Estimation of the cortical functional connectivity by directed transfer function during mental fatigue.

In this paper, the directed transfer function (DTF) method is used to characterize changes in the functional coupling of EEG rhythms in different brain cortical areas due to the mental fatigue caused by long-term cognitive tasks. There is a parietal-to-frontal functional coupling of the total (0.5-30 Hz) EEG frequency band in the right and middle brain cortical areas during the pre-task period, and an inversion of that direction, even a significant prevalence of the frontal-to-parietal direction, after the completion of the task. When mental fatigue levels increase, the parietal-to-frontal functional coupling of the alpha (8-12 Hz) frequency band is weakened, and the beta (13-30 Hz) frequency band changes from a balanced directionality of the functional cortical coupling to frontal-to-parietal functional coupling, whereas the frontal-to-center functional coupling of the total frequency band is enhanced in the right hemisphere, and the frontal-to-center functional coupling of the beta frequency band is heightened in the left hemisphere. Meanwhile, in the central cortical area, the middle-to-left functional coupling of the total, beta and alpha frequency bands increases significantly and the middle-to-right functional coupling of the total and beta frequency bands increases significantly after the task as compared to the pre-task period. These findings suggest that the functional coupling of the frontal, central and parietal brain cortical areas is strongly correlated with a change in mental fatigue levels in the wake-fatigue transition. The experimental results indicate that the DTF method can effectively explore the change of the direction and strength of the information flow underlying cortical-to-cortical functional coupling when mental fatigue is increased by long-term cognitive work. The DTF method may open a promising way to study mental fatigue.

Evaluation of urinary S100B protein level and lactate/creatinine ratio for early diagnosis and prognostic prediction of neonatal hypoxic-ischemic encephalopathy.

BACKGROUND: Early identification and prevention of hypoxic-ischemic encephalopathy (HIE) in newborns may reduce neonatal mortality and neurological dysfunction. OBJECTIVE: To analyze the diagnostic and prognostic values of urinary S100B level and lactate/creatinine ratio in newborns with HIE. METHODS: Seventy-eight full-term newborns with HIE and 25 normal newborns were enrolled. The Neonatal Behavioral Neurological Assessment (NBNA) and Developmental Screening Test were scored. The concentration of urinary S100B protein was determined using the S100B enzyme-linked immunosorbent assay and the levels of urinary lactate and creatinine were measured with the enzyme colorimetric method. RESULTS: Urinary S100B level on days 1-3 after birth and lactate/creatinine ratio on day 1 were significantly higher in newborns with HIE than those in the control group. Both indexes were positively correlated with the clinical grading of HIE. A cutoff value for the S100B level of 0.47 microg/l on day 3 after birth had a sensitivity of 90% and specificity of 92% for prediction of HIE. A lactate/creatinine ratio of more than 0.55 on day 1 showed the highest sensitivity (92%) and specificity (90%). A combination of both indexes improved the sensitivity and specificity to 99 and 97%, respectively. A negative correlation of both lactate/creatinine ratio on day 1 and S100B level on days 1-3 after birth with the NBNA score was identified on days 3, 7 and 14 after birth. The Developmental Screening Test score of 36 newborns with HIE within 6 months after birth showed that 65% of infants with moderate and high HIE had an abnormal developmental quotient. CONCLUSION: These data suggest that early measurement of both S100B level and lactate/creatinine ratio in the urine of newborns with HIE is a practical convenient and sensitive way to improve diagnosis on the third day of life and prognostic prediction of HIE.

Automatic removal of eye-movement and blink artifacts from EEG signals.

