Models of subthreshold membrane resonance in neocortical neurons

1996 ◽  
Vol 76 (2) ◽  
pp. 698-714 ◽  
Author(s):  
B. Hutcheon ◽  
R. M. Miura ◽  
E. Puil
Keyword(s):  
Frequency Response ◽  
Time Constant ◽  
High Frequency ◽  
Cortical Neurons ◽  
Room Temperature ◽  
Ionic Current ◽  
Low Frequency ◽  
Response Curves ◽  
Membrane Time Constant

1. We obtained whole cell data from sensorimotor cortical neurons of in vitro slices (juvenile rats) and observed a low-frequency resonance (1-2 Hz) in their voltage responses. We constructed models of subthreshold membrane currents to determine whether a hyperpolarization-activated cation current (IH) is sufficient to account for this resonance. 2. Parameter values for a basic IH (BH) model were estimated from voltage-clamp experiments at room temperature. The BH model formed a component of a reduced membrane (RM) model. On numerical integration, the RM model exhibited voltage sags and rebounds to injected current pulses; maximal voltage responses to injected oscillatory currents occurred near 2 Hz. 3. We compared the experimentally measured frequency-response curves (FRCs) at room temperature with the theoretical FRCs derived from the RM model. The theoretical FRCs exhibited resonant humps with peaks between 1 and 2 Hz. At 36 degrees C, the theoretical FRCs peaked near 10 Hz. The characteristics of theoretical and observed FRCs were in close agreement, demonstrating that IH is sufficient to cause resonance. Thus we classified IH as a resonator current. 4. We developed a technique, the reactive current clamp (RCC), to inject a computer-calculated current corresponding to a membrane ionic current in response to the membrane potential of the neuron. This enabled us to study the interaction of an artificial ionic current with living neurons (electronic pharmacology or EP-method). Using the RCC, a simplified version of the BH model was used to cancel an endogenous IH (electronic antagonism) and to introduce an artificial IH (electronic expression) when an endogenous IH was absent. Antagonism of IH eliminated sags and rebounds, whereas expression of IH endowed neurons with resonance and the frequency-selective firing that accompanies resonance in neurons with an endogenous IH. Previous investigations have relied on the specificity of pharmacological agents to block ionic channels, e.g., Cs+ to block IH. However, Cs+ additionally affects other currents. This represents the first time an in vitro modeling technique (RCC) has been used to antagonize a specific endogenous current, IH. 5. A simplified RM model yielded values of the resonant frequency and Q (an index of the sharpness of resonance), which rose almost linearly between -55 and -80 mV. Resonant frequencies could be much higher than fH = (2 pi tau H) - 1 where tau H is the activation time constant for IH. 6. In the FRCs, resonance appeared as a hump at intermediate frequencies because of low- and high-frequency attenuations due to IH and membrane capacitance, respectively. Changing the parameters of IH altered the low-frequency attenuation and, hence, the resonance. Changes in the leak conductance affected both the low- and high-frequency attenuations. 7. We modeled an inwardly rectifying K+ current (IIR) and a persistent Na+ current (INaP) to study their effects on resonance. Neither current produced resonance in the absence of IH. We found that IIR attenuated, whereas INaP amplified resonance. Thus IIR and INaP are classified as attenuator and amplifier currents, respectively. 8. Resonators and attenuators differ in that they have longer and shorter time constants, respectively, compared with the membrane time constant. Therefore, an increase in the leak conductance decreases the membrane time constant, which can transform an attenuator into a resonator, altering the frequency response. This suggests a novel mechanism for modulating the frequency responses of neurons to inputs. 9. These investigations have provided a theoretical framework for detailed understanding of mechanisms that produce resonance in cortical neurons. Resonance is one aspect of the intrinsic rhythmicity of neurons. The rhythmicity due to IH resonance is latent until it is revealed by oscillatory inputs. (ABSTRACT TRUNCATED)

scholarly journals Systems-based analysis of dendritic nonlinearities reveals temporal feature extraction in mouse L5 cortical neurons

2017 ◽  
Vol 117 (6) ◽  
pp. 2188-2208 ◽  
Author(s):  
Brian E. Kalmbach ◽  
Richard Gray ◽  
Daniel Johnston ◽  
Erik P. Cook
Keyword(s):  
High Frequency ◽  
Cortical Neurons ◽  
Action Potentials ◽  
Nonlinear Response ◽  
Functional Model ◽  
Low Frequency ◽  
Fast Variable ◽  
Nonlinear Component ◽  
Dendritic Spikes ◽  
Linear And Nonlinear

