The anterior paired lateral neuron normalizes odour-evoked activity in the Drosophila mushroom body calyx

To identify and memorize discrete but similar environmental inputs, the brain needs to distinguish between subtle differences of activity patterns in defined neuronal populations. The Kenyon cells of the Drosophila adult mushroom body (MB) respond sparsely to complex olfactory input, a property that is thought to support stimuli discrimination in the MB. To understand how this property emerges, we investigated the role of the inhibitory anterior paired lateral neuron (APL) in the input circuit of the MB, the calyx. Within the calyx, presynaptic boutons of projection neurons (PNs) form large synaptic microglomeruli (MGs) with dendrites of postsynaptic Kenyon cells (KCs). Combining EM data analysis and in vivo calcium imaging, we show that APL, via inhibitory and reciprocal synapses targeting both PN boutons and KC dendrites, normalizes odour-evoked representations in MGs of the calyx. APL response scales with the PN input strength and is regionalized around PN input distribution. Our data indicate that the formation of a sparse code by the Kenyon cells requires APL-driven normalization of their MG postsynaptic responses. This work provides experimental insights on how inhibition shapes sensory information representation in a higher brain centre, thereby supporting stimuli discrimination and allowing for efficient associative memory formation.

Topographic connectivity and cellular profiling reveal detailed input pathways and functionally distinct cell types in the subthalamic nucleus

SummaryThe subthalamic nucleus (STN) controls psychomotor activity and is an efficient therapeutic deep brain stimulation target in Parkinson’s disease patients. Despite evidence indicating position-dependent therapeutic effects and distinct functions within the STN, input circuit and cellular profile in the STN remain largely unclear. Using advanced neuroanatomical techniques, we constructed a comprehensive connectivity map of the indirect and hyperdirect pathways in both the mouse and human STN. Our detailed circuit- and cellular-level connectivity revealed a topographically graded organization with three convergent types of indirect and hyperdirect-pathways. Furthermore, we identified two functional types of glutamatergic STN neurons (parvalbumin, PV +/- neurons) segregated with a topographical distribution. Glutamatergic PV+ STN neurons contribute to burst firing. We confirmed synaptic connectivity from indirect and hyperdirect pathways to both PV+ and PV-. These data suggest a complex interplay of information integration within the basal ganglia underlying coordinated movement control and therapeutic effects.

The anterior paired lateral neuron normalizes odour-evoked activity at the mushroom body calyx

To identify and memorize discrete but similar environmental inputs, the brain needs to distinguish between subtle differences of activity patterns in defined neuronal populations. The Kenyon cells of the Drosophila adult mushroom body (MB) respond sparsely to complex olfactory input, a property that is thought to support stimuli discrimination in the MB. To understand how this property emerges, we investigated the role of the inhibitory anterior paired lateral neuron (APL) in the input circuit of the MB, the calyx. Within the calyx, presynaptic boutons of projection neurons (PNs) form large synaptic microglomeruli (MGs) with dendrites of postsynaptic Kenyon cells (KCs). Combining EM data analysis and in vivo calcium imaging, we show that APL, via inhibitory and reciprocal synapses targeting both PN boutons and KC dendrites, normalizes odour-evoked representations in MGs of the calyx. APL response scales with the PN input strength and is regionalized around PN input distribution. Our data indicate that the formation of a sparse code by the Kenyon cells requires APL-driven normalization of their MG postsynaptic responses. This work provides experimental insights on how inhibition shapes sensory information representation in a higher brain centre, thereby supporting stimuli discrimination and allowing for efficient associative memory formation.

