Power frequency filtering method to reduce the effect of tms electromagnetic pulse on motor evoked potentials in rats

Abstract

A power frequency filtering method to reduce the influence of TMS electromagnetic pulse on rat motor evoked potentials: a single TMS pulse is applied to the rat motor cortex, and the surface EMG signal of the hindlimb in the wakeful state of the rat is recorded with a sampling frequency of more than 1000 Hz. ; Perform Fourier transform on the EMG signal, set the Fourier coefficient corresponding to the power frequency interference and the DC component to zero, and keep the remaining Fourier coefficients unchanged, perform inverse Fourier transform to realize the filtering of power frequency interference, The filtered EMG signal is obtained; the motor evoked potential is extracted from the filtered EMG signal, and the motor evoked potential after filtering out the power frequency interference is obtained. The method of filtering out the power frequency interference by using the inverse Fourier transform of the invention does not need to establish a digital notch filter, can greatly reduce the influence of the TMS electromagnetic pulse on the motion-induced potential in the filtering process, and can better preserve the self-movement-induced potential. It is of great significance to accurately extract the waveform, amplitude and latency of motor evoked potentials in rats under the action of 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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