What do dendritic nonlinearities tell a neuron about signals injected into the dendrite? Linear and nonlinear dendritic components affect how time-varying inputs are transformed into action potentials (APs), but the relative contribution of each component is unclear. We developed a novel systems-identification approach to isolate the nonlinear response of layer 5 pyramidal neuron dendrites in mouse prefrontal cortex in response to dendritic current injections. We then quantified the nonlinear component and its effect on the soma, using functional models composed of linear filters and static nonlinearities. Both noise and waveform current injections revealed linear and nonlinear components in the dendritic response. The nonlinear component consisted of fast Na+ spikes that varied in amplitude 10-fold in a single neuron. A functional model reproduced the timing and amplitude of the dendritic spikes and revealed that they were selective to a preferred input dynamic (~4.5 ms rise time). The selectivity of the dendritic spikes became wider in the presence of additive noise, which was also predicted by the functional model. A second functional model revealed that the dendritic spikes were weakly boosted before being linearly integrated at the soma. For both our noise and waveform dendritic input, somatic APs were dependent on the somatic integration of the stimulus, followed a subset of large dendritic spikes, and were selective to the same input dynamics preferred by the dendrites. Our results suggest that the amplitude of fast dendritic spikes conveys information about high-frequency features in the dendritic input, which is then combined with low-frequency somatic integration. NEW & NOTEWORTHY The nonlinear response of layer 5 mouse pyramidal dendrites was isolated with a novel systems-based approach. In response to dendritic current injections, the nonlinear component contained mostly fast, variable-amplitude, Na+ spikes. A functional model accounted for the timing and amplitude of the dendritic spikes and revealed that dendritic spikes are selective to a preferred input dynamic, which was verified experimentally. Thus, fast dendritic nonlinearities behave as high-frequency feature detectors that influence somatic action potentials.

Computation of Unsteady Viscous Marine-Propulsor Blade Flows—Part 2: Parametric Study

1999 ◽  
Vol 121 (1) ◽  
pp. 139-147 ◽  
Author(s):  
Eric G. Paterson ◽  
Fred Stern
Keyword(s):  
Boundary Layer ◽  
Frequency Response ◽  
High Frequency ◽  
Stokes Equations ◽  
Low Frequency ◽  
Driving Mechanism ◽  
Massachusetts Institute Of Technology ◽  
Flapping Foil ◽  
Displacement Thickness ◽  
Institute Of Technology

In this two-part paper, time-accurate solutions of the Reynolds-averaged Navier-Stokes equations are presented, which address through model problems, the response of turbulent propeller-blade boundary layers and wakes to external-flow traveling waves. In Part 1, the Massachusetts Institute of Technology flapping-foil experiment was simulated and the results validated through comparisons with data. The response was shown to be significantly more complex than classical unsteady boundary layer and unsteady lifting flows thus motivating further study. In Part 2, the effects of frequency, waveform, and foil geometry are investigated. The results demonstrate that uniquely different response occurs for low and high frequency. High-frequency response agrees with behavior seen in the flapping-foil experiment, whereas low-frequency response displays a temporal behavior which more closely agrees with classical inviscid-flow theories. Study of waveform and geometry show that, for high frequency, the driving mechanism of the response is a viscous-inviscid interaction created by a near-wake peak in the displacement thickness which, in turn, is directly related to unsteady lift and the oscillatory wake sheet. Pressure waves radiate upstream and downstream of the displacement thickness peak for high frequency flows. Secondary effects, which are primarily due to geometry, include gust deformation due to steady-unsteady interaction and trailing-edge counter-rotating vortices which create a two-layered amplitude and phase-angle profile across the boundary layer.

Raman Scatteringl And Infrared Absorption in Lithium Intercalated MoS2

1988 ◽  
Vol 135 ◽  
Author(s):  
T. Sekine ◽  
C. Julien ◽  
M. Jouanne ◽  
M. Weber ◽  
M. Balkanski
Keyword(s):  
High Frequency ◽  
Room Temperature ◽  
Low Frequency ◽  
Host Lattice ◽  
Ir Absorption ◽  
High Frequency Region ◽  
Superlattice Structure ◽  
Layer Mode ◽  
Rigid Layer ◽  
Substitutional Defects

AbstractRaman scattering and IR absorption were studied in Li-intercalated MoS2 at room temperature. After intercalation, new Raman peaks were observed at low-frequency sides of the high-frequency original Raman peaks and around a rigid-layer mode. This fact indicates the formation of superlattice structure along the c-axis. An intercalation mode in which Li atoms vibrate strongly against the host lattice was observed at about 205 cm−1. Two new broad bands grow in the high-frequency region as the concentration of Li increases. The corresponding peaks were observed by IR absorption. They appears to be caused by vibrations of substitutional defects, in which the Li atoms have substituted for Mo atoms in the host lattice.

