonstrated moderate inactivation. The HVAm population of channels could be tentatively subdivided into two separate groups based upon mean channel open times. 5. Less frequently, HVA, large conductance (27 pS) Ca2+ channel activity (HVA1) was also observed. This large unitary amplitude (-1.5 pA at 0 mV) channel activity began with steps to approximately 0 mV and ensemble averages did not show any time-dependent inactivation. The dihydropyridine Ca2+ channel agonist Bay K 8644 (0.5 or 1 microM) was found to characteristically prolong these channel openings. 6. omega

  6. Neuron-specific stimulus masking reveals interference in spike timing at the cortical level.

    Science.gov (United States)

    Larson, Eric; Maddox, Ross K; Perrone, Ben P; Sen, Kamal; Billimoria, Cyrus P

    2012-02-01

    The auditory system is capable of robust recognition of sounds in the presence of competing maskers (e.g., other voices or background music). This capability arises despite the fact that masking stimuli can disrupt neural responses at the cortical level. Since the origins of such interference effects remain unknown, in this study, we work to identify and quantify neural interference effects that originate due to masking occurring within and outside receptive fields of neurons. We record from single and multi-unit auditory sites from field L, the auditory cortex homologue in zebra finches. We use a novel method called spike timing-based stimulus filtering that uses the measured response of each neuron to create an individualized stimulus set. In contrast to previous adaptive experimental approaches, which have typically focused on the average firing rate, this method uses the complete pattern of neural responses, including spike timing information, in the calculation of the receptive field. When we generate and present novel stimuli for each neuron that mask the regions within the receptive field, we find that the time-varying information in the neural responses is disrupted, degrading neural discrimination performance and decreasing spike timing reliability and sparseness. We also find that, while removing stimulus energy from frequency regions outside the receptive field does not significantly affect neural responses for many sites, adding a masker in these frequency regions can nonetheless have a significant impact on neural responses and discriminability without a significant change in the average firing rate. These findings suggest that maskers can interfere with neural responses by disrupting stimulus timing information with power either within or outside the receptive fields of neurons.

  7. Buffer capacity of rat cortical tissue as well as of cultured neurons and astrocytes.

    Science.gov (United States)

    Katsura, K; Mellergård, P; Theander, S; Ouyang, Y B; Siesjö, B K

    1993-08-06

    The primary objective of this work was to assess the intrinsic nonbicarbonate buffer capacity (beta i) of cultured neurons and astrocytes and to compare the beta i values obtained to those of neocortical tissue. A second objective was to determine the pH dependence of beta i. Titration of homogenates of whole-brain cortical tissue and cultured neurons with NaOH and HCl gave beta i values of 25-30 mmol.l-1 x pH-1. The buffer capacity was essentially constant in the pH range of 6-7. Astrocytes showed a higher buffer capacity and a clear relationship between beta i and pH. However, beta i decreased when pH was reduced from 7 to 6. The beta i values derived from microspectrofluorometric studies on neurons and astrocytes were surprisingly variable, ranging from 10 to 50 mmol.l-1 x pH-1. The ammonia "step method" suggested that beta i increased dramatically when pH was lowered from 7 to 6 but the propionic "step method" failed to reveal such a pH dependence. Some techniques obviously give erroneous values for beta i, presumably because changes in buffer base concentration (due to transmembrane fluxes of H+, HCO3-, NH4+ or anions of weak acids) violate the principles upon which the calculations are based. From the results obtained by direct titration and with the propionate technique, we tentatively conclude that beta i in neurons and astrocytes are approximately 20 and 30 mmol.l-1 x pH-1, respectively. We further suggest that the term "intrinsic buffer capacity", as commonly used, is redefined.

