Atomic magnetometers operated in the spin-exchange relaxation-free(SERF)regime are the promising sensor to replace superconducting quantum interference devices(SQUIDs)in the biomagnetism field.The SERF magnetometer wi...Atomic magnetometers operated in the spin-exchange relaxation-free(SERF)regime are the promising sensor to replace superconducting quantum interference devices(SQUIDs)in the biomagnetism field.The SERF magnetometer with compact size and good performance is crucial to the new generation of wearable magnetoencephalography(MEG)system.In this paper,we developed a compact and closed-loop SERF magnetometer with the dimensions of 15.0×22.0×30.0 mm^(3)based on a single-beam configuration.The bandwidth of the magnetometer was extended to 675 Hz while the sensitivity was maintained at 22 f T/Hz^(1/2).A nearly 3-fold enhancement of the bandwidth was obtained in comparison with the open-loop control.The implementation of the closed-loop control also greatly improved the dynamic range,enabling the magnetometer to be robust against the disturbance of the ambient field.Moreover,the magnetometer was successfully applied for the detection of humanα-rhythm and auditory evoked fields(AEFs),which demonstrated the potential to be extended to multi-channel MEG measurements for future neuroscience studies.展开更多
We studied differences in imaginary coherence (IC) of the gamma band between brain regions of female schizophrenia patients during the auditory oddball task using magnetoencephalography (MEG). Subjects were 12 right-h...We studied differences in imaginary coherence (IC) of the gamma band between brain regions of female schizophrenia patients during the auditory oddball task using magnetoencephalography (MEG). Subjects were 12 right-handed female schizophrenia patients, who were evaluated by the Positive and Negative Syndrome Scales (PANSS). Functional connectivity during an auditory oddball task was reconstructed in low gamma (30 - 50 Hz) and high gamma (50 - 100 Hz and 100 - 150 Hz) bands, and represented by IC using seeds determined by the significant oscillatory power changes obtained by event-related synchronization (ERS) and event-related desynchronization (ERD) power measurements. Gamma ERS (30 - 50 Hz) power was decreased in the left precuneus at 500 - 750 ms and in the right precuneus at 750 - 1000 ms. IC in the gamma band (50 - 100 Hz) was decreased between the right precuneus (seed) and right paracentral lobule (target) and between the right precuneus and right hypothalamus at 0 - 250 ms. IC in the gamma band (100 - 150 Hz) was increased between the left precuneus and right cuneus (Brodmann area 7) at 250 - 500 ms, between the left precuneus and right culmen at 500 - 750 ms, and between the left precuneus and right cuneus (Brodmann area 17), between the left precuneus and right posterior cingulate cortex, and between the left precuneus and right caudate nucleus at 750 - 1000 ms. In the high gamma band (50 - 100 Hz) at 0 - 250 ms, significant positive correlations were shown between IC and conceptual disorganization in PANSS scores, between IC and unusual thought content score, and between IC and positive scale score. IC within the high gamma band in female schizophrenia patients showed two types of functional disconnection, intrahemispheric and interhemispheric. IC between the right or left precuneus and other specific cortical areas showed dysfunction, suggesting that the parietal lobe plays an important role in dysfunction in connectivity in the gamma band during the oddball task.展开更多
We observed the steady-state visually evoked potential(SSVEP) from a healthy subject using a compact quad-channel potassium spin exchange relaxation-free(SERF) optically pumped magnetometer(OPM). To this end, 30 s of ...We observed the steady-state visually evoked potential(SSVEP) from a healthy subject using a compact quad-channel potassium spin exchange relaxation-free(SERF) optically pumped magnetometer(OPM). To this end, 30 s of data were collected, and SSVEP-related magnetic responses with signal intensity ranging from 150 fT to 300 f T were observed for all four channels. The corresponding signal to noise ratio(SNR) was in the range of 3.5–5.5. We then used different channels to operate the sensor as a gradiometer. In the specific case of detecting SSVEP, we noticed that the short channel separation distance led to a strongly diminished gradiometer signal. Although not optimal for the case of SSVEP detection, this set-up can prove to be highly useful for other magnetoencephalography(MEG) paradigms that require good noise cancellation.Considering its compactness, low cost, and good performance, the K-SERF sensor has great potential for biomagnetic field measurements and brain-computer interfaces(BCI).展开更多
