Depression, a mental health disorder, has emerged as one of the significant challenges in the global public health domain. Investigating the pathogenesis of depression and accurately assessing the symptomatic changes are fundamental to formulating effective clinical diagnosis and treatment strategies. Utilizing non-invasive brain imaging technologies such as functional magnetic resonance imaging and scalp electroencephalography, existing studies have confirmed that the onset of depression is closely associated with abnormal neural activities and altered functional connectivity in multiple brain regions. Magnetoencephalography, unaffected by tissue conductivity and skull thickness, boasts high spatial resolution and signal-to-noise ratio, offering unique advantages and significant value in revealing the abnormal brain mechanisms and neural characteristics of depression. This review, starting from the rhythmic characteristics, nonlinear dynamic features, and connectivity characteristics of magnetoencephalography in depression patients, revisits the research progress on magnetoencephalography features related to depression, discusses current issues and future development trends, and provides insights for the study of pathophysiological mechanisms, as well as for clinical diagnosis and treatment of depression.
Humans ; Magnetoencephalography/methods* ; Brain/physiopathology* ; Depression/diagnosis* ; Electroencephalography ; Magnetic Resonance Imaging

Establishing the significance of observed effects is a preliminary requirement for any meaningful interpretation of clinical and experimental Electroencephalography or Magnetoencephalography (MEG) data. We propose a method to evaluate significance on the level of sensors whilst retaining full temporal or spectral resolution. Input data are multiple realizations of sensor data. In this context, multiple realizations may be the individual epochs obtained in an evoked-response experiment, or group study data, possibly averaged within subject and event type, or spontaneous events such as spikes of different types. In this contribution, we apply Statistical non-Parametric Mapping (SnPM) to MEG sensor data. SnPM is a non-parametric permutation or randomization test that is assumption-free regarding distributional properties of the underlying data. The method, referred to as Maps SnPM, is demonstrated using MEG data from an auditory mismatch negativity paradigm with one frequent and two rare stimuli and validated by comparison with Topographic Analysis of Variance (TANOVA). The result is a time- or frequency-resolved breakdown of sensors that show consistent activity within and/or differ significantly between event or spike types. TANOVA and Maps SnPM were applied to the individual epochs obtained in an evoked-response experiment. The TANOVA analysis established data plausibility and identified latencies-of-interest for further analysis. Maps SnPM, in addition to the above, identified sensors of significantly different activity between stimulus types.
Electroencephalography ; Magnetoencephalography ; Methods ; Random Allocation

BACKGROUNDPrevious neuroimaging studies primarily focused on the spatial distribution of acupuncture needling stimulation. However, a salient feature of acupuncture was its long-lasting effect. This study attempted to detect the spatial-temporal neural responses evoked by acupuncture at an analgesia acupoint ST36 by using magnetoencephalography. To further verify its functional specificity, we also adopted acupuncture at Pericardium 6 and nonacupoint as separated controls.

METHODSForty-two college students, all right-handed and acupuncture naïve, participated in this study. Every participant received only one acupoint stimulation, resulting in 14 subjects in one group. Both magnetoencephalography data (151-channel whole-head system) and structural functional magnetic resonance imaging data (3D sequence with a voxel size of 1 mm(3) for anatomical localization) were collected for each subject. All processing procedures were performed in BrainStorm Toolbox.

RESULTSAcupuncture at ST36 showed a significantly time-varied brain activities with different onset time. Our results presented that acupuncture at different acupoints (or comparing with nonacupoint) can specifically induce neural responses in different brain areas-acupuncture at ST36 can specifically induce the neural responses of pain-inhibition areas, while acupuncture at PC6 can specifically induce the activities of the insula and amygdala.

CONCLUSIONSIn the present study, we attempted to detect the temporal neural responses underlying the functional specificity of acupuncture at ST36, using acupoint belonging to different meridians and non-acupoint with efficacy-irreverent as separate controls. The specific neural substrates involving acupuncture at different acupoints may be related to its functional specificity in clinical settings.

