17 results on '"Neuronal Plasticity and Repair"'
Search Results
2. Editorial: Karolinska Institutet 200-Year Anniversary Symposium on Injuries to the Spinal Cord and Peripheral Nervous System--An Update on Recent Advances in Regenerative Neuroscience.
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Sköld, Mattias K. and Fehlings, Michael G.
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SPINAL cord injuries ,BRACHIAL plexus ,WOUNDS & injuries ,NERVOUS system injuries - Published
- 2017
- Full Text
- View/download PDF
3. Capacitance measurement of dendritic exocytosis in an electrically coupled inhibitory retinal interneuron: an experimental and computational study
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Bas-Jan Zandt, Margaret Lin Veruki, and Espen Hartveit
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inhibitory interneuron ,retina ,Patch-Clamp Techniques ,Interneuron ,presynaptic ,Physiology ,AII amacrine cell ,capacitance ,030204 cardiovascular system & hematology ,Inhibitory postsynaptic potential ,Synaptic vesicle ,Capacitance ,Exocytosis ,lcsh:Physiology ,03 medical and health sciences ,0302 clinical medicine ,Neuronal Plasticity and Repair ,Postsynaptic potential ,Interneurons ,Physiology (medical) ,medicine ,Neural Circuits and Systems ,Animals ,Computer Simulation ,Original Research ,lcsh:QP1-981 ,Chemistry ,Cell Membrane ,Dendrites ,Rats ,Electrophysiology ,medicine.anatomical_structure ,Amacrine Cells ,Biophysics ,Soma ,Female ,Sensory Neuroscience ,exocytosis ,compartmental model ,030217 neurology & neurosurgery ,glycine - Abstract
Exocytotic release of neurotransmitter can be quantified by electrophysiological recording from postsynaptic neurons. Alternatively, fusion of synaptic vesicles with the cell membrane can be measured as increased capacitance by recording directly from a presynaptic neuron. The “Sine + DC” technique is based on recording from an unbranched cell, represented by an electrically equivalent RC-circuit. It is challenging to extend such measurements to branching neurons where exocytosis occurs at a distance from a somatic recording electrode. The AII amacrine is an important inhibitory interneuron of the mammalian retina and there is evidence that exocytosis at presynaptic lobular dendrites increases the capacitance. Here, we combined electrophysiological recording and computer simulations with realistic compartmental models to explore capacitance measurements of rat AII amacrine cells. First, we verified the ability of the “Sine + DC” technique to detect depolarizationevoked exocytosis in physiological recordings. Next, we used compartmental modeling to demonstrate that capacitance measurements can detect increased membrane surface area at lobular dendrites. However, the accuracy declines for lobular dendrites located further from the soma due to frequency-dependent signal attenuation. For sine wave frequencies ≥1 kHz, the magnitude of the total releasable pool of synaptic vesicles will be significantly underestimated. Reducing the sine wave frequency increases overall accuracy, but when the frequency is sufficiently low that exocytosis can be detected with high accuracy from all lobular dendrites (~100 Hz), strong electrical coupling between AII amacrines compromises the measurements. These results need to be taken into account in studies with capacitance measurements from these and other electrically coupled neurons. publishedVersion
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- 2019
4. Effects of anodal transcranial direct current stimulation on motor evoked potentials variability in humans
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Shafiq Ahmad, Woo-Kyoung Yoo, Ali Hamza, Shahid Bashir, Mohamed Sharaf, Shirely Fecteau, and Moath Alatefi
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Adult ,Male ,Central Nervous System ,medicine.medical_specialty ,Adolescent ,Physiology ,medicine.medical_treatment ,Stimulation ,030204 cardiovascular system & hematology ,Audiology ,Transcranial Direct Current Stimulation ,lcsh:Physiology ,Motor evoked potentials ,03 medical and health sciences ,0302 clinical medicine ,Neuronal Plasticity and Repair ,Physiology (medical) ,Cortex (anatomy) ,Humans ,Medicine ,Original Research ,Analysis of Variance ,lcsh:QP1-981 ,Transcranial direct-current stimulation ,business.industry ,Motor Cortex ,Healthy subjects ,Evoked Potentials, Motor ,Corticospinal excitability ,Transcranial magnetic stimulation ,medicine.anatomical_structure ,Brain stimulation ,Female ,Resting motor threshold ,Primary motor cortex ,business ,030217 neurology & neurosurgery ,Motor Control ,Motor cortex - Abstract
