Neurology & clinical neurophysiology : NCN最新文献_第10页

Effect of model complexity on EEG source localizations. 模型复杂度对脑电源定位的影响。

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

C Ramon, P H Schimpf, J Haueisen

引用次数: 0

Enhanced neural responses correlated with perceptual binding of color and motion. 增强的神经反应与颜色和运动的知觉结合有关。

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

K Amano, S Nishida, T Takeda

{"title":"Enhanced neural responses correlated with perceptual binding of color and motion.","authors":"K Amano, S Nishida, T Takeda","doi":"","DOIUrl":"","url":null,"abstract":"When both color and motion direction of visual stimuli are alternated in physical synchrony at a relatively higher frequency (approximately 2 Hz), the changes in motion direction are perceived to be delayed. On the other hand, color and motion direction changes are perceived to be in phase when the motion direction changes precede the color changes by about 100 ms [Moutoussis, 1997]. In the present study, we utilized this phenomenon to investigate the neural mechanisms underlying the binding of color and motion based on the temporal synchrony. Magnetoencephalogram (MEG) was recorded for ten human subjects under the following four conditions: color change (color), motion direction change (motion), and simultaneous color and motion direction changes (color+motion) in perceptual synchrony (physical asynchrony) or in perceptual asynchrony (physical synchrony). The wavelet analysis was applied on these MEGs to study the neural responses in time-frequency domain. The interactions of color and motion responses, defined by [color+motion]-([color]+[motion]), were calculated in time-frequency domain for both perceptually synchronous and asynchronous conditions. The results showed significantly larger interactions at gamma band (30-35 Hz) under the condition of perceptual synchrony than under the condition of perceptual asynchrony, suggesting that synchronized neural responses at gamma band are related to the synchrony-based binding of visual attributes. This result is consistent with previous studies reporting the correlation of gamma band responses with perceptual grouping [Castelo-Branco, 2000] [Tallon-Baudry, 1996].","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"48"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184683","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

Effects of filtering on computer-aided analysis for detection of chronic ischemic heart disease with unshielded rest magnetocardiographic mapping. 滤波对无屏蔽静息心磁图检测慢性缺血性心脏病计算机辅助分析的影响。

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

R Fenici, D Brisinda, A M Meloni

{"title":"Effects of filtering on computer-aided analysis for detection of chronic ischemic heart disease with unshielded rest magnetocardiographic mapping.","authors":"R Fenici, D Brisinda, A M Meloni","doi":"","DOIUrl":"","url":null,"abstract":"Unlabelled: Recent studies have reported better sensitivity of magnetocardiographic (MCG) mapping, as compared to ECG, in detecting ventricular repolarization (VR) abnormalities due to myocardial ischemia in patients (pts) with Ischemic Heart Disease (IHD). For quick data reduction, automatic analysis of MCG mapping is mostly used. The aim of our study was to evaluate if filtering modality could alter automatic analysis of MCG.Method: 39 subjects were studied: 20 normals and 19 IHD pts, with angiography-documented >70% coronary stenosis, positive stress/SPECT and ischemic 12-lead ECG in 12/19 (63%). Rest MCG was recorded with a 36-channel system (at 1 kHz; bandwidth DC-100 Hz). To assess VR, Hänninen's STalpha angle and three magnetic field dynamics parameters, [i.e. +/- poles: angle (A), distance (D) and ratio (R)] during the T-wave interval, were computed from the same MCG maps: 1) after digital 20 Hz low-pass filtering (LPF) and 2) after digital 50 Hz adaptive filtering (AF). The baseline was unchanged. Three quantitative MCG scores of the T-wave (EXT, ML, Q) were automatically calculated (with 20 Hz LPF only).Results: Whereas the filtering modality didn't affect the predictivity of the STalpha angle, the predictive values of A, D, and R were different and partially contradicting. Automatic MCG scores had a predictive values ranging between 73% and 92%.Conclusions: The diagnostic power of unshielded MCG for detection of chronic IHD, with T-wave parameters (A, D and R) might be affected by LPF. The STalpha angle is not affected by LPF. Automatic EXT, ML and Q scores have better predictivity than ECG.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"7"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184684","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 sensory gating deficit and cortical thickness in schizophrenia. 精神分裂症的听觉门控缺陷与皮质厚度。