SIMULATION OF AN ELECTROMYOGRAPHIC SIGNAL CONVERTER FOR ADAPTIVE ELECTRICAL STIMULATION TASKS

The subject matter of the article is an electromyographic signal transducer, which are an integral part of devices for adaptive electrical stimulation of muscle structures based on reverse electromyographic communication. The goal of the work is to study the features, obtaining the corresponding theoretical relationships and computer modeling of a differential biopotential converter, providing amplification of the useful component and suppression of harmful interference, the spectra of which intersect. The following tasks were solved in the article: determining the effect of electrode width and electrode spacing on crosstalk; formation of the electrode-skin model and the input circuit of the transducer, obtaining theoretical relations for calculating the rejection coefficient, construction of the transducer circuit and its computer simulation. The following methods were used – methods of mathematical modeling of processes and technical devices; methods of analysis, structural and parametric synthesis of nonlinear electronic circuits; methods of machine design. The following results were obtained – a biopotential amplifier circuit with tracking feedback on power supply is proposed; modeling of dynamic processes by means of the Multisim program was carried out; on the basis of the constructed model of the electrode-skin input circuit and the obtained analytical relationships, the rejection coefficient of the input circuit of the equivalent circuit is calculated; the requirements for the signal registration module are formulated. Conclusions: The considered version of the electromyographic signal converter circuit based on tracking communication on power supply, effectively rejects 50 Hz common mode noise. On the basis of the constructed equivalent model of the input circuit of the amplifier, the theoretical relation for calculating the rejection coefficient of such amplifiers. The circuit is simulated in the Multisim program, the results confirmed the correctness of its functioning. The requirements for the interelectrode distance and the thickness of the electrodes themselves are also formulated. The results obtained can be used to design complexes for adaptive electrical stimulation.

Potential immunity of radio control lines

In the work, a methodology for assessing the potential noise immunity of radio control lines operating with binary FT signals is presented when using both element-by-element signal processing and signal processing in toto. The calculation method is based on the criterion adopted in radio control lines. According to the proposed technique, calculation shows that potential noise immunity with element-by-element signal processing is achieved with coherent reception of the FT signal under conditions of an unlimited increase in the code width, therefore, the frequency band occupied by the signal is expands indefinitely. In this case processing a binary signal in toto is realized by transferring the clipper from the video channel to the input signal receiving circuit. The transition from element-by-element signal processing to processing it in toto accompanied by an increase in the maximum possible value of the noise immunity coefficient by a factor of / 2 . Such an effect, in comparison with the circuit of the model of the radio control line with element-by-element processing of the FT signal, is achieved due to the transfer of the clipper, which plays the role of a decisive element in the circuit when receiving a symbol, into the input circuit. As a result, a filter-clipper-filter system is formed together with bandpass F1 and F2 filters. Therein F1 filter is still tuned to the frequency of the FT signal and matched to its symbol, and the passband of F2 is much higher than the bandwidth of the matched filter so that only the first harmonic of the signal spectrum is isolated without distortion practically. In this case, the clipper (O) ensures that the probability of false reception Pl is independent of the level of input noise, and at the s-n ratio q≤1 the clipper behaves like a linear device, while it is a classical nonlinear device when it is operating in the video signal channel (fig. 2) where there is signal suppression by interference which leads to a certain decrease in the potential radio link noise immunity during signal processing in element-by-element type.

Identification of measuring part elements of numerical relay protection by its response time

The purpose of the study is to develop an identification method of a specific implementation of the elements of the measuring part (intermediate converters, analog filters) and partially computational-logical part (digital filters) of a microprocessor relay protection by the signal actuation time, which, unlike the existing approaches allows to identify and exclude the delays introduced by the executive protection elements. The method of directed graphs is used to form a mathematical model of the measuring part of the microprocessor relay protection. The solution formed as a result of differential equations is implemented using the method of analog implicit continuous integration. The time delays introduced by the input protection circuits are determined as follows: identical signals are fed to the terminal and the mathematical model of protection; signal actuation time is recorded, where the time starting point is the moment the input signal reaches the setpoint and the end point is the moment of the actuation signal occurrence. Having studied 144 different combinations of measuring part elements (intermediate converters, analog filters) and digital filters with a finite impulse response of microprocessor relay protection, the most “optimal” combination has been chosen, which features the least deviation from the response time of a real device in all studied modes as compared with other combinations. The proposed identification method of input circuit elements of microprocessor (numerical) protection is the main way to bring the model closer to a real device. It also enables to receive a table of “typical” response times of protections with the different structure of the measuring part and depending on the specific type of protection terminal choose in practice a predetermined “optimal” internal composition of protection used when setting up protection using their mathematical models.