Motor evoked potentials (MEPs) obtained from transcranial magnetic stimulation (TMS) allow corticospinal excitability (CSE) to be measured in the human primary motor cortex (M1). CSE responses to transcranial direct current stimulation (tDCS) protocols are highly variable. Here, we tested the reproducibility and reliability of individual MEPs following a common anodal tDCS protocol. In this study, 32 healthy subjects received anodal tDCS stimulation over the left M1 for three durations (tDCS‐T5, tDCS‐T10, and tDCS‐T20 min) on separate days in a crossover‐randomized order. After the resting motor threshold (RMT) was determined for the contralateral first dorsal interosseous muscle, 15 single pulses 4–8 sec apart at an intensity of 120% RMT were delivered to the left M1 to determine the baseline MEP amplitude at T0, T5, T10, T20, T30, T40, T50, and T60 min after stimulation for each durations. During TMS delivery, 3D images of the participant's cortex and hot spot were visualized for obtaining MEPs from same position. Our findings revealed that there was a significant MEPs improvement at T0 (P = 0.01) after 10 min of anodal stimulation. After the 20‐min stimulation duration, MEPs differed specifically at T0, T5, T30 min (P
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- 2019
5. Effect of adenosine on short-term synaptic plasticity in mouse piriform cortex in vitro: adenosine acts as a high-pass filter
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Lionel G. Nowak, Simon P. Perrier, Caroline Fonta, Marie Gleizes, Université Paris Nanterre - UFR Sciences sociales et administration (UPN SSA), Université Paris Nanterre (UPN), Centre de recherche cerveau et cognition (CERCO), Institut des sciences du cerveau de Toulouse. (ISCT), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), ROSITO, Maxime, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
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Central Nervous System ,Adenosine ,Time Factors ,Physiology ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Models, Neurological ,Stimulation ,030204 cardiovascular system & hematology ,In Vitro Techniques ,Synaptic Transmission ,A1 receptor ,03 medical and health sciences ,Adenosine A1 receptor ,chemistry.chemical_compound ,Cellular and Molecular Neuroscience ,piriform cortex ,0302 clinical medicine ,Neuronal Plasticity and Repair ,Postsynaptic potential ,Physiology (medical) ,Piriform cortex ,medicine ,Animals ,Neurotransmitter ,Original Research ,Neuronal Plasticity ,Receptor, Adenosine A1 ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,oscillation ,presynaptic inhibition ,Electric Stimulation ,short‐term plasticity ,Olfactory bulb ,Adenosine A1 Receptor Agonists ,Mice, Inbred C57BL ,chemistry ,Synaptic plasticity ,Biophysics ,Female ,short-term plasticity ,030217 neurology & neurosurgery ,medicine.drug - Abstract
International audience; We examined the effect of adenosine and of adenosine A1 receptor blockage on short‐term synaptic plasticity in slices of adult mouse anterior piriform cortex maintained in vitro in an in vivo‐like ACSF. Extracellular recording of postsynaptic responses was performed in layer 1a while repeated electrical stimulation (5‐pulse‐trains, frequency between 3.125 and 100 Hz) was applied to the lateral olfactory tract. Our stimulation protocol was aimed at covering the frequency range of oscillatory activities observed in the olfactory bulb in vivo. In control condition, postsynaptic response amplitude showed a large enhancement for stimulation frequencies in the beta and gamma frequency range. A phenomenological model of short‐term synaptic plasticity fitted to the data suggests that this frequency‐dependent enhancement can be explained by the interplay between a short‐term facilitation mechanism and two short‐term depression mechanisms, with fast and slow recovery time constants. In the presence of adenosine, response amplitude evoked by low‐frequency stimulation decreased in a dose‐dependent manner (IC50 = 70 μmol/L). Yet short‐term plasticity became more dominated by facilitation and less influenced by depression. Both changes compensated for the initial decrease in response amplitude in a way that depended on stimulation frequency: compensation was strongest at high frequency, up to restoring response amplitudes to values similar to those measured in control condition. The model suggested that the main effects of adenosine were to decrease neurotransmitter release probability and to attenuate short‐term depression mechanisms. Overall, these results suggest that adenosine does not merely inhibit neuronal activity but acts in a more subtle, frequency‐dependent manner.
