Differential influence of the visual framework on end point accuracy and trajectory specification of arm movements

In this study the influence of visual scene on both arm end point accuracy and spatial path kinematics was evaluated. Eight subjects, immersed in a virtual environment, were required to point to one of ten targets located at two distances and in five directions. Targets were presented in frameworks of different complexity. The simplest framework was constituted by a uniform background, the most complex framework was constituted by a perspective-arranged grid. In the other two conditions it consisted of lines having a direction parallel to either the subject's sagittal or frontal body axis. Movements were executed without vision of both target and framework. The results showed that pointing movements were hypometric in all conditions. No difference in end point localization was observed between movements executed after presentation of the simplest and the most complex scenes. However, hypometria significantly increased when the scene was formed by lines parallel to the subject's sagittal axis. Visual information on the scene was also used to specify hand path parameters. Trajectory curvature increased with decreasing complexity of the framework. Correspondingly, the pointing kinematics varied. Taken together, these results suggest that visual analysis of cues surrounding the target can influence both target localisation and hand path planning. However, scene complexity is directly related only to determining trajectory curvature. We conclude that planning an arm movement consists of at least two processes: target localisation and hand path specification. Environmental visual cues forming the scene are taken into account differently during the two processes.     

Virtual reality for acute and chronic pain management in adult patients: a narrative review

Virtual reality is a computer-generated environment that immerses the user in an interactive artificial world. This ability to distract from reality has been utilised for the purposes of providing pain relief from noxious stimuli. As technology rapidly matures, there is potential for anaesthetists and pain physicians to incorporate virtual reality devices as non-pharmacological therapy in a multimodal pain management strategy. This systematic narrative review evaluates clinical studies that used virtual reality in adult patients for management of acute and chronic pain. A literature search found 690 citations, out of which 18 studies satisfied the inclusion criteria. Studies were assessed for quality using the Jadad and Nottingham-Ottawa Scales. Agreement on scores between independent assessors was 0.87 (95%CI 0.73–0.94). Studies investigated virtual reality use: intra-operatively; for labour analgesia; for wound dressing changes; and in multiple chronic pain conditions. Twelve studies showed reduced pain scores in acute or chronic pain with virtual reality therapy, five studies showed no superiority to control treatment arms and in one study, the virtual reality exposure group had a worsening of acute pain scores. Studies were heterogeneous in: methods; patient population; and type of virtual reality used. These limitations suggest the evidence-base in adult patients is currently immature and more rigorous studies are required to validate the use of virtual reality as a non-pharmacological adjunct in multimodal pain management.     

后基因组时代的药物发现:趋势和实践

人类基因组计划深刻地影响了药物研究和开发的思路和策略，生命科学的研究方法和技术与药物研究的结合日益紧密，计算机信息技术也越来越多应用到药物研究过程中来。本文以实例说明了虚拟筛选、配体垂钓以及靶标的发现与确证方法在药物研究中的应用。     

Dextroscope虚拟现实手术规划系统在神经外科的应用

目的应用手术规划系统，探索虚拟现实技术在神经外科的应用价值和方法。方法术前采集10例颅内深部病变患者的CT、MRI、CTA、MRA、DSA影像资料输入Dextroscope工作站进行图像融合处理和三维重建，在虚拟影像上观察病变与周围组织的空间关系，设计手术入路、模拟手术过程进行骨窗开颅、颅骨磨除及肿瘤切除，并与实际术中所见进行比较。结果术中所见病变与周边重要神经血管结构的空间关系和病变解剖细节与术前模拟完全吻合，减少了手术时间。通过手术模拟，术者得以提前预演手术经过，为优化治疗方案创造了条件。结论虚拟现实手术规划系统有助于术前诊断、制定详细的手术计划、预先评价手术难度，提高手术安全性。是医疗教学和训练的得力工具。     

Analgesia through the looking-glass? A randomized controlled trial investigating the effect of viewing a ‘virtual’ limb upon phantom limb pain,sensation and movement

The extent to which viewing a 'virtual' limb, the mirror image of an intact limb, modifies the experience of a phantom limb, was investigated in 80 lower limb amputees before, during and after repeated attempts to simultaneously move both intact and phantom legs. Subjects were randomly assigned to one of two conditions, a control condition in which they only viewed the movements of their intact limb and a mirror condition in which they additionally viewed the movements of a 'virtual' limb. Although the mirror condition elicited a significantly greater number of phantom limb movements than the control condition, it did not attenuate phantom limb pain and sensations any more than the control condition. The potential of a 'virtual' limb as a treatment for phantom limb pain was discussed in terms of its ability to halt and/or reverse the cortical re-organisation of motor and somatosensory cortex following acquired limb loss.     

