Analysis of neural fragility in epileptic zone based on stereoelectroencephalography / 生物医学工程学杂志

There are some limitations in the localization of epileptogenic zone commonly used by human eyes to identify abnormal discharges of intracranial electroencephalography in epilepsy. However, at present, the accuracy of the localization of epileptogenic zone by extracting intracranial electroencephalography features needs to be further improved. As a new method using dynamic network model, neural fragility has potential application value in the localization of epileptogenic zone. In this paper, the neural fragility analysis method was used to analyze the stereoelectroencephalography signals of 35 seizures in 20 patients, and then the epileptogenic zone electrodes were classified using the random forest model, and the classification results were compared with the time-frequency characteristics of six different frequency bands extracted by short-time Fourier transform. The results showed that the area under curve (AUC) of epileptic focus electrodes based on time-frequency analysis was 0.870 (delta) to 0.956 (high gamma), and its classification accuracy increased with the increase of frequency band, while the AUC by using neural fragility could reach 0.957. After fusing the neural fragility and the time-frequency characteristics of the γ and high γ band, the AUC could be further increased to 0.969, which was improved on the original basis. This paper verifies the effectiveness of neural fragility in identifying epileptogenic zone, and provides a theoretical reference for its further clinical application.

Electroencephalogram patterns with the presence of an unknown musical stimulus

The cerebral activity presents different behaviors in different situations and levels of consciousness, especially under musical stimulation. Signals of the central nervous system may disclose bioelectrical patterns, since listening to rhythmic sequences activates specific brain areas. In this paper, we analyze 42 neurologically normal Brazilian individuals, submitted to musical stimulation based on a procedure consisting of three different steps, during which the volunteer is kept with closed eyes. The first step is associated with the preliminary control silence period, without any stimulus, as the volunteer remains at rest. The second step consisted of unknown music stimulation. Finally, the third step involves post-music rest. Quantitative signal analysis computes the power spectrum time variations. Results point out stronger changes in gamma and high gamma waves (30 ­ 100 Hz). Even though the clinical rhythms (0 ­ 30 Hz) change throughout the whole period of the experiment, quantitative differences at gamma and high gamma bands are remarkably greater. Particularly, when comparing the initial silent period and the final post-stimulation silent one, bioelectrical differences are only highlighted by gamma and high gamma rhythms. In consequence, this paper points out that the EEG analysis of cognitive issues related to musical perception cannot disregard gamma and high gamma waves.

Intelligence-aided diagnosis of Parkinson's disease with rapid eye movement sleep behavior disorder based on few-channel electroencephalogram and time-frequency deep network / 生物医学工程学杂志

Aiming at the limitations of clinical diagnosis of Parkinson's disease (PD) with rapid eye movement sleep behavior disorder (RBD), in order to improve the accuracy of diagnosis, an intelligent-aided diagnosis method based on few-channel electroencephalogram (EEG) and time-frequency deep network is proposed for PD with RBD. Firstly, in order to improve the speed of the operation and robustness of the algorithm, the 6-channel scalp EEG of each subject were segmented with the same time-window. Secondly, the model of time-frequency deep network was constructed and trained with time-window EEG data to obtain the segmentation-based classification result. Finally, the output of time-frequency deep network was postprocessed to obtain the subject-based diagnosis result. Polysomnography (PSG) of 60 patients, including 30 idiopathic PD and 30 PD with RBD, were collected by Nanjing Brain Hospital Affiliated to Nanjing Medical University and the doctor's detection results of PSG were taken as the gold standard in our study. The accuracy of the segmentation-based classification was 0.902 4 in the validation set. The accuracy of the subject-based classification was 0.933 3 in the test set. Compared with the RBD screening questionnaire (RBDSQ), the novel approach has clinical application value.

