Power frequency filtering-away method for reducing influences of TMS electromagnetic pulses on rat motor evoked potential

Abstract

The invention discloses a power frequency filtering-away method for reducing influences of TMS electromagnetic pulses on a rat motor evoked potential. The method includes the steps that the one-time TMS pulses act on a rat motor cortex, and a surface electromyogram signal of hind limbs of a rat in a waking state is recorded by the adoption of sampling frequency above 1,000 Hz; Fourier transformation conversion is performed on the electromyogram signal, Fourier coefficients corresponding to power frequency interference and a direct current component are subjected to zero setting, other Fouriercoefficients are kept unchanged, Fourier inverse conversion is performed, smoothing of power frequency interference is realized, and an electromyogram signal after smoothing is obtained; the motor evoked potential is extracted from the smoothed electromyogram signal, and a motor evoked potential is obtained after power frequency interference is filtered away. The method adopting Fourier inverse conversion for filtering away power frequency interference does not need establishment of a digital wave trap, the influences of the TMS electromagnetic pulses on the motor evoked potential can be reduced greatly during smoothing, self-characteristics of the motor evoked potential can be kept well, and the method has important meanings for accurate extraction of the motor evoked potential waveform,amplitude value and latent period of a rat under the effect of a TMS.

Description

technical field [0001] The invention relates to a method for filtering out TMS motion-induced potential power frequency interference. In particular, it relates to a power frequency filtering method for reducing the influence of TMS electromagnetic pulses on motor evoked potentials of rats. Background technique [0002] Transcranial magnetic stimulation (TMS) technology is a technology that uses time-varying pulsed magnetic fields to act on the central nervous system (mainly the brain), changing the membrane potential of cortical nerve cells, causing them to generate induced currents, and affecting brain metabolism. And nerve electrical activity, thereby triggering a series of physiological and biochemical responses of magnetic stimulation technology. Motor evoked potential (MEP) is a muscle motor compound potential recorded in the target muscle when a single TMS pulse acts on the motor cortex. At present, there are needle electrodes and surface electrodes for collecting ra...

AI Technical Summary

Problems solved by technology

However, it is still difficult to accurately extract the motor evoked potential, latency, and amplitude recorded by the surface electrodes in the awake state.

Compared with the human body, there are fine hairs on the surface of the rat limbs, which are difficult to completely remove, and the impedance is relatively large. The ability to reduce the impedance with scrub and conductive paste is limited, so the motor-evoked potentials recorded by the surface electrodes have great power frequency interference.

[0003] At present, the existing power frequency interference filtering method is mainly to filter by constructing a digital notch filter, and the surface electromyography signal recorded at the target muscle contains not only the motor evoked potential, but also the TMS electromagnetic signal with a very large amplitude. pulse, and the TMS electromagnetic pulse is located before the motor-evoked potential, and the interval is only a few milliseconds. At this time, if the digital notch filter is used to filter out the power frequency interference, the TMS electromagnetic pulse will bring obvious distortion to the motor-evoked potential after filtering. It is very difficult to extract the amplitude and latency of motor evoked potentials

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