Frequent occurrence of electrooculography (EOG) artifacts leads to serious problems in interpreting and analyzing the electroencephalogram (EEG). In this paper, a robust method is presented to automatically eliminate eye-movement and eye-blink artifacts from EEG signals. Independent Component Analysis (ICA) is used to decompose EEG signals into independent components. Moreover, the features of topographies and power spectral densities of those components are extracted to identify eye-movement artifact components, and a support vector machine (SVM) classifier is adopted because it has higher performance than several other classifiers. The classification results show that feature-extraction methods are unsuitable for identifying eye-blink artifact components, and then a novel peak detection algorithm of independent component (PDAIC) is proposed to identify eye-blink artifact components. Finally, the artifact removal method proposed here is evaluated by the comparisons of EEG data before and after artifact removal. The results indicate that the method proposed could remove EOG artifacts effectively from EEG signals with little distortion of the underlying brain signals.

[Amplitude coupling analysis of EEG using nonlinear regressive coefficients during mental fatigue].

Computing the Nonlinear regressive (NLR) coefficients of electroencephalogram (EEG) rhythms at different brain cortical areas for the mental fatigue caused by long-term cognitive task, the variations of NLR coefficients of EEG rhythms under different mental fatigue level are sought out. The experimental results show that the NLR coefficients of EEG rhythms can effectively characterize the changes of amplitude coupling at different brain cortical areas under different mental fatigue level. The NLR coefficient provides a powerful tool for the EEG functional coupling analysis of mental fatigue.

Risk factors and laser therapy for retinopathy of prematurity in neonatal intensive care unit.

BACKGROUND: With the increasing survival rates of preterm infants, the incidence of retinopathy of prematurity (ROP) is also increasing. This study aimed to investigate the risk factors for ROP in Neonatal Intensive Care Unit, and the effects of laser therapy. METHODS: Thirty-five premature infants with various other diseases were studied. Data were collected including gender, gestational age, birth weight, maternal gravidity, Apgar score, antenatal and postnatal hypoxia, anemia, jaundice, infection, pregnancy complications, and head ultrasound manifestations. All patients were subjected to fundus examinations at a postmenstrual age of 34 weeks using an indirect ophthalmoscope. The infants were divided into ROP group and non-ROP group. Infants with ROP received laser treatment. The data of the infants were analyzed using univariate analysis and the logistic regression model. RESULTS: Twenty-seven (77.1%) of the 35 infants had ROP and 21 of them also had plus diseases. The recovery rates were 74.1% and 92.6% at 2 weeks and 3 months after laser therapy, respectively. The birth weight and gestational age in the ROP group were significantly lower than those in the non-ROP group (P<0.01). The lower the gestational age and birth weight, the higher the incidence of ROP. There was a significant difference in the incidence of ROP with postnatal hypoxia (P=0.013), anemia (P=0.012) and gravidity two (P<0.05), analyzed with the Fisher's exact probability test (P<0.05). The gestational age was significantly lower in the plus disease group than in the non-plus disease group (P<0.05). CONCLUSIONS: The incidence of ROP is high in premature infants with various other diseases and is correlated with birth weight, gestational age, postnatal hypoxia, anemia and maternal gravidity. Laser therapy shows good outcomes.

Multi-channel linear descriptors for event-related EEG collected in brain computer interface.

By three multi-channel linear descriptors, i.e. spatial complexity (omega), field power (sigma) and frequency of field changes (phi), event-related EEG data within 8-30 Hz were investigated during imagination of left or right hand movement. Studies on the event-related EEG data indicate that a two-channel version of omega, sigma and phi could reflect the antagonistic ERD/ERS patterns over contralateral and ipsilateral areas and also characterize different phases of the changing brain states in the event-related paradigm. Based on the selective two-channel linear descriptors, the left and right hand motor imagery tasks are classified to obtain satisfactory results, which testify the validity of the three linear descriptors omega, sigma and phi for characterizing event-related EEG. The preliminary results show that omega, sigma together with phi have good separability for left and right hand motor imagery tasks, which could be considered for classification of two classes of EEG patterns in the application of brain computer interfaces.

[Progress of brain-neural function informatics].