Previous studies examining coherence and connectivity deviations in schizophrenia patients relied on standard coherence measures between recording sites (at the sensor level). A coherence source imaging (CSI) methodol...Previous studies examining coherence and connectivity deviations in schizophrenia patients relied on standard coherence measures between recording sites (at the sensor level). A coherence source imaging (CSI) methodology where coherence is assessed within imaged brain structures (at the source level) was developed recently by our group and applied successfully for detecting coherent areas in the cortical networks of patients with epilepsy. We applied this Magnetoencephalography (MEG)-CSI technique to measure normal and pathological patterns of brain oscillations (biomarkers) in normal subjects and patients diagnosed with schizophrenia. Twelve patients diagnosed with schizophrenia and twelve healthy control subjects were studied. A ten-minute resting state MEG brain scan was performed with eyes open. MEG-CSI analysis was performed to identify the cortical areas that interacted strongly within the 3 - 50 Hz frequency range. Statistically significant increased regions of coherence were detected in schizophrenia patients compared to controls in the right inferior frontal gyrus (BA 47—pars orbitalis), left superior frontal gyrus (BA9— dorsolateral prefrontal cortex), right middle frontal gyrus (BA 10—anterior prefrontal cortex & BA 46—dorsolateral prefrontal cortex), and right cingulate gyrus (BA 24—ventral anterior cingulate cortex). These areas are involved in language, memory, decision making, empathy, executive and, higher cognitive functioning. We conclude that MEG-CSI can detect imaging biomarkers from resting state brain activity in schizophrenia patients that deviates from normal control subjects in several behaviorally salient brain regions. Analysis with MEG-CSI can provide biomarkers of abnormalities in the resting-state. The findings and procedures described can be used to probe the pathophysiology of schizophrenia and possibly detect subtypes.展开更多
Apparent motion stimulus induces visual perception of smooth motion even though there is no speed information. We examined whether human brain response as measured by magnetoencephalography carries direction informati...Apparent motion stimulus induces visual perception of smooth motion even though there is no speed information. We examined whether human brain response as measured by magnetoencephalography carries direction information in the visually presented apparent motion of a randomdot pattern in a similar manner as continuous motions that have speed and direction information. Although there was no significant effect of motion direction on the peak response latency and amplitude, mutual information entropy (IE) significantly increased after the motion onset at approximately 36 ms after the response latency in 41% of the evaluations. Detailed analysis of the data from five subjects who participated in both the present apparent motion and our previous coherent motion studies revealed that the maximum IE latency (delay) for apparent motion was significantly longer than that for coherent motion, although the mean maximum IE was the same. The results indicate that direction is represented in the response waveform evoked by apparent motion but the manner is different from that for coherent motion probably due to the distinct neural processes engaged only for the apparent motion perception. We consider that direction and speed can be processed separately in the human brain because direction information was generated without speed information for the perception of apparent motion.展开更多
Brainwave is a kind of traceable neurophysiological energy in a living brain. Invisible to human eyes, it is only detectable using electroencephalography (EEG), electrocorticography (ECoG) and magnetoencephalography (...Brainwave is a kind of traceable neurophysiological energy in a living brain. Invisible to human eyes, it is only detectable using electroencephalography (EEG), electrocorticography (ECoG) and magnetoencephalography (MEG). The waves or oscillations or rhythms are produced mainly by the oscillatory networks of the brain. Three main oscillatory networks are thalamocortical, extrathalamic-cortical and cortical-cortical networks. Greater limbic system (reticular system, hypothalamus, thalamus, basal forebrain nuclei, limbic system) has a great influence on these oscillatory networks. This system which is in microgravity position lies deep inside and surrounded by the ventricles of the brain. It receives all information from inside and outside of our body and then projects to all areas of the brain (from all to one and from one to all—nearly similar concept to “from God back to God”). Therefore, the greater limbic system could be regarded as “a core of the neuroaxis” which lies in microgravity compartment and in microgravity position (“T”-shape or curving shape;whilst gravity position is “I”-shape or vertical shape). By knowing the origin of the brainwaves and methods to detect them, one may study seizure networks, normal and abnormal brain networks and arguably, even to explore the relationship between the “invisibles”: “invisible” brainwaves and “invisible” soul.展开更多
