The frontooccipital interaction mechanism of high-frequency acoustoelectric signal.

Based on acoustoelectric effect, acoustoelectric brain imaging has been proposed, which is a high spatiotemporal resolution neural imaging method. At the focal spot, brain electrical activity is encoded by focused ultrasound, and corresponding high-frequency acoustoelectric signal is generated. Previous studies have revealed that acoustoelectric signal can also be detected in other non-focal brain regions. However, the processing mechanism of acoustoelectric signal between different brain regions remains sparse. Here, with acoustoelectric signal generated in the left primary visual cortex, we investigated the spatial distribution characteristics and temporal propagation characteristics of acoustoelectric signal in the transmission. We observed a strongest transmission strength within the frontal lobe, and the global temporal statistics indicated that the frontal lobe features in acoustoelectric signal transmission. Then, cross-frequency phase-amplitude coupling was used to investigate the coordinated activity in the AE signal band range between frontal and occipital lobes. The results showed that intra-structural cross-frequency coupling and cross-structural coupling co-occurred between these two lobes, and, accordingly, high-frequency brain activity in the frontal lobe was effectively coordinated by distant occipital lobe. This study revealed the frontooccipital long-range interaction mechanism of acoustoelectric signal, which is the foundation of improving the performance of acoustoelectric brain imaging.

Low-intensity focused ultrasound stimulation reverses social avoidance behavior in mice experiencing social defeat stress.

The excitatory neurons of the medial prefrontal cortex (mPFC) respond to social stimuli. However, little is known about how the neural activity is altered during social avoidance, and whether it could act as a target of low-intensity focused ultrasound stimulation (LIFUS) to rescue social deficits. The present study aimed to investigate the mechanisms of neuronal activities and inflammatory responses underlying the effect of LIFUS on social avoidance. We found that chronic LIFUS stimulation can effectively improve social avoidance in the defeated mice. Calcium imaging recordings by fiber photometry in the defeated mice showed inhibited ensemble activity during social behaviors. LIFUS instantaneously triggered the mPFC neuronal activities, and chronic LIFUS significantly enhanced their neuronal excitation related to social interactions. We further found that the excessive activation of microglial cells and the overexpression of the inflammation signaling, i.e. Toll-like receptors(TLR4)/nuclear factor-kappaB(NF-КB), in mPFC were significantly inhibited by LIFUS. These results suggest that the LIFUS may inhibit social avoidance behavior by reducing activation of the inflammatory response, increasing neuronal excitation, and protecting the integrity of the neuronal structure in the mPFC. Our findings raised the possibility of LIFUS being applied as novel neuromodulation for social avoidance treatment in neuropsychiatric diseases.

The Effects of the Structural and Acoustic Parameters of the Skull Model on Transcranial Focused Ultrasound.

Transcranial focused ultrasound (tFUS) has great potential in brain imaging and therapy. However, the structural and acoustic differences of the skull will cause a large number of technical problems in the application of tFUS, such as low focus energy, focal shift, and defocusing. To have a comprehensive understanding of the skull effect on tFUS, this study investigated the effects of the structural parameters (thickness, radius of curvature, and distance from the transducer) and acoustic parameters (density, acoustic speed, and absorption coefficient) of the skull model on tFUS based on acrylic plates and two simulation methods (self-programming and COMSOL). For structural parameters, our research shows that as the three factors increase the unit distance, the attenuation caused from large to small is the thickness (0.357 dB/mm), the distance to transducer (0.048 dB/mm), and the radius of curvature (0.027 dB/mm). For acoustic parameters, the attenuation caused by density (0.024 dB/30 kg/m3) and acoustic speed (0.021 dB/30 m/s) are basically the same. Additionally, as the absorption coefficient increases, the focus acoustic pressure decays exponentially. The thickness of the structural parameters and the absorption coefficient of the acoustic parameters are the most important factors leading to the attenuation of tFUS. The experimental and simulation trends are highly consistent. This work contributes to the comprehensive and quantitative understanding of how the skull influences tFUS, which further enhances the application of tFUS in neuromodulation research and treatment.

