Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use...Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use of a carbon fiber microelectrode modified with a tetrasulfonated nickel phthalocyanine complex for the detection of MNP at a lower potential than that of direct phenol oxidation. The MNP voltammogram showed the presence of an anodic peak at -0.11 V vs SCE, corresponding to the oxidation of the hydroxylamine group generated after the reduction of the nitro group. The effect of buffer pH on the peak current and SWV parameters such as frequency, scan increment, and pulse amplitude were studied and optimized to have better electrochemical response of the proposed sensor. With these optimal parameters, the calibration curve shows that the peak current varied linearly as a function of MNP concentration, leading to a limit of detection (LoD) of 1.1 μg/L. These results show an appreciable sensitivity of the sensor for detecting the MNP at relatively low potentials, making it possible to avoid passivation phenomena.展开更多
The relationship between the parameters of Transcorneal Electrical Stimulation (TES) and its neuro-protective effect of TES on axotomised Retinal Ganglion Cells (RGCs) is still unclear. This work discusses the design ...The relationship between the parameters of Transcorneal Electrical Stimulation (TES) and its neuro-protective effect of TES on axotomised Retinal Ganglion Cells (RGCs) is still unclear. This work discusses the design strategy of a new non conventional TES stimulator, the micro fabrication processes and characterization of an array of MEMS microelectrodes over a flexible polymer layer substrate to stimulate the human cornea. The micro-array of electrodes, over a flexible smooth biocompatible polyimide substrate, fine tunes the curvature of the cornea. This tool can help researchers to define the optimal electric stimulation parameters required in TES.展开更多
Conducting polymers have been studied extensively. An interesting property of the conducting polymer is that the conductivity of some polymers, such as polypyrrolc, polyaniline, poly(3-methylthiophene) etc. , is affec...Conducting polymers have been studied extensively. An interesting property of the conducting polymer is that the conductivity of some polymers, such as polypyrrolc, polyaniline, poly(3-methylthiophene) etc. , is affected by the voltage applied to them. For polypyrrole, the oxidized state is an electronic conductor and the reduced state is essentially insulating. Using this property, one can fabricate the polymer-based electronic devices. Experimental results of展开更多
The behaviors ot PbSO4/Pb and PbO4/PbSO4 electrode prepared from PbCO3 have been examined using powder microelectrode(PME) technique and cyclic voltammetry(CV). Firstly, PMEs parked with Pb- CO3 transformed into PtSO4...The behaviors ot PbSO4/Pb and PbO4/PbSO4 electrode prepared from PbCO3 have been examined using powder microelectrode(PME) technique and cyclic voltammetry(CV). Firstly, PMEs parked with Pb- CO3 transformed into PtSO4 PME in 1. 0 mol/L H2SO4 solution at 30 C, and then the PbSO4 in the PMEs were formed to Pb or PbO2 using an unsymmetrical signal(Qa/Qe for PbSO4/Pb electrode and Qe/Qa for PsO2/ PbSO4 electrode being 0. 1-0. 3) in 2. S mol/L H2SO4 solution. The results show that the CV characteristic of either PbSO4/Pb or PsO2/PbSO4 PME prepared from PhCO3 are as good as that of both electrodes made from lead oxide powder produced by ball mill.展开更多
A microfabricated electrical impedance spectroscopy (EIS) chip with microelectrodes was developed.The substrate and the electrodes of the chip were made of glass and gold,respectively.The experimental results demonstr...A microfabricated electrical impedance spectroscopy (EIS) chip with microelectrodes was developed.The substrate and the electrodes of the chip were made of glass and gold,respectively.The experimental results demonstrated that the EIS-chip could distinguish different solutions (physiological saline,culture medium,living cell suspension etc.) by scanning from 10Hz to 45kHz.A 6-element circuit model was used for fitting the real part and the imaginary part admittance curves of the living cell suspension.An actual circuit was also built and tested to verify the 6-element circuit model proposed.The micro-EIS chip has several advantages including the use of small sample volumes,high resolution and ease of operation.It shows good application prospects in the areas of cellular electrophysioiogy,drug screening and bio-sensors etc.展开更多
Electrochemical logical operations utilizing biological molecules(protein or DNA), which can be used in disease diagnostics and bio-computing, have attracted great research interest. However, the existing logic operat...Electrochemical logical operations utilizing biological molecules(protein or DNA), which can be used in disease diagnostics and bio-computing, have attracted great research interest. However, the existing logic operations, being realized on macroscopic electrode, are not suitable for implantable logic devices. Here, we demonstrate DNA-based logic gates with electrochemical signal as output combined with gold flower microelectrodes. The designed logic gates are of fast response, enzyme-free, and micrometer scale. They perform well in either pure solution or complex matrices, such as fetal bovine serum,suggesting great potential for in vivo applications.展开更多