The inverse problem of magnetoencephalography (MEG) seeks the neuronal current within the conductive brain that generates a measured magnetic flux in the exterior of the brain-head system. This problem does not have a...The inverse problem of magnetoencephalography (MEG) seeks the neuronal current within the conductive brain that generates a measured magnetic flux in the exterior of the brain-head system. This problem does not have a unique solution, and in particular, it is not even possible to identify the support of the current if it extends over a three-dimensional set. However, a localized current supported on a zero-, one- or two-dimensional set can in principle be identified. In the present work, we demonstrate an analytic algorithm that is able to recover a one-dimensional distribution of current from the knowledge of the exterior magnetic flux field. In particular, we consider a neuronal current that is supported on a small line segment of arbitrary location and orientation in space, and we reduce the identification of its characteristics to a nonlinear algebraic system. A series of numerical tests show that this system has a unique real solution. A special case is easily solved via the use of trivial algebraic operations.展开更多
The support of a localized three-dimensional neuronal current distribution, within a conducting medium, is not identifiable from knowledge of the exterior magnetic flux density, obtained via Magnetoencephalographic (M...The support of a localized three-dimensional neuronal current distribution, within a conducting medium, is not identifiable from knowledge of the exterior magnetic flux density, obtained via Magnetoencephalographic (MEG) measurements. However, this is not true if the neuronal current is supported on a set with dimensionality less than three. That is, the support of a dipolar current distribution can be recovered if it is a set of isolated points, a segment of a curve, or a surface patch. In this work we provide an analytic algorithm for this inverse MEG problem and apply it to the case where the current is supported on a localized disk having arbitrary position and size within the brain tissue. The proposed recovery algorithm reduces the identification of the characteristics of the current to the solution of a nonlinear algebraic system, which can be handled numerically.展开更多
Neurological disorders with symptoms such as chronic pain,depression,and insomnia are widespread.Very weak electric fields applied through the skull can enhance or diminish neural activity and modulate brain waves in ...Neurological disorders with symptoms such as chronic pain,depression,and insomnia are widespread.Very weak electric fields applied through the skull can enhance or diminish neural activity and modulate brain waves in order to treat many of these common medical problems.This approach is to be contrasted with well-established pharmacological methods or more recent invasive electrical Deep Brain Stimulation(DBS)techniques that require surgery to insert electrodes deep into the brain.We claim that Non-Invasive Brain Stimulation(NIBS)will provide new treatment methods with much greater simplicity,lower cost,improved safety and in some cases,possibly greater effectiveness.This emerging use of NIBS is a branch of a new multidisciplinary field that we coined Neuro-systems Engineering[1].This field involves neuroscientists,psychologists,and electrical engineers.This emerging field relies on existing standards for the safe implementation of these novel treatment modalities[2].Methods of stimulating the brain are based on emerging electro-technologies such as transcranial Direct Current/Alternating Current(DC/AC)electric fields and pulsed magnetic fields.Application of functional and time-dependent brain imaging methods can be used to locate relevant brain regions and determine the most appropriate stimulation method.Application of tailored and individualized control can be combined with other therapy methods to effectively treat neurological disorders while minimizing or even eliminating the use of pharmaceuticals.In this paper,we are presenting our embodiment for a closed loop,feedback controlled,non-invasive application of electrical stimulation of the brain to enhance individual/group performance or to treat neurological disorders.展开更多
The spherical head model has been widely used in magnetoencephalography (MEG) as a simple forward model for calculating the external magnetic field producing by neural currents in a human brain. But this model may lea...The spherical head model has been widely used in magnetoencephalography (MEG) as a simple forward model for calculating the external magnetic field producing by neural currents in a human brain. But this model may lead to an inaccurate result, even if the computation speed is fast. For more precise computation, realistic brain-shaped head model is used with the boundary element method (BME), but at greatly increased computational cost. When solving MEG inverse problem by using optimization methods, the forward problem must often be solved for thousands of possible source configurations. So if the brain-shaped head model is used in all iterative steps of optimization, it may be computationally infeasible for practical application. In this paper, we present a method about using compound head model in MEG inverse solution. In this method, first spherical head model is used for a rough estimation, then brain-shaped head model is adopted for more precise solution. Numerical simulation indicates that under the condition of same accuracy, the computation speed for the present method is about three times faster than a method using the brain-shaped head model at all iterations.展开更多