An Instrumental Electrode Configuration for 3D Ultrasound Modulated Electrical Impedance Tomography.

Ultrasound modulated electrical impedance tomography (UMEIT) is a novel hybrid imaging technique, which utilizes coupling between electric and acoustic modalities. Based on the forward solver along different current directions, an instrumental electrode configuration is proposed for 3D UMEIT. The proposed electrode configuration can produce a similar longitudinal current, making the power density distribution on the x-y plane approximately consistent with the corresponding conductivity distribution. Then, this satisfying power density is adopted to reconstruct a higher-resolution conductivity distribution. Therefore, the proposed electrode configuration contributes to improving the image reconstruction quality of UMEIT. Also, to clearly demonstrate its meaning in theory, the forward solver results are analyzed from an electrical point of view. In addition, the nonlinear partial differential equation (PDE) relating the power density to the measured data is derived again with a more reasonable expression. Finally, simulation with realistic geometry model of human breast is done and feasibility verifying experiment is made. Both simulation and experimental results validate the feasibility of the proposed electrode configuration.

In Vivo Transcranial Acoustoelectric Brain Imaging of Different Deep Brain Stimulation Currents.

Deep brain stimulation (DBS) is an effective treatment for neurologic disease and its clinical effect is highly dependent on the DBS leads localization and current stimulating state. However, standard human brain imaging modalities could not provide direct feedback on DBS currents spatial distribution and dynamic changes. Acoustoelectric brain imaging (AEBI) is an emerging neuroimaging method that can directly map current density distribution. Here, we investigate in vivo AEBI of different DBS currents to explore the potential of DBS visualization using AEBI. According to the typical DBS stimulus parameters, four types of DBS currents, including time pattern, waveform, frequency, and amplitude are designed to implement AEBI experiments in living rat brains. Based on acoustoelectric (AE) signals, the AEBI images of each type DBS current are explored and the resolution is quantitatively analyzed for performance evaluation. Furtherly, the AE signals are decoded to characterize DBS currents from multiple perspectives, including time-frequency domain, spatial distribution, and amplitude comparation. The results show that in vivo transcranial AEBI can accurately locate the DBS contact position with a millimeter spatial resolution (< 2 mm) and millisecond temporal resolution (< 10 ms). Besides, the decoded AE signal at DBS contact position is capable of describing the corresponding DBS current characteristics and identifying current pattern changes. This study first validates that AEBI can localize in vivo DBS contact and characterize different DBS currents. AEBI is expected to develop into a noninvasive DBS real-time monitoring technology with high spatiotemporal resolution.

Multilevel analysis of the central-peripheral-target organ pathway: contributing to recovery after peripheral nerve injury.

ABSTRACT: Peripheral nerve injury is a common neurological condition that often leads to severe functional limitations and disabilities. Research on the pathogenesis of peripheral nerve injury has focused on pathological changes at individual injury sites, neglecting multilevel pathological analysis of the overall nervous system and target organs. This has led to restrictions on current therapeutic approaches. In this paper, we first summarize the potential mechanisms of peripheral nerve injury from a holistic perspective, covering the central nervous system, peripheral nervous system, and target organs. After peripheral nerve injury, the cortical plasticity of the brain is altered due to damage to and regeneration of peripheral nerves; changes such as neuronal apoptosis and axonal demyelination occur in the spinal cord. The nerve will undergo axonal regeneration, activation of Schwann cells, inflammatory response, and vascular system regeneration at the injury site. Corresponding damage to target organs can occur, including skeletal muscle atrophy and sensory receptor disruption. We then provide a brief review of the research advances in therapeutic approaches to peripheral nerve injury. The main current treatments are conducted passively and include physical factor rehabilitation, pharmacological treatments, cell-based therapies, and physical exercise. However, most treatments only partially address the problem and cannot complete the systematic recovery of the entire central nervous system-peripheral nervous system-target organ pathway. Therefore, we should further explore multilevel treatment options that produce effective, long-lasting results, perhaps requiring a combination of passive (traditional) and active (novel) treatment methods to stimulate rehabilitation at the central-peripheral-target organ levels to achieve better functional recovery.

