Assessing the mechanism of response in the retrosplenial cortex of good and poor navigators

The retrosplenial cortex (RSC) is consistently engaged by a range of tasks that examine episodic memory, imagining the future, spatial navigation, and scene processing. Despite this, an account of its exact contribution to these cognitive functions remains elusive. Here, using functional MRI (fMRI) and multi-voxel pattern analysis (MVPA) we found that the RSC coded for the specific number of permanent outdoor items that were in view, that is, items which are fixed and never change their location. Moreover, this effect was selective, and was not apparent for other item features such as size and visual salience. This detailed detection of the number of permanent items in view was echoed in the parahippocampal cortex (PHC), although the two brain structures diverged when participants were divided into good and poor navigators. There was no difference in the responsivity of the PHC between the two groups, while significantly better decoding of the number of permanent items in view was possible from patterns of activity in the RSC of good compared to poor navigators. Within good navigators, the RSC also facilitated significantly better prediction of item permanence than the PHC. Overall, these findings suggest that the RSC in particular is concerned with coding the presence of every permanent item that is in view. This mechanism may represent a key building block for spatial and scene representations that are central to episodic memories and imagining the future, and could also be a prerequisite for successful navigation.     

Comparison of two-dimensional manual and three-dimensional SurgiCase and BLUEPRINT planning software measurements of glenoid version,inclination, and humeral subluxation

IntroductionVirtual planning for shoulder arthroplasty using preoperative computed tomography (CT) has been gaining popularity, and it is imperative for surgeons to recognize any differences in measurements that may exist amongst software platforms. The purpose of this study is to compare measurements of glenoid version, inclination, and humeral head subluxation between a manual approach and two varying automated software platforms using either a best-fit sphere technique (Wright-Medical BLUEPRINT) or an anatomic landmarks technique (Materalise SurgiCase).MethodsA case control study of 289 CT images from patients preoperatively planned for a total shoulder arthroplasty or reverse shoulder arthroplasty using SurgiCase (v3.0.110.5) were also successfully analyzed by BLUEPRINT (v2.1.6). Glenoid version, inclination, and subluxation were measured manually in a blind fashion by two separate investigators using axial and coronal images oriented to the scapular plane; interobserver and intraobserver reliabilities were measured using intraclass correlation coefficients (ICCs). Concordance correlation coefficients (CCCs), mean differences, and clinically relevant agreement in measurements between the software platforms and with the manual technique were compared. The impact of greater glenoid retroversion on the differences in measurements between the software platforms was further studied by correlation analysis.ResultsThe mean differences between SurgiCase and BLUEPRINT were + 0.5° for glenoid inclination (P = .064; CCC = 0.84), -0.9° for glenoid version (P < .001; CCC = 0.92), and -1.4% for humeral subluxation (P = .002; CCC = 0.88). Agreement within 5 units was 78.9% for inclination, 89.3% for version, and 64.1% for subluxation. Glenoid retroversion had no relation with the degree of variation in measured inclination (P = .59) or version (P = .56). There were significant differences between manual and 3D software measurements for glenoid inclination, version, and subluxation (P < .001). Both software measurements were more inferiorly inclined (average difference, SurgiCase -3.2° and BLUEPRINT -3.9°), more retroverted (average difference, SurgiCase -4.0° and BLUEPRINT -3.2°), and more posteriorly subluxated (average difference, SurgiCase + 3.4% and BLUEPRINT + 4.8%).ConclusionThe SurgiCase and BLUEPRINT preoperative planning software yield clinically similar measurements for glenoid version, inclination, and subluxation. The degree of glenoid retroversion does not impact the variability of inclination or version between the landmark and best-fit sphere software techniques. Compared to the 2D manual technique, both 3D software programs reported greater inferior inclination, retroversion, and posterior subluxation.Level of evidenceLevel III; Retrospective Diagnostic Study     