Multichannel biomagnetometers can be used to measure the spatio temporal magnetic field produced by neural activity in a human brain. The measured data are usually contaminated by noise and some artifact signals. Thes...Multichannel biomagnetometers can be used to measure the spatio temporal magnetic field produced by neural activity in a human brain. The measured data are usually contaminated by noise and some artifact signals. These artifact signals may be caused by heart beats or eye blinks. Actually, these artifact signal sources are also bioelectric activities. In this paper, we demonstrate the effectiveness of MEG MUSIC algorithm for eliminating the artifacts. In the paper, the artifact fields are not considered as noise but as signals that have a linear relationship with their bioelectric source activities. Computer simulations demonstrate that for the localization of sources distributed in the cortical region, the MEG MUSIC algorithm is also efficient under the presence of the artifacts.展开更多
Vagus nerve stimulation(VNS)is an important treatment option for drug-refractory epilepsy(DRE),with well-established efficacy and safety in clinical practice for more than 20 years.However,it is very difficult to find...Vagus nerve stimulation(VNS)is an important treatment option for drug-refractory epilepsy(DRE),with well-established efficacy and safety in clinical practice for more than 20 years.However,it is very difficult to find the optimal electrophysiological indicators for the effectiveness of VNS on DRE because the mechanism of action is unknown.In this review,we provide an update of the potential applications of VNS outcomes in patients with drug-resistant epilepsy.Electroencephalographic(EEG)activity,event-related potentials,EEG synchronization levels,magnetoencephalographic,laryngeal muscle evoked potentials,and heart rate variability are potential biomarkers for VNS outcomes in people with DRE.展开更多
A superluminescent diode (SLD) as an alternative of laser is used to detect optical rotation for atomic spin precession. A more uniform Gauss configuration without additional beam shaping and a relatively high power o...A superluminescent diode (SLD) as an alternative of laser is used to detect optical rotation for atomic spin precession. A more uniform Gauss configuration without additional beam shaping and a relatively high power of the SLD have a potential for atomic magnetometers, which is demonstrated in theory and experiments. In addition, the robustness and compactness enable a more practical way for optical rotation detections, especially for applications in magnetoencephalography systems.展开更多
We propose a dual-mode optically pumped magnetometer(OPM)that can flexibly switch between single-beam modulation mode and double-beam DC mode.Based on a 4 mm×4 mm×4 mm miniaturized vapor cell,the double-beam...We propose a dual-mode optically pumped magnetometer(OPM)that can flexibly switch between single-beam modulation mode and double-beam DC mode.Based on a 4 mm×4 mm×4 mm miniaturized vapor cell,the double-beam DC mode achieves a sensitivity of 7 fT=Hz^(1/2) with probe noise below 4 fT=Hz^(1/2) and working bandwidth over 65 Hz.This mode is designed to precisely measure the noise floor of a mu-metal magnetic shield.The single-beam modulation mode(sensitivity 20 fT=Hz^(1/2))exhibits bandwidth characteristics suitable for biomagnetic measurements.Thus,our design is suitable for a miniaturized OPM with multiple functions,including magnetic-shield background noise measurement and medical imaging.展开更多
Epilepsy is a common disease with frequent occurrences.Many precipitating factors contribute to epileptic seizures,such as hyperventilation and alcohol consumption.An increasing number of studies have also found that ...Epilepsy is a common disease with frequent occurrences.Many precipitating factors contribute to epileptic seizures,such as hyperventilation and alcohol consumption.An increasing number of studies have also found that electromagnetic activity in the environment can also affect epileptic seizures.However,many neuromodulatory devices that produce electromagnetic fields have been applied in the diagnosis and treatment of epilepsy.In this paper,we performed literature search in the PubMed,Medline and EMBASE databases and reviewed retrospective,prospective,or cross-sectional studies and case reports on the effects of electromagnetic activity on epilepsy.The application of electromagnetic activity in the diagnosis and treatment of epilepsy is also reviewed.展开更多
In this study,we investigated how empathic neural responses unfold over time in different empathy networks when viewing same-race and other-race individuals in dynamic painful conditions.We recorded magnetoencephalogr...In this study,we investigated how empathic neural responses unfold over time in different empathy networks when viewing same-race and other-race individuals in dynamic painful conditions.We recorded magnetoencephalography signals from Chinese adults when viewing video clips showing a dynamic painful(or non-painful)stimulation to Asian and White models’faces to trigger painful(or neutral)expressions.We found that perceived dynamic pain in Asian models modulated neural activities in the visual cortex at 100 ms–200 ms,in the orbitofrontal and subgenual anterior cingulate cortices at 150 ms–200 ms,in the anterior cingulate cortex around 250 ms–350 ms,and in the temporoparietal junction and middle temporal gyrus around 600 ms after video onset.Perceived dynamic pain in White models modulated activities in the visual,anterior cingulate,and primary sensory cortices after 500 ms.Our findings unraveled earlier dynamic activities in multiple neural circuits in response to same-race(vs other-race)individuals in dynamic painful situations.展开更多