  8. The effects of realistic synaptic distribution and 3D geometry on signal integration and extracellular field generation of hippocampal pyramidal cells and inhibitory neurons

    Directory of Open Access Journals (Sweden)

    Attila I Gulyas

    2016-11-01

    Full Text Available In vivo and in vitro multichannel field and somatic intracellular recordings are frequently used to study mechanisms of network pattern generation. When interpreting these data, neurons are often implicitly considered as electrotonically compact cylinders with a homogeneous distribution of excitatory and inhibitory inputs. However, the actual distributions of dendritic length, diameter, and the densities of excitatory and inhibitory input are non-uniform and cell type-specific. We first review quantitative data on the dendritic structure and synaptic input and output distribution of pyramidal cells and interneurons in the hippocampal CA1 area. Second, using multicompartmental passive models of four different types of neurons, we quantitatively explore the effect of differences in dendritic structure and synaptic distribution on the errors and biases of voltage clamp measurements of inhibitory and excitatory postsynaptic currents. Finally, using the 3-dimensional distribution of dendrites and synaptic inputs we calculate how different inhibitory and excitatory inputs contribute to the generation of local field potential in the hippocampus. We analyze these effects at different realistic background activity levels as synaptic bombardment influences neuronal conductance and thus the propagation of signals in the dendritic tree.We conclude that, since dendrites are electrotonically long and entangled in 3D, somatic intracellular and field potential recordings miss the majority of dendritic events in some cell types, and thus overemphasize the importance of perisomatic inhibitory inputs and belittle the importance of complex dendritic processing. Modeling results also suggest that pyramidal cells and inhibitory neurons probably use different input integration strategies. In pyramidal cells, second- and higher-order thin dendrites are relatively well-isolated from each other, which may support branch-specific local processing as suggested by studies

  9. Cadmium induces reactive oxygen species generation and lipid peroxidation in cortical neurons in culture.

    Science.gov (United States)

    López, E; Arce, C; Oset-Gasque, M J; Cañadas, S; González, M P

    2006-03-15

    Cadmium is a toxic agent that it is also an environmental contaminant. Cadmium exposure may be implicated in some humans disorders related to hyperactivity and increased aggressiveness. This study presents data indicating that cadmium induces cellular death in cortical neurons in culture. This death could be mediated by an apoptotic and a necrotic mechanism. The apoptotic death may be mediated by oxidative stress with reactive oxygen species (ROS) formation which could be induced by mitochondrial membrane dysfunction since this cation produces: (a) depletion of mitochondrial membrane potential and (b) diminution of ATP levels with ATP release. Necrotic death could be mediated by lipid peroxidation induced by cadmium through an indirect mechanism (ROS formation). On the other hand, 40% of the cells survive cadmium action. This survival seems to be mediated by the ability of these cells to activate antioxidant defense systems, since cadmium reduced the intracellular glutathione levels and induced catalase and SOD activation in these cells.

  10. Neuronal dysfunction and disconnection of cortical hubs in non-demented subjects with elevated amyloid burden

    Science.gov (United States)

    Drzezga, Alexander; Van Dijk, Koene R. A.; Sreenivasan, Aishwarya; Talukdar, Tanveer; Sullivan, Caroline; Schultz, Aaron P.; Sepulcre, Jorge; Putcha, Deepti; Greve, Doug; Johnson, Keith A.; Sperling, Reisa A.

    2011-01-01

    Disruption of functional connectivity between brain regions may represent an early functional consequence of β-amyloid pathology prior to clinical Alzheimer's disease. We aimed to investigate if non-demented older individuals with increased amyloid burden demonstrate disruptions of functional whole-brain connectivity in cortical hubs (brain regions typically highly connected to multiple other brain areas) and if these disruptions are associated with neuronal dysfunction as measured with fluorodeoxyglucose-positron emission tomography. In healthy subjects without cognitive symptoms and patients with mild cognitive impairment, we used positron emission tomography to assess amyloid burden and cerebral glucose metabolism, structural magnetic resonance imaging to quantify atrophy and novel resting state functional magnetic resonance imaging processing methods to calculate whole-brain connectivity. Significant disruptions of whole-brain connectivity were found in amyloid-positive patients with mild cognitive impairment in typical cortical hubs (posterior cingulate cortex/precuneus), strongly overlapping with regional hypometabolism. Subtle connectivity disruptions and hypometabolism were already present in amyloid-positive asymptomatic subjects. Voxel-based morphometry measures indicate that these findings were not solely a consequence of regional atrophy. Whole-brain connectivity values and metabolism showed a positive correlation with each other and a negative correlation with amyloid burden. These results indicate that disruption of functional connectivity and hypometabolism may represent early functional consequences of emerging molecular Alzheimer's disease pathology, evolving prior to clinical onset of dementia. The spatial overlap between hypometabolism and disruption of connectivity in cortical hubs points to a particular susceptibility of these regions to early Alzheimer's-type neurodegeneration and may reflect a link between synaptic dysfunction and functional