Impact of landmark reliability on the planar Procrustes analysis of tooth shape

In a recent study, the ideas of Procrustes analysis were introduced to the study of tooth shape for teeth represented as configurations of 'landmarks' from digital images. This study aimed to establish how well the method could be expected to perform (in its standard form) when used on surfaces from a variety of tooth types and, in particular, how much impact inconsistencies in the positioning of landmarks would have on investigations of shape.Using four different operators' images and landmarks from 10 different surfaces from each of 20 patients, the consequences of location inconsistency are evaluated by calculating its effect on the recorded variation in Procrustes fits, obtained for each set of multiple representations. The proportion of variation in shape attributable to actual differences between patients, rather than other sources of error, ranged from only 36 to 65% for the five buccal-surfaces considered and was no more than 30% for any of the five occlusal surfaces. Further examination of these results indicated that consistent orientation differences before imaging might be a particular source of error in obtaining any occlusal-landmark data, as might location ambiguities around the edges of the teeth. Orientation effects were also suggested for the buccal-surfaces of the molar teeth. In contrast, the relatively flatter buccal-surfaces of the incisors and canines produced the most reliable data.Methods of analysis need to accommodate these problems if landmark data are to be used to describe variations in tooth shape. Different surfaces each present their own particular difficulties and so a variety of solutions may be required.     

Geometry of the humeroulnar joint

Clinical results with elbow prostheses have been disappointing. A detailed knowledge of elbow joint geometry and mechanics is necessary to improve prosthetic design. In this study, the humeroulnar articulation of four human cadaver elbows was examined using surface analytic methods. In this article, the location of the transverse axis of elbow flexion-extension is suggested in relation to well-defined landmarks, the medial and lateral epicondyles, and subsequently to the line connecting their most lateral points--the transepicondylar line. The geometry of the structures responsible for the carrying angle is discussed, as is the extent of cartilage-covered bearing areas of the lower humerus and upper ulna. Implications pertaining to prosthetic design and surgical technique resulting from this study are discussed.     

Acute myocardial infarction — Historical notes

For the time being, acute myocardial infarction represents a history of success concerning diagnose, management and treatment, whereas it was considered a fatal disease in the beginning of the 1900s. The present paper is aimed at reviewing the landmarks of acute myocardial infarction, as key historical concepts are an important tool for understanding disease management, the daily dilemmas and future perspectives.     

基于盆腔自主神经为解剖标志的腹腔镜下直肠癌系膜 全切除术

目的:探讨以盆腔自主神经为解剖标志寻找安全的手术操作平面,进行腹腔镜下直肠癌的直肠系膜全切除(TME)的临床效果。方法:回顾性分析2010年1月—2015年12月腹腔镜低位直肠癌切除术157例男性患者的临床资料及手术视频,将2012年后的81例患者作为观察组,该组患者术中以盆腔自主神经为解剖标志行TME,从中间入路进行解剖游离,采用双吻合器技术进行消化道重建,将2012年前未按以上解剖标志手术的76例作为对照组,比较两组手术相关指标以及对患者术后泌尿和性功能情况。结果:与对照组比较,观察组术中出血量明显减少(14.9 mL vs.26.5 mL)、手术质量3级率明显增加(89.2%vs.59.6%),淋巴结清扫数目明显增加(19枚vs.15枚),术后勃起功能障碍率明显降低(2.3%vs.4.5%,P0.05),尿潴留率明显降低(6.2%vs.10.5%)差异均有统计学意义(均P0.05)。结论:TME中以盆腔自主神经为解剖标志可以最大程度完整切除直肠系膜的同时减少对盆腔内脏神经的损伤,而且对低位直肠癌TME手术的标准化和熟练掌握有帮助。     

腹腔镜胰十二指肠切除术相关肠系膜上血管应用解剖学研究

目的:探讨肠系膜上血管的解剖特点,为钩突入路腹腔镜胰十二指肠切除术的实施提出可供参考的解剖学标志。方法:对4具成人尸体标本作解剖学观察,并分析96例上腹部64排螺旋CT血管成像资料与13例钩突入路腹腔镜胰十二指肠切除术的视频资料。结果:门静脉-肠系膜上静脉可分为3个部分,包括胰腺上段,左侧可有胃冠状静脉汇入(22.1%);胰腺段,有较多的属支汇入,主要有胃结肠干、胰十二指肠上后静脉、胰十二指肠下静脉等,并可有肠系膜下静脉汇入该段左侧(7.5%);十二指肠水平段,未见血管分支,且左侧与肠系膜上动脉紧密相邻。肠系膜上动脉在胰头十二指肠区域内走行于肠系膜上静脉的左后侧,胰十二指肠下动脉为其主要分支,另见有与第一空肠动脉共干起源者(33.0%)。肠系膜上动脉起源的替代肝右动脉2例(1.8%)。结论:充分认识肠系膜上血管及其相关血管的分布及走行对腹腔镜胰十二指肠切除术有重要的临床意义,肠系膜上静脉的十二指肠段可作为钩突入路的重要解剖标志。     