基金Project supported by Ji Hua Laboratory(Grant No.X190131TD190)the Research and Development Project for Equipment of Chinese Academy of Sciences(Grant No.YJKYYQ20210051)+1 种基金the Suzhou pilot project of basic research(Grant No.SJC2021024)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20200215)。
文摘Atomic magnetometers operated in the spin-exchange relaxation-free(SERF)regime are the promising sensor to replace superconducting quantum interference devices(SQUIDs)in the biomagnetism field.The SERF magnetometer with compact size and good performance is crucial to the new generation of wearable magnetoencephalography(MEG)system.In this paper,we developed a compact and closed-loop SERF magnetometer with the dimensions of 15.0×22.0×30.0 mm^(3)based on a single-beam configuration.The bandwidth of the magnetometer was extended to 675 Hz while the sensitivity was maintained at 22 f T/Hz^(1/2).A nearly 3-fold enhancement of the bandwidth was obtained in comparison with the open-loop control.The implementation of the closed-loop control also greatly improved the dynamic range,enabling the magnetometer to be robust against the disturbance of the ambient field.Moreover,the magnetometer was successfully applied for the detection of humanα-rhythm and auditory evoked fields(AEFs),which demonstrated the potential to be extended to multi-channel MEG measurements for future neuroscience studies.
文摘We studied differences in imaginary coherence (IC) of the gamma band between brain regions of female schizophrenia patients during the auditory oddball task using magnetoencephalography (MEG). Subjects were 12 right-handed female schizophrenia patients, who were evaluated by the Positive and Negative Syndrome Scales (PANSS). Functional connectivity during an auditory oddball task was reconstructed in low gamma (30 - 50 Hz) and high gamma (50 - 100 Hz and 100 - 150 Hz) bands, and represented by IC using seeds determined by the significant oscillatory power changes obtained by event-related synchronization (ERS) and event-related desynchronization (ERD) power measurements. Gamma ERS (30 - 50 Hz) power was decreased in the left precuneus at 500 - 750 ms and in the right precuneus at 750 - 1000 ms. IC in the gamma band (50 - 100 Hz) was decreased between the right precuneus (seed) and right paracentral lobule (target) and between the right precuneus and right hypothalamus at 0 - 250 ms. IC in the gamma band (100 - 150 Hz) was increased between the left precuneus and right cuneus (Brodmann area 7) at 250 - 500 ms, between the left precuneus and right culmen at 500 - 750 ms, and between the left precuneus and right cuneus (Brodmann area 17), between the left precuneus and right posterior cingulate cortex, and between the left precuneus and right caudate nucleus at 750 - 1000 ms. In the high gamma band (50 - 100 Hz) at 0 - 250 ms, significant positive correlations were shown between IC and conceptual disorganization in PANSS scores, between IC and unusual thought content score, and between IC and positive scale score. IC within the high gamma band in female schizophrenia patients showed two types of functional disconnection, intrahemispheric and interhemispheric. IC between the right or left precuneus and other specific cortical areas showed dysfunction, suggesting that the parietal lobe plays an important role in dysfunction in connectivity in the gamma band during the oddball task.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFA0300600 and 2016YFA0301500)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB07030000 and XDBS32000000)+1 种基金the National Natural Science Foundation of China(Grant Nos.11474347 and 31730039)the Fund from the Ministry of Science and Technology of China(Grant No.2015CB351701)
文摘We observed the steady-state visually evoked potential(SSVEP) from a healthy subject using a compact quad-channel potassium spin exchange relaxation-free(SERF) optically pumped magnetometer(OPM). To this end, 30 s of data were collected, and SSVEP-related magnetic responses with signal intensity ranging from 150 fT to 300 f T were observed for all four channels. The corresponding signal to noise ratio(SNR) was in the range of 3.5–5.5. We then used different channels to operate the sensor as a gradiometer. In the specific case of detecting SSVEP, we noticed that the short channel separation distance led to a strongly diminished gradiometer signal. Although not optimal for the case of SSVEP detection, this set-up can prove to be highly useful for other magnetoencephalography(MEG) paradigms that require good noise cancellation.Considering its compactness, low cost, and good performance, the K-SERF sensor has great potential for biomagnetic field measurements and brain-computer interfaces(BCI).