Prevention and alleviation of allergic rhinitis by oral administration of Lacticaseibacillus paracasei GOLDGUT-Lpc969.

Introduction: Allergic rhinitis (AR) is a widespread upper airway disorder characterized by inflammation of the nasal passages. It is immunologically mediated via the hypersensitivity type I mechanism, which is primarily elicited by the immunoglobulin E (IgE)-linking allergen-induced imbalance of the Th2/Th1 immune response. Owing to the limited efficacy of current medications, probiotics have received attention for their potential in preventing and ameliorating AR. Methods: In this study, a Lacticaseibacillus paracasei strain, GOLDGUTLpc969 (Lpc969), isolated from the feces of healthy adults, was proven to be effective in preventing AR by LPA-induced RBL-2H3 in-vitro and OVA-induced AR mice in-vivo evaluation. Results: The strain significantly attenuated the release of histamine and degranulation in LPS-induced RBL-2H3 cells. In the OVA-induced AR mice, L. paracasei GOLDGUT-Lpc969 also exhibited a significant decrease in disease indicators such as the disease activity index (DAI score), serum IgE, and serum histamine. Treatment with L. paracasei GOLDGUT-Lpc969 led to significant suppression of the Th2-related cytokines IL-4, IL-5, IL-6, IL-13, and TNF-α in the serum of mice. Discussion: Furthermore, a comparison of the genomes of three previously reported AR-effective L. paracasei strains (including GOLDGUTLpc969) and one non-effective L. paracasei strain revealed that the gene K03671 may play a key role in alleviating AR symptoms. In conclusion, this study highlights the efficacy of L. paracasei GOLDGUT-Lpc969 in AR prevention by suppressing the Th2 immune response and proposes the potential involvement of the functional gene K03671 in ameliorating AR symptoms. Therefore, L. paracasei GOLDGUT-Lpc969 shows promise as a probiotic for preventing AR.

Magnetic Nanoparticles and Methylprednisolone Based Physico-Chemical Bifunctional Neural Stem Cells Delivery System for Spinal Cord Injury Repair.

Neural stem cells (NSCs) transplantation is an attractive and promising treatment strategy for spinal cord injury (SCI). Various pathological processes including the severe inflammatory cascade and difficulty in stable proliferation and differentiation of NSCs limit its application and translation. Here, a novel physico-chemical bifunctional neural stem cells delivery system containing magnetic nanoparticles (MNPs and methylprednisolone (MP) is designed to repair SCI, the former regulates NSCs differentiation through magnetic mechanical stimulation in the chronic phase, while the latter alleviates inflammatory response in the acute phase. The delivery system releases MP to promote microglial M2 polarization, inhibit M1 polarization, and reduce neuronal apoptosis. Meanwhile, NSCs tend to differentiate into functional neurons with magnetic mechanical stimulation generated by MNPs in the static magnetic field, which is related to the activation of the PI3K/AKT/mTOR pathway. SCI mice achieve better functional recovery after receiving NSCs transplantation via physico-chemical bifunctional delivery system, which has milder inflammation, higher number of M2 microglia, more functional neurons, and axonal regeneration. Together, this bifunctional NSCs delivery system combined physical mechanical stimulation and chemical drug therapy is demonstrated to be effective, which provides new treatment insights into clinical transformation of SCI repair.

Recent advances in the application of ionic liquids in antimicrobial material for air disinfection and sterilization.