New High-Efficiency Resonant O-Type Devices as the Promising Sources of Microwave Power

New O-type high-power vacuum resonant microwave devices are considered in this study: COM klystrons, CSM klystrons and resotrodes. All these devices can output a large amount of power (up to units of MW and higher) with an efficiency of up to 90%. Such devices are promising microwave sources for industrial microwave technologies as well as for microwave energy. The principle of GSP-equivalence for klystrons is described herein, allowing a complete physical analog of this device with other parameters to be created. The existing mathematical and computer models of klystrons are analyzed. The processes of stage-by-stage optimization and the embedding procedure, which leads to COM and to CSM klystrons, are considered. Resotrodes, IOT-type devices with energy regeneration in the input circuit, are also considered. It is shown that these devices can combine high power with an efficiency of up to 90% and a gain of more than 30 dB. Resotrodes with 0-regeneration can be effective sources of radio frequency (RF) power in the range of 20 to 200 MHz. Resotrodes with 2π-regeneration are an effective source of RF/microwave energy in the range of 200 MHz to 1000 MHz.

A Novel Current-Controlled Oscillator-Based Low-Supply-Voltage Microbolometer Readout Architecture

In this paper, we present a novel, almost-digital approach for bolometer readout circuits to overcome the area and power dissipation bottlenecks of analog-based classical microbolometer circuits. A current-controlled oscillator (CCO)-based analog-to-digital converter (ADC) is utilized instead of a capacitive transimpedance amplifier (CTIA) in the classical readout circuits. This approach, which has not been reported before, both produces the required gain in the bolometer input circuit and directly digitizes the bolometer signal. With the proposed architecture, the need for large capacitances (of the order of 10–15[Formula: see text]pF for each column) at which the current is accumulated in the bolometer circuits and the voltage headroom limitation of classical microbolometer circuits are eliminated. Therefore, the proposed architecture permits to design readout circuits with reduced pixel pitch and lower power supply, both of which in turn lead to higher-resolution Focal Plane Arrays (FPAs) with lower power dissipation. The new architecture is modeled and simulated using a 180-nm CMOS process for sensitivity, noise performance, and power dissipation. Unlike the 3.3-V power supply usage of classical readout circuits, the proposed design utilizes 1.2-V analog and 0.9-V digital supply voltages with a power dissipation of almost half of the classical approach.

METHOD OF STRUCTURAL SYNTHESIS OF RECEIVING AND TRANSMITTING RADIO DEVICES BLOCK SCHEMES

This paper is devoted to development of an algorithm for the synthesis of receiving and transmitting radio devices block schemes. Based on the presented algorithm, it is possible to develop a program that implements automated circuit synthesis. Such a program allows to a developer to obtain the most optimal scheme in the class of Pareto-optimal solutions. The algorithm is based on the method of exhaustive search of structural and elemental designs, and the decision-making method based on the criteria convolution method. The application of the exhaustive search of possible structural-element designs method allows creating a complete set of implementations and thus making choice decision of a scheme according to certain criteria among all possible constructions. This allows asserting the optimality of the obtained solutions, selected from a complete ensemble of possible designs. The use of the vector optimization method to select the optimal structural block scheme design of receiving and transmitting radio devices allows determining the most optimal construction according to the criterion for the highest value of the optimization function formed by the criteria convolution method. In the paper also considered a practical example of the synthesis of the input circuit of the receiving module RF part. As an example, the task of change the electronic components of the input part of the receiving module RF part with alternative microcircuits is given. To solve the described problem, a program was developed in the MATLAB. The results of the program are also given in the paper. The effectiveness of the developed algorithm and method for solving the task of synthesizing a block scheme from an elemental base represented by modern electronic components and circuit solutions is shown. Recommendations on further promising application of the proposed algorithm and method are presented.