文摘Previous studies examining coherence and connectivity deviations in schizophrenia patients relied on standard coherence measures between recording sites (at the sensor level). A coherence source imaging (CSI) methodology where coherence is assessed within imaged brain structures (at the source level) was developed recently by our group and applied successfully for detecting coherent areas in the cortical networks of patients with epilepsy. We applied this Magnetoencephalography (MEG)-CSI technique to measure normal and pathological patterns of brain oscillations (biomarkers) in normal subjects and patients diagnosed with schizophrenia. Twelve patients diagnosed with schizophrenia and twelve healthy control subjects were studied. A ten-minute resting state MEG brain scan was performed with eyes open. MEG-CSI analysis was performed to identify the cortical areas that interacted strongly within the 3 - 50 Hz frequency range. Statistically significant increased regions of coherence were detected in schizophrenia patients compared to controls in the right inferior frontal gyrus (BA 47—pars orbitalis), left superior frontal gyrus (BA9— dorsolateral prefrontal cortex), right middle frontal gyrus (BA 10—anterior prefrontal cortex & BA 46—dorsolateral prefrontal cortex), and right cingulate gyrus (BA 24—ventral anterior cingulate cortex). These areas are involved in language, memory, decision making, empathy, executive and, higher cognitive functioning. We conclude that MEG-CSI can detect imaging biomarkers from resting state brain activity in schizophrenia patients that deviates from normal control subjects in several behaviorally salient brain regions. Analysis with MEG-CSI can provide biomarkers of abnormalities in the resting-state. The findings and procedures described can be used to probe the pathophysiology of schizophrenia and possibly detect subtypes.
文摘Apparent motion stimulus induces visual perception of smooth motion even though there is no speed information. We examined whether human brain response as measured by magnetoencephalography carries direction information in the visually presented apparent motion of a randomdot pattern in a similar manner as continuous motions that have speed and direction information. Although there was no significant effect of motion direction on the peak response latency and amplitude, mutual information entropy (IE) significantly increased after the motion onset at approximately 36 ms after the response latency in 41% of the evaluations. Detailed analysis of the data from five subjects who participated in both the present apparent motion and our previous coherent motion studies revealed that the maximum IE latency (delay) for apparent motion was significantly longer than that for coherent motion, although the mean maximum IE was the same. The results indicate that direction is represented in the response waveform evoked by apparent motion but the manner is different from that for coherent motion probably due to the distinct neural processes engaged only for the apparent motion perception. We consider that direction and speed can be processed separately in the human brain because direction information was generated without speed information for the perception of apparent motion.
文摘Brainwave is a kind of traceable neurophysiological energy in a living brain. Invisible to human eyes, it is only detectable using electroencephalography (EEG), electrocorticography (ECoG) and magnetoencephalography (MEG). The waves or oscillations or rhythms are produced mainly by the oscillatory networks of the brain. Three main oscillatory networks are thalamocortical, extrathalamic-cortical and cortical-cortical networks. Greater limbic system (reticular system, hypothalamus, thalamus, basal forebrain nuclei, limbic system) has a great influence on these oscillatory networks. This system which is in microgravity position lies deep inside and surrounded by the ventricles of the brain. It receives all information from inside and outside of our body and then projects to all areas of the brain (from all to one and from one to all—nearly similar concept to “from God back to God”). Therefore, the greater limbic system could be regarded as “a core of the neuroaxis” which lies in microgravity compartment and in microgravity position (“T”-shape or curving shape;whilst gravity position is “I”-shape or vertical shape). By knowing the origin of the brainwaves and methods to detect them, one may study seizure networks, normal and abnormal brain networks and arguably, even to explore the relationship between the “invisibles”: “invisible” brainwaves and “invisible” soul.