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- 2019
6. Age‐related neuromuscular changes affecting human vastus lateralis
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Jamie S. McPhee, Daniel W. Stashuk, David A. Jones, Mathew Piasecki, Alex Ireland, and Andrew Hamilton-Wright
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Adult ,Male ,Aging ,medicine.medical_specialty ,Weakness ,Knee Joint ,Skeletal Muscle ,Physiology ,Action Potentials ,Electromyography ,Quadriceps Muscle ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Neuronal Plasticity and Repair ,Internal medicine ,medicine ,Humans ,Young adult ,Exercise ,Anterior compartment of thigh ,Aged ,Motor Neurons ,Aging and Degeneration ,medicine.diagnostic_test ,business.industry ,030229 sport sciences ,Anatomy ,Magnetic Resonance Imaging ,Intensity (physics) ,Motor unit ,Ageing ,Cardiology ,medicine.symptom ,business ,030217 neurology & neurosurgery ,Muscle Contraction ,Research Paper ,Muscle contraction - Abstract
Key points Skeletal muscle size and strength decline in older age.The vastus lateralis, a large thigh muscle, undergoes extensive neuromuscular remodelling in healthy ageing, as characterized by a loss of motor neurons, enlargement of surviving motor units and instability of neuromuscular junction transmission.The loss of motor axons and changes to motor unit potential transmission precede a clinically‐relevant loss of muscle mass and function. Abstract The anterior thigh muscles are particularly susceptible to muscle loss and weakness during ageing, although how this is associated with changes to neuromuscular structure and function in terms of motor unit (MU) number, size and MU potential (MUP) stability remains unclear. Intramuscular (I.M.) and surface electromyographic signals were recorded from the vastus lateralis (VL) during voluntary contractions held at 25% maximal knee extensor strength in 22 young (mean ± SD, 25.3 ± 4.8 years) and 20 physically active older men (71.4 ± 6.2 years). MUP size, firing rates, phases, turns and near fibre (NF) jiggle were determined and MU number estimates (MUNEs) were made by comparing average surface MUP with maximal electrically‐evoked compound muscle action potentials. Quadriceps cross‐sectional area was measured by magnetic resonance imaging. In total, 379 individual MUs were sampled in younger men and 346 in older men. Compared to the MU in younger participants, those in older participants had 8% lower firing rates and larger MUP size (+25%), as well as increased complexity, as indicated by phases (+13%), turns (+20%) and NF jiggle (+11%) (all P, Key points Skeletal muscle size and strength decline in older age.The vastus lateralis, a large thigh muscle, undergoes extensive neuromuscular remodelling in healthy ageing, as characterized by a loss of motor neurons, enlargement of surviving motor units and instability of neuromuscular junction transmission.The loss of motor axons and changes to motor unit potential transmission precede a clinically‐relevant loss of muscle mass and function.
- Published
- 2015
7. Epileptic pilocarpine‐treated rats exhibit aberrant hippocampal EPSP‐spike potentiation but retain long‐term potentiation
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Robert S. Sloviter, Morris Benveniste, Edyta K. Bichler, Matthew Smith, and Ezekiel Carpenter-Hyland
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0301 basic medicine ,Physiology ,long‐term potentiation ,Long-Term Potentiation ,Nonsynaptic plasticity ,Action Potentials ,Muscarinic Agonists ,Hippocampus ,Neurological Conditions, Disorders and Treatments ,Rats, Sprague-Dawley ,03 medical and health sciences ,0302 clinical medicine ,Status Epilepticus ,Neuronal Plasticity and Repair ,Physiology (medical) ,Metaplasticity ,medicine ,Animals ,Cognitive and Behavioural Neuroscience ,Original Research ,E‐S plasticity ,spike‐timing‐dependent plasticity ,Epilepsy ,Neuronal Plasticity ,Homosynaptic plasticity ,Post-tetanic potentiation ,Chemistry ,Spike-timing-dependent plasticity ,musculoskeletal, neural, and ocular physiology ,Pilocarpine ,Excitatory Postsynaptic Potentials ,Long-term potentiation ,Electric Stimulation ,030104 developmental biology ,medicine.anatomical_structure ,nervous system ,Epilepsy, Temporal Lobe ,Schaffer collateral ,Anesthesia ,Excitatory postsynaptic potential ,Neuroscience ,030217 neurology & neurosurgery - Abstract
Hippocampal neuron plasticity is strongly associated with learning, memory, and cognition. In addition to modification of synaptic function and connectivity, the capacity of hippocampal neurons to undergo plasticity involves the ability to change nonsynaptic excitability. This includes altering the probability that EPSPs will generate action potentials (E‐S plasticity). Epilepsy is a prevalent neurological disorder commonly associated with neuronal hyperexcitability and cognitive dysfunction. We examined E‐S plasticity in chronically epileptic Sprague–Dawley rats 3–10 weeks after pilocarpine‐induced status epilepticus. CA1 neurons in hippocampal slices were assayed by whole‐cell current clamp to measure EPSPs evoked by Schaffer collateral stimulation. Using a weak spike‐timing‐dependent protocol to induce plasticity, we found robust E‐S potentiation in conjunction with weak long‐term potentiation (LTP) in saline‐treated rats. In pilocarpine‐treated rats, a similar degree of LTP was found, but E‐S potentiation was reduced. Additionally, the degree of E‐S potentiation was not correlated with the degree of LTP for either group, suggesting that they independently contribute to neuronal plasticity. E‐S potentiation also differed from LTP in that E‐S plasticity could be induced solely from action potentials generated by postsynaptic current injection. The calcium chelating agent BAPTA in the intracellular solution blocked LTP and E‐S potentiation, revealing the calcium dependence of both processes. These findings suggest that LTP and E‐S potentiation have overlapping but nonidentical mechanisms of inducing neuronal plasticity that may independently contribute to cognitive disruptions observed in the chronic epileptic state.