Acupuncture Points ; Acupuncture Therapy ; Adult ; Female ; Humans ; Magnetic Resonance Imaging ; Magnetoencephalography ; methods ; Male ; Pain ; physiopathology ; psychology ; Young Adult

The magnetoencephalography (MEG) can be used as a control signal for brain computer interface (BCI). The BCI also includes the pattern information of the direction of hand movement. In the MEG signal classification, the feature extraction based on signal processing and linear classification is usually used. But the recognition rate has been difficult to improve. In the present paper, a principal component analysis (PCA) and linear discriminant analysis (LDA) method has been proposed for the feature extraction, and the non-linear nearest neighbor classification is introduced for the classifier. The confusion matrix is analyzed based on the results. The experimental results show that the PCA + LDA method is effective in the analysis of multi-channel MEG signals, improves the recognition rate to the extent of the average recognition rate 55.7%, which is better than the recognition rate 46.9% in the BCI competition IV.
Algorithms ; Brain ; physiology ; Discriminant Analysis ; Electroencephalography ; Hand ; physiology ; Humans ; Magnetoencephalography ; methods ; Movement ; physiology ; Principal Component Analysis ; Signal Processing, Computer-Assisted ; User-Computer Interface

Epilepsy ; diagnosis ; drug therapy ; surgery ; Humans ; Magnetoencephalography ; Positron-Emission Tomography ; Stereotaxic Techniques ; Surgery, Computer-Assisted ; methods ; Treatment Failure

Adolescent ; Adult ; Audiometry, Pure-Tone ; methods ; Auditory Cortex ; physiopathology ; Case-Control Studies ; Female ; Hearing Loss, Sensorineural ; diagnosis ; physiopathology ; Humans ; Magnetoencephalography ; Male ; Young Adult

OBJECTIVETo evaluate the applied value of magnetoencephalography (MEG) localization in microsurgery of brain tumors in the region of motor cortex.

METHODSFrom January 2003 to April 2005, 36 patients with 19 meningomas, 14 gliomas, 2 metastases and 1 cavernous angioma underwent MEG and MRI before operation. These individualized functional brain maps were integrated into a neuronavigation system. Preoperative mapping of somatosensory and/or motor cortex was performed, and sites were compared, and all tumors were resected microsurgerically.

RESULTSA space-occupying lesion could change the region of motor cortex in all the patients. Thirty-four cases were resected totally. The patient's myodynamia after operation improved in 19 cases, unchanged in 15 cases, descended in 2 cases.

CONCLUSIONSMEG is an effective localization method of function, providing the relationship between the region of motor cortex and the tumor. And it is valuable for accurate planning in the treatment of brain tumors in the region of motor cortex.

Adolescent ; Adult ; Aged ; Brain Neoplasms ; diagnosis ; surgery ; Female ; Humans ; Magnetoencephalography ; Male ; Microsurgery ; Middle Aged ; Neuronavigation ; Neurosurgical Procedures ; methods ; Treatment Outcome

BACKGROUNDBlood oxygen level dependent functional magnetic resonance imaging (fMRI) and magnetoencephalography are new techniques of brain functional imaging which can provide the information of excitation of neurons by measure the changes of hemodynamics and electrophysiological data of local brain tissue. The purpose of this study was to study functional brain areas evoked by pure tones in healthy and sensorineural hearing loss subjects with these techniques and to compare the differences between the two groups.

METHODSThirty healthy and 30 sensorineural hearing loss subjects were included in this study. In fMRI, block-design paradigm was used. During the active epoch the participants listened to 1000 Hz, sound pressure level 140 dB pure tones at duration 500 ms, interstimulus interval 1000 ms, which presented continuously via a magnetic resonance-compatible audio system. None stimulus was executed in control epoch. In magnetoencephalography study, every subject received stimuli of 1000 Hz tone bursts delivered to the bilateral ear at duration 8 ms, interstimulus intervals 1000 ms. Sound pressure level in healthy subjects was 30 dB; in sensorineural hearing loss subjects was 20 dB above everyone's hearing threshold respectively. All subjects were examined with 306-channel whole-scalp neuromagnetometer.