A new PVC matrix membrane double-barreled calcium ion-selective microelectrode based on liquid ion exchanger has been designed and constructed.The tip diameter of about 2.5μm as well as lower selectivity coefficients...A new PVC matrix membrane double-barreled calcium ion-selective microelectrode based on liquid ion exchanger has been designed and constructed.The tip diameter of about 2.5μm as well as lower selectivity coefficients for K+,Na and Mg2+are adequate for in-tracellular measurements of Ca activities.The inner wall of the selective channel was made to be hydrophobic by treatment withalkyl-alcohols.By means of this microelectrode some physiologicalphenomena related to Ca2+activities have been studied,and Caconcentrations in clinical microsamples have also been determined.展开更多
The paper is aimed to investigate the adhesion and growth of neural cells on different microelectrode surfaces and their possible mechanism, thereby an optimum interfacial material or substrate for neural microelectro...The paper is aimed to investigate the adhesion and growth of neural cells on different microelectrode surfaces and their possible mechanism, thereby an optimum interfacial material or substrate for neural microelectrode can be chosen. Three different materials including platinum, gold, and pyrolyzed photoresist derived carbon material, in the forms of plasma-treated and non-treated ones, were tested. Surface properties of the microelectrodes in terms of surface morphology and wettability were examined; then their biocompatibility was tested by co-culturing with SK-N-SH neuroblastoma cells. Results of experiments demonstrated that, compared with platinum and gold, carbon could be a better substrate for cell adhesion and growth,especially for the plasma-treated carbon surface. The high wetting property of plasma-treated carbon accounted for the preferable adhesion of cell on its surface. Therefore, plasma-treated carbon can potentially be employed for fabrication of biocompatible and stable neural electrodes, which is beneficial for neural engineering research, such as regeneration from injury or disease therapy of neural system.展开更多
The emerging field of neuroprosthetics is focused on design and implementation of neural prostheses to restore some of the lost neural functions. Remarkable progress has been reported at most bioelectronic levels—par...The emerging field of neuroprosthetics is focused on design and implementation of neural prostheses to restore some of the lost neural functions. Remarkable progress has been reported at most bioelectronic levels—particularly the various brain-machine interfaces (BMIs)—but the electrode-tissue contacts (ETCs) remain one of the major obstacles. The success of these BMIs relies on electrodes which are in contact with the neural tissue. Biological response to chronic implantation of Microelectrode arrays (MEAs) is an essential factor in determining a successful electrode design. By altering the material compositions and geometries of the arrays, fabrication techniques of MEAs insuring these ETCs try to obtain consistent recording signals from small groups of neurons without losing microstimulation capabilities, while maintaining low-impedance pathways for charge injection, high-charge transfer, and high-spatial resolution in recent years. So far, none of these attempts have led to a major breakthrough. Clearly, much work still needs to be done to accept a standard model of MEAs for clinical purposes. In this paper, we review different microfabrication techniques of MEAs with their advantages and drawbacks, and comment on various coating materials to enhance electrode performance. Then, we propose high-density, three-dimensional (3D), silicon-based MEAs using micromachining methods. The geometries that will be used include arrays of penetrating variable-height probes.展开更多
3-methyl-4-nitrophenol (MNP) is the main by-product of the organophosphate insecticide fenitrothion (FT), used in locust control. MNP is highly toxic because it is an endocrine disruptor and then may cause adverse in ...3-methyl-4-nitrophenol (MNP) is the main by-product of the organophosphate insecticide fenitrothion (FT), used in locust control. MNP is highly toxic because it is an endocrine disruptor and then may cause adverse in the biological systems. Then, it is necessary to develop analytical methods for determination of this pollutant in the environment. In this sense, we reported herein the development of an electrochemical sensor for the detection of 3-methyl-4-nitrophenol (MNP), one of the metabolites of fenitrothion (FT), by using naked and modified carbon fiber microelectrode (CFME) by nickel tetrasulfonated phthalocyanine polymer (CFME/p-NiTSPc). The voltammogram showed that MNP presents one irreversible anodic peak corresponding to the oxidation of the phenol group at 0.9 V vs Ag/AgCl. The effect of pH of the buffer on the peak current and SWV parameters such as frequency, scan increment and pulse amplitude were investigated in order to optimize the electrochemical response of the sensor. The obtained results lead to the following optimum value: pH = 6;frequency = 25 Hz, pulse amplitude = 50 mV, scan increment = 10 mV. With these optimum values, the calibration curves show that the peak current varied linearly upon MNP concentration leading to a limit of detection (LoD) for naked CFME close to 3 μg/L whereas for CFME modified by p-NiTSPc, it reaches 0.75 μg/L. This results prove that the presence of p-NiTSPc increasing the sensitivity of the sensor could be used to monitor 3-methyl-4-nitrophenol residue in real matrix.展开更多
