Hemodynamic Response Detection Using Integrated EEG-fNIRS-VPA for BCI

For BCI systems,it is important to have an accurate and less complex architecture to control a device with enhanced accuracy.In this paper,a novel methodology for more accurate detection of the hemodynamic response has been developed using a multimodal brain-computer interface(BCI).An integrated classifier has been developed for achieving better classification accuracy using two modalities.An integrated EEG-fNIRS-based vector-phase analysis(VPA)has been conducted.An open-source dataset collected at the TechnischeUniversit鋞Berlin,including simultaneous electroencephalography(EEG)and functional near-infrared spectroscopy(fNIRS)signals of 26 healthy participants during n-back tests,has been used for this research.Instrumental and physiological noise removal has been done using preprocessing techniques followed by individually detecting activity in both modalities.With resting state threshold circle,VPA has been used to detect a hemodynamic response in fNIRS signals,whereas phase plots for EEG signals have been constructed using Hilbert Transform to detect the activity in each trial.Multiple threshold circles are drawn in the vector plane,where each circle is drawn after task completion in each trial of EEG signal.Finally,both processes are integrated into one vector-phase plot to get combined detection of hemodynamic response for activity.Results of this study illustrate that the combined EEG-fNIRS VPA yields considerably higher average classification accuracy,that is 91.35%,as compared to other classifiers such as support vector machine(SVM),convolutional neural networks(CNN),deep neural networks(DNN)and VPA(with dual-threshold circles)with classification accuracies 82%,89%,87%and 86%respectively.Outcomes of this research demonstrate that improved classification performance can be feasibly achieved using multimodal VPA for EEG-fNIRS hybrid data.

Acupuncture enhances brain function in patients with mild cognitive impairment: evidence from a functional-near infrared spectroscopy study

Mild cognitive impairment(MCI)is a precursor to Alzheimer’s disease.It is imperative to develop a proper treatment for this neurological disease in the aging society.This observational study investigated the effects of acupuncture therapy on MCI patients.Eleven healthy individuals and eleven MCI patients were recruited for this study.Oxy-and deoxy-hemoglobin signals in the prefrontal cortex during working-memory tasks were monitored using functional near-infrared spectroscopy.Before acupuncture treatment,working-memory experiments were conducted for healthy control(HC)and MCI groups(MCI-0),followed by 24 sessions of acupuncture for the MCI group.The acupuncture sessions were initially carried out for 6 weeks(two sessions per week),after which experiments were performed again on the MCI group(MCI-1).This was followed by another set of acupuncture sessions that also lasted for 6 weeks,after which the experiments were repeated on the MCI group(MCI-2).Statistical analyses of the signals and classifications based on activation maps as well as temporal features were performed.The highest classification accuracies obtained using binary connectivity maps were 85.7%HC vs.MCI-0,69.5%HC vs.MCI-1,and 61.69%HC vs.MCI-2.The classification accuracies using the temporal features mean from 5 seconds to 28 seconds and maximum(i.e,max(5:28 seconds))values were 60.6%HC vs.MCI-0,56.9%HC vs.MCI-1,and 56.4%HC vs.MCI-2.The results reveal that there was a change in the temporal characteristics of the hemodynamic response of MCI patients due to acupuncture.This was reflected by a reduction in the classification accuracy after the therapy,indicating that the patients’brain responses improved and became comparable to those of healthy subjects.A similar trend was reflected in the classification using the image feature.These results indicate that acupuncture can be used for the treatment of MCI patients.

Hemodynamic monitoring and management of patients undergoing high-risk surgery:a survey among Chinese anesthesiologists

Hemodynamic monitoring and optimization improve postoperative outcome during high-risk surgery.However,hemodynamic management practices among Chinese anesthesiologists are largely unknown.This study sought to evaluate the current intraoperative hemodynamic management practices for high-risk surgery patients in China.From September 2010 to November 2011,we surveyed anesthesiologists working in the operating rooms of 265 hospitals representing 28 Chinese provinces.All questionnaires were distributed to department chairs of anesthesiology or practicing anesthesiologists.Once completed,the 29-item questionnaires were collected and analyzed.Two hundred and 10 questionnaires from 265 hospitals in China were collected.We found that 91.4%of anesthesiologists monitored invasive arterial pressure,82.9%monitored central venous pressure（CVP）,13.3%monitored cardiac output（CO）,10.5%monitored mixed venous saturation,and less than 2%monitored pulse pressure variation（PPV） or systolic pressure variation（SPV） during high-risk surgery.The majority（88%） of anesthesiologists relied on clinical experience as an indicator for volume expansion and more than 80%relied on blood pressure,CVP and urine output.Anesthesiologists in China do not own enough attention on hemodynamic parameters such as PPV,SPV and CO during fluid management in high-risk surgical patients.The lack of CO monitoring may be attributed largely to the limited access to technologies,the cost of the devices and the lack of education on how to use them.There is a need for improving access to these technologies as well as an opportunity to create guidelines and education for hemodynamic optimization in China.

A New General Linear Convolution Model for fMRI Data Process

General linear model (GLM) is the most popular method for functional magnetic resource imaging (fMRI) data analysis . However, its theory is imperfect. The key of this model is how to constitute the design-matrix to model the interesting effects better and separate noises better. For the purpose of detecting brain function activation , according to the principle of GLM,a new convolution model is presented by a new dynamic function convolving with design-matrix,which combining with t-test can be used to detect brain active signal. The fMRI imaging result of visual stimulus experiment indicates that brain activities mainly concentrate among v1and v2 areas of visual cortex, and also verified the validity of this technique.

