Curvature-processing network in macaque visual cortex

Our visual environment abounds with curved features. Thus, the goal of understanding visual processing should include the processing of curved features. Using functional magnetic resonance imaging in behaving monkeys, we demonstrated a network of cortical areas selective for the processing of curved features. This network includes three distinct hierarchically organized regions within the ventral visual pathway: a posterior curvature-biased patch (PCP) located in the near-foveal representation of dorsal V4, a middle curvature-biased patch (MCP) located on the ventral lip of the posterior superior temporal sulcus (STS) in area TEO, and an anterior curvature-biased patch (ACP) located just below the STS in anterior area TE. Our results further indicate that the processing of curvature becomes increasingly complex from PCP to ACP. The proximity of the curvature-processing network to the well-known face-processing network suggests a possible functional link between them.Decades of research have focused on understanding visual feature processing, particularly along the ventral visual pathway. Such studies have shown that neurons in lower-order visual areas (e.g., V1) respond strongly to simple oriented contours (1), whereas neurons in higher-order visual areas (e.g., inferior temporal cortex) respond selectively to more complex image features and/or visual categories (2–4), in ways that are not yet fully understood. To link these extremes in visual information processing, many studies have aimed to clarify the optimal “trigger” features at intermediate levels of the visual cortical hierarchy.Among these features, stimulus curvature has not been well studied. This is surprising because, strictly, all lines are curved to some extent, except for the single exception of a perfectly straight line. This ubiquity of curved shapes also extends to 3D surfaces (5). In nature, where much of our visual system presumably evolved, perfectly flat surfaces are rare. Even the flattest of natural features (e.g., oceans, sandy beaches) are often curved to some extent, due to wind, water motion, and even the curvature of the earth. Thus, it is important to understand curvature processing to fully unravel the steps in cortical visual processing.Among the few studies to test single neuron responses to curvature per se, Gallant et al. (6, 7) reported that a significant percentage of neurons in macaque cortical area V4 is selective for curved stimuli. Intriguingly, these authors also noted that neurons preferring curved patterns were often anatomically clustered together. Subsequently, Pasupathy and Connor (8–10) demonstrated that neurons in the parafoveal representation of dorsal V4 respond robustly to the curvature component of complex shapes. To our knowledge, there have been no systematic studies of curvature at levels below V4 in macaques.Intriguingly, some evidence suggests that the processing of curvature may interact selectively with the processing of faces. For instance, perceptual deficits in face recognition (prosopagnosia) are sometimes associated with deficits in curvature discrimination (11). In addition, some neurons in face-selective regions of the temporal lobe also respond to rounded nonface objects (12, 13). A human functional magnetic resonance imaging (fMRI) study (14) reported that a concentrically curved grating produced a larger response in the fusiform face-selective area (FFA) (15, 16), compared with an otherwise identical linear grating.Here, we tested for a cortical specialization of curvature processing, using fMRI in fixating macaque monkeys. Given the previous single-unit studies (6–10), we expected that curved stimulus features would activate V4, either in specific patches or distributed throughout the area. The present fMRI approach also allowed us to test whether curvature processing is confined to V4, or whether it extends into additional brain regions. If specialized areas for curvature processing were identified, we could then ask whether they might be topographically linked with face-selective regions. Such an arrangement would shorten the mean axonal length between curvature- and face-processing regions, if these regions were functionally related.     

Methods for measurement of root canal curvature: a systematic and critical review

The assessment of root canal curvature is essential for clinical and research purposes. This systematic review presents an overview of the published techniques for the measurement of root canal curvature features using imaging and to provide a critique of their clinical application. A database search in PubMed, PubMed Central, Embase, Scopus, EBSCO Dentistry & Oral Sciences Source and Virtual Health Library was conducted, using appropriate key words to identify measurement methods for root canal curvatures. The search strategy retrieved 10594 records in total, and 31 records fulfilled the inclusion criteria. From 2D image acquisitions, eleven studies measured exclusively the angle of curvature, an additional thirteen measured other curvature features (level, height, radius, length and shape). Seven reports described methods from 3D imaging (CBCT, μCT). Root canal curvatures should be measured, for clinical proposes, to facilitate endodontic treatment planning, and in research, to reduce the risk of selection bias. This review has revealed that there are many methods described in the literature; however, no consensus exists on which method should be used. Some of the methodologies have potential clinical translation, whereas others are suitable for research purpose only, as they require a specific software or radiographic exposure in the mesiodistal direction.     

Peripheral blood lymphocyte subsets (CD4+, CD8+ T cells), leptin level and weight loss after laparoscopic greater curvature plication in morbidly obese patients

Introduction

The aim of the study was to detect the effect of laparoscopic greater curvature plication (LGCP) on peripheral blood lymphocyte subsets (helper and cytotoxic T lymphocytes – CD4+ and CD8+ T cells respectively), leptin level and weight loss in morbidly obese patients.

