EEG versus MEG localization accuracy: Theory and experiment

Summary We first review the theoretical and computer modelling studies concerning localization accuracy of EEG and MEG, both separately and together; the source is here a dipole. The results show that, of the three causes of localization errors, noise and head modelling errors have about the same effect on EEG and MEG localization accuracies, while the results for measurement placement errors are inconclusive. Thus, these results to date show no significant superiority of MEG over EEG localization accuracy. Secondly, we review the experimental findings, where there are again localization accuracy studies of EEG and MEG both separately and together. The most significant EEG-only study was due to dipoles implanted in the heads of patients, and produced an average localization error of 20 mm. Various MEG-only studies gave an average error of 2–3 mm in saline spheres and 4–8 mm in saline-filled skulls. In the one study where EEG and MEG localization were directly compared in the same actual head, again using dipoles implanted in patients, the average EEG and MEG errors of localization were 10 and 8 mm respectively. The MEG error was later confirmed by a similar (but MEG-only) experiment in another study, using a more elaborate MEG system. In summary, both theory and experiment suggests that the MEG offers no significant advantage over the EEG in the task of localizing a dipole source. The main use of the MEG, therefore, should be based on the proven feature that the MEG signal from a radial source is highly suppressed, allowing it to complement the EEG in selecting between competing source configurations. A secondary useful feature is that it handles source modelling errors differently than does the EEG, allowing it to help clarify non-dipolar extended sources.This work was supported by grants RO1NS26433, RO1NS19558 and RO1NS22703 from the National Institutes of Health.     

Anatomy of the hyoid apparatus in odontoceli (toothed whales): Specializations of their skeleton and musculature compared with those of terrestrial mammals

Background: The hyoid apparatus of odontocetes (toothed whales) serves as a major attachment point for many of the muscles and ligaments subserving breathing, swallowing, and sound production. Methods: This study examines the hyoid apparatus in 48 specimens of ten odontocete genera (Phocoena, Lagenorhynchus, Stenella, Delphinus, Tursiops, Grampus, Globicephala, Mesoplodon, Physeter, and Kogia) collected post mortem from beach strandings. Results: The odontocete hyoid apparatus, as that of their closest terrestrial relatives, the artiodactyls, is divisible into a basal portion (bashyal, paired thyrohyals) and a suspensory portion (paired ceratohyals, epihyals, stylohyals, and tympanohyals) connecting the basal portion to the skull base. Unlike other terrestrial mammals, the basal portion lies inferior to the laryngeal aditus, is flattened dorso-ventrally, and is relatively large, thus providing a broad surface area for muscle attachments. The suspensory elements are not as flattened and are joined by synovial joints (except for epihyal-stylohyal fusion). Muscular specializations include enlargement of those which retract the hyoid apparatus (e.g., sternohyoid) or control the tongue (e.g., styloglossus, hyoglossus). These muscles may be particularly important in a specialized prey capture behavior called suction feeding. In addition, the hyoid apparatus has a tilted placement, which allows asymmetrical enlargement of the piriform sinuses. Asymmetry is also seen in the muscular attachment between the larynx and the hyoid apparatus. The most pronounced differences from the basic pattern are observed in two families: Physeteridae and Ziphiidae. Conclusions: The derived position and shape of the odontocete hyoid apparatus may have evolved to subserve several specialized upper respiratory/digestive tract functions, such as simultaneous feeding (suction and swallowing) and sound production. © 1994 Wiley-Liss, Inc.     

pH电极位置对反流性食管炎酸监测的影响

为探讨ｐＨ电极位置对反流性食管炎酸监测的影响,将６０例反流性食管炎随机分为对照（Ｃ）组和试验（Ｔ）组。 Ｃ组 ３０例用测压法将 ｐＨ电极置于下食管括约肌（ＬＥＳ）上缘 ５ ｃｍ处;Ｔ组 ３０例用 ｐＨ梯度法将电极放于胃食管连接处（ＧＥＪ）上方 ５ ｃｍ处。连续 ２４ ｈ ｐＨ监测。结果显示,Ｃ与Ｔ组前鼻孔至ＧＥＪ平均距离分别为（４６． ２±４．１） ｃｍ与（４６． ５±４． ５） ｃｍ,两者无明显差异（Ｐ＝０． ８）。两组前鼻孔至ＧＥＪ平均距离（４６． ３±４． ３） ｃｍ比 Ｃ组前鼻孔至ＬＥＳ上缘平均距离（４３． ３±３． １） ｃｍ低 ３． ０ ｃｍ（Ｐ＝０． ０００３）。食管酸监测的 ｐＨ＜４,总百分时间和总计分在Ｔ组（８．５和 ４５． ５）和Ｔ组中ＧＥＪ＞ＬＥＳ上缘＋３ ｃｍ和＜－３ｃｍ范围者（１０． ０和 ９９． ３）较Ｃ组（４． ８和 ２６． ３）均有明显增高, Ｐ均＜０． ０１）,而Ｔ组中ＧＥＪ≤ＬＥＳ上缘＋３ ｃｍ和≥－３ ｃｍ范围者（７． １和 ３９． ４）则无明显差异（ Ｐ均＞０． ０５）。研究结果表明,因 ＧＥＪ常比 ＬＥＳ上缘偏低,故以 ＧＥＪ安放电极（尤其是ＧＥＪ＞ＬＥＳ上缘 ＋ ３ｃｍ或＜－ ３ｃｍ范围者）对反流性食管炎行 ｐＨ监测时     

Comparison of the precision of two standardized co-ordinate systems for the quantitation of brain anatomy: preliminary results