64层CT仿真内镜评价冠状动脉狭窄程度的临床研究

目的评价64层螺旋CT仿真内镜（CT virtual endoscopy；CTVE）冠状动脉成像诊断不同程度狭窄的临床价值。方法20例在1周内接受64层CT冠状动脉成像和数字减影血管造影（digital subtraction angiography，DSA）患者的CT图像行仿真内镜重建，14分段法分为280个血管单元，目测直径法将狭窄分为无狭窄、微度、轻度、中度及重度狭窄和闭塞，回顾性双盲对照分析，采用SPSS13．0计算kappa一致性（P〈0．05），并分别计算不同程度狭窄的特异性、敏感性、阳性预测值和阴性预测值。结果1．251（251/280）段能够满足影像学评价要求，与DSA诊断中度一致（Kappa=0．515，P=0．000）；2．CTVE判断冠状动脉微小、轻度、中度、重度狭窄及闭塞病变的灵敏度、特异度、阳性预测值、阴性预测值分别为23．08％、93．88％、20．00％、94．85％，40．00％、97．13％、25．00％、98．54％，41．18％、98．60％、70．00％、95．48％，38．46％、100％、100．％、96．65％，71．43％、100％、100％、99．19％。结论64层CTVE能理想显示冠状动脉内腔。对狭窄的判断与DSA具有中度一致性，随狭窄程度的加重CTVE的诊断效能增强，可以作为冠状动脉疾病的一种无创检查方法。     

虚拟现实技术及其在航天医学工程领域的应用前景

虚拟现实是一门新兴的仿真技术，已成功地应用于工程设计、军事与航空航天和娱乐等领域，并在影响到人们的日常生活。本文在综合分析国外资料折基础上，较系统地阐述了虚拟现实技术基础和应用研究情况，提出了虚拟现实在航天医学工程领域的可能应用场合，并根据目前技术现状，对虚拟现实未来发展提出了若干建议。     

Anticipation of public speaking in virtual reality reveals a relationship between trait social anxiety and startle reactivity.

BACKGROUND: Startle reflex modification has become valuable to the study of fear and anxiety, but few studies have explored startle reactivity in socially threatening situations. METHODS: Healthy participants ranging in trait social anxiety entered virtual reality (VR) that simulates standing center-stage in front of an audience to anticipate giving a speech and count backward. We measured startle and autonomic reactivity during anticipation of both tasks inside VR after a single baseline recording outside VR. RESULTS: Trait social anxiety, but not general trait anxiety, was positively correlated with startle before entering VR and most clearly during speech anticipation inside VR. Speech anticipation inside VR also elicited stronger physiologic responses relative to anticipation of counting. CONCLUSIONS: Under social-evaluative threat, startle reactivity showed robust relationships with fear of negative evaluation, a central aspect of social anxiety and clinical social phobia. Context-specific startle modification may be an endophenotype for subtypes of pathological anxiety.     

A multisensory approach to spatial updating: the case of mental rotations

Mental rotation is the capacity to predict the outcome of spatial relationships after a change in viewpoint. These changes arise either from the rotation of the test object array or from the rotation of the observer. Previous studies showed that the cognitive cost of mental rotations is reduced when viewpoint changes result from the observer’s motion, which was explained by the spatial updating mechanism involved during self-motion. However, little is known about how various sensory cues available might contribute to the updating performance. We used a Virtual Reality setup in a series of experiments to investigate table-top mental rotations under different combinations of modalities among vision, body and audition. We found that mental rotation performance gradually improved when adding sensory cues to the moving observer (from None to Body or Vision and then to Body & Audition or Body & Vision), but that the processing time drops to the same level for any of the sensory contexts. These results are discussed in terms of an additive contribution when sensory modalities are co-activated to the spatial updating mechanism involved during self-motion. Interestingly, this multisensory approach can account for different findings reported in the literature.