Material and methods

Morbidly obese patients (n = 20, age range: 25–50 years, body mass index (BMI) range: 37–45 kg/m²) who underwent LGCP were enrolled in a prospective study to determine the percentages of their peripheral blood T cells (CD4+ and CD8+) before and 4 months postoperatively using flow cytometry. Also, the level of their leptin before and 4 months postoperatively was established using enzyme-linked immunosorbent assay (ELISA). The data are expressed as the percentage of total lymphocytes ± the standard error of the mean.

Results

A decrease in the BMI and loss of weight (31.20 ±1.2%) were confirmed 4 months postoperatively since BMI was 44.71 ±4.3 (range: 37–45) kg/m² preoperatively, and decreased to 31.80 ±1.1 (range: 24–33) kg/m² after surgery. The mean percentage of CD4+ and CD8+ T lymphocytes significantly decreased postoperatively (38.2 ±1.5 before and 29.3 ±2.6 after operation for CD4+, 17.3 ±1.8 preoperatively and 9.5 ±1.7 postoperatively for CD8+, p < 0.05). The mean leptin level was 43.01 ±22.01 preoperatively while postoperatively it was 24.8 ±11.1 (p < 0.05), so the leptin level substantially decreased compared to its preoperative values.

Conclusions

This study found that weight loss after LGCP in morbidly obese patients led to decreases in levels of leptin and circulating immune cells compared to their preoperative values.     

影响近视患者眼压测量值的多因素分析

目的通过对影响近视眼眼压的多因素分析,指导临床对眼压测量值进行正确评估。方法随机选取非青光眼性近视眼患者1200例2332眼,采用非接触压平式及Schiotz压陷式眼压计(双砝码矫正)测眼压,同时测角膜中央厚度、角膜曲率及屈光度,将所得数据应用统计学方法处理,分析影响眼压的因素。结果近视眼患者的眼压与性别、年龄无关,非接触眼压与角膜中央厚度、曲率、屈光度呈正相关(r=0.319,P<0.001;r=0.130,P<0.001;r=0.105,P<0.001),建立多元线性回归方程:Y=0.119X1 3.178X2 0·296X3-14.856(P<0.001);Schiotz眼压与中央角膜厚度、屈光度呈正相关(r=0.117,P<0.001;r=0.056,P<0·01),建立多元线性回归方程:Y=6.191X1 1.130X2 10.198(P<0.001),Y:眼压(mmHg),X1:屈光度(D),X2:角膜中央厚度(μm),X3:角膜曲率(D);2种不同眼压测量值均数间有非常显著性差异(P<0.001),且Schiotz眼压测量值大于非接触眼压值。结论影响近视患者眼压的主要因素是角膜中央厚度、屈光度和角膜曲率,在临床诊断时,应考虑到以上因素影响,从而对近视眼眼压测量值有一更准确认识和判断,以免造成误诊及漏诊。     

基于定量瞳孔阻滞力仿真实验的虹膜组织生物力学特性分析

目的分析瞳孔阻滞力作用下的虹膜特性,探讨虹膜生物力学特性参量与瞳孔阻滞力和前后房压强差的关系。方法利用设计的瞳孔阻滞力仿真装置模拟瞳孔阻滞力,用液体加压装置模拟前后房压强差,对实验动物的虹膜进行整体加压,定量分析瞳孔阻滞力作用下的虹膜面应变、曲率半径的变化与前后房压强差的关系,以及不同大小的瞳孔阻滞力与前后房压强差的关系。结果获得了与临床现象相近的实验模型,与前期实验工作的方法相比,该实验方法更接近生理状态。得出分别以面应变、虹膜膨隆最高点的曲率半径与前后房压强差关系表达的方程,虹膜面应变δ与前后房压强差ΔP成以下规律:ΔP=b0eb1δ(b0=3.3373,b1=30.3909);虹膜曲率半径r与前后房压强差ΔP关系:r=e(b0 b1/ΔP)(b0=0.4761,b1=21.6604)。初步完成了虹膜特性和瞳孔阻滞力的定量研究,描述了不同大小的瞳孔阻滞力与前后房压强差的关系。结论实现了软组织小力学量的定量测量。面应变和曲率半径是可量化的虹膜形变特性参量,能够敏感的反映前后房压强差的变化,虹膜膨隆最高点的曲率半径是临床上容易测量的指标,对其的测量将帮助人们更好的进行早期临床诊断和治疗。     

