Objective: To compare the difference between the built-in and external reference electrode of microwire electrode array in the process of recording rat brain neuron firings, optimizing the production and embedding of the microwire electrode array, and providing a more affordable and excellent media tool for multi-channel electrophysiological real-time recording system. Methods: A 16 channel microwire electrode array was made by using nickel chromium alloy wires, circuit board, electrode pin and ground wires (silver wires). The reference electrode of the microwire electrode array was built-in (the reference electrode and electrode array were arranged in parallel) or external (the reference electrode and ground wire were welded at both ends of one side of the electrode), and the difference between the two electrodes was observed and compared in recording neuronal discharges in ACC brain area of rats. Experimental rats were divided into built-in group and external group, n=8-9. The test indicators included signal-to-noise ratio (n=8), discharge amplitude (n=380) and discharge frequency (n=54). Results: The microwire electrode array with both built-in and external reference electrodes successfully recorded the electrical signals of neurons in the ACC brain region of rats. Compared with the external group, the electrical signals of neurons in built-in group had the advantages of a higher signal-to-noise ratio (P＜0.05), a smaller amplitude of background signals and less noise interference, and a larger discharge amplitude(P＜0.05); there was no significant difference in spike discharge frequency recorded by these two types of electrodes (P＞0.05). Conclusion: When recording the electrical activity of neurons in the ACC brain region of rats, the microwire electrode array with built-in reference electrode recorded electrical signals with higher signal-to-noise ratio and larger discharge amplitude, providing a more reliable tool for multi-channel electrophysiology technology.
Action Potentials/physiology* ; Animals ; Brain ; Electrophysiological Phenomena ; Microelectrodes ; Neurons ; Rats

As an interface between external electronic devices and internal neural nuclei, microelectrodes play an important role in many fields, such as animal robots, deep brain stimulation and neural prostheses. Aiming at the problem of high price and complicated fabrication process of microelectrode, a microelectrode twisting machine based on open source electronic prototyping platform (Arduino) and three-dimensional printing technology was proposed, and its microelectrode fabrication performance and neural stimulation performance were verified. The results show that during the fabrication of microelectrodes, the number of positive twisting turns of the electrode wire should generally be set to about 1.8 times of its length, and the number of reverse twisting rings is independent of the length, generally about 5. Moreover, compared with the traditional instrument, the device is not only inexpensive and simple to manufacture, but also has good expandability. It has a positive significance for both the personalization and popularization of microelectrode fabrication and the reduction of experimental cost.
Equipment Design ; Microelectrodes ; Printing, Three-Dimensional

Spike recorded by multi-channel microelectrode array is very weak and susceptible to interference, whose noisy characteristic affects the accuracy of spike detection. Aiming at the independent white noise, correlation noise and colored noise in the process of spike detection, combining principal component analysis (PCA), wavelet analysis and adaptive time-frequency analysis, a new denoising method (PCWE) that combines PCA-wavelet (PCAW) and ensemble empirical mode decomposition is proposed. Firstly, the principal component was extracted and removed as correlation noise using PCA. Then the wavelet-threshold method was used to remove the independent white noise. Finally, EEMD was used to decompose the noise into the intrinsic modal function of each layer and remove the colored noise. The simulation results showed that PCWE can increase the signal-to-noise ratio by about 2.67 dB and decrease the standard deviation by about 0.4 μV, which apparently improved the accuracy of spike detection. The results of measured data showed that PCWE can increase the signal-to-noise ratio by about 1.33 dB and reduce the standard deviation by about 18.33 μV, which showed its good denoising performance. The results of this study suggests that PCWE can improve the reliability of spike signal and provide an accurate and effective spike denoising new method for the encoding and decoding of neural signal.
Algorithms ; Microelectrodes ; Principal Component Analysis ; Reproducibility of Results ; Signal Processing, Computer-Assisted ; Signal-To-Noise Ratio ; Wavelet Analysis