Airborne transmission is one of the most unpredictable routes of infection. Nowadays, airborne diseases increase ever than before because of the complex living air environment. Apart from the inorganic particles, active microorganisms including bacteria, viruses, and fungi are incorporated in the pathogens acting as threaten to public health, which can hardly be treated by the traditional air purification methods based on adsorption. Therefore, effective filtration material with antimicrobial activity is demanded to solve the problem. Ionic liquids (ILs) are a category of salts that remain liquid at room temperature. The stable physico-chemical properties and extremely low vapor pressure make them suitable for a wide range of applications. Thanks to the numerous combinations of cations and anions, as well as the ability of inheriting properties from the parent ions, Ils are believed to be a promising industrial material. In recent decades, several Ils, such as imidazolium, pyridinium, pyrrolidinium, phosphonium, and choline, have been found to have antimicrobial activity in their monomeric or polymeric forms. This work focuses on the antimicrobial activity and safety of the latest types of ionic liquids, discussing the synthesis or manufacturing methods of Ils for air purification and filtration. Furthermore, possible applications of Ils antimicrobial materials in medical instruments and indoor environments are mentioned to encourage the scientific community to further explore the potential applications of Ils.

Multielectrode Array-Based Percutaneous Nerve Stimulation Strategy With Ultrasound Guidance for Ulnar Nerve Injury.

Studies have shown that percutaneous nerve stimulation can promote repair of ulnar neuropathy. However, this approach requires further optimization. We evaluated multielectrode array-based percutaneous nerve stimulation for treatment of ulnar nerve injury. The optimal stimulation protocol was determined using a multi-layer model of the human forearm using the finite element method. We optimized the number and distance between electrodes, and used ultrasound to aid in electrode placement. Six electrical needles in series along the injured nerve at alternating distances of five and seven centimeters. We validated the model in a clinical trial. Twenty-seven patients were randomly assigned to a control group (CN) and an electrical stimulation with finite element group (FES). The results showed that disability of arm shoulder and hand (DASH) scores decreased and grip strength increased to a greater extent in the FES group than those in the CN group following treatment (P<0.05). Furthermore, the amplitudes of compound motor action potentials (cMAPs) and sensory nerve action potentials (SNAPs) improved in the FES group to a greater extent than those in the CN group. The results showed that our intervention improved hand function and muscle strength, and aided in neurologic recovery, as shown using electromyography. Analysis of blood samples indicated that our intervention may have promoted conversion of the precursor form of brain-derived neurotrophic factor (pro-BDNF) to mature brain-derived neurotrophic factor (BDNF) to promote nerve regeneration. Our percutaneous nerve stimulation regimen for ulnar nerve injury has potential to become a standard treatment option.

Acoustoelectric brain imaging with different conductivities and acoustic distributions.

Objective: Acoustoelectric brain imaging (AEBI) is a promising imaging method for mapping brain biological current densities with high spatiotemporal resolution. Currently, it is still challenging to achieve human AEBI with an unclear acoustoelectric (AE) signal response of medium characteristics, particularly in conductivity and acoustic distribution. This study introduces different conductivities and acoustic distributions into the AEBI experiment, and clarifies the response interaction between medium characteristics and AEBI performance to address these key challenges. Approach: AEBI with different conductivities is explored by the imaging experiment, potential measurement, and simulation on a pig's fat, muscle, and brain tissue. AEBI with different acoustic distributions is evaluated on the imaging experiment and acoustic field measurement through a deep and surface transmitting model built on a human skullcap and pig brain tissue. Main results: The results show that conductivity is not only inversely proportional to the AE signal amplitude but also leads to a higher AEBI spatial resolution as it increases. In addition, the current source and sulcus can be located simultaneously with a strong AE signal intensity. The transcranial focal zone enlargement, pressure attenuation in the deep-transmitting model, and ultrasound echo enhancement in the surface-transmitting model cause a reduced spatial resolution, FFT-SNR, and timing correlation of AEBI. Under the comprehensive effect of conductivity and acoustics, AEBI with skull finally shows reduced imaging performance for both models compared with no-skull AEBI. On the contrary, the AE signal amplitude decreases in the deep-transmitting model and increases in the surface-transmitting model. Significance: This study reveals the response interaction between medium characteristics and AEBI performance, and makes an essential step toward developing AEBI as a practical neuroimaging technique.

Numerical Simulation Study of Firing Threshold of STN Neuron Stimulated by Focused Ultrasound.

