fMRI differences in encoding and retrieval of pictures due to encoding strategy in the elderly

Functional MRI (fMRI) was used to examine the neural correlates of depth of processing during encoding and retrieval of photographs in older normal volunteers (n = 12). Separate scans were run during deep (natural vs. man-made decision) and shallow (color vs. black-and-white decision) encoding and during old/new recognition of pictures initially presented in one of the two encoding conditions. A baseline condition consisting of a scrambled, color photograph was used as a contrast in each scan. Recognition accuracy was greater for the pictures on which semantic decisions were made at encoding, consistent with the expected levels of processing effect. A mixed-effects model was used to compare fMRI differences between conditions (deep-baseline vs. shallow-baseline) in both encoding and retrieval. For encoding, this contrast revealed greater activation associated with deep encoding in several areas, including the left parahippocampal gyrus (PHG), left middle temporal gyrus, and left anterior thalamus. Increased left hippocampal, right dorsolateral, and inferior frontal activations were found for recognition of items that had been presented in the deep relative to the shallow encoding condition. We speculate that the modulation of activity in these regions by the depth of processing manipulation shows that these regions support effective encoding and successful retrieval. A direct comparison between encoding and retrieval revealed greater activation during retrieval in the medial temporal (right hippocampus and bilateral PHG), anterior cingulate, and bilateral prefrontal (inferior and dorsolateral). Most notably, greater right posterior PHG was found during encoding compared to recognition. Focusing on the medial temporal lobe (MTL) region, our results suggest a greater involvement of both anterior MTL and prefrontal regions in retrieval compared to encoding.     

Investigating local network interactions underlying first- and second-order processing

We compared the spatial lateral interactions for first-order cues to those for second-order cues, and investigated spatial interactions between these two types of cues. We measured the apparent modulation depth of a target Gabor at fixation, in the presence and the absence of horizontally flanking Gabors. The Gabors' gratings were either added to (first-order) or multiplied with (second-order) binary 2-D noise. Apparent "contrast" or modulation depth (i.e., the perceived difference between the high and low luminance regions for the first-order stimulus, or between the high and low contrast regions for the second-order stimulus) was measured with a modulation depth-matching paradigm. For each observer, the first- and second-order Gabors were equated for apparent modulation depth without the flankers. Our results indicate that at the smallest inter-element spacing, the perceived reduction in modulation depth is significantly smaller for the second-order than for the first-order stimuli. Further, lateral interactions operate over shorter distances and the spatial frequency and orientation tuning of the suppression effect are broader for second- than first-order stimuli. Finally, first- and second-order information interact in an asymmetrical fashion; second-order flankers do not reduce the apparent modulation depth of the first-order target, whilst first-order flankers reduce the apparent modulation depth of the second-order target.     

Resin modified glass-ionomers: strength,cure depth and translucency

BACKGROUND: According to the classification suggested by McLean, Wilson and Nicholson only three materials, currently marketed, fit the designation of resin modified glass-ionomers. These materials will undergo an acid/base setting reaction but also contain a limited quantity of a monomer that will polymerize as a result of irradiation. The quantity of polymer is limited to the extent that it will not interfere with the normal acid/base setting reaction and will therefore allow for the ion exchange adhesion with tooth structure that is typical of glass-ionomer. There is a third setting reaction incorporated to ensure remaining monomer, that is not affected by irradiation, will still polymerize. A series of experiments were carried out to determine the effect of the three types of setting reaction on the strength, depth of cure and translucency of these three materials. METHODS: Specimens, both with and without irradiation, were subjected to a shear punch strength test. To determine the depth of cure brought about through irradiation, specimens were tested immediately after construction according to the test in ISO - 4049 2000 (E). Translucency is clinically significant and will vary according to whether the material has been subjected to irradiation or cured through the acid/base reaction alone. RESULTS: The strength of all materials tested was higher in specimens subject to irradiation. The depth of cure was found to be both shade and irradiation time dependent. Irradiated specimens were found to be only marginally more translucent than those allowed to set without irradiation. CONCLUSIONS: It was concluded that, for cavities more than 3 mm deep, these materials should be placed incrementally to allow for a full irradiation initiated cure.     

