Neurology & clinical neurophysiology : NCN最新文献_第6页

Investigation of color motion using MEG and binocular rivalry stimuli. 用MEG和双眼竞争刺激研究颜色运动。

Neurology & clinical neurophysiology : NCN Pub Date : 2004-11-30

T Shinozaki, T Takeda

{"title":"Investigation of color motion using MEG and binocular rivalry stimuli.","authors":"T Shinozaki, T Takeda","doi":"","DOIUrl":"","url":null,"abstract":"Previous psychophysical studies have reported a few hundred millisecond difference in the reaction time (RT) to luminance versus color motion in low speed condition. Electroencephalogram (EEG) studies have reported a small difference between initial responses to luminance and color motion, but a big difference comparable to that reported in psychophysical studies has not been observed. The present study aimed to investigate late responses in low speed condition in order to clarify the difference of RTs between luminance and color motion. In general, measurement of the late responses is difficult because the late responses are weaker than the initial responses. A previous EEG study of binocular rivalry has reported that binocular rivalry stimuli amplify late responses. Therefore, we used binocular rivalry stimuli to measure late responses. Visual evoked fields were recorded with a whole-head MEG system. A rivalry-related field (RRF) was obtained from the subtraction between the rivalry and a control condition. The RRF was measured between 400 to 550 ms after the stimulus onset for each motion. Results of source localizations of RRFs had similar positions for both the luminance and the color motion. No statistically significant difference between the latencies of the two RRFs was found.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"108"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25185833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Summary of some results on an EEG inverse problem. 一个脑电图反问题的一些结果综述。

Neurology & clinical neurophysiology : NCN Pub Date : 2004-11-30

A El Badia

引用次数: 0

ICA methods for MEG imaging. MEG成像的ICA方法。

Neurology & clinical neurophysiology : NCN Pub Date : 2004-11-30

J E Moran, C L Drake, N Tepley

引用次数: 0

Time-frequency and coherence analysis of fMEG signals. fMEG信号的时频和相干分析。

Neurology & clinical neurophysiology : NCN Pub Date : 2004-11-30

X Wu, Y Chan, H Preissl, H Eswaran, J Wilson, P Murphy, C L Lowery

引用次数: 0

Calibration of a vector-MEG helmet system. 矢量- meg头盔系统的标定。

Neurology & clinical neurophysiology : NCN Pub Date : 2004-11-30

A Pasquarelli, M De Melis, L Marzetti, H-P Müller, S N Erné

引用次数: 0

Low-cost 7-channel magnetocardiographic system for unshielded environment. 用于无屏蔽环境的低成本7通道心脏磁图系统。

Neurology & clinical neurophysiology : NCN Pub Date : 2004-11-30

M M Budnyk, I D Voytovych, Y D Minov, P G Sutkovyi, M A Primin, I V Nedayvoda, V V Vasyliev

{"title":"Low-cost 7-channel magnetocardiographic system for unshielded environment.","authors":"M M Budnyk, I D Voytovych, Y D Minov, P G Sutkovyi, M A Primin, I V Nedayvoda, V V Vasyliev","doi":"","DOIUrl":"","url":null,"abstract":"The purpose of this work was to develop a low-cost magnetocardiography (MCG) system for use at cardiology clinics, without any magnetic shielding. The device consists of seven channels: four signal and three reference channels. The signal channels are based on relaxation-oscillation SQUIDs. The reference channels are assembled into an orthogonal reference vector magnetometer (RVM). The 11-litre magnetotransparent helium cryostat allows operation for 5 days without refilling. With the 4-channel device, it is possible to perform measurements of magnetic maps in a standard 36-point grid so that only 9 spatial positions of the multichannel magnetometer are used; acquiring 30 s of data for each observation point takes about 10-15 minutes. Software was developed for the device adjustment, data acquisition, and data processing, including preliminary processing, MCG-mapping, and medical analysis. Digital filtering, adaptive noise compensation, and averaging are used to suppress magnetic noises. Cardiac sources were modelled with effective magnetic dipoles, and with estimated 2D current density distributions at a frontal plane.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"112"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25185829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Detection of coronary artery disease with MCG. MCG检测冠状动脉疾病。

