On the role of static and dynamic visual afferent information in goal-directed aiming movements

Movement planning has been shown to be optimized when the participant is permitted to see his or her hand resting on the starting base prior to movement initiation. However, this proposition is opposed by contradictory results. In the present study, we wanted to determine whether these conflicting results were caused by procedural differences. The results showed that seeing one's hand on the starting base did not result in more accurate aiming movement than when this information was not available. However, lower aiming errors were found when one was asked to foveate the starting base and then the target prior to movement initiation, but only when no dynamic visual information was available during movement. When an aiming movement was performed while one's hand was visible in visual periphery, foveating the starting base or not prior to movement initiation did not modify aiming accuracy. These results suggest that gazing at the starting base and then at the target provides an eye-based representation of the movement to be performed that can be used by the CNS to plan a manual aiming movement. Information for better planning of the direction – but not the extent – dimension of an upcoming movement can also be derived from dynamic visual information available in peripheral vision. Electronic Publication     

基于粗配准和混合互信息的医学图像配准算法

利用边缘检测算子和数学形态学方法提取医学图像轮廓,采用主轴矩法配准两幅图像的轮廓,使其达到粗略配准的目的。通常的互信息测度是基于香农熵的,因为香农熵对于局部极值具有很强吸引域,而某些参数下的雷尼熵可以消除局部极值,将两种测度分别用于精配过程中不同的搜索阶段。首先利用全局搜索算法,寻找基于雷尼熵的归一化互信息测度的全局最优初值,再通过局部优化算法对当前的最优解寻找基于香农熵的更精确的全局最优解。实验表明,这种配准算法是有效的。     

Event-Related Potential Correlates of Two Stages of Information Processing in Physical and Semantic Discrimination Tasks

Event-related potentials were studied while subjects performed physical and semantic discrimination tasks. Two negative components, N_A and N2, were observed in both kinds of discriminations. The earlier component, N_A, had a constant onset latency, but its peak latency varied as a function of stimulus complexity. N2 latency varied in relation to changes in the peak of N_A. RT and P3 followed N2 by similar amounts of time across tasks. The N_A and N2 components were interpreted as reflecting partially overlapping sequential stages of processing associated with pattern recognition and stimulus classification, respectively.     

应用检验信息系统在医院检验科实现全面质量管理

本文介绍了全面质量管理的概念，并认为TQM实际上是一个数据驱动的管理活动。检验信息系统的优点就在于能够提供各种检验数据，文中阐述了如何利用检验信息系统的这一优点，使其成为医院检验科进行全面质量管理的重要工具。     

混合遗传算法在医学图像配准中的应用

针对遗传算法和梯度算法各自的优点和缺陷,提出了遗传算法和梯度算法相结合的松散耦合和紧密耦合两种混合遗传算法,并利用基于排挤的小生境技术对其性能进行了改进,使其在搜索能力和收敛速度上都有了较大提高。利用此算法成功实现了以互信息为相似性测度的医学图像配准。计算实例结果表明,本算法能够有效克服局部极值的影响,具备较强的抗噪能力,是一个精度高、稳定性好的医学图像配准算法。     

Probe selection algorithm for oligonucleotide array-based medium-resolution genotyping

Medium-resolution genotyping has the goal of distinguishing different subgroups instead of each element in a group. An oligonucleotide array provides an inexpensive, high-throughput method to identify differences in DNA sequence among individuals, which is fundamental for genotyping. As the cost and difficulty of designing and fabricating the oligonucleotide array dramatically increase with the number of probes used, it is therefore important to have a design with a minimum number of probes meeting the requirement of medium-resolution genotyping. The first algorithm for designing and selecting probes for oligonucleotide array-based medium-resolution typing is reported. The goal in deriving the algorithm was to select a minimum number of probes from a large probe set on the premise of minimum loss of resolution. The algorithm, which was based on entropy, conditional entropy and mutual information theory, was used to select the minimum number of probes from a large probe set. The algorithm was tested on a human leukocyte antigen (HLA) sequence data set. Thirty probes were selected from 390 probes for HLA-A, and 60 probes were selected from 767 probes for HLA-B. Although the number of probes was reduced by almost ten times, the distinguishability was reduced only a little, by 0.45% (from 99.90% to 99.45%) for HLA-A and 0.27% (from 99.84% to 99.57%) for HLA-B, respectively. This is a satisfactory and practical result.     