Jitter Transmission Analysis and Experimental Research for Frame Structure in the Median and High Frequency Regions

2012 ◽  
Vol 271-272 ◽  
pp. 981-985
Author(s):  
You Yi Wang ◽  
Yang Zhao ◽  
Wen Lai Ma
Keyword(s):  
Dynamic Response ◽  
Frequency Response ◽  
Dynamic Model ◽  
Experimental Research ◽  
High Frequency ◽  
Low Frequency ◽  
Frame Structure ◽  
Wave Method ◽  
Simulation Results ◽  
Theoretical Results

Frame structure is widely used in practical projects. For jitter of the frame structure excited by median and high frequency disturbances, firstly, the dynamic model of thin plate substructure is built by wave method, and then the dynamic model of frame structure is established by combining wave method and substructure technique. At last, the accurate dynamic response was obtained. The simulation of dynamic characteristic is made, and simulation results are compared with FEM results. On this basis, modal experiment and frequency response experiment is done to verify theoretical results. In comparison to FEM, the results by wave method are accurate in low frequency regions, and the results are more accurate in the median and high frequency regions. The experiment proves wave method is correct and effective for jitter transmission analysis of frame structure in the median and high frequency regions.

Application of ABRS to the Hearing-Aid Selection Process

1986 ◽  
Vol 29 (1) ◽  
pp. 120-128 ◽  
Author(s):  
Kathryn A. Beauchaine ◽  
Michael P. Gorga ◽  
Jan K. Reiland ◽  
Lori L. Larson
Keyword(s):  
Frequency Response ◽  
Preliminary Data ◽  
High Frequency ◽  
Selection Process ◽  
Hearing Aid ◽  
Low Frequency ◽  
Evaluation Process ◽  
Acoustic Reflex ◽  
Technical Factors ◽  
Functional Gain

This paper describes preliminary data on the use of click-evoked ABRs in the hearing aid selection process. Four normal-hearing and 4 hearing-impaired subjects were tested with a hearing aid set at three different frequency response settings. Estimates of gain were calculated using shifts in Wave V thresholds, shifts in Wave V latency-level functions, acoustic-reflex measurements, coupler gain measurements, and measurements of functional gain. Results suggest that the click-evoked ABR does not distinguish between differing amounts of low-frequency gain, although reasonable estimates of high-frequency gain appear possible. Also discussed are technical factors that must be considered when using the ABR in the hearing aid evaluation process.

Gap junction formation and regulation in myometrium

1980 ◽  
Vol 239 (5) ◽  
pp. C217-C228 ◽  
Author(s):  
R. E. Garfield ◽  
D. Merrett ◽  
A. K. Grover
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
High Frequency ◽  
Actinomycin D ◽  
Low Frequency ◽  
Synthesis Inhibitor ◽  
Pregnant Rats ◽  
Junction Formation ◽  
Prostacyclin Analog

Myometrial tissues from pregnant rats were examined by electron microscopy for the presence of gap junctions after incubation in vitro with a variety of agents. Gap junctions were present in low frequency or absent prior to incubation in vitro. The junctions were present in control tissues in high frequency after 48 h incubation. The addition of cycloheximide or actinomycin D inhibited the incorporation of [3H]leucine into TCA-precipitable proteins and prevented gap junction formation. A prostacyclin analog (carbacyclin), a thromboxane synthesis inhibitor, and indomethacin also prevented gap junction formation. Oxytocin had no effect on gap junction formation but isoxsuprine decreased their number and increased their size. Isoxsuprine and isoproterenol also produced electron opaque crystals associated with the gap junctions. Dibutyryl cAMP treatment but not monobutyryl cGMP also increased the size of gap junctions. Based upon this and previous studies, we propose at least four sites for regulation of gap junctions and possible control of labor.

scholarly journals Spontaneous and Perturbational Complexity in Cortical Cultures