X线颅颌面影像自动识别定点研究

目的 研究计算机对X线颅颌面影像的自动识别定点。方法 ①X线颅颌面影像的自动识别:X线颅颌侧位定位片经扫描仪将图像输入计算机,图像处理后重建该图象。②X线颅颌面影像的自动定点:以FH平面为基准进行分区,运用三次样条插值法使曲线光滑,使用轮廓跟踪技术进行标志点的寻找,使用拟合逼近进行拟圆,进行二值化确定两曲线的交点。结果提取出了颅颌面软组织外轮廓、硬组织外轮廓及部分内部结构,提取出了颅颌面31个标志点。结论进行了计算机对X线颅颌面影像轮廓和特征点的识别研究,为全自动识别分析奠定了基础。     

不同标记点对肺癌图像引导放疗图像配准结果的影响

目的 分析不同标记点对千伏锥形束CT(KVCBCT)图像与计划设计参考图像配准的影响,为选择适合于肺癌图像引导放疗的标记点提供依据.方法 共20例(男18例,女2例)行立体定向放疗的非小细胞肺癌患者进入研究.每位患者每次治疗均行KVCBCT在线引导放疗技术分析.选择每例患者每次治疗时获得的第1幅KVCBCT图像用于研究,20例患者100幅KVCBCT图像进入分析.将胸椎、隆突和肿瘤作为标记点,采用自动加手动法配准KVCBCT图像与参考图像.分别对同一幅KVCBCT图像与参考图像进行配准,比较3个不同标记点图像配准结果差异.结果 胸椎,隆突和肿瘤标记点患者左右、头脚、前后方向上的摆位误差分别为(-0.08±0.32)、(-0.16±0.45)、(0.06±0.23)cm,(0.06±0.34)、(-0.13±0.45)、(-0.02±0.23)cm和(-0.17±0.25)、(0.03±0.47)、(0.15±0.38)cm,比较结果显示肿瘤与胸椎标记点配准结果均相似(q=1.85,P=0.195;q=2.54,P=0.075;q=1.89,P=0.185),隆突与胸椎标记点配准结果相似(q=2.76,P=0.054;q=0.31,P=0.826;q=1.55,P=0.276),隆突与肿瘤标记点配准结果大部不同(q=4.61,P=0.002;q=2.23,P=0.118;q=3.44,P=0.017).结论 对行立体定向放疗的非小细胞肺癌患者,选择肿瘤和胸椎进行图像配准无差别;由于受呼吸运动影响明显,不推荐选择隆突作为肺癌图像引导放疗图像配准的标记点.     

Presynaptic inhibition compared with homosynaptic depression as an explanation for soleus H-reflex depression in humans

 Head direction (HD) and place cells were recorded in rats that had previously exhibited significant acquisition deficits on a radial arm maze task following disorientation treatment. In this study we determined whether this behavioral impairment was associated with a lack of landmark stimulus control over the preferred orientations of HD and place cells. Neurons were recorded as animals retrieved food pellets in a cylindrical apparatus containing a single cue card. Some of these HD cells were also recorded while animals explored an eight-arm radial maze in a similar cue-controlled environment. The stimulus control of the landmarks in each environment was assessed by rotating the landmark and examining the subsequent preferred orientations of HD and place cells. Animals underwent disorientation treatment before and after each recording session. Despite this disorientation, rotation of the cue card in the cylindrical apparatus resulted in a corresponding shift in the preferred orientations of HD and place cells in 13 of 15 and 7 of 7 recording sessions, respectively. On the radial arm maze, rotation of the landmark cue was associated with a corresponding shift in the HD cell’s preferred orientation in 7 of 9 sessions. These results suggest that a visual landmark’s stimulus control may not require a learned association between that landmark and an animal’s stable experience in an environment. Furthermore, instability in the HD cell system is unlikely to account for the impaired performance of the disoriented animals in the radial arm maze. Rather, these impairments may be due to the animal’s inability to utilize stable representations of the environment provided by HD and place cells. Received: 18 November 1996 / Accepted: 24 January 1997