近视眼患者角膜直径和角膜曲率的研究

目的探讨近视眼患者角膜直径和角膜曲率的正常值及二者之间的关系。方法对220例(440眼)近视眼患者(年龄17～41岁,男118例236眼,女102例204眼)采用美国Lasersight公司的AstraMax角膜地形图进行角膜前表面摄像,测量3次并获取角膜水平直径(白到白)和角膜前表面平均曲率的平均值,并对这2项参数进行相关的统计学分析。结果本组中角膜直径平均值为(12.00±0.40)mm,男性为(12.12±0.36)mm,女性为(11.86±0.40)mm。角膜曲率平均值为(43.51±1.37)D,男性为(43.10±1.29)D,女性为(43.99±1.31)D。角膜直径和角膜曲率的回归方程为Y=19.060-0.162X(Y代表角膜直径,X代表角膜曲率)。结论男女之间角膜直径存在着统计学差别,男性大于女性;角膜曲率之间亦有统计学意义,女性大于男性。近视眼患者角膜直径和角膜曲率之间存在统计学负相关性,即角膜曲率越高,角膜直径越小。     

准分子激光原位角膜磨镶术后角膜曲率的变化及意义

目的探讨准分子激光原位角膜磨镶术(LASIK)后角膜曲率改变的特点及其临床指导意义。方法对在我院准分子近视矫治中心已行LASIK术且随访6个月以上的238例467眼近视患者,按术前等效球镜屈光度数不同分为低度(<-3.0D)、中度(-3.25D-6.0D)、高度(-6.25D-10.0D),超高度(>-12.0D)四组,分别于术前、术后1个月、3个月、6个月采用TMS-4角膜地形图检查,收集数据进行分析。结果术前平均SimK值分别为(44.15±1.56),(43.78±1.45),(43.89±1.37),(44.46±1.64),统计学上无显著差异。术后与术前的SimK差值分别为(2.43±0.36),(3.65±0.42),(5.73±0.56),(7.89±1.23),有统计学意义。亦即术前预矫等效球镜屈光度数越高,则术前、后角膜曲率差值越大,术后3个月与1个月的SimK差值分别为(0.29±0.63),(0.6±80.55),(0.73±0.42),(1.57±0.95),而术后6个月与3个月的SimK差值分别为(0.12±0.36),(0.31±0.45),(0.36±0.48),(0.78±0.64),即术后角膜曲率的增加与术前预矫屈光度数的高低相关。随访的病例中有13例患者出现视力的下降、角膜曲率增加、屈光度回退,在进行散瞳松弛睫状肌、降眼压、护眼袋的治疗后,曲率的增加得到控制,视力得以稳定。结论LASIK术矫正近视直接改变了角膜的曲率,其变化与术前预矫屈光度数的高低相关,术后角膜曲率的增高与屈光回退一致,因此可采取干预手段阻止曲率的增长以减少屈光回退量。     

颈椎曲度弧顶点的分布特征

为研究采用Borden氏法测量法探讨颈椎曲度弧顶点的分布规律 ,采用Borden氏测量法在 15 4例颈椎侧位X线片上 ,测量颈椎生理曲度弧顶点的分布情况。显示 15 4例健康志愿者的颈椎曲度弧顶点位置分布的频数以C4中最多 (4 6 .1% ) ,C5中次之(18.2 % ) ,C6上最少 (仅 0 .6 % ) ;对不同弧顶点颈椎曲度值方差分析结果 :P >0 .0 5 ,差异无统计学意义。表明颈椎曲度弧顶点的分布有一定规律 ,主要分布C4中点和C5中点 ,且不同弧顶点的颈椎曲度值无明显差异。     

四维悬吊牵引调腰曲为主治疗颈腰椎间盘病

目的：探讨以四维悬吊牵引调腰曲为主的整脊法治疗颈腰椎间盘病的临床效果。方法：采取俯卧四维悬吊牵引调腰曲为主。配合颈胸椎整脊手法和针刺、内外用药综合疗法，观察各类型颈腰椎间盘病201例的治疗效果。结果：本综合疗法对颈腰椎间盘病的总有效率为97．01％，其中，临床治愈率为89．05％，颈曲恢复优良率为74．13％，腰曲恢复优良率为73．63％。平均16个月随访优良率为90．59％，治疗效果满意。结论：本疗法以调椎曲为主要治疗目标．椎曲恢复和稳定与功能锻练呈正相关。从随访病例中了解到，坚持功能锻练是巩固疗效的可靠措施。     

Postural and Time-Dependent Effects on Body Height and Scoliosis Angle in Adolescent Idiopathic Scoliosis

Changes in body height and scoliosis angle under the influence of gravity were studied in 40 patients with adolescent scoliosis. The average decrease in body height was 1% during a day. There were no significant changes in the mean angles of the scoliosis curves during the day. The patients were grouped according to age, standing and sitting heights, weight and skeletal maturation. A decrease in the scoliosis angles occurred in younger, more skeletally immature and lighter individuals, while an increase occurred in older, more skeletally mature and heavier individuals.

The difference between the scoliosis angles measured from standing and supine views was also analyzed. The correction of the scoliosis angle in the supine position was on average 19%. No correlation was found between the change in angle and any of the growth factors studied. There was also no correlation between the change in angle and the degree of curvature.