In-situ monitoring of neurochemicals is of vital importance for the understanding of brain functions.Microelectrode-based photoelectrochemical(PEC) sensing has emerged as a promising tool for in vivo analysis since it...In-situ monitoring of neurochemicals is of vital importance for the understanding of brain functions.Microelectrode-based photoelectrochemical(PEC) sensing has emerged as a promising tool for in vivo analysis since it inherits the merits of both optical and electrochemical methods. However, the in-situ excitation of photoactive materials on the photoelectrode in living body is still a challenge because of limited tissue penetration depth of light. To circumvent this problem, we herein developed an implantable optical fiber(OF)-based microelectrode for in vivo PEC analysis. The working electrode was constructed by coating Au film as conducting layer and CdS@ZnO as photoactive material on a micron-sized OF,which was free of the limitation of light penetration in biological tissues. Further decoration of an antibiofouling layer on the surface made the sensor robust in biosamples. It was successfully applied for monitoring Cu^(2+) level in three different brain regions in the rat model of cerebral ischemia/reperfusion.展开更多
Implantable intracortical microelectrodes can record a neuron’s rapidly changing action potentials(spikes).In vivo neural activity recording methods often have either high temporal or spatial resolution,but not both....Implantable intracortical microelectrodes can record a neuron’s rapidly changing action potentials(spikes).In vivo neural activity recording methods often have either high temporal or spatial resolution,but not both.There is an increasing need to record more neurons over a longer duration in vivo.However,there remain many challenges to overcome before achieving long-term,stable,high-quality recordings and realizing comprehensive,accurate brain activity analysis.Based on the vision of an idealized implantable microelectrode device,the performance requirements for microelectrodes are divided into four aspects,including recording quality,recording stability,recording throughput,and multifunctionality,which are presented in order of importance.The challenges and current possible solutions for implantable microelectrodes are given from the perspective of each aspect.The current developments in microelectrode technology are analyzed and summarized.展开更多
Threatened animals respond with appropriate defensive behaviors to survive.It has been accepted that midbrain periaqueductal gray(PAG)plays an essential role in the circuitry system and organizes defensive behavioral ...Threatened animals respond with appropriate defensive behaviors to survive.It has been accepted that midbrain periaqueductal gray(PAG)plays an essential role in the circuitry system and organizes defensive behavioral responses.However,the role and correlation of different PAG subregions in the expression of different defensive behaviors remain largely unexplored.Here,we designed and manufactured a microelectrode array(MEA)to simultaneously detect the activities of dPAG and vPAG neurons in freely behaving rats.To improve the detection performance of the MEAs,PtNP/PEDOT:PSS nanocomposites were modified onto the MEAs.Subsequently,the predator odor was used to induce the rat’s innate fear,and the changes and information transmission in neuronal activities were detected in the dPAG and vPAG.Our results showed that the dPAG and vPAG participated in innate fear,but the activation degree was distinct in different defense behaviors.During flight,neuronal responses were stronger and earlier in the dPAG than the vPAG,while vPAG neurons responded more strongly during freezing.By applying high-performance MEA,it was revealed that neural information spread from the activated dPAG to the weakly activated vPAG.Our research also revealed that dPAG and vPAG neurons exhibited different defensive discharge characteristics,and dPAG neurons participated in the regulation of defense responses with burst-firing patterns.The slow activation and continuous firing of vPAG neurons cooresponded with the regulation of long-term freezing responses.The results demonstrated the important role of PAG neuronal activities in controlling different aspects of defensive behaviors and provided novel insights for investigating defense from the electrophysiological perspective.展开更多
文摘Electrochemical detection of 3-methyl-4-nitrophenol (MNP) in direct phenol oxidation occurs at high potentials and generally leads to progressive passivation of the electrochemical sensor. This study describes the use of a carbon fiber microelectrode modified with a tetrasulfonated nickel phthalocyanine complex for the detection of MNP at a lower potential than that of direct phenol oxidation. The MNP voltammogram showed the presence of an anodic peak at -0.11 V vs SCE, corresponding to the oxidation of the hydroxylamine group generated after the reduction of the nitro group. The effect of buffer pH on the peak current and SWV parameters such as frequency, scan increment, and pulse amplitude were studied and optimized to have better electrochemical response of the proposed sensor. With these optimal parameters, the calibration curve shows that the peak current varied linearly as a function of MNP concentration, leading to a limit of detection (LoD) of 1.1 μg/L. These results show an appreciable sensitivity of the sensor for detecting the MNP at relatively low potentials, making it possible to avoid passivation phenomena.