BACKGROUND: Recently, carbon fibers have been utilized to develop a depth-type microelectrode array for chronic neural recording. Since the diameter of carbon fibers is smaller than the conventional electrodes made of metal wires or microfabricated silicon, the carbon fiber electrodes showed an improved capability for chronic neural recording with less tissue damages. However, the carbon fiber based microelectrodes have a limitation of short insertion depth due to a low stiffness. METHODS: We proposed a carbon fiber based microelectrode array embedded with a mechanical support structure to facilitate the penetration into the deeper brain. The support is made of biodegradable silk fibroin to reduce the reactive tissue responses. The 4-channel carbon fiber based microelectrode arrays were fabricated and accessed in terms of electrochemical impedance, recording capability for 1-month implantation in rat hippocampi. The electrodes with tungsten supports were fabricated and tested as a control group. Immunohistochemical analysis was performed to identify the reactive glial responses. RESULTS: The carbon fiber based electrode arrays with silk supports showed about 2-fold impedance increase 2 weeks after implantation while the number of active electrodes decreased simultaneously. However, after 1 month, the electrode impedance decreased back to its initial value and the percentage of active electrodes also increased above 70%. Immunohistochemical staining clearly showed that the electrodes with silk supports induced less reactive glial responses than that with tungsten supports. CONCLUSION: The proposed carbon fiber based microelectrode array is expected to be used for long-term in vivo neural recording from deep brain regions with the minimized reactive tissue response.
Animals ; Brain ; Carbon ; Electric Impedance ; Electrodes ; Fibroins ; Microelectrodes* ; Rats ; Silicon ; Silk* ; Tungsten

Tetrodes, consisting of four twisted micro-wires can simultaneously record the number of neurons in the brain. To improve the quality of neuronal activity detection, the tetrode tips should be modified to increase the surface area and lower the impedance properties. In this study, tetrode tips were modified by the electrodeposition of Au nanoparticles (AuNPs) and dextran (Dex) doped poly (3,4-ethylenedioxythiophene) (PEDOT). The electrochemical properties were measured using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A decrease in the impedance value from 4.3 MΩ to 13 kΩ at 1 kHz was achieved by the modified tetrodes. The cathodic charge storage capacity (CSC(C)) of AuNPs-PEDOT deposited tetrodes was 4.5 mC/cm², as determined by CV measurements. The tetrodes that were electroplated with AuNPs and PEDOT exhibited an increased surface area, which reduced the tetrode impedance. In vivo recording in the ventral posterior medial (VPM) nucleus of the thalamus was performed to investigate the single-unit activity in normal rats. To evaluate the recording performance of modified tetrodes, spontaneous spike signals were recorded. The values of the L-ratio, isolation distance and signal-to-noise (SNR) confirmed that electroplating the tetrode surface with AuNPs and PEDOT improved the recording performance, and these parameters could be used to effectively quantify the spikes of each cluster.
Animals ; Brain ; Dextrans ; Dielectric Spectroscopy ; Electric Impedance ; Electrodes ; Electroplating ; Microelectrodes ; Nanoparticles* ; Neurons ; Rats ; Thalamus

PURPOSE: To simultaneously monitor electrical discharges in various bladder regions and the external urethral sphincter (EUS) during voiding contractions, and to assess the functional role of myogenic modulation of the lower urinary tract (LUT) by ionotropic purinergic receptors containing the P2X3 subunit. METHODS: Female Sprague-Dawley rats were anesthetized with urethane, and implanted with a suprapubic catheter for open cystometry. Flexible microelectrodes were placed ventrally in the bladder dome, upper bladder, lower bladder, and bladder base, along with the middle section of the exposed EUS. Intravesical P2X3-containing receptors were blocked with AF-323, a specific P2X3-P2X2/3 receptor antagonist. A digital electrophysiology amplifier was used to record electrical and cystometric signals throughout the LUT. RESULTS: Electrical activity in the LUT started before effective voiding contractions. Bladder pressure and electrical waveforms showed consistent out-of-phase activity when compared with the recordings made at the EUS. This pattern was also observed during voiding contractions in the presence of AF-353, supporting the hypothesis that during bladder distension, activation of P2X3-containing receptors is required for voiding contractions. Furthermore, the inhibition of P2X3-containing receptors significantly decreased the amplitude of electrical signals in the urinary bladder, but not the base or EUS. CONCLUSIONS: Our results provide novel information about the regulation of the micturition process by P2X3-containing receptors located in the inner layers of the bladder.
Animals ; Catheters ; Electrophysiology ; Female* ; Humans ; Lower Urinary Tract Symptoms ; Microelectrodes ; Purinergic P2X Receptor Antagonists ; Rats* ; Rats, Sprague-Dawley ; Receptors, Purinergic ; Urethane ; Urethra ; Urinary Bladder* ; Urinary Tract ; Urination*

Vision is one of the most important human sensations about the surrounding world. Visual deprivation not only markedly affects the life of blind people, but also gives a heavy burden to their family and the society. A visual prosthesis is an electronic device that helps the blinds to regain visual perception by directly stimulating the visual pathway using the microelectrodes implanted into the body. In recent years, visual prostheses have been developed rapidly and some devices have already become clinically available. In this paper, we reviewed the history of visual prosthesis, introduced different visual prostheses classified according to the location of the implanted stimulating electrodes. Clinical study results as well as the functional status of the currently available visual prosthesis devices were also summarized.
Blindness ; Electrodes, Implanted ; Humans ; Microelectrodes ; Visual Perception ; Visual Prosthesis