Autonomic and cardiovascular effects of pentobarbital anesthesia during trigeminal stimulation in cats

Stimulation of the trigeminal nerve can elicit various cardiovascular and autonomic responses;however,the effects of anesthesia with pentobarbital sodium on these responses are unclear.Pentobarbital sodium was infused intravenously at a nominal rate and the lingual nerve was electrically stimulated at each infusion rate.Increases in systolic blood pressure（SBP） and heart rate（HR） were evoked by lingual nerve stimulation at an infusion rate between 5 and 7 mg？kg 21 ？h 21.This response was associated with an increase in the low-frequency band of SBP variability（SBP-LF）.As the infusion rate increased to 10 mg？kg 21 ？h 21 or more,decreases in SBP and HR were observed.This response was associated with the reduction of SBP-LF.In conclusion,lingual nerve stimulation has both sympathomimetic and sympathoinhibitory effects,depending on the depth of pentobarbital anesthesia.The reaction pattern seems to be closely related to the autonomic balance produced by pentobarbital anesthesia.

Effect of fiberoptic bronchoscope compared with direct laryngoscope on hemodynamic responses to orotracheal intubation

Fiberoptic bronchoscope （FOB） is an important instrument for respiratory, disorder examination and difficult airway can avoid management. The fiberoptic intubation the mechanical stimulus to oropharyngolaryngeal structures thereby it is likely to attenuate hemodynamic responses during orotracheal intubation. However, the relevant studies showed conflicting results. In this study, we observed the hemodynamic responses to orotracheal intubation using an FOB and a direct laryngoscope （DLS） in healthy adults under general anesthesia to examine the efficacy of the FOB in attenuating the hemodynamic responses to orotracheal intubation.

Spinal Cord Stimulation Frequency Influences the Hemodynamic Response in Patients with Disorders of Consciousness

Spinal cord stimulation （SCS） is a promising technique for treating disorders of consciousness （DOCs）. However, differences in the spatio-temporal responsiveness of the brain under varied SCS parameters remain unclear. In this pilot study, functional near-infrared spectroscopy was used to measure the hemodynamic responses of 10 DOC patients to different SCS frequencies （5 Hz, 10 Hz, 50 Hz, 70 Hz, and 100 Hz）. In the prefrontal cortex, a key area in consciousness circuits, we found significantly increased hemodynamic responses at 70 Hz and 100 Hz, and significantly different hemodynamic responses between 50 Hz and 70 Hz/100 Hz. In addition, the functional connectivity between prefrontal and occipital areas was significantly improved with SCS at 70 Hz. These results demonstrated that SCS modulates the hemodynamic responses and long-range connectivity in a frequency-specific manner （with 70 Hz apparently better）, perhaps by improving the cerebral blood volume and information transmission through the reticular formation-thalamus-cortex pathway.

Comparative study of hemodynamic responses to orotra- cheal intubation with intubating laryngeal mask airway and direct laryngoscope

Background Intubating laryngeal mask airway （ILMA） offers a new approach for orotracheal intubation and is expected to produce less cardiovascular stress responses. However, the available studies provide inconsistent results. The purpose of this study was to identify whether there is a clinically relevant difference in hemodynamic responses to orotracheal intubation by using ILMA and direct laryngoscope （DLS）. Methods A total of 53 adult patients, ASA physical status I-II, scheduled for elective plastic surgery under general anesthesia requiring the orotracheal intubation, were randomly allocated to either DLS or ILMA groups. After a standard intravenous anesthesia induction, orotracheal intubation was performed. Noninvasive blood pressure and heart rate were recorded before （baseline values） and after anesthesia induction （post-induction values）, at intubation and every minute for the first 5 minutes after intubation. The data were analyzed using Chisquare test, paired and unpaired Student＇s t test, and repeated-measures analysis of variance as appropriate. Results The mean intubation time in the ILMA group was longer than that in the DLS group （P〈0.05）. The blood pressure and heart rate increased significantly after intubation in the two groups compared to the postinduction values （P〈0.05）, but the maximum value of blood pressure during the observation did not exceed the baseline value, while the maximum value of heart rate was higher than the baseline （P〈0.05）. During the observation, there were no significant differences in blood pressure and heart rate among each time point and in the maximum values between the two groups. Conclusions Orotracheal intubations by using ILMA and DLS produce similar hemodynamic response. ILMA has no advantage in attenuating the hemodynamic responses to orotracheal intubation compared with DLS.

A review on functional near-infrared spectroscopy and application in stroke rehabilitation

Functional near-infrared spectroscopy(fNIRS)has gained great interest as a noninvasive modality to study the changes in cerebral hemodynamics related to brain activity.The unique and beneficial characteristics of fNIRS allow ecologically effective investigations of all ages and conditions in more realistic and clinical environments.In this review,we provide a comprehensive description of fNIRS basics,analytical method developments and applications in stroke rehabilitation.We first review various new methods for the time-series processing and functional analysis of fNIRS data.Then,we review the fNIRS-based application in clinical research for stroke rehabilitation and highlight the exciting developments based on fNIRS.Finally,we discuss the possible technical limitations of the implementation of fNIRS and provide suggestions from different aspects for practical application.