基金the support of the National Science Council and Technology of México,CONACyT,Hospital Dr.Luis Sánchez Bulnes.
文摘The relationship between the parameters of Transcorneal Electrical Stimulation (TES) and its neuro-protective effect of TES on axotomised Retinal Ganglion Cells (RGCs) is still unclear. This work discusses the design strategy of a new non conventional TES stimulator, the micro fabrication processes and characterization of an array of MEMS microelectrodes over a flexible polymer layer substrate to stimulate the human cornea. The micro-array of electrodes, over a flexible smooth biocompatible polyimide substrate, fine tunes the curvature of the cornea. This tool can help researchers to define the optimal electric stimulation parameters required in TES.
基金Supported by the National Natural Science Foundation of China
文摘Conducting polymers have been studied extensively. An interesting property of the conducting polymer is that the conductivity of some polymers, such as polypyrrolc, polyaniline, poly(3-methylthiophene) etc. , is affected by the voltage applied to them. For polypyrrole, the oxidized state is an electronic conductor and the reduced state is essentially insulating. Using this property, one can fabricate the polymer-based electronic devices. Experimental results of
基金Supported by the National Natural Science of China (29677013) Chenguang Foundation of Wuhan Municipal Science and Technology
文摘The behaviors ot PbSO4/Pb and PbO4/PbSO4 electrode prepared from PbCO3 have been examined using powder microelectrode(PME) technique and cyclic voltammetry(CV). Firstly, PMEs parked with Pb- CO3 transformed into PtSO4 PME in 1. 0 mol/L H2SO4 solution at 30 C, and then the PbSO4 in the PMEs were formed to Pb or PbO2 using an unsymmetrical signal(Qa/Qe for PbSO4/Pb electrode and Qe/Qa for PsO2/ PbSO4 electrode being 0. 1-0. 3) in 2. S mol/L H2SO4 solution. The results show that the CV characteristic of either PbSO4/Pb or PsO2/PbSO4 PME prepared from PhCO3 are as good as that of both electrodes made from lead oxide powder produced by ball mill.
文摘A microfabricated electrical impedance spectroscopy (EIS) chip with microelectrodes was developed.The substrate and the electrodes of the chip were made of glass and gold,respectively.The experimental results demonstrated that the EIS-chip could distinguish different solutions (physiological saline,culture medium,living cell suspension etc.) by scanning from 10Hz to 45kHz.A 6-element circuit model was used for fitting the real part and the imaginary part admittance curves of the living cell suspension.An actual circuit was also built and tested to verify the 6-element circuit model proposed.The micro-EIS chip has several advantages including the use of small sample volumes,high resolution and ease of operation.It shows good application prospects in the areas of cellular electrophysioiogy,drug screening and bio-sensors etc.
基金supported by the National Natural Science Foundation of China(Nos.31470960 and 21422508)
文摘Electrochemical logical operations utilizing biological molecules(protein or DNA), which can be used in disease diagnostics and bio-computing, have attracted great research interest. However, the existing logic operations, being realized on macroscopic electrode, are not suitable for implantable logic devices. Here, we demonstrate DNA-based logic gates with electrochemical signal as output combined with gold flower microelectrodes. The designed logic gates are of fast response, enzyme-free, and micrometer scale. They perform well in either pure solution or complex matrices, such as fetal bovine serum,suggesting great potential for in vivo applications.