OBJECTIVE: Electroencephalography (EEG) is one of the functional brain imaging techniques to effectively measure neuronal activity, but its low spatial resolution makes it difficult to localize evoked excitatory neurons or areas of abnormal firing. Multimodal imaging techniques are expected to combine the high spatial resolution (mm level) of focused ultrasound (FUS) with the high temporal resolution (ms level) of EEG. The technique must be performed under the premise that ultrasound stimulation does not affect neuronal firing, and there is an urgent need to determine the threshold of this ultrasound stimulation parameter. METHODS: In this paper, the subthalamic nucleus neuronal firing model and the bilayer sonophore model are combined to numerically simulate the neuronal firing rhythm under the conditions of different stimulation parameters. The correlation and frequency differences of neuronal firing rhythms with and without ultrasound stimulation were compared and used as an index to evaluate the degree of change, and the final range of effective threshold parameters for ultrasound stimulation of neurons but not inducing neuronal firing was obtained. RESULTS: The results showed that the correlation of neuronal firing rhythms in both conditions with and without stimulation decreased and the frequency difference increased with increasing ultrasound parameters such as duty cycle, intensity, center frequency and pulse repetition frequency. CONCLUSION: An effective range of stimulation threshold parameters can be obtained based on the correlation coefficients and frequency difference matrices under different parameter combinations. SIGNIFICANCE: The threshold can further promote the safe and effective application of FUS for multimodal electrophysiological imaging.

An ultrasound-guided percutaneous electrical nerve stimulation regimen devised using finite element modeling promotes functional recovery after median nerve transection.

Percutaneous electrical nerve stimulation of an injured nerve can promote and accelerate peripheral nerve regeneration and improve function. When performing acupuncture and moxibustion, locating the injured nerve using ultrasound before percutaneous nerve stimulation can help prevent further injury to an already injured nerve. However, stimulation parameters have not been standardized. In this study, we constructed a multi-layer human forearm model using finite element modeling. Taking current density and activated function as optimization indicators, the optimal percutaneous nerve stimulation parameters were established. The optimal parameters were parallel placement located 3 cm apart with the injury site at the midpoint between the needles. To validate the efficacy of this regimen, we performed a randomized controlled trial in 23 patients with median nerve transection who underwent neurorrhaphy. Patients who received conventional rehabilitation combined with percutaneous electrical nerve stimulation experienced greater improvement in sensory function, motor function, and grip strength than those who received conventional rehabilitation combined with transcutaneous electrical nerve stimulation. These findings suggest that the percutaneous electrical nerve stimulation regimen established in this study can improve global median nerve function in patients with median nerve transection.

The processing network of high-frequency acoustoelectric signal in the living rat brain.

Objective.Acoustoelectric brain imaging (ABI) is a potential noninvasive electrophysiological neuroimaging method with high spatiotemporal resolution. At the focal spot of the focused ultrasound, with the couple of acoustic and electric fields, high-frequency acoustoelectric (HF AE) signal is generated. Because the brain is a volume conductor, HF AE signal can be detected in other brain cortex. The processing of HF AE signal is critical for improving decoding precision, further improving the spatial resolution performance of ABI. This study investigates the processing network of HF AE signal in the living rat brain.Approach.When HF AE generated on the left primary visual cortex (V1-L), low-frequency (LF) electroencephalography and HF AE signals on different cortex were recorded at the same time. Firstly, AE signal on different sides of the brain cortex were compared, including prefrontal cortex (FrA) and primary somatosensory cortex (S1FL). Then, we constructed and analyzed functional networks of two signals.Main results.In the same cortex, HF AE signal on the right side had stronger intensity. And compared with LF networks, HF AE network had larger global efficiency and shorter characteristic path length, denoting the stronger processing and transmission of AE signal. Additionally, in HF AE network, the node had significantly increased local properties and the connection were concentrated in the occipital lobe, reflecting the occipital lobe plays an important role in the processing.Significance.Experiment results demonstrate that, compared with LF network, HF AE network is more efficient and had stronger transmission capabilities. And the connection of HF AE network is concentrated in the occipital lobe. This work preliminarily reveals the HF AE signal processing, which is significant for improving the ABI quality and provides a new insight for understanding the brain HF signal.