Raman scattering determination of the depth of cure of light-activated composites: influence of different clinically relevant parameters

The purpose of this research was to determine the depth of cure of light-activated composites in relation with different clinically relevant parameters. A Raman spectroscopic method has been used. The measurement of cure is made on a relative basis by comparing the vibration band of the residual unpolymerized methacrylate C=C bond at 1640 cm-1 against the aromatic C=C stretching band at 1610 cm-1 used as an internal standard. The information gained draw attention to the importance of light transmission during the exposure. The influence of sample's thickness on the depth of cure is illustrated by a second order polynomial regression. The shade and translucency of the resin composite also modify the light transmission and thus have a significant influence on the degree of conversion. Moreover the light-source intensity and the distance from the curing tip are important parameters of influence. A significant reduction of the depth of cure is observed for all sample thickness of resin composite tested when using a light device with an intensity of 300 mW cm-2 as well as using a distance from the curing tip higher than 20 mm.     

Weighted linear cue combination with possibly correlated error

We test hypotheses concerning human cue combination in a slant estimation task. Observers repeatedly adjusted the slant of a plane to 75 degrees. Feedback was provided after each setting and the observers trained extensively until their setting error stabilized. The slant of the plane was defined by either linear perspective alone (a grid of lines) or texture gradient alone (diamond-shaped texture elements) or the two cues together. We chose a High and Low variance version of each cue type and measured setting variability in four single-cue conditions (Low, High for each cue) and in the four possible combined-cue conditions (Low-Low, Low-High, etc.). We compared performance in the combined-cue conditions to predictions based on single-cue performance. The results were consistent with a linear combination of estimates from cues. Six out of eight observers did better with combined cues than with either cue alone. For three observers, performance was consistent with optimal combination of uncorrelated cues. Three other observers' results were also consistent with optimal combination, but with the assumption that internal cue estimates were correlated. The remaining two observers were consistent with sub-optimal cue combination.     

不同内径前房维持器在兔眼连续环形撕前囊中所创前房深度的研究

目的：研究不同内径的前房维持器（anterior chamber maintainer,ACM)在兔眼实验性连续环形撕前囊（continuous curvilinear anterior capsulorhexis,CCC)中所创前房深度（anterior chamber depth,ACD)及眼压（intraocular pressure,IOP)的变化, 探讨ACM内径大小及灌注瓶高度（bottle height,BH)对ACD及IOP的影响。方法：将20只兔40眼随机分为4组,每组10眼,均在ACM维持前房下接受CCC。4个实验组所用ACM内径分别是0．4,0．5,0．6,0．7mm,BH由20cm阶梯式升至100cm,每10cm为一个提升高度,对术前及每个BH,应用A超测定ACD,应用Schiotz眼压计测定IOP,结果：内径为0．7,0．6,0．5mm的ACM在BH分别为50,60,70cm时使ACD较术前显著性加深,所提供IOP较术前较高,结论：内径较大的ACM形成前房及提高IOP迅速,所需BH相对较低,对于兔眼的CCC,内径为0．7,0．6,0．5mm的ACM均可提供理想的ACD及IOP,适宜的BH分别是50,60,70cm.     

Geographies of infant feeding and access to primary health-care

Although the benefits of breastfeeding to mother and infant are now well established, within Britain initiation rates are low and have changed little since 1980. This is despite many health promotion initiatives aiming to increase breastfeeding. In this paper we discuss some of the findings of an exploratory qualitative research study of infant feeding decisions in Newcastle upon Tyne, England, where health professionals are actively seeking to increase local breastfeeding initiation and duration rates. Our findings suggest that for health promotion initiatives to be effective across all social groups, there needs to be (i) a socio-cultural understanding of different social groups' access to and interpretation of pre- and postnatal formal breastfeeding support health services, and (ii) more appreciation of how mothers' informal support networks impact on their access to, interpretation and use of formal breastfeeding support.     