基金Projects supported by the science Fund of the Chinese Academy of Sciences.
文摘A new PVC matrix membrane double-barreled calcium ion-selective microelectrode based on liquid ion exchanger has been designed and constructed.The tip diameter of about 2.5μm as well as lower selectivity coefficients for K+,Na and Mg2+are adequate for in-tracellular measurements of Ca activities.The inner wall of the selective channel was made to be hydrophobic by treatment withalkyl-alcohols.By means of this microelectrode some physiologicalphenomena related to Ca2+activities have been studied,and Caconcentrations in clinical microsamples have also been determined.
基金National Basic Research Program of China (973 Program) (No.2011CB707505)National Natural Science Foundations of China(No.30872629,30900315,60906055)National High-Tech R & D Program of China (863 Program) (No.2009AA04Z326)
文摘The paper is aimed to investigate the adhesion and growth of neural cells on different microelectrode surfaces and their possible mechanism, thereby an optimum interfacial material or substrate for neural microelectrode can be chosen. Three different materials including platinum, gold, and pyrolyzed photoresist derived carbon material, in the forms of plasma-treated and non-treated ones, were tested. Surface properties of the microelectrodes in terms of surface morphology and wettability were examined; then their biocompatibility was tested by co-culturing with SK-N-SH neuroblastoma cells. Results of experiments demonstrated that, compared with platinum and gold, carbon could be a better substrate for cell adhesion and growth,especially for the plasma-treated carbon surface. The high wetting property of plasma-treated carbon accounted for the preferable adhesion of cell on its surface. Therefore, plasma-treated carbon can potentially be employed for fabrication of biocompatible and stable neural electrodes, which is beneficial for neural engineering research, such as regeneration from injury or disease therapy of neural system.
文摘The emerging field of neuroprosthetics is focused on design and implementation of neural prostheses to restore some of the lost neural functions. Remarkable progress has been reported at most bioelectronic levels—particularly the various brain-machine interfaces (BMIs)—but the electrode-tissue contacts (ETCs) remain one of the major obstacles. The success of these BMIs relies on electrodes which are in contact with the neural tissue. Biological response to chronic implantation of Microelectrode arrays (MEAs) is an essential factor in determining a successful electrode design. By altering the material compositions and geometries of the arrays, fabrication techniques of MEAs insuring these ETCs try to obtain consistent recording signals from small groups of neurons without losing microstimulation capabilities, while maintaining low-impedance pathways for charge injection, high-charge transfer, and high-spatial resolution in recent years. So far, none of these attempts have led to a major breakthrough. Clearly, much work still needs to be done to accept a standard model of MEAs for clinical purposes. In this paper, we review different microfabrication techniques of MEAs with their advantages and drawbacks, and comment on various coating materials to enhance electrode performance. Then, we propose high-density, three-dimensional (3D), silicon-based MEAs using micromachining methods. The geometries that will be used include arrays of penetrating variable-height probes.
文摘3-methyl-4-nitrophenol (MNP) is the main by-product of the organophosphate insecticide fenitrothion (FT), used in locust control. MNP is highly toxic because it is an endocrine disruptor and then may cause adverse in the biological systems. Then, it is necessary to develop analytical methods for determination of this pollutant in the environment. In this sense, we reported herein the development of an electrochemical sensor for the detection of 3-methyl-4-nitrophenol (MNP), one of the metabolites of fenitrothion (FT), by using naked and modified carbon fiber microelectrode (CFME) by nickel tetrasulfonated phthalocyanine polymer (CFME/p-NiTSPc). The voltammogram showed that MNP presents one irreversible anodic peak corresponding to the oxidation of the phenol group at 0.9 V vs Ag/AgCl. The effect of pH of the buffer on the peak current and SWV parameters such as frequency, scan increment and pulse amplitude were investigated in order to optimize the electrochemical response of the sensor. The obtained results lead to the following optimum value: pH = 6;frequency = 25 Hz, pulse amplitude = 50 mV, scan increment = 10 mV. With these optimum values, the calibration curves show that the peak current varied linearly upon MNP concentration leading to a limit of detection (LoD) for naked CFME close to 3 μg/L whereas for CFME modified by p-NiTSPc, it reaches 0.75 μg/L. This results prove that the presence of p-NiTSPc increasing the sensitivity of the sensor could be used to monitor 3-methyl-4-nitrophenol residue in real matrix.