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- 2017
8. Cross talk between β subunits, intracellular Ca
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Selma Angèlica, Serra, Gemma G, Gené, Xabier, Elorza-Vidal, and José M, Fernández-Fernández
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presynaptic voltage‐gated CaV2.1 channels ,syntaxin‐1A ,CaV2.1 steady‐state inactivation ,Syntaxin 1 ,Receptor Cross-Talk ,Synaptic Transmission ,Signalling Pathways ,Calcium Channels, N-Type ,HEK293 Cells ,CaVβ subunits ,Neuronal Plasticity and Repair ,Ca2+‐calmodulin ,Membrane Physiology ,Humans ,Calcium Signaling ,CaV2.1 domains for SNARE‐mediated modulation ,SNARE Proteins ,Original Research - Abstract
Modulation of CaV2.1 channel activity plays a key role in interneuronal communication and synaptic plasticity. SNAREs interact with a specific synprint site at the second intracellular loop (LII‐III) of the CaV2.1 pore‐forming α 1A subunit to optimize neurotransmitter release from presynaptic terminals by allowing secretory vesicles docking near the Ca2+ entry pathway, and by modulating the voltage dependence of channel steady‐state inactivation. Ca2+ influx through CaV2.1 also promotes channel inactivation. This process seems to involve Ca2+‐calmodulin interaction with two adjacent sites in the α 1A carboxyl tail (C‐tail) (the IQ‐like motif and the Calmodulin‐Binding Domain (CBD) site), and contributes to long‐term potentiation and spatial learning and memory. Besides, binding of regulatory β subunits to the α interaction domain (AID) at the first intracellular loop (LI‐II) of α 1A determines the degree of channel inactivation by both voltage and Ca2+. Here, we explore the cross talk between β subunits, Ca2+, and syntaxin‐1A‐modulated CaV2.1 inactivation, highlighting the α 1A domains involved in such process. β 3‐containing CaV2.1 channels show syntaxin‐1A‐modulated but no Ca2+‐dependent steady‐state inactivation. Conversely, β 2a‐containing CaV2.1 channels show Ca2+‐dependent but not syntaxin‐1A‐modulated steady‐state inactivation. A LI‐II deletion confers Ca2+‐dependent inactivation and prevents modulation by syntaxin‐1A in β 3‐containing CaV2.1 channels. Mutation of the IQ‐like motif, unlike CBD deletion, abolishes Ca2+‐dependent inactivation and confers modulation by syntaxin‐1A in β 2a‐containing CaV2.1 channels. Altogether, these results suggest that LI‐II structural modifications determine the regulation of CaV2.1 steady‐state inactivation either by Ca2+ or by SNAREs but not by both.
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- 2017
9. Acetazolamide potentiates the afferent drive to prefrontal cortex in vivo
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Rafael N. Ruggiero, João Pereira Leite, Osvaldo D. Uchitel, Matheus Teixeira Rossignoli, Elaine Aparecida Del Bel, and Lezio S. Bueno-Junior
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0301 basic medicine ,Central Nervous System ,Male ,Physiology ,hippocampus ,Neuromuscular transmission ,Hippocampus ,PREFRONTAL CORTEX ,Synaptic Transmission ,Signalling Pathways ,0302 clinical medicine ,SYNAPTIC PLASTICITY ,Premovement neuronal activity ,Prefrontal cortex ,Carbonic Anhydrase Inhibitors ,Original Research ,Carbonic Anhydrases ,prefrontal cortex ,Neocortex ,Carbonic anhydrase ,Neuronal Plasticity ,Chemistry ,single‐unit activity ,purl.org/becyt/ford/3.1 [https] ,Medicina Básica ,medicine.anatomical_structure ,Anesthesia ,SINGLE-UNIT ACTIVITY ,purl.org/becyt/ford/3 [https] ,Acetazolamide ,medicine.drug ,CIENCIAS MÉDICAS Y DE LA SALUD ,Inmunología ,Neurotransmission ,03 medical and health sciences ,Neuronal Plasticity and Repair ,CARBONIC ANHYDRASE ,Physiology (medical) ,parasitic diseases ,medicine ,Animals ,Neurons, Afferent ,Rats, Wistar ,synaptic plasticity ,Electric Stimulation ,Rats ,030104 developmental biology ,Synaptic plasticity ,HIPPOCAMPUS ,Neuroscience ,030217 neurology & neurosurgery - Abstract