Neurology & clinical neurophysiology : NCN Pub Date : 2004-11-30

B Hailer, P Van Leeuwen

{"title":"Detection of coronary artery disease with MCG.","authors":"B Hailer, P Van Leeuwen","doi":"","DOIUrl":"","url":null,"abstract":"The diagnosis of cardiac ischemia related to coronary artery disease (CAD) is a clinical challenge. Despite many methods clinically available, the predictive value of each is still limited. Magnetocardiography (MCG) offers new insights in the electrogenesis of the disease. In the last decade a number of studies using biomagnetometers have dealt with the identification of CAD patients using coronary angiography as a gold standard. As the availability of these systems is limited, studies have focused either on exercise-induced ischemia or on chronic ischemia and the infarct scar at rest. Different parameters have been developed based on signal morphology, time intervals, source parameters or magnetic field map analysis. Concerning signal morphology, main work concentrates on ST-depression, ST-T signal amplitude as well as QRS and ST-T integrals. Dealing with time intervals, most studies focus on the QT interval. The evaluation of of QT dispersion spatially in the MCG, reflecting regional heterogeneity of repolarization, improved the identification of CAD patients. Besides the calculation of the equivalent current dipole during de- and repolarization, parameters of the magnetic field orientation were used to identify CAD patients and localize exercise-induced ischemic regions. Heart rate adjusted alteration in the magnetic field orientation allowed the quantification of ischemia-induced changes in MCG. The estimation of current density (CDV) further enabled to separate healthy subjects from CAD patients at rest. In the course of interventional therapy CDV maps returned toward that of healthy subjects.Thus, there is justification for routine clinical use of the MCG in the diagnosis of CAD.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"82"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Whole-head SQUID system in a superconducting magnetic shield. 超导磁屏蔽中的全头SQUID系统。

Neurology & clinical neurophysiology : NCN Pub Date : 2004-11-30

H Ohta, T Matsui, Y Uchikawa

{"title":"Whole-head SQUID system in a superconducting magnetic shield.","authors":"H Ohta, T Matsui, Y Uchikawa","doi":"","DOIUrl":"","url":null,"abstract":"We have constructed a mobile whole-head SQUID system in a superconducting magnetic shield - a cylinder of high Tc superconductor BSCCO of 65 cm in diameter and 160 cm in length. We compared the noise spectra of several SQUID sensors of SNS Josephson junctions in the superconducting magnetic shield with those of the same SQUID sensors in a magnetically shielded room of Permalloy. The SQUID sensors in the superconducting magnetic shield are more than 100 times more sensitive than those in a magnetically shielded room of Permalloy below 1 Hz. We tested the whole-head SQUID system in the superconducting magnetic shield observing somatosensory signals evoked by stimulating the median nerve in the right wrist of patients by current pulses. We present data of 64 and 128 traces versus the common time axis for comparison. Most sensory responses of human brains phase out near 250 ms. However monotonic rhythms still remain even at longer latencies than 250 ms. The nodes of these rhythm are very narrow even at these longer latencies just indicating low noise characteristics of the SQUID system at low-frequencies. The current dipoles at the secondary somatosensory area SII are evoked at longer latencies than 250 ms contributing to a higher-level brain function. The SQUID system in a superconducting magnetic shield will also have advantages when it is used as a DC MEG to study very slow activities and function of the brain.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"58"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical calculation of eddy currents in transcranial magnetic stimulation for psychiatric treatment. 经颅磁刺激治疗精神疾病涡流的数值计算。

Neurology & clinical neurophysiology : NCN Pub Date : 2004-11-30

M Sekino, S Ueno

引用次数: 0

Assessment of fetal growth on the basis of signal strength in fetal magnetocardiography. 基于胎儿心磁图信号强度评估胎儿生长。

Neurology & clinical neurophysiology : NCN Pub Date : 2004-11-30

P Van Leeuwen, Y Beuvink, S Lange, A Klein, D Geue, D Grönemeyer

{"title":"Assessment of fetal growth on the basis of signal strength in fetal magnetocardiography.","authors":"P Van Leeuwen, Y Beuvink, S Lange, A Klein, D Geue, D Grönemeyer","doi":"","DOIUrl":"","url":null,"abstract":"Fetal magnetocardiography has shown that fetal P wave and QRS complex durations increase with gestational age, reflecting change in cardiac muscle mass. The latter should, in principle, be associated with an increase in signal strength. We examined two approaches for determining QRS signal strength in a healthy fetus on a weekly basis in the second and third trimester. Twenty-two fetal magnetocardiograms of the same fetus were obtained using a 61 channel Magnes 1300 biomagnetometer (20th-42nd week of gestation). In the signal averaged fetal beat produced at each week, signal strength was assessed on the basis of 1) peak-to-peak QRS signal amplitudes and 2) strength of an equivalent current dipole (ECD) computed at R peak. The results were assessed on the basis of correlation to week of gestation and by comparison to changes in QRS interval duration. All values increased with advancing gestation and regression analysis suggested a nonlinear dependency on age. ECD strength reflected gestational age slightly more reliably (r2=0.93) than signal amplitude values (mean, median, maximum: r2=089, 0.88, 0.85, respectively). ECD strength and mean signal amplitude also correlated well (r=0.97, p<0.0005) Values calculated from QRS complexes determined immediately before and after a clear change in fetal position (acquisition week 24) demonstrated a certain instability in both approaches. Nonetheless, the overall correlation of the amplitude to gestational age compared favorably with that of QRS complex duration. This indicates that not only magnetocardiographically determined fetal cardiac time intervals but also signal strength may be used to assess fetal growth.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"47"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0