  11. Neurotoxicity of Ecstasy metabolites in rat cortical neurons, and influence of hyperthermia.

    Science.gov (United States)

    Capela, João Paulo; Meisel, Andreas; Abreu, Artur Reis; Branco, Paula Sério; Ferreira, Luísa Maria; Lobo, Ana Maria; Remião, Fernando; Bastos, Maria Lurdes; Carvalho, Félix

    2006-01-01

    3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") is a widely abused, psychoactive recreational drug. There is growing evidence that the MDMA neurotoxic profile may be highly dependent on both its hepatic metabolism and body temperature. Metabolism of MDMA involves N-demethylation to 3,4-methylenedioxyamphetamine (MDA), which is also a drug of abuse. MDMA and MDA are O-demethylenated to N-methyl-alpha-methyldopamine (N-Me-alpha-MeDA) and alpha-methyldopamine (alpha-MeDA), respectively, both of which are catechols that can undergo oxidation to the corresponding ortho-quinones. In the presence of glutathione (GSH), ortho-quinones may be conjugated with GSH to form glutathionyl adducts. In this study, we evaluated the neurotoxicity of MDMA and three of its metabolites obtained by synthesis, N-Me-alpha-MeDA, alpha-MeDA, and 5-(GSH)-alpha-MeDA [5-(glutathion-S-yl)-alpha-methyldopamine] in rat cortical neuronal serum-free cultures under normal (36.5 degrees C) and hyperthermic (40 degrees C) conditions. Cell viability was assessed, and the mechanism of cell death was also evaluated. Our study shows that these metabolites are more neurotoxic [5-(GSH)-alpha-MeDA being the most toxic] than the parent compound MDMA. The neurotoxicity of MDMA metabolites was partially prevented by the antioxidants N-acetylcystein and also, in a minor extent, by alpha-phenyl-N-tert-butyl nitrone. All the tested compounds induced apoptotic cell death in cortical neurons, and their neurotoxic effect was potentiated under hyperthermic conditions. These data suggest that MDMA metabolites, especially under hyperthermic conditions, contribute to MDMA-induced neurotoxicity.

  12. Restoration of Progranulin Expression Rescues Cortical Neuron Generation in an Induced Pluripotent Stem Cell Model of Frontotemporal Dementia

    Directory of Open Access Journals (Sweden)

    Susanna Raitano

    2015-01-01

    Full Text Available To understand how haploinsufficiency of progranulin (PGRN causes frontotemporal dementia (FTD, we created induced pluripotent stem cells (iPSCs from patients carrying the GRNIVS1+5G > C mutation (FTD-iPSCs. FTD-iPSCs were fated to cortical neurons, the cells most affected in FTD. Although generation of neuroprogenitors was unaffected, their further differentiation into CTIP2-, FOXP2-, or TBR1-TUJ1 double-positive cortical neurons, but not motorneurons, was significantly decreased in FTD-neural progeny. Zinc finger nuclease-mediated introduction of GRN cDNA into the AAVS1 locus corrected defects in cortical neurogenesis, demonstrating that PGRN haploinsufficiency causes inefficient cortical neuron generation. RNA sequencing analysis confirmed reversal of the altered gene expression profile following genetic correction. We identified the Wnt signaling pathway as one of the top defective pathways in FTD-iPSC-derived neurons, which was reversed following genetic correction. Differentiation of FTD-iPSCs in the presence of a WNT inhibitor mitigated defective corticogenesis. Therefore, we demonstrate that PGRN haploinsufficiency hampers corticogenesis in vitro.