Parkinson's disease diagnosis based on local statistics of speech signal in time-frequency domain / 生物医学工程学杂志

For speech detection in Parkinson's patients, we proposed a method based on time-frequency domain gradient statistics to analyze speech disorders of Parkinson's patients. In this method, speech signal was first converted to time-frequency domain (time-frequency representation). In the process, the speech signal was divided into frames. Through calculation, each frame was Fourier transformed to obtain the energy spectrum, which was mapped to the image space for visualization. Secondly, deviations values of each energy data on time axis and frequency axis was counted. According to deviations values, the gradient statistical features were used to show the abrupt changes of energy value in different time-domains and frequency-domains. Finally, KNN classifier was applied to classify the extracted gradient statistical features. In this paper, experiments on different speech datasets of Parkinson's patients showed that the gradient statistical features extracted in this paper had stronger clustering in classification. Compared with the classification results based on traditional features and deep learning features, the gradient statistical features extracted in this paper were better in classification accuracy, specificity and sensitivity. The experimental results show that the gradient statistical features proposed in this paper are feasible in speech classification diagnosis of Parkinson's patients.

EEG Signal Analysis Methods and Their Applications / 中国医疗器械杂志

EEG is a weak physiological electrical signal, which has important value in clinical and laboratory research. This paper mainly introduces several common methods of EEG signal processing, including power spectrum analysis, time-frequency analysis, bispectral analysis, etc, it mainly introduces their principles and applications in EEG signal processing, and provides methods and approaches for studying EEG.

A research for single trial detection of error related negativity / 生物医学工程学杂志

Error related negativity (ERN) is generated in frontal and central cortical regions when individuals perceive errors. Because ERN has low signal-to-noise ratio and large individual difference, it is difficult for single trial ERN recognition. In current study, the optimized electroencephalograph (EEG) channels were selected based on the brain topography of ERN activity and ERN offline recognition rate, and the optimized EEG time segments were selected based on the ERN offline recognition rate, then the low frequency time domain and high frequency time-frequency domain features were analyzed based on wavelet transform, after which the ERN single detection algorithm was proposed based on the above procedures. Finally, we achieved average recognition rate of 72.0% ± 9.6% in 10 subjects by using the sample points feature in 0~3.9 Hz and the power and variance features in 3.9~15.6 Hz from the EEG segments of 200~600 ms on the selected 6 channels. Our work has the potential to help the error command real-time correction technique in the application of online brain-computer interface system.

Effects of two fatigue protocols on lower extremity kinematics and time/frequency-domain characteristics of impact forces during drop landing / 医用生物力学

Objective To compare the influence of two fatigue protocols on kinematics of lower extremities as well as time/frequency-domain characteristics of impact force during human landing. Methods A total of 15 trained male athletes (sprint/jumping events) were selected and their kinematics in sagittal/frontal plane and time/frequency-domain characteristics of ground reaction force (GRF) under pre- and post-fatigue conditions with two fatigue protocols (constant speed running, shuttle running + vertical jumping) were collected by the Vicon motion capture system and Kistler 3D force plates. Results (1) Both fatigue protocols showed a significant decrease in the angle of hip and knee joints on the sagittal plane, and an increase in the flexion range of motion (ROM). The running + jumping fatigue protocol showed a significant increase in the flexion ROM of ankle joint, the maximum flexion angular velocity of knee joint (P<0.05), the abduction ROM of hip joint and the maximum abduction angular velocity of hip and knee joints (P<0.05). (2) No significant differences were found in time/frequency-domain characteristics of impact force between pre- and post-tests for both fatigue protocols. The running and running + jumping fatigue protocols showed lower amplitude spectra of the GRF in the frequency domain at 3.51, 8.20 Hz and 1.17, 3.51, 7.03 Hz, respectively (P<0.05). Conclusions Both fatigue protocols can induce a more flexed landing posture of lower extremities under the impact of landing, and the running + jumping fatigue protocol shows a better effect with shorter intervention time, which indicates such fatigue protocol has more advantages from the perspective of experimental methodology. The research findings can provide further references for studying force characteristics after fatigue.