文摘The inverse problem of magnetoencephalography (MEG) seeks the neuronal current within the conductive brain that generates a measured magnetic flux in the exterior of the brain-head system. This problem does not have a unique solution, and in particular, it is not even possible to identify the support of the current if it extends over a three-dimensional set. However, a localized current supported on a zero-, one- or two-dimensional set can in principle be identified. In the present work, we demonstrate an analytic algorithm that is able to recover a one-dimensional distribution of current from the knowledge of the exterior magnetic flux field. In particular, we consider a neuronal current that is supported on a small line segment of arbitrary location and orientation in space, and we reduce the identification of its characteristics to a nonlinear algebraic system. A series of numerical tests show that this system has a unique real solution. A special case is easily solved via the use of trivial algebraic operations.
文摘The support of a localized three-dimensional neuronal current distribution, within a conducting medium, is not identifiable from knowledge of the exterior magnetic flux density, obtained via Magnetoencephalographic (MEG) measurements. However, this is not true if the neuronal current is supported on a set with dimensionality less than three. That is, the support of a dipolar current distribution can be recovered if it is a set of isolated points, a segment of a curve, or a surface patch. In this work we provide an analytic algorithm for this inverse MEG problem and apply it to the case where the current is supported on a localized disk having arbitrary position and size within the brain tissue. The proposed recovery algorithm reduces the identification of the characteristics of the current to the solution of a nonlinear algebraic system, which can be handled numerically.
文摘Neurological disorders with symptoms such as chronic pain,depression,and insomnia are widespread.Very weak electric fields applied through the skull can enhance or diminish neural activity and modulate brain waves in order to treat many of these common medical problems.This approach is to be contrasted with well-established pharmacological methods or more recent invasive electrical Deep Brain Stimulation(DBS)techniques that require surgery to insert electrodes deep into the brain.We claim that Non-Invasive Brain Stimulation(NIBS)will provide new treatment methods with much greater simplicity,lower cost,improved safety and in some cases,possibly greater effectiveness.This emerging use of NIBS is a branch of a new multidisciplinary field that we coined Neuro-systems Engineering[1].This field involves neuroscientists,psychologists,and electrical engineers.This emerging field relies on existing standards for the safe implementation of these novel treatment modalities[2].Methods of stimulating the brain are based on emerging electro-technologies such as transcranial Direct Current/Alternating Current(DC/AC)electric fields and pulsed magnetic fields.Application of functional and time-dependent brain imaging methods can be used to locate relevant brain regions and determine the most appropriate stimulation method.Application of tailored and individualized control can be combined with other therapy methods to effectively treat neurological disorders while minimizing or even eliminating the use of pharmaceuticals.In this paper,we are presenting our embodiment for a closed loop,feedback controlled,non-invasive application of electrical stimulation of the brain to enhance individual/group performance or to treat neurological disorders.
基金This work is supported by the National Natural Science Foundation of China(No.30 0 0 0 0 34 )
文摘The spherical head model has been widely used in magnetoencephalography (MEG) as a simple forward model for calculating the external magnetic field producing by neural currents in a human brain. But this model may lead to an inaccurate result, even if the computation speed is fast. For more precise computation, realistic brain-shaped head model is used with the boundary element method (BME), but at greatly increased computational cost. When solving MEG inverse problem by using optimization methods, the forward problem must often be solved for thousands of possible source configurations. So if the brain-shaped head model is used in all iterative steps of optimization, it may be computationally infeasible for practical application. In this paper, we present a method about using compound head model in MEG inverse solution. In this method, first spherical head model is used for a rough estimation, then brain-shaped head model is adopted for more precise solution. Numerical simulation indicates that under the condition of same accuracy, the computation speed for the present method is about three times faster than a method using the brain-shaped head model at all iterations.
