Role of slow temporal dynamics in reliable activity of stochastically driven neurons

Mapping Intimacies ◽

10.1101/2020.12.11.422204 ◽

2020 ◽

Author(s):

Subhadra Mokashe ◽

Suhita Nadkarni

Keyword(s):

Temporal Dynamics ◽

Network Motif ◽

Neuronal Firing ◽

Input Current ◽

Switching Frequency ◽

Quiescent State ◽

Extrinsic Noise ◽

Gabaergic Synapse ◽

Pass Filter ◽

Low Pass Filter

ABSTRACTNeuronal networks maintain robust patterns of activity despite a backdrop of noise from various sources. Mutually inhibiting neurons is a standard network motif implicated in rhythm generation. In an elementary network motif of two neurons capable of swapping from an active state to a quiescent state, we ask how different sources of stochasticity alter firing patterns. In this system, the alternating activity occurs via combined action of a calcium-dependent potassium current, sAHP (slow afterhyperpolarization), and a fast GABAergic synapse. We show that simulating extrinsic noise arising from background activity extends the dynamical range of neuronal firing. Extrinsic noise also has the effect of increasing the switching frequency via a faster build-up of sAHP current. We show that switching frequency as a function of input current has a non-monotonic behavior. Interestingly the noise tolerance of this system varies with the input current. It shows maximum robustness to noise at an input current that corresponds to the minimum switching frequency between the neurons. The slow decay time scale of sAHP conductance allows neurons to act as a low-pass filter, attenuate noise, and integrate over ion channel fluctuations. Additionally, we show that the slow inactivation time of the sAHP channel allows the neuron to act as an action potential counter. We propose that this intrinsic property of the current allows the network to maintain rhythmic activity critical for various functions, despite the noise, and operate as a temporal integrator.

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Short-term depression shapes information transmission in a constitutively active GABAergic synapse

Scientific Reports ◽

10.1038/s41598-019-54607-y ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Hagar Lavian ◽

Alon Korngreen

Keyword(s):

Basal Ganglia ◽

Information Transmission ◽

Indirect Pathway ◽

Short Term ◽

Gabaergic Synapse ◽

Pass Filter ◽

Low Pass Filter ◽

Whole Cell ◽

Firing Rates ◽

Whole Cell Recordings

AbstractShort-term depression is a low-pass filter of synaptic information, reducing synaptic information transfer at high presynaptic firing frequencies. Consequently, during elevated presynaptic firing, little information passes to the postsynaptic neuron. However, many neurons fire at relatively high frequencies all the time. Does depression silence their synapses? We tested this apparent contradiction in the indirect pathway of the basal ganglia. Using numerical modeling and whole-cell recordings from single entopeduncular nucleus (EP) neurons in rat brain slices, we investigated how different firing rates of globus pallidus (GP) neurons affect information transmission to the EP. Whole-cell recordings showed significant variability in steady-state depression, which decreased as stimulation frequency increased. Modeling predicted that this variability would translate into different postsynaptic noise levels during constitutive presynaptic activity. Our simulations further predicted that individual GP-EP synapses mediate gain control. However, when we consider the integration of multiple inputs, the broad range of GP firing rates would enable different modes of information transmission. Finally, we predict that changes in dopamine levels can shift the action of GP neurons from rate coding to gain modulation. Our results thus demonstrate how short-term depression shapes information transmission in the basal ganglia in particular and via GABAergic synapses in general.

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Fuzzy Logic Enhanced Direct Torque Control with Space Vector Modulation

Indonesian Journal of Electrical Engineering and Computer Science ◽

10.11591/ijeecs.v11.i2.pp704-710 ◽

2018 ◽

Vol 11 (2) ◽

pp. 704

Author(s):

Jian-Ding Tan ◽

Siaw-Paw Koh ◽

Sieh-Kiong Tiong ◽

Kharudin Ali ◽

Ahmed Abdalla

Keyword(s):

Fuzzy Logic ◽

Direct Torque Control ◽

Torque Control ◽

Switching Frequency ◽

Space Vector Modulation ◽

Space Vector ◽

Pass Filter ◽

Low Pass Filter ◽

Stator Flux ◽

Vector Modulation

Over the past few years, multiple types of modifications have been proposed onto the Direct Torque Control (DTC) scheme. Among others is the implementation of Space Vector Modulation (SVM). In this paper, two new control strategies are proposed onto an SVM-DTC. Instead of using PI torque and flux controllers, a fuzzy logic control method is implemented in the proposed modification to achieve a more constant switching frequency while minimizing the torque error. The fuzzy logic controller controls the voltages in direct and quadratic reference frame (Vd, Vq). This approach fully utilizes the switching capability of the inverter and thus improving the overall system performance. To overcome issues in open loop stator flux such as DC drift and saturation, a closed loop estimation method of stator flux is also proposed based on voltage model and low pass filter. The performance of the proposed control strategy is benchmarked with that of a conventional DTC–SVM. Simulations and experiments were carried out and the results show that the proposed method outperforms the conventional DTC-SVM in terms of DC-offset elimination and overall system robustness. Over the past few years, multiple types of modifications have been proposed onto the Direct Torque Control (DTC) scheme. Among others is the implementation of Space Vector Modulation (SVM). In this paper, two new control strategies are proposed onto an SVM-DTC. Instead of using PI torque and flux controllers, a fuzzy logic control method is implemented in the proposed modification to achieve a more constant switching frequency while minimizing the torque error. The fuzzy logic controller controls the voltages in direct and quadratic reference frame (Vd, Vq). This approach fully utilizes the switching capability of the inverter and thus improving the overall system performance. To overcome issues in open loop stator flux such as DC drift and saturation, a closed loop estimation method of stator flux is also proposed based on voltage model and low pass filter. The performance of the proposed control strategy is benchmarked with that of a conventional DTC–SVM. Simulations and experiments were carried out and the results show that the proposed method outperforms the conventional DTC-SVM in terms of DC-offset elimination and overall system robustness.