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

R J Thoma, F M Hanlon, N Sanchez, M P Weisend, M Huang, A Jones, G A Miller, J M Canive

{"title":"Auditory sensory gating deficit and cortical thickness in schizophrenia.","authors":"R J Thoma, F M Hanlon, N Sanchez, M P Weisend, M Huang, A Jones, G A Miller, J M Canive","doi":"","DOIUrl":"","url":null,"abstract":"Both an EEG P50 sensory gating deficit and abnormalities of the temporal lobe structure are considered characteristic of schizophrenia. The standard P50 sensory gating measure does not foster differential assessment of left- and right-hemisphere contributions, but its analogous MEG M50 component may be used to measure gating of distinct auditory source dipoles localizing to left- and right-hemisphere primary auditory cortex. The present study sought to determine how sensory gating ratio may relate to cortical thickness at the site of the auditory dipole localization. A standard auditory paired-click paradigm was used during MEG for patients (n=22) and normal controls (n=11). Sensory gating ratios were determined by measuring the strength of the 50 ms response to the second click divided by that of the first click (S2/S1). Cortical thickness was assessed by two reliable raters using 3D sMRI. Results showed that: (1) patients had a P50 and left M50 sensory gating deficit relative to controls; (2) cortex in both hemispheres was thicker in the control group; (3) in schizophrenia, poorer left-hemisphere M50 sensory gating correlated with thinner left-hemisphere auditory cortical thickness; and (4) poorer right-hemisphere M50 auditory sensory gating ratio correlated with thinner right-hemisphere auditory cortical thickness in patients. The MEG-assessed hemisphere-specific auditory sensory gating ratio may be driven by this structural abnormality in auditory cortex.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"62"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184983","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

Argos 500: operation of a helmet vector-MEG. Argos 500:头盔矢量meg的操作。

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

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

引用次数: 0

MEG latency difference measurement for priming experiments. 启动实验的脑磁图潜伏期差测量。

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

A Matani, T Hayakawa, S Munetsuna, N Fujimaki

{"title":"MEG latency difference measurement for priming experiments.","authors":"A Matani, T Hayakawa, S Munetsuna, N Fujimaki","doi":"","DOIUrl":"","url":null,"abstract":"Latency analysis of magnetoencephalography (MEG) for priming experiments, not in motor readiness level but in cognition level, may be useful for identification of the brain system. We performed a masked priming experiment for repetitive presentation of visual words. The subjects of the experiment were asked to perform a categorization task and button-pressing. The stimuli of the experiment consisted of mask (duration: 700 ms) - prime (70 ms) - target (1000 ms). There were four types of experiment which depended on the combinations of primes and targets: #1) in-category/in-category; #2) pseudo-characters/in-category; #3) out-category/out-category; and #4) pseudo-characters/out-category. As a result, the order of reaction times (RTs) were #1 < #2 < #3 approximately #4. We performed MEG recording with the above experiment simultaneously. Due to such a short stimulus onset asynchrony (SOA) of 70 ms and higher-order brain activity for language processing, the MEG activity continued for several hundred milliseconds, did not have conspicuous peaks, and could not be separated in the prime and target responses. This kind of MEG data is difficult to investigate with conventional signal processing methods, such as subtraction or signal source estimation. We applied a pattern analyzing method that measured the similarity time course between two sets of MEG data. The similarity time courses between experiments #3 and #4 and the other experiments were calculated. The order of the peak latencies of the time course was the same as that of RTs.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"54"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24895548","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