基金It is supported by the National Natural Science Foundation of China(No.5994 70 0 4)
文摘Multichannel biomagnetometers can be used to measure the spatio temporal magnetic field produced by neural activity in a human brain. The measured data are usually contaminated by noise and some artifact signals. These artifact signals may be caused by heart beats or eye blinks. Actually, these artifact signal sources are also bioelectric activities. In this paper, we demonstrate the effectiveness of MEG MUSIC algorithm for eliminating the artifacts. In the paper, the artifact fields are not considered as noise but as signals that have a linear relationship with their bioelectric source activities. Computer simulations demonstrate that for the localization of sources distributed in the cortical region, the MEG MUSIC algorithm is also efficient under the presence of the artifacts.
文摘Vagus nerve stimulation(VNS)is an important treatment option for drug-refractory epilepsy(DRE),with well-established efficacy and safety in clinical practice for more than 20 years.However,it is very difficult to find the optimal electrophysiological indicators for the effectiveness of VNS on DRE because the mechanism of action is unknown.In this review,we provide an update of the potential applications of VNS outcomes in patients with drug-resistant epilepsy.Electroencephalographic(EEG)activity,event-related potentials,EEG synchronization levels,magnetoencephalographic,laryngeal muscle evoked potentials,and heart rate variability are potential biomarkers for VNS outcomes in people with DRE.
文摘A superluminescent diode (SLD) as an alternative of laser is used to detect optical rotation for atomic spin precession. A more uniform Gauss configuration without additional beam shaping and a relatively high power of the SLD have a potential for atomic magnetometers, which is demonstrated in theory and experiments. In addition, the robustness and compactness enable a more practical way for optical rotation detections, especially for applications in magnetoencephalography systems.
基金This work was supported by the National Key R&D Program of China(No.2018YFB2002405)the National Natural Science Foundation of China(No.61903013).
文摘We propose a dual-mode optically pumped magnetometer(OPM)that can flexibly switch between single-beam modulation mode and double-beam DC mode.Based on a 4 mm×4 mm×4 mm miniaturized vapor cell,the double-beam DC mode achieves a sensitivity of 7 fT=Hz^(1/2) with probe noise below 4 fT=Hz^(1/2) and working bandwidth over 65 Hz.This mode is designed to precisely measure the noise floor of a mu-metal magnetic shield.The single-beam modulation mode(sensitivity 20 fT=Hz^(1/2))exhibits bandwidth characteristics suitable for biomagnetic measurements.Thus,our design is suitable for a miniaturized OPM with multiple functions,including magnetic-shield background noise measurement and medical imaging.
基金the National Natural Science Foundation ofChina(No.81671301).
文摘Epilepsy is a common disease with frequent occurrences.Many precipitating factors contribute to epileptic seizures,such as hyperventilation and alcohol consumption.An increasing number of studies have also found that electromagnetic activity in the environment can also affect epileptic seizures.However,many neuromodulatory devices that produce electromagnetic fields have been applied in the diagnosis and treatment of epilepsy.In this paper,we performed literature search in the PubMed,Medline and EMBASE databases and reviewed retrospective,prospective,or cross-sectional studies and case reports on the effects of electromagnetic activity on epilepsy.The application of electromagnetic activity in the diagnosis and treatment of epilepsy is also reviewed.
基金supported by the National Natural Science Foundation of China(32230043)the Ministry of Science and Technology of China(2019YFA0707103)+1 种基金Das Chinesisch-Deutsche Zentrum fur Wissenschaftsforderung(M-0093)the High-performance Computing Platform of Peking University。
文摘In this study,we investigated how empathic neural responses unfold over time in different empathy networks when viewing same-race and other-race individuals in dynamic painful conditions.We recorded magnetoencephalography signals from Chinese adults when viewing video clips showing a dynamic painful(or non-painful)stimulation to Asian and White models’faces to trigger painful(or neutral)expressions.We found that perceived dynamic pain in Asian models modulated neural activities in the visual cortex at 100 ms–200 ms,in the orbitofrontal and subgenual anterior cingulate cortices at 150 ms–200 ms,in the anterior cingulate cortex around 250 ms–350 ms,and in the temporoparietal junction and middle temporal gyrus around 600 ms after video onset.Perceived dynamic pain in White models modulated activities in the visual,anterior cingulate,and primary sensory cortices after 500 ms.Our findings unraveled earlier dynamic activities in multiple neural circuits in response to same-race(vs other-race)individuals in dynamic painful situations.