Effects of two fatigue protocols on lower extremity kinematics and time/frequency-domain characteristics of impact forces during drop landing / 医用生物力学

Objective To compare the influence of two fatigue protocols on kinematics of lower extremities as well as time/frequency-domain characteristics of impact force during human landing.Methods A total of 15 trained male athletes (sprint/jumping events) were selected and their kinematics in sagittal/frontal plane and time/frequency-domain characteristics of ground reaction force (GRF) under pre-and post-fatigue conditions with two fatigue protocols (constant speed running,shuttle running + vertical jumping) were collected by the Vicon motion capture system and Kistler 3 D force plates.Results (1) Both fatigue protocols showed a significant decrease in the angle of hip and knee joints on the sagittal plane,and an increase in the flexion range of motion (ROM).The running + jumping fatigue protocol showed a significant increase in the flexion ROM of ankle joint,the maximum flexion angular velocity of knee joint (P＜0.05),the abduction ROM of hip joint and the maximum abduction an gular velocity of hip and knee joints (P ＜ 0.05).(2) No significant differences were found in time/frequency-domain characteristics of impact force between pre-and post-tests for both fatigue protocols.The running and running + jumping fatigue protocols showed lower amplitude spectra of the GRF in the frequency domain at 3.51,8.20 Hz and 1.17,3.51,7.03 Hz,respectively (P＜0.05).Conclusions Both fatigue protocols can induce a more flexed landing posture of lower extremities under the impact of landing,and the running + jumping fatigue protocol shows a better effect with shorter intervention time,which indicates such fatigue protocol has more ad vantages from the perspective of experimental methodology.The research findings can provide further references for studying force characteristics after fatigue.

ECG arrhythmia classification using time frequency distribution techniques

In this paper, we focus on classifying cardiac arrhythmias. The MIT-BIH database is used with 14 original classes of labeling which is then mapped into 5 more general classes, using the Association for the Advancement of Medical Instrumentation standard. Three types of features were selected with a focus on the time-frequency aspects of ECG signal. After using the Wigner-Ville distribution the time-frequency plane is split into 9 windows considering the frequency bandwidth and time duration of ECG segments and peaks. The summation over these windows are employed as pseudo-energy features in classification. The “subject-oriented” scheme is used in classification, meaning the train and test sets include samples from different subjects. The subject-oriented method avoids the possible overfitting issues and guaranties the authenticity of the classification. The overall sensitivity and positive predictivity of classification is 99.67 and 98.92%, respectively, which shows a significant improvement over previous studies.

Recognition of heart sound based on distribution of Choi-Williams

IntroductionTo realize noninvasive diagnosis and early diagnosis of coronary heart disease, the study proposes a new time-frequency method for analyzing heart sound signals. This method is based on Choi-Williams Distribution (CWD).MethodsCWD distribution is developed and modified from Wigner Ville distribution (WVD). To solve the problem of cross-term interference existing in WVD there is an improved version of WVD, called Choi-Williams Distribution (CWD), which introduces the smoothing window as the kernel function and deals with the time-frequency analysis of heart sound signal.ResultsThe improved method has good performance and can be implemented simply without much increase of operation complexity.ConclusionIn this paper, 21 cases of heart sound signals are acquired from the outpatients and hospitalized patients with coronary heart diseases. The research results of 21 cases show that the CWD method can be used to analyze heart sounds. It accurately identifies the 9 cases of heart sounds of health people and 12 cases of heart sounds of patients with coronary heart disease. Besides, the CWD displays obvious differences between heart sounds of healthy people and abnormal heart sounds. The contour line of heart sounds from healthy people shows the following characteristics: concise, columnar and non-divergence; while the contour line of abnormal heart sounds is divergent and has many columnar links. These research shows that CWD method can effectively distinguish heart sounds between healthy people and patients with coronary heart disease.