In the neural engineering field, physiological dysfunctions are approached by identifying the target nerves and providing artificial stimulation to restore the function. Neural stimulation and recording technologies play a central role in this approach, and various engineering devices and stimulation techniques have become available to the medical community. For bladder control problems, electrical stimulation has been used as one of the treatments, while only a few emerging neurotechnologies have been used to tackle these problems. In this review, we introduce some recent developments in neural stimulation technologies including microelectrode array, closed-loop neural stimulation, optical stimulation, and ultrasound stimulation.
Electric Stimulation ; Microelectrodes ; Ultrasonography ; Urinary Bladder*

OJECTIVETo explore whether different acupuncture signals were afferent to the cerebellar fastigial nucleus (FN) neuron and to find out their corresponding effect features through observing the effect of spontaneous discharge of cerebellar FN neuron by needling at different acupoints.

METHODSTotally 120 male SD rats were anesthetized by 20% urethane and their right cerebellar FN were positioned (AP 11. 6 mm, RL 1. 0 mm, H 5. 6 mm). Extracelluar discharge was recorded by glass microelectrode (AP: -11. 6 mm, R: 1. 0 mm, H: 5.7 -7. 0 mm), using extracellular microelectrode recording method, recording the spontaneous discharge of cerebellar FN neurons as a baseline. Random order of needling at zusanli (ST36), quchi (Lil1), weishu (BL21), and zhongwan (CV12) were compared with the baseline before each acupuncture. Their effects on the discharge of cerebellar FN neurons were observed and compared with baselines.

RESULTSThe frequency of FN neuronal discharge could be elevated by needling at zusanli (ST36), quchi (LiI), weishu (BL21), and zhongwan (CV12) (P <0. 01, P <0. 05). The response rate of needling at Zhongwan (CV12, 56. 00%) was higher than that of needling at Zusanli (ST36), Quchi (Ll1), and Weishu (BL21) (35. 00%, 34. 62%, 36. 63%, respectively) with statistical difference (P <0. 05). The response rate of needling at zhongwan (CV12) was obviously higher than that of needing at other points (F = 2. 101, P < 0. 05).

CONCLUSIONSNeedling at zusanli (ST36 ), quchi (Lil), weishu (BL21), and zhongwan (CV12) could elevate the spontaneous discharge frequency of cerebellar FN neurons. Needling at Zhongwan (CV12) had advantageous roles in regulating cerebellar FN.

Acupuncture Points ; Acupuncture Therapy ; Animals ; Cerebellar Nuclei ; physiology ; Male ; Microelectrodes ; Neurons ; Rats ; Rats, Sprague-Dawley

Little human tissue data are available for slow waves and migrating motor complexes, which are the main components of small bowel motility. We investigated the electrophysiological and mechanical characteristics of human ileal motility, in vitro. Ileum was obtained from patients undergoing bowel resection. Electrophysiological microelectrode recordings for membrane potential changes and mechanical tension recordings for contraction from smooth muscle strips and ileal segments were performed. Drugs affecting the enteric nervous system were applied to measure the changes in activity. Slow waves were detected with a frequency of 9~10/min. There were no cross-sectional differences in resting membrane potential (RMP), amplitude or frequency between outer and inner circular muscle (CM), suggesting that electrical activities could be effectively transmitted from outer to inner CM. The presence of the interstitial cell of Cajal (ICC) at the linia septa was verified by immunohistochemistry. Contractions of strips and segments occurred at a frequency of 3~4/min and 1~2/min, respectively. The frequency, amplitude and area under the curve were similar between CM and LM. In segments, contractions of CM were associated with LM, but propagation varied with antegrade and retrograde directions. Atropine, NW-oxide-L-arginine, and sodium nitroprusside exhibited different effects on RMP and contractions. There were no cross-sectional differences with regard to the characteristics of slow waves in CM. The frequency of contractions in smooth muscle strips and ileal segments was lower than slow waves. The directions of propagation were diverse, indicating both mixing and transport functions of the ileum.
Atropine ; Enteric Nervous System ; Humans* ; Ileum ; Immunohistochemistry ; Membrane Potentials ; Microelectrodes ; Muscle, Smooth ; Myoelectric Complex, Migrating ; Nitroprusside