  13. Evaluation of the Neuroactivity of ToxCast Compounds Using Multi-well Microelectrode Array Recordings in Primary Cortical Neurons

    Science.gov (United States)

    Evaluation of the Neuroactivity of ToxCast Compounds Using Multi-well Microelectrode Array Recordings in Primary Cortical Neurons P Valdivia1, M Martin2, WR LeFew3, D Hall3, J Ross1, K Houck2 and TJ Shafer3 1Axion Biosystems, Atlanta GA and 2NCCT, 3ISTD, NHEERL, ORD, US EPA, RT...

  14. Expression of exogenous LIN28 contributes to proliferation and survival of mouse primary cortical neurons in vitro.

    Science.gov (United States)

    Bhuiyan, M I H; Lee, J-H; Kim, S Y; Cho, K-O

    2013-09-17

    LIN28, an RNA-binding protein, is known to be involved in the regulation of many cellular processes, such as embryonic stem cell proliferation, cell fate succession, developmental timing, and oncogenesis. In this study, we investigated the effect of constitutively expressing exogenous LIN28 on neuronal cell proliferation and viability in vitro. Plasmids containing LIN28-green fluorescent protein (GFP) or GFP were introduced into the embryonic mouse brains at E14.5 by in utero electroporation. Two days after electroporation, embryonic cortices were harvested and cultured. It was found that transfected cells stably overexpressed LIN28 in vitro. Viability curve from live cell imaging showed that the number of GFP-expressing cells decreased over time in line with naive primary cortical neurons. In contrast, the number of LIN28-GFP-overexpressing neurons initially increased and remained high at later time-points in culture than GFP-expressing cells. Double immunofluorescence showed that at an early time in culture, the number of Ki-67/GFP double-positive cells was higher in the LIN28-GFP group than that of controls. Moreover, there were significantly lower numbers of condensed nuclei/GFP- and cleaved caspase-3/GFP-positive cells in the LIN28-GFP groups compared to control GFP. Furthermore, it was confirmed that the LIN28-GFP-expressing cells at days in vitro (DIV)13 were neuronal nuclei (NeuN)-positive mature neurons. Finally, the expression of insulin-like growth factor 2 (IGF-2) was induced in LIN28-expressing primary cortical neurons, which was not detected in controls. Taken together, our results indicate that the expression of exogenous LIN28 can promote the proliferation of neural progenitor cells and exert prosurvival effect on primary cortical neurons by inhibiting caspase-dependent apoptosis, possibly via upregulation of IGF-2. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  15. The mammalian neocortical pyramidal cell: a new theory on prenatal development

    Directory of Open Access Journals (Sweden)

    Miguel eMarín-Padilla

    2014-01-01

    Full Text Available Mammals’ new cerebral cortex (neocortex and the new type of pyramidal neuron are mammalian innovations that have evolved for operating their increasing motor capabilities using essentially analogous anatomical and neural makeups. The human neocortex starts to develop in the 6-week-old embryo with the establishment of a primordial cortical organization that resembles the primitive cortices of amphibian and reptiles that operated his early motor activities. From the 8th to the 15th week of age, the new pyramidal neurons, of ependymal origin, are progressively incorporated within this primordial cortex forming a cellular plate that divide its components into those above it (neocortex first lamina and those below it (neocortex subplate elements. From the 16th week of age to birth and postnatally, the new pyramidal neurons continue to elongate functionally their apical dendrite by adding synaptic membrane to incorporate the needed sensory information for operating the animal muscular activities. The new pyramidal neuron’ distinguishing feature is the capacity of elongating anatomically and functionally its apical dendrite (its main receptive surface without losing its original attachment to first lamina or the location of its soma retaining its essential nature. The number of pyramidal cell functional strata established in the motor cortex increases and reflects each mammalian species motor capabilities: the hedgehog needs 2 pyramidal cell functional strata to carry out all its motor activities, the mouse three, cat four, primates 5 and humans 6. The presence of six pyramidal cell functional strata distinguish the human motor cortex from that of others primates. Homo sapiens represent a new evolutionary stage that have transformed his primate brain for operating his unique motor capabilities, such as speaking, writing, painting, sculpturing including thinking as a premotor activity.

