Memory function in normal aging

Basic findings obtained on memory functions in normal aging are presented and discussed with respect to five separate but interacting memory systems. These systems are: episodic memory, semantic memory, short-term memory, perceptual representation system and procedural memory. All available evidence from cross-sectional research shows that there is a linear, decreasing memory performance as a function of age for episodic memory. Longitudinal studies suggest, however, that this age deficit may be an overestimation, by showing a relatively stable performance level up to middle age, followed by a sharp decline. Studies on semantic memory, short-term memory, perceptual representation system, and procedural memory show a relatively constant performance level across the adult life span, although some tasks used to assess short-term memory and procedural memory have revealed an age deficit. Disregarding the mixed results for these latter two memory systems, it can be concluded that episodic memory is unique in showing an age deficit. Episodic memory is also unique in the sense that it is the only memory system showing gender differences in performance throughout the adult life span with a significantly higher performance for women.     

睡眠剥夺对内隐记忆的影响

目的:探讨不同时间睡眠剥夺(sleep deprivation,SD)对内隐记忆的影响。方法:将32名青年男性随机分为4组:对照组、SD21、SD45和SD69组,每组8名。采用补笔测验和组词测验对4组被试进行测试。结果:SD 后无论知觉启动还是语义启动,启动量降低,并随SD 时间延长而减少。同一组内,两种测验进行比较,除对照组外,其他SD 组两两比较,语义启动的启动量大于知觉启动(P<0.05)。知觉启动中,SD45同SD69 相比无显著差异(P=0.245),其他两两比较差异均有统计学意义(P<0.01);语义启动中,SD21同对照组相比差异无统计学意义(P=0.316),其他两两比较差异均有统计学意义(P<0.01)。结论:SD 后内隐记忆受损,并同SD 时间有关;SD 后语义启动和知觉启动出现分离,知觉启动更受SD 影响。     

用Flash动态演示PN结的形成过程

本文通过用Flash 5．0制作《医学电子学》中PN结的形成过程的介绍，在熟悉Flash 5．0制作方法的同时．完成相应的多媒体教学。     

法律理念之动物文化解读

动物与法历来有着文化上的不解之缘。在中外法律思想史上 ,人们喜用各种动物以及相关的故事来阐发自己的法律思想和主张 ,用形象有趣的譬喻箴言来解说深奥艰涩的法学理念。有的作象征式解说 ,有的作寓言式的解说 ,有的作隐喻式解说 ,这些解说渗透到法学本体论、价值论、工具论、目的论、运作论及通变论等各个层面中 ,从而使得法学的理性思维获得一种鲜活的感性语境 ,也形成了一种独特的法律文化。当然 ,这种法律文化也有其黯淡的一面 ,表现为缺乏逻辑实证与规范分析 ,因此我们面对这种文化 ,还应结合法学发展的理性成果去批判地审视它     

Speed-invariant encoding of looming object distance requires power law spike rate adaptation

Neural representations of a moving object’s distance and approach speed are essential for determining appropriate orienting responses, such as those observed in the localization behaviors of the weakly electric fish, Apteronotus leptorhynchus. We demonstrate that a power law form of spike rate adaptation transforms an electroreceptor afferent’s response to “looming” object motion, effectively parsing information about distance and approach speed into distinct measures of the firing rate. Neurons with dynamics characterized by fixed time scales are shown to confound estimates of object distance and speed. Conversely, power law adaptation modifies an electroreceptor afferent’s response according to the time scales present in the stimulus, generating a rate code for looming object distance that is invariant to speed and acceleration. Consequently, estimates of both object distance and approach speed can be uniquely determined from an electroreceptor afferent’s firing rate, a multiplexed neural code operating over the extended time scales associated with behaviorally relevant stimuli.     

Perception or reality: Can thermal perceptions inform management of firefighters in the heat?

