Neurology & clinical neurophysiology : NCN最新文献_第5页

Linearly constrained minimum variance source imaging using cortical bases. 使用皮质基底的线性约束最小方差源成像。

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

T Limpiti, B D Van Veen, R D Nowak, R T Wakai

引用次数: 0

Interaction of artificial metallic objects with biosusceptometric measurements. 人造金属物体与生物敏感度测量的相互作用。

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

R Engelhardt, E B Fung, P Kelly, T R Biehl, Z Pakbaz, P Nielsen, P Harmatz, R Fischer

{"title":"Interaction of artificial metallic objects with biosusceptometric measurements.","authors":"R Engelhardt, E B Fung, P Kelly, T R Biehl, Z Pakbaz, P Nielsen, P Harmatz, R Fischer","doi":"","DOIUrl":"","url":null,"abstract":"In human subjects, metallic objects cause distortions of the magnetic fields used by magnetic resonance imaging (0.5 - 3.0 T) or by SQUID biomagnetic liver susceptometry (0.1 - 30 mT) and may lead to artifacts in the measurement of the relaxation rate or the magnetic susceptibility. In biosusceptometry, the measured signal will depend not only on the magnetic susceptibility of the object, but also on its distance to the sensor assembly, and in case of ferromagnetic objects, on the direction of its remanent field. The magnetic susceptibility of a vascular access port-a-cath and of surgical clips have been measured by a SQUID biosusceptometer. Additionally, the impact from port-a-caths and dental braces on liver iron concentration (LIC) measurements was measured in vivo with respect to their radial distance from the gradiometer center axis. For the port-a-cath, a mean magnetic volume susceptibility of (83.5 +/- 0.3).10(-6) SI-units was found, which may be compared with the magnetic susceptibility of titanium at room temperature of (180 +/- 2).10(-6) SI demonstrating the absence of ferromagnetic contamination. At a radial distance of 5 cm from the gradiometer center axis, the voltage amplitude is similar to the signal generated by a normal liver. Modern surgical clips have nearly no impact on LIC measurements. However, dental braces although further away from the center axis, often superimpose the signal even from an iron overloaded liver. Depending on the Ni-content, these objects reveal ferromagnetic properties and contribute in first order with a one parameter reciprocal distance function to the measured liver iron signal.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"32"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25185834","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

MEG analysis of "theory of mind" in emotional vignettes comprehension. 情绪小品理解中“心理理论”的MEG分析。

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

R Ishii, C Gojmerac, D T Stuss, G G Gallup, M P Alexander, W Chau, C Pantev

{"title":"MEG analysis of \"theory of mind\" in emotional vignettes comprehension.","authors":"R Ishii, C Gojmerac, D T Stuss, G G Gallup, M P Alexander, W Chau, C Pantev","doi":"","DOIUrl":"","url":null,"abstract":"Objective: Several studies suggested that an impaired \"theory of mind\" might play a key role in psychiatric disorders, such as autism and schizophrenia. Medial frontal lobe lesions of the right frontal lobe were reported to impair this ability. The aim of our study was to locate areas of the brain associated with the process of \"theory of mind\" in normal subjects.Methods: In order to index the activity of brain areas related to \"theory of mind\" reasoning in sixteen normal adults, we administered an emotional (\"happy\", \"sad\", \"angry\" and \"neutral\") vignettes comprehension task during magnetoencephalography (MEG) recordings and analyzed these data by using SAM (synthetic aperture magnetometry), SPM99 and the permutation method. Subjects were presented with eight different videotaped social situations (each emotion has two vignettes) and were asked to indicate which emotion they represented.Results: Statistically significant activation in the comparison of \"happy\"-\"sad\" and \"angry\"-\"sad\" was observed in the bilateral medial prefrontal cortices in the alpha frequency band. There were no significant differences in comparisons of each type of emotional vignette to the neutral vignettes, \"happy\"-\"angry\" comparison, and male-female comparisons. There was no significant difference in other frequency bands.Conclusion: This result suggests that bilateral medial prefrontal cortex are involved in the comprehension of emotional states of others.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"28"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24895550","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