The knowledge on real-time neurophysiological effects of acetazolamide is still far behind the wide clinical use of this drug. Acetazolamide – a carbonic anhydrase inhibitor – has been shown to affect the neuromuscular transmission, implying a pH-mediated influence on the central synaptic transmission. To start filling such a gap, we chose a central substrate: hippocampal-prefrontal cortical projections; and a synaptic phenomenon: paired-pulse facilitation (a form of synaptic plasticity) to probe this drug's effects on interareal brain communication in chronically implanted rats. We observed that systemic acetazolamide potentiates the hippocampal-prefrontal paired-pulse facilitation. In addition to this field electrophysiology data, we found that acetazolamide exerts a net inhibitory effect on prefrontal cortical single-unit firing. We propose that systemic acetazolamide reduces the basal neuronal activity of the prefrontal cortex, whereas increasing the afferent drive it receives from the hippocampus. In addition to being relevant to the clinical and side effects of acetazolamide, these results suggest that exogenous pH regulation can have diverse impacts on afferent signaling across the neocortex. Fil: Bueno Junior, Lezio. Universidade de Sao Paulo; Brasil Fil: Ruggiero, Rafael N.. Universidade de Sao Paulo; Brasil Fil: Rossignoli, Matheus T.. Universidade de Sao Paulo; Brasil Fil: Del Bel, Elaine A.. Universidade de Sao Paulo; Brasil Fil: Leite, Joao. Universidade de Sao Paulo; Brasil Fil: Uchitel, Osvaldo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina
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- 2017
10. High- and low-conductance NMDA receptors are present in layer 4 spiny stellate and layer 2/3 pyramidal neurons of mouse barrel cortex
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Scheppach, Christian
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Central Nervous System ,Glutamic Acid ,layer 4 spiny stellate neuron ,Receptors, N-Methyl-D-Aspartate ,Membrane Potentials ,Cellular and Molecular Neuroscience ,Mice ,layer 2/3 pyramidal neuron ,Neuronal Plasticity and Repair ,Excitatory Amino Acid Agonists ,Animals ,Original Research ,Neurons ,synaptic plasticity ,Ambient glutamate ,Pyramidal Cells ,Somatosensory Cortex ,NMDA receptor ,Mice, Inbred C57BL ,NMDA spike ,nervous system ,Quantitative Biology - Neurons and Cognition ,FOS: Biological sciences ,barrel cortex ,Neurons and Cognition (q-bio.NC) ,tonic activation - Abstract
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.
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- 2016
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11. The most sensitive inputs to cutaneous representing regions of primary somatosensory cortex do not change with behavioral training
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Elsie Spingath and David Blake
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Cutaneous Receptive Fields ,Physiology ,Surround suppression ,map plasticity ,receptive field ,Sensory system ,Biology ,Stimulus (physiology) ,Somatosensory system ,somatosensory ,03 medical and health sciences ,0302 clinical medicine ,Neuronal Plasticity and Repair ,Physiology (medical) ,medicine ,Sensory cortex ,Cognitive and Behavioural Neuroscience ,030304 developmental biology ,Original Research ,0303 health sciences ,Implant ,Subjective constancy ,medicine.anatomical_structure ,Receptive field ,Sensory Neuroscience ,Neuroscience ,030217 neurology & neurosurgery - Abstract
Learning a sensory detection task leads to an increased primary sensory cortex response to the detected stimulus, while learning a sensory discrimination task additionally leads to a decreased sensory cortex response to the distractor stimulus. Neural responses are scaled up, and down, in strength, along with concomitant changes in receptive field size. The present work considers neural response properties that are invariant to learning. Data are drawn from two animals that were trained to detect and discriminate spatially separate taps delivered to positions on the skin of their fingers. Each animal was implanted with electrodes positioned in area 3b, and responses were derived on a near daily basis over 84 days in animal 1 and 202 days in animal 2. Responses to taps delivered in the receptive field were quantitatively measured each day, and receptive fields were audiomanually mapped each day. In the subset of responses that had light cutaneous receptive fields, a preponderance of the days, the most sensitive region of the field was invariant to training. This skin region was present in the receptive field on all, or nearly all, occasions in which the receptive field was mapped, and this region constituted roughly half of the most sensitive region. These results suggest that maintaining the most sensitive inputs as dominant in cortical receptive fields provide a measure of stability that may be transformationally useful for minimizing reconstruction errors and perceptual constancy.