Investigation of feline brain anatomy for the detection of cortical spreading depression with magnetic resonance imaging

Cortical spreading depression (CSD) and peri‐infarct depolarisation (PID) are related phenomena that have been associated with the human clinical syndromes of migraine (CSD), head injury and stroke (PID). Nevertheless the existence of CSD in man remains controversial, despite the detection of this phenomenon in the brains of most, if not all, other animal species investigated. This failure to unambiguously detect CSD clinically may be at least partly due to the anatomically complex, gyrencephalic structure of the human brain. This study was designed to establish conditions for the study of CSD in the brain of a gyrencephalic species using the noninvasive technique of magnetic resonance imaging (MRI). The 3‐dimensional (3D) gyrencephalic anatomy of the cat brain was examined to determine the imaging conditions necessary to detect CSD events. Orthogonal transverse, sagittal and horizontal T₁‐weighted image slices showed that the marginal and suprasylvian gyri were the most appropriate cortical structures to study CSD. This was in view of (1) their simple geometry: (2) their lengthy extent of grey matter orientated rostrocaudally in the cortex: (3) their separation by a sulcus across which CSD spread could be studied and (4) the discontinuity in the grey matter in these regions between the right and left hemispheres dorsal to the corpus callosum. The structure suggested by the T₁‐weighted images was corroborated by systematic diffusion tensor imaging to map the fractional anisotropy and diffusion trace. Thus a single horizontal image plane could visualise the neighbouring suprasylvian and marginal gyri of both cerebral hemispheres, whereas its complex shape and position ruled out the ectosylvian gyrus for CSD studies. With the horizontal imaging plane, CSD events were reproducibly detected by animating successive diffusion‐weighted MR images following local KCl stimulation of the cortical surface. In single image frames, CSD detection and characterisation required image subtraction or statistical mapping methods that, nevertheless, yielded concordant results. In repeat experiments, CSD events were qualitatively similar in appearance whether elicited by sustained or transient KCl applications. Our experimental approach thus successfully describes cat brain anatomy in vivo, and elucidates the necessary conditions for the application of MRI methods to detect CSD propagation.     

Bilateral receptive field neurons in the hindlimb region of the postcentral somatosensory cortex in awake macaque monkeys

Single-neuron activities were recorded in the hindlimb region of the primary somatosensory cortex and part of area 5 in awake Japanese monkeys. A total of 1050 units were isolated from five hemispheres of four animals. Receptive fields (RFs) and submodalities were identified for 90% of isolated neurons in areas 3a and 3b. The percentage decreased as the recoding site moved to the more caudal areas. Deep or skin submodality neurons were dominant in area 3a or area 3b, respectively. Deep submodality neurons increased in more caudal areas and were the majority in areas 2 and 5. These observations were consistent with those in the hand and/or digit or arm and/or trunk region. The identified neurons were classified by their RF positions into four types: the foot, leg, foot and leg, or hindlimb and other body parts type. Among 831 identified neurons, 33 neurons had bilateral RFs, 14 had ipsilateral RFs, and the rest (N=784) had contralateral RFs. The relative incidence of neurons with bilateral or ipsilateral RFs among identified neurons was less than 1% in areas 3a, 3b, and 1, and 16% or 25% in areas 2 or 5, respectively. Within areas 2 and 5, the percentage of neurons with bilateral or ipsilateral RFs was significantly smaller in the foot type (5%) than in other RF types (24-57%). RFs of the foot type were on the sole or single toe but never on multiple toes. These observations contrasted with the previous findings that neurons with bilateral RFs were more frequently seen in the hand and/or digit region and that RFs on multiple digit tips were dominant there. The present study thus demonstrated that neurons with bilateral RFs do exist in the hindlimb region. Similarly to the forelimb region, they were found mostly in areas 2 and 5, the caudalmost areas of the postcentral gyrus and hierarchically higher stages in information processing. The relative paucity of neurons with bilateral RFs on the foot, especially those with RFs on multiple toes, may reflect functional differences between the foot and the hand.     

"军字1号"工程使用前后病案首页质量对照统计分析

为探讨“军字1号”工程使用前后的病案首页质量变化,本文通过作者所在医院近八年病案首页的质量调查统计,对“军字1号”工程使用前后的病案首页质量作了详细的对照分析比较,为进一步加强“军字1号”工程中的病案首页质量管理提供经验。