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A Wideband Low-Pass Filter for Differential Mode Distortion

Acta Polytechnica ◽

10.14311/1424 ◽

2011 ◽

Vol 51 (5) ◽

Author(s):

M. Brejcha

Keyword(s):

Frequency Band ◽

Switching Frequency ◽

Switching Converters ◽

Differential Mode ◽

Pass Filter ◽

Low Pass Filter ◽

Pwm Converters ◽

Low Pass ◽

Specific Part

This paper deals with the solution for a wideband low-pass filter that can be used for filtering the input currents of switching converters, which are distorted by the switching frequency of PWM. Initially, the filter was proposed for the special type of AC converter, which is described in the paper. However, these solutions can also be used in the inputs of active PFC converters and in the outputs of PWM converters, where there are similar problems with switching frequency.The frequency band of the filter is given by the switching frequency of the filtered device and by the demands of EMC standards. This makes the filter able to work in the frequency band from 10 kHz to 30 MHz. To ensure such a frequency band, the filter should be proposed with two sections, each for a specific part of the band.

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A Step-by-Step Design for Low-Pass Input Filter of the Single-Stage Converter

Energies ◽

10.3390/en14237901 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7901

Author(s):

Qingqing He ◽

Lei Liu ◽

Mingyang Qiu ◽

Quanming Luo

Keyword(s):

Power Factor ◽

Power Factor Correction ◽

Design Method ◽

Single Stage ◽

Input Current ◽

Higher Harmonics ◽

Pass Filter ◽

Low Pass Filter ◽

Input Filter ◽

Low Pass

Active power factor correction converters are often introduced as the front stage of power electronic equipment to improve the power factor and eliminate higher harmonics. A Boost or Buck-Boost converter operating in discontinuous current mode is always adopted to achieve high power factor correction. In addition, the input current contains a large amount of higher harmonics, and a low-pass input filter is commonly adopted to filter it out. In this paper, a single-stage high-frequency AC/AC converter is taken as an example to demonstrate the design method of a passive low-pass filter. Firstly, the input side of the grid needs to meet the power factor and harmonic requirements. The preset parameters are set to a range to characterize the performance of the LC filter. The quantitative design method of input filter is proposed and summarized. Moreover, the sensitivity of the filter parameters is analyzed, providing a direction in practical applications. Preset parameters are all proved to conform to the preset range through PSIM simulation. Finally, a 130-W prototype is established to verify the correction of proposed design method. The power factor is around 0.935 and harmonic content in the input current is about 26.4%. All requirements can be satisfied.

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Robust Sliding Mode Control of a Unipolar Power Inverter

Energies ◽

10.3390/en14175405 ◽

2021 ◽

Vol 14 (17) ◽

pp. 5405

Author(s):

Muhammad Awais ◽

Abdul Rehman Yasin ◽

Mudassar Riaz ◽

Bilal Saqib ◽

Saba Zia ◽

...

Keyword(s):

Electromagnetic Interference ◽

Sliding Mode ◽

Practical Implementation ◽

Switching Frequency ◽

Sigmoid Function ◽

Pass Filter ◽

Low Pass Filter ◽

Pulse Width Modulated ◽

Simulation Based ◽

Low Pass

The key issue in the practical implementation of the sliding mode (SM) control–based power inverter is the variable switching frequency. This variable switching frequency not only induces electromagnetic interference (EMI) noise, but also reduces the efficiency of the inverter, as the size of the inductor and capacitor does not alter in tandem with this variable frequency. In this context, fixed switching frequency–based SM control techniques are proposed; however, some of them are too complex, while others compromise the inherent properties of SM control. In this research, a fixed frequency SM controller is proposed, which is based on the novel low-pass filter extraction of the discontinuous control signal. This allows the technique to be implemented with fewer hardware components, thus reducing the complications of implementation, while maintaining the robustness and parametric invariance of SM control. A simulation-based comparison with an existing pulse width modulated (PWM) SM controller is presented as the benchmark. In comparison with the sigmoid function SM controller, an improvement of 50% in the settling time along with zero steady-state errors and a further 37% and 42% improvement in the undershoot and overshoot, respectively, is reported in the simulation. A hardware setup is established to validate the proposed technique, which substantiates the simulation results and its disturbance rejection properties.

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