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- 2015
12. Nonspecific block of voltage-gated potassium channels has greater effect on distal schaffer collaterals than proximal schaffer collaterals during periods of high activity
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Lawrence M. Grover, Benjamin Owen, and Rishi Reddy
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Male ,Central Nervous System ,0301 basic medicine ,Physiology ,Action Potentials ,Stimulation ,Hippocampal formation ,Biology ,Rats, Sprague-Dawley ,03 medical and health sciences ,0302 clinical medicine ,Neuronal Plasticity and Repair ,Physiology (medical) ,Membrane Physiology ,Potassium Channel Blockers ,medicine ,Extracellular ,Animals ,High activity ,Theta Rhythm ,Axon ,CA1 Region, Hippocampal ,Cells, Cultured ,Original Research ,burst stimulation ,musculoskeletal, neural, and ocular physiology ,high‐frequency stimulation ,Anatomy ,Voltage-gated potassium channel ,Burst stimulation ,CA3 Region, Hippocampal ,Axon excitability ,Axons ,Rats ,voltage‐gated potassium channel ,030104 developmental biology ,medicine.anatomical_structure ,nervous system ,Potassium Channels, Voltage-Gated ,Schaffer collateral ,Female ,030217 neurology & neurosurgery - Abstract
Previous studies established different responses between proximal and distal portions of Schaffer collateral axons during high‐frequency and burst stimulation, with distal axons demonstrating biphasic changes in excitability (hyperexcitability followed by depression), but proximal axons showing only monophasic depression. Voltage‐dependent potassium (KV) channels are important determinants of axonal excitability, and block of KV channels can promote axon hyperexcitability. We therefore hypothesized that block of KV channels should lead to biphasic response changes in proximal Schaffer collaterals, like those seen in distal Schaffer collaterals. To test this hypothesis, we made extracellular recordings of distal Schaffer collateral responses in stratum radiatum of hippocampal area CA1 and proximal Schaffer collateral responses in stratum pyramidale of area CA3 during high‐frequency stimulation (HFS) at 100 Hz and burst stimulation at 200 msec intervals (5 Hz or theta frequency). We then applied a nonselective KV channel blocker, tetraethlylammonium (TEA, 10 mmol/L) or 4‐aminopyridine (4‐AP, 100 μmol/L), and assessed effects on Schaffer collateral responses. Surprisingly, block of KV channels had little or no effect on proximal Schaffer collateral responses during high‐frequency or burst stimulation. In contrast, KV channel blockade caused more rapid depression of distal Schaffer collateral responses during both high‐frequency and burst stimulation. These findings indicate that KV channels are important for maintaining distal, but not proximal, Schaffer collateral excitability during period of sustained high activity. Differential sensitivity of distal versus proximal Schaffer collaterals to KV channel block may reflect differences in channel density, diversity, or subcellular localization.
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- 2017
13. Blindfolding during wakefulness causes decrease in sleep slow wave activity
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Matthias Mölle, Hong-Viet V. Ngo, Eva Magdalena Korf, and Jan Born
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Male ,Central Nervous System ,0301 basic medicine ,medicine.medical_specialty ,genetic structures ,Physiology ,Sleep spindle ,Audiology ,Non-rapid eye movement sleep ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Neuronal Plasticity and Repair ,Physiology (medical) ,Unihemispheric slow-wave sleep ,Humans ,Medicine ,slow wave sleep ,Wakefulness ,Neuroscience of sleep ,Vision, Ocular ,Visual Cortex ,Original Research ,Slow-wave sleep ,synaptic plasticity ,business.industry ,Motor Cortex ,Brain Waves ,Sleep in non-human animals ,030104 developmental biology ,Visual cortex ,medicine.anatomical_structure ,Visual Perception ,Evoked Potentials, Visual ,Sleep ,Sensory Neuroscience ,business ,030217 neurology & neurosurgery - Abstract
Slow wave activity (SWA, 0.5–4 Hz) represents the predominant EEG oscillatory activity during slow wave sleep (SWS). Its amplitude is considered in part a reflection of synaptic potentiation in cortical networks due to encoding of information during prior waking, with higher amplitude indicating stronger potentiation. Previous studies showed that increasing and diminishing specific motor behaviors produced corresponding changes in SWA in the respective motor cortical areas during subsequent SWS. Here, we tested whether this relationship can be generalized to the visual system, that is, whether diminishing encoding of visual information likewise leads to a localized decrease in SWA over the visual cortex. Experiments were performed in healthy men whose eyes on two different days were or were not covered for 10.5 h before bedtime. The subject's EEG was recorded during sleep and, after sleep, visual evoked potentials (VEPs) were recorded. SWA during nonrapid eye movement sleep (NonREM sleep) was lower after blindfolding than after eyes open (P
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- 2017
14. The hyperexcitability of dentate granule neurons in organotypic hippocampal slice cultures is due to reorganization of synaptic inputs in vitro
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Charlie J. Gilbride