Accurately assessing the physiological status of firefighters during work in the heat is critical to ensuring their safety. Evaluating core temperatures (T_c) in the field is problematic due to cost and limitations in technology and accuracy. As such, fire services rely on individual perceptions of wellbeing. The present study aimed to establish whether perceptual responses measured using the perceptual strain index (PeSI), calculated from rate of perceived exertion (RPE) and thermal sensation (TS), could reliably predict the physiological strain (PSI) encountered by experienced firefighters working in a hot environment. We conducted two firefighting simulations (set-pace and self-paced) in a purposefully built heat chamber (100 ± 5°C) comprised of two 20-min periods separated by a 10-min recovery outside the chamber. Physiological strain was measured via heart rate (HR) and gastrointestinal temperature (T_gi) and compared with PeSI at 5-min intervals. To evaluate the predictive ability of the PeSI for PSI, mean differences and the 95% limits of agreement (LOA) were established, along with correlation coefficients at each 5-min interval. Moderately significant correlations occurred in the second work bout of the self-paced trial only (10 min: r = 0.335, 15 min: r = 0.498, 20 min r = 0.439) with no other correlations observed at any other time during either trial or during the rest periods. Bland-Altman analysis revealed mean differences of ?0.74 ± 2.70 (self-paced) and +0.04 ± 2.04 (set-paced) between PeSI and PSI with the 95% LOA being ?4.77 to 3.28 (self-paced) and ?4.01 to 2.01 (set-paced). The wide LOA and lack of correlations observed between perceptual and physiological strain in both self-paced and set-paced work trials indicate that PeSI is not sufficiently reliable as a sole measure of wellbeing for firefighters working in the heat. Hence, we recommend that fire services prioritise the development of reliable and effective monitoring tools for use in the field.     

知觉学习训练重建共同性外斜视术后立体视功能的作用

目的：采用知觉学习训练方法对斜视矫正术后无立体视功能或者立体视功能不能恢复至正常的共同性外斜视患者进行训练，探讨知觉学习训练在斜视术后立体视功能重建中的作用。方法：前瞻性研究。选择2009年8月至2011年8月在安徽医科大学第一附属医院行斜视矫正术后眼位正位的共同性外斜视患者23例，均为术后3个月以上Titmus立体图检查立体视功能未达到正常者。采用心理物理学中的知觉学习方法进行立体视功能训练，观察训练前后视差辨别正确率、立体视锐度的变化。训练前后的数据比较采用配对t检验。结果：23例患者中有2例不能完成训练任务，21例患者顺利完成训练，平均训练（6.9±3.8）d，经知觉学习训练后立体视功能较训练前明显改善，差异具有统计学意义（t=8.228，P < 0.001）。视差辨别正确率检测显示，受试者在视差分别为320″、440″、580″时，训练后应答正确率高于训练前应答正确率，差异均具有统计学意义（t=-3.102，P=0.01；t=-2.360，P=0.02；t=-2.177，P=0.03）。结论：知觉学习训练可有效重建共同性外斜视术后患者的立体视功能，但具体机制有待进一步研究。     

Perceptual Embodiment of Prosthetic Limbs by Transcutaneous Electrical Nerve Stimulation

Objectives: In able‐bodied participants, it is possible to induce a sense of perceptual embodiment in an artificial hand using a visual‐tactile illusion. In amputee patients, electrical stimulation of sensory afferents using transcutaneous electrical nerve stimulation (TENS) has been shown to generate somatic sensations in an amputee's phantom limb(s). However, the effects of TENS on the perceptual embodiment of an artificial limb are not known. Our objective was to investigate the effects of TENS on the perceptual embodiment of an artificial limb in fully intact able‐bodied participants. Materials and Methods: We used a modified version of the rubber hand illusion presented to 30 able‐bodied participants (16 women, 14 men) to convey TENS paresthesia to an artificial hand. TENS electrodes were located over superficial radial nerve on the lateral aspect of the right forearm (1 cm proximal to the wrist), which was hidden from view. TENS intensity was increased to a strong non‐painful TENS sensation (electrical paresthesia) was felt beneath the electrodes and projecting into the fingers of the hand. The electrical characteristics of TENS were asymmetric biphasic electrical pulsed waves, continuous pulse pattern, 120 Hz pulse frequency (rate), and 80 µs pulse duration (width). Results: Participants reported significantly higher intensities of the rubber hand illusion during the two TENS conditions (mean = 5.8, standard deviation = 1.9) compared with the two non‐TENS conditions (mean = 4.9, standard deviation = 1.7), p < 0.0005. Conclusions: Our findings provide initial evidence that TENS paresthesia can be projected into an artificial limb, and this can enhance the sense of perceptual embodiment of an artificial hand. Further exploratory studies involving an amputee population are warranted.