A new dynamical approach to auditory evoked magnetic field by blind identification. 听觉诱发磁场的动态盲识别新方法。

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

K Kishida, Y Ohi, M Tonoike, S Iwaki

引用次数: 0

MUSIC seeded multi-dipole MEG modeling using the Constrained Start Spatio-Temporal modeling procedure. MUSIC种子多偶极子MEG建模使用约束启动时空建模程序。

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

D M Ranken, J M Stephen, J S George

{"title":"MUSIC seeded multi-dipole MEG modeling using the Constrained Start Spatio-Temporal modeling procedure.","authors":"D M Ranken, J M Stephen, J S George","doi":"","DOIUrl":"","url":null,"abstract":"The Constrained Start Spatio-Temporal modeling program (CSST) is an objective multi-dipole, multi-start MEG/EEG analysis procedure that randomly selects from 100 to 100,000 initial dipole configurations, and runs a nonlinear simplex search on each of these configurations employing a reduced Chi-square statistic as the minimization criterion, to obtain a set of dipole configurations that best fit the data [Ranken, 2002]. A parallel version of CSST is implemented in IDL and MPI, making CSST usable on a single computer, or on a Linux cluster. We have now developed a multi-resolution version of MUSIC [Mosher, 1992] [Mosher, 1998] that provides an 80% or more reduction in the number of forward calculations needed to obtain results comparable to a 160,000 point MUSIC scan, on a 2 mm grid that defines a brain volume. The multi-resolution MUSIC scan provides an improved set of initial dipole estimates for the CSST analysis. In preliminary tests on real and simulated MEG data, with model orders ranging between 5 and 7 dipoles, the best performance improvements were obtained by mixing in 1 to 3 dipole locations randomly drawn from the best MUSIC locations, with randomly selected locations from the brain volume to complete the selected model order. We have also developed an improved method for sampling the brain volume for initial configurations. These improvements have led to a 75% reduction in the number of starting configurations required to obtain 5-10 best solutions with equal or lower reduced Chi-square values, when compared to the best solutions from the previous version of CSST.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"80"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24895642","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

MEG measurement of event-related brain activity evoked by emotional prosody recognition. 情绪韵律识别诱发的事件相关脑活动的MEG测量。

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

H Yagura, M Tonoike, M Yamaguchi, S Nakagawa, K Sutani, S Ogino

引用次数: 0

Neuromagnetic responses associated with perceptual segregation of pitch. 与音高知觉分离相关的神经磁反应。

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

B W Johnson, S D Muthukumaraswamy, M J Hautus, W C Gaetz, D O Cheyne

{"title":"Neuromagnetic responses associated with perceptual segregation of pitch.","authors":"B W Johnson, S D Muthukumaraswamy, M J Hautus, W C Gaetz, D O Cheyne","doi":"","DOIUrl":"","url":null,"abstract":"In recent EEG investigations [Johnson, 2003] [Hautus, 2005], we described a novel late negative ERP component associated with binaural processing of auditory pitch based solely on interaural timing differences (\"dichotic pitch\"), an acoustic phenomenon that is closely analogous to visual perception of stereoscopic depth based on retinal disparities. The present study extends this research with neuromagnetic recordings of auditory evoked fields (AEFs) elicited by dichotically-embedded pitches. Eight healthy adult subjects listened to control stimuli consisting of 500 ms segments of broadband acoustic noise presented identically to both ears via earphones, and dichotic pitch stimuli created by introducing a dichotic delay to a narrow frequency region of the same noise segments and resulting in a perception of a pitch lateralized to the left or right of auditory space. Auditory-evoked fields (AEFs) were recorded using a 151 channel whole-head MEG system. Comparison of control and dichotic-pitch AEFs showed reliable amplitude differences during a time window of 150-350 ms. AEFs over the left hemisphere showed larger effects for contralateral than ipsilateral pitches, while the right hemisphere showed no differences for differently lateralized sources. The results indicate a relatively late stage of neural processing of binaurally-derived cues for the perceptual segregation of concurrent sound sources and support a right-hemisphere dominance for the processing of sound-source localization.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"33"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24895641","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