基金financially supported by the National Natural Science Foundation of China(Nos.21625503 and 21906047)Natural Science Fund for Creative Research Groups of Hubei Province of China(No.2020CFA035)。
文摘In-situ monitoring of neurochemicals is of vital importance for the understanding of brain functions.Microelectrode-based photoelectrochemical(PEC) sensing has emerged as a promising tool for in vivo analysis since it inherits the merits of both optical and electrochemical methods. However, the in-situ excitation of photoactive materials on the photoelectrode in living body is still a challenge because of limited tissue penetration depth of light. To circumvent this problem, we herein developed an implantable optical fiber(OF)-based microelectrode for in vivo PEC analysis. The working electrode was constructed by coating Au film as conducting layer and CdS@ZnO as photoactive material on a micron-sized OF,which was free of the limitation of light penetration in biological tissues. Further decoration of an antibiofouling layer on the surface made the sensor robust in biosamples. It was successfully applied for monitoring Cu^(2+) level in three different brain regions in the rat model of cerebral ischemia/reperfusion.
基金supported by the National Key Technologies Research and Development Program of China (2017YFA0205903 and 2017YFA0701100)the National Natural Science Foundation of China (61634006 and 62071447)+1 种基金Shanghai Municipal Science and Technology Major Project (2021SHZDZX)and the Strategic Priority Research Program of the Chinese Academy of Sciences Pilot Project (XDB32030102,XDB32040203,and XDA16021305).
文摘Implantable intracortical microelectrodes can record a neuron’s rapidly changing action potentials(spikes).In vivo neural activity recording methods often have either high temporal or spatial resolution,but not both.There is an increasing need to record more neurons over a longer duration in vivo.However,there remain many challenges to overcome before achieving long-term,stable,high-quality recordings and realizing comprehensive,accurate brain activity analysis.Based on the vision of an idealized implantable microelectrode device,the performance requirements for microelectrodes are divided into four aspects,including recording quality,recording stability,recording throughput,and multifunctionality,which are presented in order of importance.The challenges and current possible solutions for implantable microelectrodes are given from the perspective of each aspect.The current developments in microelectrode technology are analyzed and summarized.
基金This work was sponsored by the National Natural Science Foundation of China(T2293731,L2224042,61988102,62121003,61960206012,62171434,61971400,61975206,and 61973292)the Frontier Interdisciplinary Project of the Chinese Academy of Sciences(XK2022XXC003)+2 种基金STI 2030-Major Projects 2021ZD0201600the National Key R&D Program of China(2022YFC2402501)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(GJJSTD20210004).
文摘Threatened animals respond with appropriate defensive behaviors to survive.It has been accepted that midbrain periaqueductal gray(PAG)plays an essential role in the circuitry system and organizes defensive behavioral responses.However,the role and correlation of different PAG subregions in the expression of different defensive behaviors remain largely unexplored.Here,we designed and manufactured a microelectrode array(MEA)to simultaneously detect the activities of dPAG and vPAG neurons in freely behaving rats.To improve the detection performance of the MEAs,PtNP/PEDOT:PSS nanocomposites were modified onto the MEAs.Subsequently,the predator odor was used to induce the rat’s innate fear,and the changes and information transmission in neuronal activities were detected in the dPAG and vPAG.Our results showed that the dPAG and vPAG participated in innate fear,but the activation degree was distinct in different defense behaviors.During flight,neuronal responses were stronger and earlier in the dPAG than the vPAG,while vPAG neurons responded more strongly during freezing.By applying high-performance MEA,it was revealed that neural information spread from the activated dPAG to the weakly activated vPAG.Our research also revealed that dPAG and vPAG neurons exhibited different defensive discharge characteristics,and dPAG neurons participated in the regulation of defense responses with burst-firing patterns.The slow activation and continuous firing of vPAG neurons cooresponded with the regulation of long-term freezing responses.The results demonstrated the important role of PAG neuronal activities in controlling different aspects of defensive behaviors and provided novel insights for investigating defense from the electrophysiological perspective.
