Neurology & clinical neurophysiology : NCN最新文献_第2页

Automatic localization of epileptic zones using magnetoencephalography. 脑磁图自动定位癫痫区。

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

J Xiang, S Holowka, H Qiao, B Sun, Z Xiao, Y Jiang, D Wilson, S Chuang

{"title":"Automatic localization of epileptic zones using magnetoencephalography.","authors":"J Xiang, S Holowka, H Qiao, B Sun, Z Xiao, Y Jiang, D Wilson, S Chuang","doi":"","DOIUrl":"","url":null,"abstract":"Conventional visual identification of epileptic spike is a challenging problem in the clinical application of magnetoencephalography (MEG). More importantly, the conventional method has problems of detecting other abnormalities such as high frequency oscillation in the human epileptic brain. The objective of this study was to develop a new approach using magnetic spectral analysis and spatial filtering. Twelve patients with seizure have been studied with a whole cortex MEG system. Fifteen epochs were recorded for each patient; each epoch was 120 seconds. Neuromagnetic spectrum was analyzed using a new method called accumulated spectrogram. Focal increases of spectral power were localized using synthetic aperture magnetometry (SAM). The MEG results were then compared with clinical findings. Focal increases of spectral power have been identified in all patients (12/12, 100%). The locations of the focal increases of spectral power were in agreement with dipole locations of spikes in 9 patients (9/12, 75%). A comparison between MEG results and clinical findings indicated that SAM revealed focal epileptic activities in two patients when dipole fitting failed. The results suggest that epileptic regions could be quantitatively identified and accurately localized using accumulated spectrogram and SAM. In comparison to visual identification of spike, the new approach is objective and sensitive, and provides the possibility of analyzing much wider frequency bands.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"98"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184981","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

Auditory evoked magnetic fields to speech stimuli in newborns--effect of sleep stages. 新生儿语音刺激的听觉诱发磁场——睡眠阶段的影响。

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

E Pihko, A Sambeth, P H T Leppänen, Y Okada, L Lauronen

{"title":"Auditory evoked magnetic fields to speech stimuli in newborns--effect of sleep stages.","authors":"E Pihko, A Sambeth, P H T Leppänen, Y Okada, L Lauronen","doi":"","DOIUrl":"","url":null,"abstract":"The aim of the study was to examine whether a newborn can detect changes in a speech stimulus consisting of a fricative followed by a vowel /su/. In addition, we studied possible effect of the two sleep stages (active and quiet sleep) on the evoked magnetic responses. In young children (6 years), the same stimulus evokes a prominent deflection, consisting of two peaks. The first one (P1m) is evoked by the beginning of the fricative consonant and has a latency of about 145 ms. The second peak (P2m) with a latency of 340 ms, is evoked by the switch to the vowel. In newborns (n = 10), the waveform resembled that of the older children but latencies of the corresponding peaks were longer, 190 and 435 ms, correspondingly. The results suggest that already the newborn brain detects the change inside the auditory speech stimulus, namely the fricative sound changing into a vowel. However, the immaturity of the brain is reflected in the prolonged latencies. In addition, the responses were higher in amplitude in quiet sleep than in active sleep (F (1.9) = 36.5; p < 0.0002). This is in line with the enhanced somatosensory magnetic fields to tactile stimulation in quiet compared to active sleep in newborns.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"6"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184984","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

Cleaning fetal MEG using a beamformer search for the optimal forward model. 使用波束形成器搜索胎儿MEG的最佳正演模型。

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

S E Robinson, J Vrba

{"title":"Cleaning fetal MEG using a beamformer search for the optimal forward model.","authors":"S E Robinson, J Vrba","doi":"","DOIUrl":"","url":null,"abstract":"We present a new method for improving the signal-to-noise ratio (SNR) of event-related fetal MEG signals based upon the SAM minimum-variance beamformer. SAM could separate the evoked response source activity from the remaining fMEG signal and interference if the evoked response source coordinates and forward model were know. However, this requires knowledge of both the coordinate of the evoked response source and its forward model. In late gestation, the vernix caseosa effectively insulates the fetus from the amniotic fluid. Hence, the forward model could be approximated by an equivalent current dipole in a homogeneously conducting sphere with its origin at the center of the fetal head. In the absence of accurate anatomical data, a beamformer could be used to evaluate all feasible source-origin combinations--selecting the combination giving the best SNR for the evoked response. Application of this approach to measured fMEG data reveals that the optimal model sphere location is described not by a single local sphere origin, but rather by all origins lying within an extended region. This result is explained by model predictions showing the same region of ambiguity [Vrba, 2004]. Although the model search does not localize the sources of the fetal evoked response, it does significantly improve SNR. This was demonstrated by analysis of fetal auditory evoked response data.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"73"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25185584","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

Magnetic resonance imaging of mean values and anisotropy of electrical conductivity in the human brain. 人脑电导率的平均值和各向异性的磁共振成像。