  16. Genotype-specific effects of Mecp2 loss-of-function on morphology of Layer V pyramidal neurons in heterozygous female Rett Syndrome model mice

    Directory of Open Access Journals (Sweden)

    Leslie eRietveld

    2015-04-01

    Full Text Available Rett Syndrome (RTT is a progressive neurological disorder primarily caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2. The heterozygous female brain consists of mosaic of neurons containing both wildtype MeCP2 (MeCP2+ and mutant MeCP2 (MeCP2-. 3-dimensional morphological analysis was performed on individually genotyped layer V pyramidal neurons in the primary motor cortex of heterozygous (Mecp2+/- and wild-type (Mecp2+/+ female mice (>6 mo. from the Mecp2tm1.1Jae line. Comparing basal dendrite morphology, soma and nuclear size of MeCP2+ to MeCP2- neurons reveals a significant cell autonomous, genotype specific effect of Mecp2. MeCP2- neurons have 15% less total basal dendritic length, predominantly in the region 70-130 μm from the cell body and on average 3 fewer branch points, specifically loss in the 2nd and 3rd branch orders. Soma and nuclear areas of neurons of mice were analyzed across a range of ages (5-21 mo. and X-chromosome inactivation (XCI ratios (12-56%. On average, MeCP2- somata and nuclei were 15% and 13% smaller than MeCP2+ neurons respectively. In most respects branching morphology of neurons in wild-type brains (MeCP2 WT was not distinguishable from MeCP2+ but somata and nuclei of MeCP2 WT neurons were larger than those of MeCP2+ neurons. These data reveal cell autonomous effects of Mecp2 mutation on dendritic morphology, but also suggest non-cell autonomous effects with respect to cell size. MeCP2+ and MeCP2- neuron sizes were not correlated with age, but were correlated with XCI ratio. Unexpectedly the MeCP2- neurons were smallest in brains where the XCI ratio was highly skewed towards MeCP2+, i.e. wild-type. This raises the possibility of cell non-autonomous effects that act through mechanisms other than globally secreted factors; perhaps competition for synaptic connections influences cell size and morphology in the genotypically mosaic brain of RTT model mice.

  17. Genotype-specific effects of Mecp2 loss-of-function on morphology of Layer V pyramidal neurons in heterozygous female Rett syndrome model mice.

    Science.gov (United States)

    Rietveld, Leslie; Stuss, David P; McPhee, David; Delaney, Kerry R

    2015-01-01

    Rett syndrome (RTT) is a progressive neurological disorder primarily caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2). The heterozygous female brain consists of mosaic of neurons containing both wild-type MeCP2 (MeCP2+) and mutant MeCP2 (MeCP2-). Three-dimensional morphological analysis was performed on individually genotyped layer V pyramidal neurons in the primary motor cortex of heterozygous (Mecp2(+/-) ) and wild-type (Mecp2(+/+) ) female mice ( > 6 mo.) from the Mecp2(tm1.1Jae) line. Comparing basal dendrite morphology, soma and nuclear size of MeCP2+ to MeCP2- neurons reveals a significant cell autonomous, genotype specific effect of Mecp2. MeCP2- neurons have 15% less total basal dendritic length, predominantly in the region 70-130 μm from the cell body and on average three fewer branch points, specifically loss in the second and third branch orders. Soma and nuclear areas of neurons of mice were analyzed across a range of ages (5-21 mo.) and X-chromosome inactivation (XCI) ratios (12-56%). On average, MeCP2- somata and nuclei were 15 and 13% smaller than MeCP2+ neurons respectively. In most respects branching morphology of neurons in wild-type brains (MeCP2 WT) was not distinguishable from MeCP2+ but somata and nuclei of MeCP2 WT neurons were larger than those of MeCP2+ neurons. These data reveal cell autonomous effects of Mecp2 mutation on dendritic morphology, but also suggest non-cell autonomous effects with respect to cell size. MeCP2+ and MeCP2- neuron sizes were not correlated with age, but were correlated with XCI ratio. Unexpectedly the MeCP2- neurons were smallest in brains where the XCI ratio was highly skewed toward MeCP2+, i.e., wild-type. This raises the possibility of cell non-autonomous effects that act through mechanisms other than globally secreted factors; perhaps competition for synaptic connections influences cell size and morphology in the genotypically mosaic brain of RTT model mice.