Firstly the fundamental concept and research hotspots of Brain-Neural Function Informatics (BNFI) are described. Then the main study fields and progresses of BNFI are expounded. Finally the prospects of BNFI research are given. Studies on BNFI not only promote the "Brain Science" progress, but also boost the industry of a new kind of medical instruments - function rehabilitation equipment and artificial functional prostheses.

Effects and wavelet spectral entropy analysis of rhubarb extracts rhein on synaptic transmission in rat hippocampal ca1 area in vitro.

BACKGROUND: 5-dihydroxyanthraquinone-2-carboxylic acid (rhein) inhibits oxidoreduction induced by reducing nicotingamide adenine dinucleotide in the mitochondria and reducing reactive oxygen species, it also suppresses lipid peroxidation in rat brain homogenates. This study was to assess the effects of anthraquinone derivatives, rhein on synaptic transmission in the rat hippocampal CA1 pyramidal cell layer by intracellular recording. METHODS: The excitatory postsynaptic potential (EPSP) evoked by stimulation of the Schaffer collaterals in the presence of bicuculline (15 micromol/L) was depressed by application of rhein (0.3 - 30 micromol/L). The amplitude of the EPSP was restored within 20 minutes after removal of rhein from the supernatant. At a concentration of 30 micromol/L, rhein reduced the amplitude of the EPSP to 42% +/- 3.7% (n = 24) of the control. Subsequently, wavelet spectral entropy was used to analyze the EPSP. RESULTS: A strong positive correlation was observed between the wavelet spectral entropy and other parameters such as amplitude, slope of rising phase and slope of descending phase of the EPSP. The paired-pulse facilitation (PPF) of the EPSP was significantly increased by rhein (30 micromol/L). The inhibitory postsynaptic potential (IPSP) recorded in the presence of CNQX (20 micromol/L) and APV (40 micromol/L) is not altered by rhein (30 micromol/L). CONCLUSIONS: Rhein (30 micromol/L) can decrease the frequency but not the amplitude of the miniature EPSP (mEPSP). It is suggested that rhein inhibits excitatory synaptic transmission by decreasing the release of glutamate in rat hippocampal CA1 pyramidal neurons.

Discussion on "Towards a quantitative characterization of functional states of the brain: from the non-linear methodology to the global linear description" by J. Wackermann.

Wackermann (1999) [Wackermann, J., 1999. Towards a quantitative characterization of functional states of the brain: from the non-linear methodology to the global linear description. Int. J. Psychophysiol. 34, 65-80] proposed Sigma-phi-Omega system for describing the global brain macro-state, in which Omega complexity was used to quantify the degree of synchrony between spatially distributed EEG processes. In this paper the effect of signal power on Omega complexity is discussed, which was not considered in Wackermann's paper (1999). Then an improved method for eliminating the effect of signal power on Omega complexity is proposed. Finally a case study on the degree of synchrony between two-channel EEG signals over different brain regions during hand motor imagery is given. The results show that the improved Omega complexity measure would characterize the true degree of synchrony among the EEG signals by eliminating the influence of signal power.

Study on a non-contact life parameter detection system using millimeter wave.

OBJECTIVE: To study the basic principle and design method of a non-contact life detection system using 36 GHz millimeter wave. METHOD: Continuous wave radar techniques and signal processing techniques including zero intermediate frequency, frequency domain accumulation and adaptive noise cancellation were used in the system. RESULT: When the radiated power was about a milliwatt (mW) and detection range was up to 3 meters, the experimental results showed that this system can well detect the heartbeat and respiration signals from human subjects through common clothes and quilts. CONCLUSION: The system is feasible and effective due to its high detection sensitivity, small antenna, simple structure, easy miniaturization and safety to the human subject. It can be used for long-term continuous monitoring, especially suitable for the astronauts.

[The developments of medical monitoring techniques].

Based on analyzing the problems of the existing medical monitoring systems and the clinical needs in medicine the main development aspects of modern medical monitoring techniques are discussed in the paper. Then the urgent needs of monitoring techniques are presented here.