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

M Sekino, Y Inoue, S Ueno

{"title":"Magnetic resonance imaging of mean values and anisotropy of electrical conductivity in the human brain.","authors":"M Sekino, Y Inoue, S Ueno","doi":"","DOIUrl":"","url":null,"abstract":"The conductivity distribution in the human brain is difficult to obtain by conventional impedance tomography methods, in which currents are applied via surface electrodes. In this study, we obtained images of anisotropic conductivity in the human brain using diffusion magnetic resonance imaging (MRI). Diffusion-weighted images of the brain were acquired by a 1.5 T MRI system using an echo planar imaging sequence. Motion-probing gradients (MPGs) were applied with 25 arrayed b-factors up to 5000 s/mm2. The fast and slow diffusion components were estimated by fitting a biexponential attenuation function to the measured signals. The effective conductivities in each direction were calculated from the fast diffusion components. The mean conductivities of the cortex, the corpus callosum, and the internal capsule were 0.10 +/- 0.03 S/m, 0.12 +/- 0.02 S/m, and 0.08 +/- 0.01 S/m, respectively. Tissues with highly anisotropic cellular structures, such as the corpus callosum and the internal capsule, exhibited high anisotropy in conductivity. The anisotropy indices in the cortex, the corpus callosum, and the internal capsule were 0.07 +/- 0.03, 0.60 +/- 0.07, and 0.65 +/- 0.05, respectively.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"55"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25185827","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

Development of a portable pneumomagnetic measurement device. 便携式气磁测量装置的研制。

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

Y Zheng, M Kotani, Y Utsukawa, T Nakadate

{"title":"Development of a portable pneumomagnetic measurement device.","authors":"Y Zheng, M Kotani, Y Utsukawa, T Nakadate","doi":"","DOIUrl":"","url":null,"abstract":"For some time, we have been using a large device, in our laboratory, to measure the remanent field from magnetic contaminants in the human lung (magnetopneumography, or MPG). But this device is too large and cumbersome to transport to worksites to assess the magnetic contaminants in the lungs of workers. Further, it is inconvenient and expensive for workers of small or medium-sized companies to come to our campus to be magnetically examined. To solve this problem, we have developed a succession of portable devices which can easily be transported to worksites to perform MPG measurements. We here describe our most recent portable MPG device, and present a typical result of the MPG measurements. The lungs of many workers have so far been measured, and we find that the device can produce accurate measurements at the worksites, beyond our expectation. One reason, we find, is that the background magnetic noise at worksites usually is much less than that at our Kanda campus, located in the center of Tokyo, where the level of magnetic noise caused by subways is high. Therefore, some measurements, which are unable to be done at our campus,can be successfully completed at worksites by using this portable device. We note that the level of the magnetic noise during the recordings greatly depends on the exact location of the workplace measuring site.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"10"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184015","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

Regional resolving power of combined MEG/EEG. 脑磁图/脑电组合的区域分辨能力。

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

M E Pflieger, R E Greenblatt, J Kirkish

{"title":"Regional resolving power of combined MEG/EEG.","authors":"M E Pflieger, R E Greenblatt, J Kirkish","doi":"","DOIUrl":"","url":null,"abstract":"Different modeling frameworks (such as error analyses for dipole localization [Fuchs, 1998] [Huizenga, 2001]; crosstalk and point spread analyses for linear estimators [Liu, 2002]; etc.) have demonstrated improved three-dimensional (3D) resolution for combined MEG/EEG (or EMEG) source estimation. Complementary to these, an empirical analysis of 2D surface data suggested that MEG and EEG information content could be superadditive [Pflieger, 2000]. Taking a hybrid approach in the present study, we made simulations within a regional activity estimation (REGAE, [Pflieger, 2001]) framework, which quantifies the ability of EMEG to discriminate brain activity originating within a 3D region of interest (ROI) from simultaneous non-ROI activity. Two metrics were employed: Kullback-Leibler divergence (KLD) and area under the receiver operator characteristic curve (AUROC). High-density sensor configurations (248 magnetometers, 256 electrodes) were combined with a gray matter source space model (7931 dipole triples, maximum entropy activities), assuming magnetic 3-shell sphere and electric BEM head models. Superadditive KLD was observed frequently across 89 representative brain ROIs and 3 ROI sizes (5, 10, and 15 mm radii), especially for regions already fairly visible to each modality. We also report an observed functional relationship between AUROC and KLD.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"79"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25185580","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

Cortical thickness in a case of congenital unilateral perisylvian syndrome. 先天性单侧perisylvian综合征1例皮质厚度分析。