Immediate Effects of Sustained Forced-blowing Exercise on Phonation Function in Healthy Youths / 中国康复理论与实践

@#Objective To observe the immediate effects of the sustained forced-blowing exercise (SFBE) on the phonation function in young healthy people. Methods 43 young healthy people were asked to pronounce a longest /a/ in a comfortable situation within one breath for 3 times before and after SFBE. The sound files were analyzed with computer sound analysis system, with the parameters of mean maximum phonation time (MMPT), mean frequency (MF) and mean sound pressure level (MSPL). Results The MMPT and MSPL increased (P< 0.01) after SFBE. There was no significant difference in the MF (P>0.05) before and after SFBE. Conclusion The SFBE can improve the MPT and MSPL of the healthy people obviously, without affections on the MF.

Binocular rivalry estimated objectively under face awareness and fusiform correlation analysis / 军事医学

Objective To study binocular rivalry (BR)objectively and the correlation between fusiform face area (FFA)and visual cortex.Methods Six subjects participated in this study,with one eye presented a normal face expres-sion picture flickered at 8.57 Hz,while the other presented a fearful face flickered at 12 Hz or 15 Hz,respectively.Electro-encephalogram(EEG)was recorded during this process.Steady state visual evoked potential(SSVEP)evoked by two flick-ering rates was analyzed by time-frequency analysis of short time fourier transformation(STFT).The time index of BR was estimated and the correlation coefficient between FFA and visual cortex compared.Results The total average time was (411.6 ±73.8)ms for the left eye and (547.6 ±126.7)ms for the right eye.The switch rate of the two groups was not different,but the left FFA was more sensitive than the right FFA in process of the fearful face.Neither side of FFA had any frequency preference to the flickered fearful face.Conclusion SSVEP can be used as a frequency tag of BR or as a tool to evaluate visual sensation under BR objectively.SSVEP combined with BR can be used in research of neural mechanisms of visual awareness.

An Introduction to Quantitative Analyses of Sleep EEG Via a Wavelet Method / 수면정신생리

OBJECTIVE: Among various methods developed to quantitatively explore electroencephalograms (EEG), we focused on a wavelet method that was known to yield robust results under nonstationary conditions. The aim of this study was thus to introduce the wavelet method and demonstrate its potential use in clinical sleep studies. METHOD: This study involved artificial EEG specifically designed to validate the wavelet method. The method was performed to obtain time-dependent spectral power and phase angles of the signal. Synchrony of multichannel EEG was analyzed by an order parameter of the instantaneous phase. The standard methods, such as Fourier transformation and coherence, were also performed and compared with the wavelet method. The method was further validated with clinical EEG and ERP samples available as pilot studies at academic sleep centers. RESULT: The time-frequency plot and phase synchrony level obtained by the wavelet method clearly showed dynamic changes in the EEG waveforms artificially fabricated. When applied to clinical samples, the method successfully detected changes in spectral power across the sleep onset period and identified differences between the target and background ERP. CONCLUSION: Our results suggest that the wavelet method could be an alternative and/or complementary tool to the conventional Fourier method in quantifying and identifying EEG and ERP biomarkers robustly, especially when the signals were nonstationary in a short time scale (1-100 seconds).

Time-frequency analysis based on matching pursuit and its application in epilepsy EEG / 国际生物医学工程杂志

ObjectiveMatching pursuit algorithm(MAP),for its good parametric characterization,was applied in epileptic electroencephalography(EEG) to study time-frequency distribution.MethodsSimulation experiment of time-frequency analysis was carried out to verify the matching pursuit algorithm s superiority on frequency resolution and parametric characterization.Fourier transform,Wigner-Ville distribution and matching pursuit algorithm were applied to the time-frequency analysis on normal EEG and epileptic EEG to study epileptic discharge in the time-frequency plane and the results were compared.ResultsSimulation results showed that the matching pursuit algorithm obtained a better time-frequency distribution.Distributions of epileptic EEG and normal EEG had significant difference in time-frequency plane.ConclusionTime-frequency analysis based on matching pursuit can better reveal the EEG characteristics.

Time-frequency analysis of ECG signals / 医疗卫生装备

In this paper,a time-frequency approach is used for the recognition and analysis of ECG signals for a normal or an abnormal patient.An iterative deconvolution procedure is applied to calculate the time-frequency representations.This method can enhance the resolutions of the signals.