RESULTSIn fMRI, all subjects showed significant activations in bilateral Heschl's gyri, anterior pole of planum temporale, planum temporale, precentral gyri, postcentral gyri, supramarginal gyri, superior temporal gyri, inferior frontal gyri, occipital lobes and cerebellums. The healthy subjects had more intensive activation in bilateral Heschl's gyri, anterior pole of planum temporale, inferior frontal gyri, left superior temporal gyri and right planum temporale than the hearing loss subjects. But in precentral gyri, postcentral gyri and occipital lobes, the activation is more intensive in the hearing loss subjects. In magnetoencephalography study, both in the hearing loss and the healthy subjects, the most evident audio evoked fields activated by pure tone were N100m, which located precisely on the Heschl's gyrus. Compared with the hearing loss subjects, N100m of the healthy subjects was stronger and had longer latencies in right hemisphere.

CONCLUSIONSUnder proper pure tone stimulus the activation of auditory cortex can be elicited both in the healthy and the sensorineural hearing loss subjects. Either at objective equivalent stimuli or at subjectively perceived equivalent stimuli, the auditory responses were more intensive in healthy subjects than hearing loss subjects. The tone stimuli were processed in a network in human brain and there was an intrinsic relation between the auditory and visual cortex. Blood oxygen level dependent fMRI and magnetoencephalography could reinforce each other.

Acoustic Stimulation ; Adolescent ; Adult ; Audiometry, Evoked Response ; Audiometry, Pure-Tone ; methods ; Auditory Cortex ; physiology ; physiopathology ; Brain ; physiology ; physiopathology ; Female ; Hearing Loss, Sensorineural ; chemically induced ; physiopathology ; Humans ; Magnetic Resonance Imaging ; methods ; Magnetoencephalography ; methods ; Male ; Occipital Lobe ; physiology ; physiopathology

Independent component analysis (ICA) is a new method of signal statistical processing and widely used in many fields. We face several problems such as the different nature of source signals (e.g. both super-Gaussian and sub-Gaussian sources exist), unknown number of sources and contamination of the sensor signals with a high level of additive noise in the analysis of signal. A robust approach was proposed to solve these problems in this paper. Firstly, observations (noisy data) possessing high dimensionality were preprocessed and decomposed into a source signal subspace and a noise subspace. Then the number of sources was got through the cross-validation method, and this solved the problem that ICA could not confirm the number of sources. At last the transformed low-dimensional source signals were further separated with the fast and stable ICA algorithm. Through the analysis of artificially synthesized data and the real-world Magnetoencephalographic data, the efficacy of this robust approach was illustrated.
Algorithms ; Humans ; Magnetoencephalography ; methods ; Principal Component Analysis ; Signal Processing, Computer-Assisted

In the last few years, brain science has exhibited an explosive growth in hemodynamic/metabolic data on brain function. In particular, PET and functional MRI provide excellent spatial resolution, but their temporal resolutions are severely limited by relatively slow responses of brain metabolism. By contrast, EEG and MEG are able to track modulations of current source activity at millisecond time scales, but suffer from poor spatial resolution. Hence, high-resolution spatiotemporal imaging of brain activity requires integration of information from multiple signal modalities. In this paper we discuss what is known about the physical and physiological basis of the imaging signals, suggest various approaches that have been proposed for integrating information across multiple modalities, and briefly analyze the future directions and remaining challenges in the field of multi-modality integration.
Brain ; physiopathology ; Brain Diseases ; diagnosis ; physiopathology ; Brain Mapping ; methods ; Electroencephalography ; methods ; Humans ; Magnetic Resonance Imaging ; Magnetoencephalography ; Systems Integration ; Tomography, Emission-Computed ; methods