Implications of Deep Electrode Insertion on Cochlear Implant Fitting

Using long Med-El Combi40+ electrode arrays, it is now possible to cover the whole range of the cochlea, up to about two turns. Such insertion depths have received little attention. To evaluate the contribution of deeply inserted electrodes, five Med-El cochlear implant users were tested on vowel and consonant identification tests with fittings with first one, two, and up to five apical electrodes being deactivated. In addition, subjects performed pitch-ranking experiments, using loudness-balanced stimuli, to identify electrodes creating pitch confusions. Radiographs were taken to measure each electrode insertion depth. All subjects used each modified fitting for two periods of about 3 weeks. During the experiment, the same stimulation rate and frequency range were maintained across all the fittings used for each individual subject. After each trial period the subject had to perform three consonant and three vowel identification tests. All subjects showed deep electrode insertions ranging from 605° to 720°. The two subjects with the deepest electrode insertions showed significantly increased vowel- and consonant-identification performances with fittings with the two or three most apical electrodes deactivated compared to their standard fitting with all available electrodes activated. The other three subjects did not show significant improvements in performance when one or two of their most apical electrodes were deactivated. Four out of five subjects preferred to continue use of a fitting with one or more apical electrodes deactivated. The two subjects with the deepest insertions also showed pitch confusions between their most apical electrodes. Two possible reasons for these results are discussed. One is to reduce neural interactions related to electrodes producing pitch confusions. Another is to improve the alignment of the frequency components of sounds coded by the electrical signals delivered to each electrode to the overall pitch of the auditory perception produced by the electrical stimulation of auditory nerve fibers.     

大鼠脑缺血再灌流后Bcl-2、Caspase-3 mRNA水平表达与大脑皮层及纹状体区炎性细胞浸润的影响

目的探讨大鼠脑缺血再灌流后Bcl-2蛋白、Caspase-3mRNA的表达及炎性细胞浸润与神经细胞凋亡的关系。方法将54只Wistar大鼠随机分为二组：假手术组，缺血再灌流组。采用原位末端标记(TUNEL)、免疫组化和原位杂交技术分别观察脑缺血再灌流后不同时间点神经细胞凋亡及损伤的变化与Bcl-2、Caspase-3mRNA表达。结果Bcl-2表达于缺血再灌流12～24h迭高峰，再灌流2～4d呈下降趋势，至16d略高于假手术组；Caspase-3mRNA于缺血再灌流12～24h迭高峰，2～4d呈降低趋势，至16d略高于假手术组。结论脑缺血再灌流后细胞凋亡介导神经细胞损伤、坏死是一个渐进的动态演变过程。Bcl-2蛋白、Caspase-3mRNA表达在押制细胞凋亡和介导神经细胞损伤等方面起非常重要的作用。     

基于EDI-OCT技术观察远视性弱视儿童脉络膜结构的变化

目的:通过增强深度成像光学相干断层扫描(EDI-OCT)技术比较远视性弱视与同龄正常儿童脉络膜结构的差异。方法:选取2021-01/12就诊于我院的远视性弱视儿童35例50眼纳入弱视组,选取同期就诊一般资料相匹配的健康儿童30例51眼纳入对照组,均进行EDI-OCT检查,测量脉络膜厚度(CT),并对图像进行处理后获取总脉络膜面积(TCA)、血管腔面积(LA)、基质面积(SA)、脉络膜血管指数(CVI)。结果:弱视组各区域TCA(下方除外)、SA(外环下方除外)、LA与CT(下方、颞侧除外)均明显大于对照组(P<0.05);除外环颞侧外,两组各区域CVI无明显差异(P>0.05);除鼻侧外,不同远视程度弱视儿童CT无明显差异(P>0.05)。结论:远视性弱视存在脉络膜结构异常,随着远视度数增加,TCA、LA、SA有增大趋势,脉络膜结构改变与远视性弱视有关。