2021 ◽  
Vol 11 (11) ◽  
pp. 1453
Author(s):  
Ilaria Colombi ◽  
Thierry Nieus ◽  
Marcello Massimini ◽  
Michela Chiappalone
Keyword(s):  
Cortical Neurons ◽  
Low Frequency ◽  
Initial Response ◽  
Moderate Increase ◽  
Electrode Arrays ◽  
In Vivo Experiments ◽  
Cortical Cultures ◽  
Cortical Slices

Dissociated cortical neurons in vitro display spontaneously synchronized, low-frequency firing patterns, which can resemble the slow wave oscillations characterizing sleep in vivo. Experiments in humans, rodents, and cortical slices have shown that awakening or the administration of activating neuromodulators decrease slow waves, while increasing the spatio-temporal complexity of responses to perturbations. In this study, we attempted to replicate those findings using in vitro cortical cultures coupled with micro-electrode arrays and chemically treated with carbachol (CCh), to modulate sleep-like activity and suppress slow oscillations. We adapted metrics such as neural complexity (NC) and the perturbational complexity index (PCI), typically employed in animal and human brain studies, to quantify complexity in simplified, unstructured networks, both during resting state and in response to electrical stimulation. After CCh administration, we found a decrease in the amplitude of the initial response and a marked enhancement of the complexity during spontaneous activity. Crucially, unlike in cortical slices and intact brains, PCI in cortical cultures displayed only a moderate increase. This dissociation suggests that PCI, a measure of the complexity of causal interactions, requires more than activating neuromodulation and that additional factors, such as an appropriate circuit architecture, may be necessary. Exploring more structured in vitro networks, characterized by the presence of strong lateral connections, recurrent excitation, and feedback loops, may thus help to identify the features that are more relevant to support causal complexity.

Afferent and association fiber differences in short-term potentiation in piriform (olfactory) cortex of the rat

1990 ◽  
Vol 64 (1) ◽  
pp. 179-190 ◽  
Author(s):  
M. E. Hasselmo ◽  
J. M. Bower
Keyword(s):  
Time Constant ◽  
Piriform Cortex ◽  
Low Frequency ◽  
Pyramidal Cells ◽  
Olfactory Cortex ◽  
Short Term ◽  
Term Potentiation ◽  
Association Fibers ◽  
Stimulation Of

1. The effects of low-frequency stimulus trains on synaptically evoked responses in piriform cortex pyramidal cells were studied by the use of intracellular recording techniques in an in vitro slice preparation. Afferent and association fiber systems were differentially stimulated with electrodes placed in layer 1a or layer 1b, respectively. To quantify synapse modifiability, the heights of postsynaptic potentials (PSPs) elicited by paired-pulse stimulation (100-ms interval) were averaged over a 50-s period before and after a set of 10 stimulus trains (10 pulses each, 20 Hz, 5-s interpulse interval). 2. Afferent and association fibers showed consistent differences in their response to stimulation during the period lasting from approximately 10 to 200 s after presentation of trains. During this time period, the responses to stimulation of association fibers in layer 1b displayed a short-term potentiation, which over the 10 posttrain trials, produced an average increase in PSP height of 23.2 +/- 3.7% (mean +/- SE). On the other hand, responses to layer 1a stimulation showed an average depression of 10.9 +/- 3.6%. Layer 1b potentiation decayed with time constant roughly estimated at 79 s. Layer 1b potentiation appeared even at very low stimulus voltages and after local association fiber input had been cut, suggesting that it was largely a monosynaptic effect. 3. In the period immediately after train presentations, responses evoked by both layers showed a short-term augmentation with a time constant around 3 s. In layer 1a, this augmentation was superimposed on a depression with slow recovery. At longer times after train presentation (greater than 5 min), 2 cells out of 46 showed changes (increases) in synaptic efficacy in response to layer 1b stimulation. 4. In the current experiments both layers 1a and 1b showed statistically significant facilitation before the presentation of stimulus trains. However, layer 1b facilitation decreased from 22.7 +/- 3.5% to a statistically insignificant 3.9 +/- 3.3% after the presentation of trains, whereas layer 1a facilitation remained at a statistically significant level of 23.1 +/- 5.7%. 5. These experiments show that pyramidal cell responses to stimulation of the afferent and association fiber systems are affected differently by the previous presentation of trains of stimuli. This suggests that mechanisms of synaptic modification may differ between the afferent and intrinsic association synaptic projections onto single pyramidal cells in olfactory cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

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