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

A Kotini, S Camposano, K Hara, D Salat, A Cole, S Stufflebeam, E Halgren

{"title":"Cortical thickness in a case of congenital unilateral perisylvian syndrome.","authors":"A Kotini, S Camposano, K Hara, D Salat, A Cole, S Stufflebeam, E Halgren","doi":"","DOIUrl":"","url":null,"abstract":"In congenital perisylvian syndrome, there is polymicrogyric cortex distributed in variable extensions around the sylvian fissure. Unilateral cases usually present with congenital hemiparesis, while bilateral cases have pseudobulbar paralysis of the oropharingoglossal region. Both unilateral and bilateral cases have a high rate of epilepsy. Polymicrogyric cortex is characterized by too many small convolutions. Often there are no intervening sulci, and almost no white matter can be seen under them. On MRI they appear to have increased thickness. Bilateral and symmetric polimycrogiria can be hard to recognize on standard MRIs. Accurate and automated methods for measuring the thickness of cerebral cortex are available. They have mainly been used to study a variety of disorders with diminished cortical thickness. We studied a case of right perisylvian polymicrogyria, who presented in adult life with epilepsy and had a normal neurological exam. Fischl and Dale's automated cortical thickness analysis rendered a very clear picture of increased cortical thickness with values up to 9 mm in the affected areas (normal cortical thickness varies between 1 and 4.5 mm). The thickest areas were seen over grossly abnormal gyri on the reconstructed cerebral cortex. On MEG he presented a prominent and monotonous 9 Hz activity that was located within the limits of a thick gyrus. There was a significant difference of thickness between homologous hemispheric areas. To our surprise some areas of the left hemisphere also appeared to have increased thickness, raising the question of a bilateral asymmetric case.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"4"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25185581","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

Behavioral detection of spatial stimuli is reflected in auditory cortical dynamics. 空间刺激的行为检测反映在听觉皮层动力学中。

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

H Tiitinen, K J Palomäki, V Mäkinen, P J C May, P Alku

引用次数: 0

Averaging algorithm based on data statistics in magnetocardiography. 基于磁心图数据统计的平均算法。

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

K Kim, Y H Lee, H Kwon, J M Kim, I S Kim, Y K Park

{"title":"Averaging algorithm based on data statistics in magnetocardiography.","authors":"K Kim, Y H Lee, H Kwon, J M Kim, I S Kim, Y K Park","doi":"","DOIUrl":"","url":null,"abstract":"An algorithm for automatic averaging of a magnetocardiogram (MCG) is described. Due to the relatively low signal-to-noise ratio in the MCG, the measured MCG data are often averaged to be analyzed. Generally, R-peaks are used as trigger points, which become anchors for superposition and we can obtain an averaged epoch eventually. However, we have to determine several parameters, such as the threshold magnitude for recognizing R-peak, the time-period of the epoch window, and which channel has dominant R-peaks. In order to determine these parameters automatically, we utilize the magnitude histogram of the root-mean-square waveform of all the channels. We can determine the threshold magnitudes for recognizing R-peaks and T-peaks, respectively, by using the characteristic distribution of the MCG signal histogram. Peak detection procedure using these thresholds records all the locations of the R-peaks and T-peaks, thus we get the average latencies of the R-T intervals and the R-R intervals. From these latencies, we estimate the full width of the epoch window. By adding a routine for processing double R-peaks, our algorithm could conduct the MCG averaging sequence fully automatically. The algorithm has been tested on recordings of 40 normal subjects and 15 patients suffering from myocardial ischemia, and we conclude that this algorithm reliably performs the averaging sequence. The MCG recordings are measured by our 62-channel planar gradiometer system in a magnetically shielded room.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"42"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25188026","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

The colon transit time in different phases of the menstrual cycle: assessed with biomagnetic technique. 结肠在月经周期不同阶段的过境时间:生物磁技术评估。

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

T Córdova-Fraga, R Huerta-Franco, G Gutiérrez-Juárez, M Sosa-Aquino, M Vargas-Luna

{"title":"The colon transit time in different phases of the menstrual cycle: assessed with biomagnetic technique.","authors":"T Córdova-Fraga, R Huerta-Franco, G Gutiérrez-Juárez, M Sosa-Aquino, M Vargas-Luna","doi":"","DOIUrl":"","url":null,"abstract":"Twenty measurements of the colon transit time (CTT) were performed by biomagnetic technique in five young women. Subjects were assessed during 12 hours a day for four phases of the menstrual cycle (MC): early follicular (EF), days 1-4 of the MC; late follicular (LF), days 9-14; early luteal (EL), days 15-18; and late luteal (LL), days 23-28 of the MC. Comparison intra and inter-subjects were made. The results of a t test for dependent samples, demonstrate that women with regular MC had higher CTT on LF (3.29 +/- 1.40 m/hr) than on LL phases of the MC (1.28 +/- 0.4 m/hr) t = 3.22, p = 0.04. Also we found differences from EL to LL phases of the MC (4.49 +/- 1.72 m/hr vs. 1.29 +/- 0.35 m/hr, t = 3.05, p = 0.05). However, in a patient with polycystic ovary syndrome (PCOS), we found a CTT of 3.1 m/hr on day 3; 2 m/hr on day 15; and 0.8 m/hr on day 30 of the MC. The time of the magnetic marker displacement was higher on days 3 of the MC, if we compared these values with those from women with regular MC (1.8 +/- 0.67 m/hr). We demonstrate that biomagnetic technique is a powerful method to assess changes in CTT presented in female subjects during the MC. Furthermore, the results found for the CTT in different phases of the MC of the females subjects, are in agreement with those reported by using other techniques.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"31"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184003","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