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Central Nervous System ,Male ,0301 basic medicine ,Pathology ,medicine.medical_specialty ,Physiology ,Hippocampal formation ,Biology ,Hippocampus ,Synaptic Transmission ,Rats, Sprague-Dawley ,Cellular and Molecular Neuroscience ,03 medical and health sciences ,0302 clinical medicine ,Slice preparation ,Neuronal Plasticity and Repair ,Physiology (medical) ,medicine ,Animals ,CA1 Region, Hippocampal ,Original Research ,Neurons ,synaptic plasticity ,Microscopy, Confocal ,Neuronal Plasticity ,Pyramidal Cells ,Granule (cell biology) ,Brain ,Excitatory Postsynaptic Potentials ,electrophysiology ,In vitro ,Rats ,Confocal microscopy ,Electrophysiology ,030104 developmental biology ,Cell culture ,organotypic slice culture ,Dentate Gyrus ,Synapses ,Synaptic plasticity ,Excitatory postsynaptic potential ,sense organs ,Neuroscience ,030217 neurology & neurosurgery - Abstract
Organotypic hippocampal slice cultures (OHSCs) provide the experimental flexibility of cell culture while leaving much of the natural neuronal connectivity intact. Previously, it was shown that the functional and morphological features of CA1 pyramidal neurons in OHSCs resemble, to a surprising extent, those of CA1 neurons in the acute brain slice preparation. However, the extent to which the characteristics of other principle hippocampal neurons change or are preserved in cultured slices remains to be determined. In the present study, I initially sought to understand whether and how the synaptic inputs and morphology of cultured dentate granule neurons (GCs) differ from GCs that have developed in vivo. To this end, I compared GCs in OHSCs and GCs in acute slices at two equivalent developmental time points (P14 vs. DIV7 and P21 vs. DIV21). The findings suggest that there is considerable reorganization of synaptic input to the organotypic GCs, such that these cells are more susceptible to hyperexcitation than GCs in acute slices after 3 weeks. It appears that this hyperexcitability emerges through an increase in the proportion of mature synapses at proximal dendritic sites and is accompanied by an increase in inhibitory neuron activity. These alterations appear to arise in a coordinated manner such that the substantial increase in excitatory synaptic drive received by the DIV21 GCs in OHSCs remains local and is not translated into excessive output possibly leading to damage or major morphological alterations of downstream pyramidal neurons.
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- 2016
15. The delayed strengthening of synaptic connectivity in the amygdala depends on NMDA receptor activation during acute stress
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Bruce S. McEwen, Kapil Saxena, Farhana Yasmin, and Sumantra Chattarji
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Central Nervous System ,Male ,0301 basic medicine ,N-Methylaspartate ,Dendritic spine ,Physiology ,Hippocampus ,Biology ,Receptors, N-Methyl-D-Aspartate ,Amygdala ,Neurological Conditions, Disorders and Treatments ,03 medical and health sciences ,0302 clinical medicine ,Neuronal Plasticity and Repair ,Physiology (medical) ,medicine ,Animals ,Rats, Wistar ,Receptor ,Original Research ,synaptic plasticity ,excitatory synaptic currents ,Excitatory Postsynaptic Potentials ,dendritic spines ,Rats ,030104 developmental biology ,medicine.anatomical_structure ,nervous system ,Anesthesia ,Synaptic plasticity ,Excitatory postsynaptic potential ,NMDA receptor ,Neuroscience ,030217 neurology & neurosurgery ,Basolateral amygdala - Abstract
There is growing evidence that stress leads to contrasting patterns of structural plasticity in the hippocampus and amygdala, two brain areas implicated in the cognitive and affective symptoms of stress‐related psychiatric disorders. Acute stress has been shown to trigger a delayed increase in the density of dendritic spines in the basolateral amygdala (BLA) of rodents. However, the physiological correlates of this delayed spinogenesis in the BLA remain unexplored. Furthermore, NMDA receptors (NMDARs) have been known to underlie chronic stress‐induced structural plasticity in the hippocampus, but nothing is known about the role of these receptors in the delayed spinogenesis, and its physiological consequences, in the BLA following acute stress. Here, using whole‐cell recordings in rat brain slices, we find that a single exposure to 2‐h immobilization stress enhances the frequency, but not amplitude, of miniature excitatory postsynaptic currents (mEPSCs) recorded from principal neurons in the BLA 10 days later. This was also accompanied by faster use‐dependent block of NMDA receptor currents during repeated stimulation of thalamic inputs to the BLA, which is indicative of higher presynaptic release probability at these inputs 10 days later. Furthermore, targeted in vivo infusion of the NMDAR‐antagonist APV into the BLA during the acute stress prevents the increase in mEPSC frequency and spine density 10 days later. Together, these results identify a role for NMDARs during acute stress in both the physiological and morphological strengthening of synaptic connectivity in the BLA in a delayed fashion. These findings also raise the possibility that activation of NMDA receptors during stress may serve as a common molecular mechanism despite the divergent patterns of plasticity that eventually emerge after stress in the amygdala and hippocampus.