Active magnetic compensation composed of shielding panels. 主动磁补偿由屏蔽板组成。

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

K Kato, K Yamazaki, T Sato, A Haga, T Okitsu, K Muramatsu, T Ueda, K Kobayashi, M Yoshizawa

引用次数: 0

Spatiotemporal analysis of neuromagnetic activation associated with mirror reading. 与镜像阅读相关的神经磁激活的时空分析。

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

J Xiang, S Holowka, S Chuang

{"title":"Spatiotemporal analysis of neuromagnetic activation associated with mirror reading.","authors":"J Xiang, S Holowka, S Chuang","doi":"","DOIUrl":"","url":null,"abstract":"Our previous report has confirmed that visually presented words can elicit neuromagnetic activities from the visual cortex, angular gyrus and Broca's area. It is not clear how the words are visuospatially transformed and recognized by the human brain. Mirror reading is characterized by reading which runs in the opposite direction to normal reading, with reversals of letters. It would be very interesting to find out if there are any neuromagnetic differences between the mirror reading and normal reading. Four right-handed healthy adults have been studied with a whole cortex Magnetoencephalography (MEG) system. The stimuli consisted of eight normal oriented words and eight inverted exclamation mark section \"reversed words\" (mirror-image of the words). All stimuli were randomly presented on the screen in front of the subjects using DirectX. MEG data were analyzed using both single dipole modeling and synthetic aperture magnetometry (SAM). Four responses to the reversed words were identified in all four subjects. In comparison to the normally oriented words, the reversed words elicited a stronger response at a latency of 248+/-6 ms. SAM results indicated that the reversed words invoked strong activations in the left and right parietal cortices but the normally oriented words did not. The mirror reading elicited one magnetic response which is different from that of the normal reading. The difference between the mirror reading and the normal reading in terms of neuromagnetic activation may reflect the development of novel representations for reversed words.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"90"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25185573","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

Bayesian classification of myocardial excitation abnormality using magnetocardiogram maps for mass screening. 心肌兴奋异常的贝叶斯分类应用心磁图进行大规模筛查。

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

Y Ono, A Ishiyama, N Kasai, S Yamada, K On, S Watanabe, I Yamaguchi, T Miyashita, K Tsukada

{"title":"Bayesian classification of myocardial excitation abnormality using magnetocardiogram maps for mass screening.","authors":"Y Ono, A Ishiyama, N Kasai, S Yamada, K On, S Watanabe, I Yamaguchi, T Miyashita, K Tsukada","doi":"","DOIUrl":"","url":null,"abstract":"We propose a novel classification method based on the Bayes rule to utilize the magnetocardiogram (MCG) in noninvasive mass screening. The cardiac excitation is directly tracked by maps of the MCG field generated by myocardial excitation current through the excited wave front. To adopt the characteristics of the excited wave fronts as a parameter for the Bayes theorem, we developed a parameterization procedure that consists of a two-dimensional wavelet approximation and a cluster analysis of magnetic field maps. With the parameter determined by this procedure, the probability of a subject to belong to a disease group or to the normal group is estimated by the Bayes theorem. The subject is classified into the group of the highest probability. We applied the proposed method to ST-T period of MCG data of 6 old myocardial infarction (OMI) patients and 15 normal controls. The method showed sensitivity of 83%; specificity, 100%; positive predictive value, 100%; and negative predictive value, 94% in the classification of OMI patients and normal controls. The processing time is less than 5 seconds per one subject. It suggests a possible application of the proposed method in mass screening of abnormal MCG patterns.","PeriodicalId":83814,"journal":{"name":"Neurology & clinical neurophysiology : NCN","volume":"2004 ","pages":"43"},"PeriodicalIF":0.0,"publicationDate":"2004-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25185589","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