Sistema hardware de diagnostico de fibrilación ventricular en tiempo real mediante métodos de analisis tiempo-frecuencia / System hardware diagnostic of ventricular fibrillation in real time using methods of time-frequency analysis

Nowadays our society has to face different diseases related to cardiac pathologies which become more and more common. This is due to the daily life habits increasing the risk of suffering cardiac problems such as heart attack which could lead to death...

Algorithms to calculate the AQD distribution with exponential Kernel for ultrasonic doppler blood flow measurement

One of the main goals in ultrasonic Doppler blood flow assessment in the estimation of the mean speed. The aim of this work is focused in Carotid artery blood flow signals...

The Heart Sound Data Analysis, Management System using the Wireless Stethoscope / 대한의료정보학회지

This paper is about the system using a wireless stethoscope to analysis the FFT and the time-frequency for a heart sound and to manage the collected data for a web-based system. We reformed a wireless stethoscope, connected to PC interface and added the analysis function. In result, we combined merits of an existed wireless system to be convenient for measuring the heart sound and to be available for many listener to ausculate the heart sound simultaneously, and an existed wired system to supply the various analysis functions. The heart sounds data was made into the database to search or refer to the patient data. It is possible to search and refer by the web-browser to the recorded heart sound file, the analyzed file by FFT and the STFT time-frequency method.

The Effect of Brimonidine Premedication on the Sympathetic Nervous System during Ketamine Anesthesia in the Ratv / 대한마취과학회지

BACKGROUND: The use of ketamine as the sole anesthetic induces marked central sympathetic stimulation, causing an increase of heart rate and blood pressure. alpha2-receptor agonist has been demonstrated to attenuate many of these undesirable effects when used as a premedicant. Brimonidine is a new and highly selective alpha2-receptor agonist, and rauwolscine is a selective alpha2-receptor antagonist with little affinity for imidazoline receptors. Using power spectral analysis of heart rate variability, this study examines the effect of brimonidine premedication during ketamine anesthesia on the changes in the autonomic nervous system. METHODS: From 57 Sprague-Dawley rats, 12 rats were anesthetized by urethane (U Group, 1.5 g/kg), 18 rats by ketamine (K Group, 100 mg/kg, 2 mg/kg/min continuous infusion) intraperitoneal injection after saline premedication. Brimonidine (BK Group, 30 microgram/kg, n=15), brimonidine with rauwolscine (BRK Group, 30 microgram/kg, 20 mg/kg, n=12) were adminstered as a premedicant before induction of ketamine anesthesia. ECG signals were recorded for 5 min after a period of 10 min of anesthetic stabilization. Power spectal analysis of the data was computed, using short-time Fourier transform. The spectral peaks within each measurement were calculated; a low frequency area (0.04~1.0 Hz), a high frequency area (1.0~5.0 Hz), and a total frequency area (0.04~5.0 Hz) were measured. RESULTS: The results documented that the K Group showed sympathetic activation as compared with the U Group (p<0.001). The BK Group showed sympathetic depression compared with the K and BRK Groups (p<0.001). There were no significant differences in sympatho-vagal balance between the K and BRK Groups. CONCLUSIONS: These results suggest that premedication with brimonidine is effective in attenuating the sympathetic stimulatory effect of ketamine.

Study of Detection Method on QRS Complexes Based on Wavelet Transform / 医疗卫生装备

Objective To present a method based on wavelet transform for detecting the QRS complexes of electrocardio-gram(ECG) without preprocessing.Methods By comparing three different kinds of wavelets,the first derivative of Gaussian function wavelet whose coefficient of wavelet is more sensitive adopted for MIT-BIH Arrhythmia Database which is widely and internationally accepted in the end.The catastrophe points of QRS complexes are detected by time-frequency analyz-ing.Results The method is proved to be precise and effective by applied to detect the QRS complexes of the ECG record provided by MIT-BIH.Conclusion The method is satisfied real time of ECG monitoring system and has preferable potential application.