- Published
- 2016
16. Bidirectional variability in motor cortex excitability modulation following 1 mA transcranial direct current stimulation in healthy participants
- Author
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Wolfgang Strube, Tilmann Bunse, Frank Padberg, Ulrich Palm, Alexandra Nikolaeva, Alkomiet Hasan, Michael A. Nitsche, and Peter Falkai
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Central Nervous System ,Adult ,Male ,Anodal tdcs ,Physiology ,medicine.medical_treatment ,Stimulation ,Transcranial Direct Current Stimulation ,050105 experimental psychology ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Neuronal Plasticity and Repair ,Physiology (medical) ,medicine ,Cluster Analysis ,Humans ,0501 psychology and cognitive sciences ,ddc:610 ,Motor‐cortical plasticity ,Original Research ,response variability ,Transcranial direct-current stimulation ,Stimulation technique ,business.industry ,05 social sciences ,Motor Cortex ,Evoked Potentials, Motor ,Response Variability ,Transcranial magnetic stimulation ,medicine.anatomical_structure ,Cortical Excitability ,Female ,business ,Neuroscience ,030217 neurology & neurosurgery ,Motor Control ,Motor cortex - Abstract
Due to the high interindividual response variability following transcranial direct current stimulation (tDCS), it is apparent that further research of the long‐lasting effects of the stimulation technique is required. We aimed to investigate interindividual variability following anodal tDCS and cathodal tDCS in a large‐scale prospective cross‐over study. Motor cortex physiology measurements were obtained using transcranial magnetic stimulation (TMS) in 59 healthy participants comparing motor‐evoked potential (MEP) magnitudes following two tDCS paradigms: 1 mA anodal tDCS for 13 min and 1 mA cathodal tDCS for 9 min. Analysis compared MEP changes over time for both polarities. Additionally, we applied hierarchical cluster analysis to assess the dynamics of poststimulation changes. Overall, anodal tDCS resulted in a significant increase in corticospinal excitability lasting for 40 min poststimulation, whereas cathodal tDCS did not alter corticospinal excitability. Cluster analysis revealed for cathodal tDCS both a cluster showing significant stable MEP reduction and a second cluster displaying MEP increase over time. Two diametrical clusters were also found for anodal tDCS. Regardless of polarity, individuals with MEP increase following stimulation showed steeper cortical recruitment curves compared to the clusters with decreased MEP magnitudes. The observed findings confirm a bidirectional modulation of corticospinal excitability following 1 mA tDCS in separate subgroups and the relationship to cortical recruitment.
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- 2016
17. Changes in corticospinal drive to spinal motoneurones following tablet-based practice of manual dexterity
- Author
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Henning Langberg, Jens Nielsen, Lisbeth H. Larsen, Thor Bern Jensen, Mark Schram Christensen, and Jesper Lundbye-Jensen
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medicine.medical_specialty ,manual dexterity ,Physiology ,Pyramidal Tracts ,Neuromuscular Junction ,Electromyography ,Thumb ,Electroencephalography ,050105 experimental psychology ,Fingers ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Physical medicine and rehabilitation ,Neuronal Plasticity and Repair ,corticomuscular ,Physiology (medical) ,medicine ,Humans ,0501 psychology and cognitive sciences ,Motor skill ,Original Research ,Motor Neurons ,Cross-Over Studies ,Pyramidal tracts ,medicine.diagnostic_test ,business.industry ,05 social sciences ,Motor Cortex ,coherence ,body regions ,Electrophysiology ,medicine.anatomical_structure ,Motor Skills ,Computers, Handheld ,plasticity ,Physical therapy ,Female ,Primary motor cortex ,Tablet‐based practice ,business ,030217 neurology & neurosurgery ,Motor Control ,Motor cortex - Abstract
The use of touch screens, which require a high level of manual dexterity, has exploded since the development of smartphone and tablet technology. Manual dexterity relies on effective corticospinal control of finger muscles, and we therefore hypothesized that corticospinal drive to finger muscles can be optimized by tablet‐based motor practice. To investigate this, sixteen able‐bodied females practiced a tablet‐based game (3 × 10 min) with their nondominant hand requiring incrementally fast and precise pinching movements involving the thumb and index fingers. The study was designed as a semirandomized crossover study where the participants attended one practice‐ and one control session. Before and after each session electrophysiological recordings were obtained during three blocks of 50 precision pinch movements in a standardized setup resembling the practiced task. Data recorded during movements included electroencephalographic (EEG) activity from primary motor cortex and electromyographic (EMG) activity from first dorsal interosseous (FDI) and abductor pollicis brevis (APB) muscles. Changes in the corticospinal drive were evaluated from coupling in the frequency domain (coherence) between EEG–EMG and EMG–EMG activity. Following motor practice performance improved significantly and a significant increase in EEG‐EMG APB and EMG APB ‐EMG FDI coherence in the beta band (15–30 Hz) was observed. No changes were observed after the control session. Our results show that tablet‐based motor practice is associated with changes in the common corticospinal drive to spinal motoneurons involved in manual dexterity. Tablet‐based motor practice may be a motivating training tool for stroke patients who struggle with loss of dexterity.
- Published
- 2016
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