MCG measurement in the environment of active magnetic shield. 有源磁屏蔽环境下的MCG测量。

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

K Yamazaki, K Kato, K Kobayashi, A Igarashi, T Sato, A Haga, N Kasai

引用次数: 0

Cortical activity elicited by isolated vowels and diphthongs. 由孤立的元音和双元音引起的皮层活动。

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

A M Mäkelä, P Alku, P J C May, V Mäkinen, H Tiitinen

{"title":"Cortical activity elicited by isolated vowels and diphthongs.","authors":"A M Mäkelä, P Alku, P J C May, V Mäkinen, H Tiitinen","doi":"","DOIUrl":"","url":null,"abstract":"Cortical activity underlying speech perception has been studied mostly by using isolated vowels with constant formant frequencies. Speech, however, is characterized by formant transitions whereby formant frequencies change as a function of time. We used magnetoencephalography (MEG) to investigate cortical activity elicited by isolated vowels and diphthongs containing formant transitions. Ten subjects were presented with two isolated vowels /a/ and /u/ and diphthongs /au/ and /ua/. Stimulus duration was 200 ms, and the diphthongs started and ended with a 50-ms constant-formant period and included a 100-ms linear transition period. Apart from studying the auditory N100m response, we examined subsequent brain activity in a 500-ms poststimulus time window, as the transitions were expected to elicit activity also in later stages of cognitive processing. All the stimuli elicited prominent N100m responses. Thereafter, both the isolated vowels and diphthongs elicited sustained brain activity lasting up to 500 ms. The present observations indicate that identification of the speech sounds as well as changes in their identity are reflected in the auditory N100m. Notably, the stimuli appeared to elicit left-hemispheric activity resembling the N400, typically obtained by using more complicated speech stimuli such as words and sentences.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"91"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24901708","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

Discrimination of multiple sources using a SQUID vector magnetometer. 用SQUID矢量磁强计识别多信号源。

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

M Burghoff, A Schnabel, D Drung, F Thiel, S Knappe-Grüneberg, S Hartwig, O Kosch, L Trahms, H Koch

{"title":"Discrimination of multiple sources using a SQUID vector magnetometer.","authors":"M Burghoff, A Schnabel, D Drung, F Thiel, S Knappe-Grüneberg, S Hartwig, O Kosch, L Trahms, H Koch","doi":"","DOIUrl":"","url":null,"abstract":"For many biomagnetic applications the discrimination between simultaneously active sources is required. To evaluate the performance of a given SQUID system in this respect, the angle between the signal vectors of different sources is used. If the angle reaches large values, discrimination between the multiple sources is possible. We tested this approach with the first module of a new vector magnetometer system consisting of 19 identical modules. Two examples of measurements illustrate the differentiation of multiple sources, i.e. the fetal and the mother's heart signal, and alpha rhythm and heart signal in MEG recordings. This first module of a vector magnetometer system containing 16 SQUIDs is operated at PTB in the new Berlin Magnetically Shielded Room (BMSR 2) The spatial configuration of the 16 integrated SQUID magnetometers of the module is such that all three vector components of the magnetic field can be calculated in three measurement planes at 1.5 cm, 5 cm, and 10.5 cm above the Dewar bottom, respectively. The SQUID magnetometer channels have a typical white noise level of less than 2.3 fT/square root of Hz1/2 at 1 kHz.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"67"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184014","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 power changes between conditions using split-half resampling of synthetic aperture magnetometry data. 利用合成孔径磁强计数据的分半重采样来检测不同条件下的功率变化。

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

W Chau, A T Herdman, T W Picton

{"title":"Detection of power changes between conditions using split-half resampling of synthetic aperture magnetometry data.","authors":"W Chau, A T Herdman, T W Picton","doi":"","DOIUrl":"","url":null,"abstract":"Synthetic Aperture Magnetometry (SAM) measures changes in task-related power using pseudo-t values which are affected by changes in both signal and noise. Detecting significant signal power changes between two separate experimental conditions should not be done directly due to possible fluctuation in the noise as well as the response. This study proposes a method to estimate the noise within a single condition, which is then used to test the null hypothesis of no difference between the conditions. The noise estimation is based on a split-half resampling technique. For each resampling, the data of a given condition is divided into two halves. The difference of the pseudo-t volumes between the pair of the datasets is calculated. After multiple resamplings, the confidence limits of the differences within this single condition are computed for a given p-value so that one can test the null hypotheses that the second condition is within the same distribution as the first. The limits are calculated using a bootstrap technique to correct for any bias in the estimated threshold. Power changes between the two conditions are considered significantly different if the difference of the pseudo-t value is larger than expected within conditions. To demonstrate the effectiveness of the technique, the proposed method was applied to MEG responses to two distinct visual stimuli recorded from a single subject. Major differences of brain activity between the two conditions were found in the occipital region. These results were validated using four pairs of split-half datasets, generated from either the odd or even trials in each condition. The method of split-half resampling should therefore be useful for localizing significant differences in brain activity between conditions within individual subjects.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"24"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25184016","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