In Vivo Transcranial Acoustoelectric Brain Imaging of Different Steady-State Visual Stimulation Paradigms.

OBJECTIVE: Based on the acoustoelectric (AE) effect, transcranial acoustoelectric brain imaging (tABI) is of potential for brain functional imaging with high temporal and spatial resolution. With nonlinear and non-steady-state, brain electrical signal is microvolt level which makes the development of tABI more difficult. This study demonstrates for the first time in vivo tABI of different steady-state visual stimulation paradigms. METHOD: To obtain different brain activation maps, we designed three steady-state visual stimulation paradigms, including binocular, left eye and right eye stimulations. Then, tABI was implemented with one fixed recording electrode. And, based on decoded signal power spectrum (tABI-power) and correlation coefficient between steady-state visual evoked potential (SSVEP) and decoded signal (tABI-cc) respectively, two imaging methods were investigated. To quantitatively evaluate tABI spatial resolution performance, ECoG was implemented at the same time. Finally, we explored the performance of tABI transient imaging. RESULTS: Decoded AE signal of activation region is consistent with SSVEP in both time and frequency domains, while that of the nonactivated region is noise. Besides, with transcranial measurement, tABI has a millimeter-level spatial resolution (< 3mm). Meanwhile, it can achieve millisecond-level (125ms) transient brain activity imaging. CONCLUSION: Experiment results validate tABI can realize brain functional imaging under complex paradigms and is expected to develop into a brain functional imaging method with high spatiotemporal resolution.

Living Rat SSVEP Mapping With Acoustoelectric Brain Imaging.

OBJECTIVE: Acoustoelectric Brain Imaging (ABI) is a potential method for mapping brain electrical activity with high spatial resolution (millimeter). To resolve the key issue for eventual realization of ABI, testing that recorded acoustoelectric (AE) signal can be used to decode intrinsic brain electrical activity, the experiment of living rat SSVEP measurement with ABI is implemented. METHOD: A 1-MHz ultrasound transducer is focused on the visual cortex of anesthetized rat. With visual stimulus, the electroencephalogram and AE signal are simultaneously recorded with Pt electrode. Besides, with FUS transducer scanning at the visual cortex, corresponding AE signals at different spatial positions are decoded and imaged. RESULTS: Consistent with the directly measured SSVEP, decoded AE signal presents a clear event-related spectral perturbation (ERSP). And, decoded AE signal is of high amplitude response at the base and harmonics of the visual stimulus frequency. What's more, for timing signal, a significant positive amplitude correlation is observed between decoded AE signal and simultaneously measured SSVEP. In addition, the mean SNRs of SSVEP and decoded AE signal are both significantly higher than that of background EEG. Finally, with one fixed recording electrode, the active area with an inner diameter of 1mm is located within the 4 mm×4 mm measurement region. CONCLUSION: Experimental results demonstrate that the millimeter-level spatial resolution SSVEP measurement of living rat is achieved through ABI for the first time. SIGNIFICANCE: This study confirms that ABI should shed light on high spatiotemporal resolution neuroimaging.

Biological current source imaging method based on acoustoelectric effect: A systematic review.

Neuroimaging can help reveal the spatial and temporal diversity of neural activity, which is of utmost importance for understanding the brain. However, conventional non-invasive neuroimaging methods do not have the advantage of high temporal and spatial resolution, which greatly hinders clinical and basic research. The acoustoelectric (AE) effect is a fundamental physical phenomenon based on the change of dielectric conductivity that has recently received much attention in the field of biomedical imaging. Based on the AE effect, a new imaging method for the biological current source has been proposed, combining the advantages of high temporal resolution of electrical measurements and high spatial resolution of focused ultrasound. This paper first describes the mechanism of the AE effect and the principle of the current source imaging method based on the AE effect. The second part summarizes the research progress of this current source imaging method in brain neurons, guided brain therapy, and heart. Finally, we discuss the problems and future directions of this biological current source imaging method. This review explores the relevant research literature and provides an informative reference for this potential non-invasive neuroimaging method.