  18. Golgi Analysis of Neuron Morphology in the Presumptive Somatosensory Cortex and Visual Cortex of the Florida Manatee (Trichechus manatus latirostris).

    Science.gov (United States)

    Reyes, Laura D; Harland, Tessa; Reep, Roger L; Sherwood, Chet C; Jacobs, Bob

    2016-01-01

    The current study investigates neuron morphology in presumptive primary somatosensory (S1) and primary visual (V1) cortices of the Florida manatee (Trichechus manatus latirostris) as revealed by Golgi impregnation. Sirenians, including manatees, have an aquatic lifestyle, a large body size, and a relatively large lissencephalic brain. The present study examines neuron morphology in 3 cortical areas: in S1, dorsolateral cortex area 1 (DL1) and cluster cortex area 2 (CL2) and in V1, dorsolateral cortex area 4 (DL4). Neurons exhibited a variety of morphological types, with pyramidal neurons being the most common. The large variety of neuron types present in the manatee cortex was comparable to that seen in other eutherian mammals, except for rodents and primates, where pyramid-shaped neurons predominate. A comparison between pyramidal neurons in S1 and V1 indicated relatively greater dendritic branching in S1. Across all 3 areas, the dendritic arborization pattern of pyramidal neurons was also similar to that observed previously in the afrotherian rock hyrax, cetartiodactyls, opossums, and echidnas but did not resemble the widely bifurcated dendrites seen in the large-brained African elephant. Despite adaptations for an aquatic environment, manatees did not share specific neuron types such as tritufted and star-like neurons that have been found in cetaceans. Manatees exhibit an evolutionarily primitive pattern of cortical neuron morphology shared with most other mammals and do not appear to have neuronal specializations for an aquatic niche.

  19. Increased proximal bifurcation of CA1 pyramidal apical dendrites in sema3A mutant mice.

    Science.gov (United States)

    Nakamura, Fumio; Ugajin, Kozue; Yamashita, Naoya; Okada, Takako; Uchida, Yutaka; Taniguchi, Masahiko; Ohshima, Toshio; Goshima, Yoshio

    2009-10-10

    Semaphorin-3A (Sema3A) is an attractive guidance molecule for cortical apical dendrites. To elucidate the role of Sema3A in hippocampal dendritic formation, we examined the Sema3A expression pattern in the perinatal hippocampal formation and analyzed hippocampal dendrites of the brains from young adult sema3A mutant mice. Sema3A protein was predominantly expressed in the hippocampal plate and the inner marginal zone at the initial period of apical dendritic growth. Neuropilin-1 and plexin-A, the receptor components for Sema3A, were also localized in the same regions. The Golgi impregnation method revealed that in wildtype mice more than 90% of hippocampal CA1 pyramidal neurons extended a single trunk or apical trunks bifurcated in stratum radiatum. Seven percent of the pyramidal neurons showed proximal bifurcation of apical trunks in stratum pyramidale or at the border of the stratum pyramidale and stratum radiatum. In sema3A mutant mice, proximally bifurcated apical dendrites were increased to 32%, while the single apical dendritic pyramidal neurons were decreased. We designate this phenotype in sema3A mutant mice as "proximal bifurcation." In the dissociated culture system, approximately half of the hippocampal neurons from wildtype mice resembled pyramidal neurons, which possess a long, thick, and tapered dendrite. In contrast, only 30% of the neurons from sema3A mutants exhibited pyramidal-like morphology. Proximal bifurcation of CA1 pyramidal neurons was also increased in the mutant mice of p35, an activator of cyclin-dependent kinase 5 (Cdk5). Thus, Sema3A may facilitate the initial growth of CA1 apical dendrites via the activation of p35/Cdk5, which may in turn signal hippocampal development.