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Hardware and software for neurophysiology experiments

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V. O. Molodtsov – Ph.D. (Eng.), Associate Professor, St. Petersburg Electro-Technical University (LETI). E-mail: vomolodсov@mail.eltech.ru
V. Yu. Smirnov – Post-graduate Student, St. Petersburg Electro-Technical University (LETI). E-mail: vysmirnov@etu.ru
S. D. Solnushkin – Senior Research Scientist, Pavlov Institute of Physiology RAS (St. Petersburg). E-mail: solnushkin@list.ru
V. N. Chikhman – Ph.D. (Eng.), Senior Research Scientist, Pavlov Institute of Physiology RAS (St. Petersburg). E-mail: niv@pavlov.infran.ru


The new hardware and software modules for neurophysiological experiments are presented. Previously number of tools for computer support of experiments has been introduced for systems based on IBM PC. This were ADC of differing digit capacity and performance for ISA-bus (MD42, MD142, MD70, MD88, MD93, MD32), amplifiers (MD90, MD95, MD42U), module for input of interpulse intervals (MD79), remote control system for input responses (MD74). Modules had high metrological characteristics, autoadjustment Bias zero and nonlinearity. Recently, a new class of sigma-delta ADC with wide dynamic range and digital filtering functions has appeared as the basis for measuring instruments for the next generation. Device MD155 was provided for converting to digital code of low frequency signals on eight channels, as well as input-output digital signals. To register of visual evoked potentials a portable device MD171 with 26 measuring channels was created, characterized by the presence of a separate ADC chip for each channel. The device MD226 was created for measuring signals with transfer of results via BLUETOOTH to a PC. The radio module is implemented on a chip WT11 BLUEGIGA, adjusts parameters and the transfer of measurement results. MD226 module is based on ADC ADS1298, focused on biomedical applications. Programmable structure allows realizing standard wiring diagrams for reference electrode, adopted in cardiography and encephalography. Microcontroller implemented on a chip ATtiny167 performs the functions of the block management unit. The module MD236 designed for monitoring changes in the frequency of the impulse activity of neurons when exposed to a biological object. MD236 counts the pulses in a given time interval with the issuance of the result via USB to PC. The reference range of the interval of time is from 2 to 65536 s (or ms). MD236 contains two 24-bit counter, working alternately as the input pulses are asynchronous with respect to the measurement of time intervals. Communication via the USB interface is implemented on a chip FT245RL. The basic units of the device performed on chip programmable logic EPM570T100C5. MD228 for generating pulses of a certain frequency, amplitude, and duty cycle has four independent channels. There is pulse discriminator at the input of MD228, created with comparator LT1671. It is possible modulation of top-level variable voltage pulses linearly (LIN). Software support of modules is organized by a driver, realized start by timer, interrupt handling, direct access to memory. In the Delphi environment using DirectX program designed to control the equipment, processing and visualization of signals, control experiment in interactive mode. Digitized processes are stored in a relational database. Programs include procedures for digital filtering, scaling axes (used functions of Matlab).
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