An adaptive acoustoelectric signal decoding algorithm based on Fourier fitting for brain function imaging.

Acousticelectric brain imaging (ABI), which is based on the acoustoelectric (AE) effect, is a potential brain function imaging method for mapping brain electrical activity with high temporal and spatial resolution. To further enhance the quality of the decoded signal and the resolution of the ABI, the decoding accuracy of the AE signal is essential. An adaptive decoding algorithm based on Fourier fitting (aDAF) is suggested to increase the AE signal decoding precision. The envelope of the AE signal is first split into a number of harmonics by Fourier fitting in the suggested aDAF. The least square method is then utilized to adaptively select the greatest harmonic component. Several phantom experiments are implemented to assess the performance of the aDAF, including 1-source with various frequencies, multiple-source with various frequencies and amplitudes, and multiple-source with various distributions. Imaging resolution and decoded signal quality are quantitatively evaluated. According to the results of the decoding experiments, the decoded signal amplitude accuracy has risen by 11.39% when compared to the decoding algorithm with envelope (DAE). The correlation coefficient between the source signal and the decoded timing signal of aDAF is, on average, 34.76% better than it was for DAE. Finally, the results of the imaging experiment show that aDAF has superior imaging quality than DAE, with signal-to noise ratio (SNR) improved by 23.32% and spatial resolution increased by 50%. According to the experiments, the proposed aDAF increased AE signal decoding accuracy, which is vital for future research and applications related to ABI.

Sensorimotor rhythm neurofeedback training relieves anxiety in healthy people.

Timely relief of anxiety in healthy people is important, but there is little research on this topic at present. Neurofeedback training allows subjects to regulate their specific brain activities autonomously and thus alter their corresponding cognitive functions. Inattention is a significant cognitive deficit in patients with anxiety. Sensorimotor rhythm (SMR) was reported to be closely related to attention. In this study, trainability, frequency specificity, and brain-behavior relationships were utilized to verify the validity of a relative SMR power protocol. An EEG neurofeedback training system was developed for alleviating anxiety levels in healthy people. The EEG data were collected from 33 subjects during SMR up-training sessions. Subjects attended six times neurofeedback training for about 2 weeks. The feedback value of the neurofeedback group was the relative SMR power at the feedback electrode (electrode C3), while the feedback values for the control group were pseudorandom numbers. The trainability index revealed that the learning trend showed an increase in SMR power activity at the C3 electrode, confirming effects across training. The frequency specificity index revealed only that SMR band activity increased significantly in the neurofeedback group. The brain-behavior relationships index revealed that increased SMR activity correlated negatively with the severity of anxiety. This study indicates that neurofeedback training using a relative SMR power protocol, based on activity at the C3 electrode, could relieve anxiety levels for healthy people and increase the SMR power. Preliminary studies support the feasibility and efficacy of the relative SMR power protocol for healthy people with anxiety. Supplementary Information: The online version contains supplementary material available at 10.1007/s11571-021-09732-8.

Experimental and simulation studies of localization and decoding of single and double dipoles.

Objective. Electroencephalography is a technique for measuring normal or abnormal neuronal activity in the human brain, but its low spatial resolution makes it difficult to locate the precise locations of neurons due to the volume conduction effect of brain tissue.Approach. The acoustoelectric (AE) effect has the advantage of detecting electrical signals with high temporal resolution and focused ultrasound with high spatial resolution. In this paper, we use dipoles to simulate real single and double neurons, and further investigate the localization and decoding of single and double dipoles based on AE effects from numerical simulations, brain tissue phantom experiments, and fresh porcine brain tissue experiments.Main results. The results show that the localization error of a single dipole is less than 0.3 mm, the decoding signal is highly correlated with the source signal, and the decoding accuracy is greater than 0.94; the location of double dipoles with an interval of 0.4 mm or more can be localized, the localization error tends to increase as the interval of dipoles decreases, and the decoding accuracy tends to decrease as the frequency of dipoles decreases.Significance. This study localizes and decodes dipole signals with high accuracy, and provides a technical method for the development of EEG.