We assessed reproducible definition of two standardized co-ordinate systems for intersubject analysis of brain images. The baselines in the two co-ordinate systems were a modification of the canthomeatal (inCM) line and the anterior-posterior commissural )AC-PC) line. Axial spin-echo MR images of four subjects at 1.5T were used. Operator error was computed from the replicate analyses of two operators. The mCM line was determined by the lens of the eye and the internal auditory canal, and the AC-PC line was determined by the intersection of the AC and PC with the interhemispheric fissure. Reproducibility of the mCM markers (SD=0.59 mm) did not differ significantly from that of the AC-PC line (SD=0.68 mm). The measurement error of the angle of the baseline (), however, was more than 7 times as large for the AC-PC line as for the mCM line. An additional error affecting the rostrocaudal rotation of the co-ordinate systems, attributable to the distance between the anatomic markers, was 2.1 and 3.6° (3 mm and 5 mm slice thickness) for the mCM co-ordinate system and 8.2 and 11.0° (3 mm and 5 mm slice thickness) for the AC-PC system. The AC-PC line based co-ordinate system is therefore, less reproducible than the mCM line based system. this could be improved if a combination of axial and sagittal images were used for the definition of the AC-PC line.     

A new model for non-invasive,reproducible fixation of a stereotaxic frame using an orthodontic resin plate

Summary The authors describe a new method for reproducible, non-invasive fixation of a stereotaxic localizing frame. A localizing system similar to that of Brown-Roberts-Wells for MR can be fixed at the base of the facial skeleton to the upper dental arch by an orthodontic resin plate. Results of trials with CT scan, advantages and disadvantages are discussed.The new fixture could be employed in open surgery and in fractionated radiotherapy.     

神阙穴贴药对原发性骨质疏松症超声穿透速度的影响

目的：观察神阙穴贴补血益精透皮贴剂，对原发性骨质疏松症超声穿透速度（SOS）的影响。方法：选择原发性骨质疏松症患者130例。分4组治疗。即补血益精透皮贴剂组（A组），西药对照组（B组），补血益精药丸组（C组），空白对照组（D组）。结果：补血益精透皮贴剂组能显著提高超声穿透速度。结论：补血益精透皮贴剂组与补血益精药丸组和西药对照组对原发性骨质疏松症的调整作用基本一致。为治疗原发性骨质疏松症提供了一种新的方法。     

成年男性额面颈部红外热像的定位定量研究

目的:探索人体红外辐射(IRR)的表达规律。方法:应用国产DW—9100医用红外热像仪,采集成年男性额、面、颈部IRI,IRIAS专用软件自动定位、定量,Excel 统计学处理。结果:成年男性额、面、颈部IRI有效色码表达可达11级,色码分布具有明显的定位规律;Ⅰ～Ⅺ级色码温区呈递减状态,同级色码平均温差为1.03℃,P<0.01; 逐级色码平均递减温差为1.05℃,P<0.01 ,均有显著差异。不同年龄的色码温差亦有显著差异。结论:人体额面颈部IRR具有明显的定位、定量规律。有助于进一步探索人体IRR表达的多元信息。     

Electron microscopic localization of nitric oxide I synthase in the organ of Corti of the guinea pig

Nitric oxide synthase (NOS) activity has been detected previously in the mammalian cochlea at a light microscopic level. Here we present results of electron microscopic analysis for post-embedding immunoreactivity of neural-type NOS I in the cochlea of the guinea pig. Strong enzyme immunoreactivity was identified in the cytoplasm of inner and outer hair cells. Gold-labeled NOS I antibodies were mainly located in electron-dense areas of the cytoplasm, whereas electron-lucent regions of the receptor cells were nearly free from any immunoreactivity. In both types of hair cells anti-NOS I antibodies were also visible in the cuticular plates, hair bundles and nuclei. Further ultrastructural analysis revealed that the submembranous cisternae of the outer hair cells were nearly free from any reaction product, demonstrating that the whole cytoplasm of this hair cell was not immunoreactive. Other NOS I immunoreactivity was identified in the cuticular plates of the inner and outer pillar cells and in the cytoskeletal elements located in the apical parts of Deiter cells, forming the lamina reticularis or in cytoskeletal-containing regions in basal Deiter cells. Anti-NOS antibodies were visible in the nuclei of various cell types. Our findings suggest that nitric oxide produced by NO I synthase in the organ of Corti may act as a modulator of hair cell physiology during the processes of signal transduction with frequence selectivity.     

Triggers of hair cell regeneration in the avian inner ear

We performed an in vitro study in order to determine possible triggers of hair cell regeneration in the chick basilar papilla following degeneration. We compared the response of sensory epithelium damaged by collagenase treatment with that damaged by acoustic trauma. The former exhibited no proliferative activity, but the latter did. The basilar papillae damaged by acoustic trauma could have proliferating activity in medium containing fetal bovine serum (FBS) or epidermal growth factor (EGF) but not in the medium without FBS or EGF. These findings indicate that regeneration of basilar papillae depends on the manner of cell death and that FBS or EGF is required for regeneration.     

用声轨迹标定大肠经体表线路研究的新进展

目前我们又进一步提高了检测技术，首次具备了准确标定经络体表线路的手段，对大肠经检测的结果，有四点新发现：①发现三间至阳溪段线路的双线并行线路，由三间分支到阳溪相合；②发现巨骨到天鼎段线路，是由巨骨分为前后二支。前支经缺盆到天鼎，后支由巨骨交会秉风、大椎，绕颈到天鼎与前支会合；③发现扶突到迎香段线路，是由扶突直上，到下颌角前约１．０ｃｍ上行，呈弧形弯曲到对侧，经对侧禾到对侧迎香；④发现肺经与大肠经的衔接是由列缺到阳溪与大肠经衔接。