Interference from retrieval cues in Parkinson's disease.

Objective: Existing studies on memory interference in Parkinson's disease (PD) patients have provided mixed results and it is unknown whether PD patients have problems in overcoming interference from retrieval cues. We investigated this issue by using a part-list cuing paradigm. In this paradigm, after the study of a list of items, the presentation of some of these items as retrieval cues hinders the recall of the remaining ones. Method: We tested PD patients' (n = 19) and control participants' (n = 16) episodic memory in the presence and absence of part-list cues, using initial-letter probes, and following either weak or strong serial associative encoding of list items. Results: Both PD patients and control participants showed a comparable and significant part-list cuing effect after weak associative encoding (13% vs. 12% decrease in retrieval in part-list cuing vs. no part-list cuing -control- conditions in PD patients and control participants, respectively), denoting a similar effect of cue-driven interference in the two populations when a serial retrieval strategy is hard to develop. However, only PD patients showed a significant part-list cuing effect after strong associative encoding (20% vs. 5% decrease in retrieval in patients and controls, respectively). Conclusions: When encoding promotes the development of an effective serial retrieval strategy, the presentation of part-list cues has a specifically disruptive effect in PD patients. This indicates problems in strategic retrieval, probably related to PD patients' increased tendency to rely on external cues. Findings in control conditions suggest that less effective encoding may have contributed to PD patients' memory performance. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Verbal memory in drug-naive, newly diagnosed Parkinson's disease. The retrieval deficit hypothesis revisited.

Objective: The retrieval deficit hypothesis on memory impairment in patients with Parkinson's disease (PD) implies a selective impairment in recall of learned material with normal encoding, retention, and recognition. This hypothesis has been challenged by new data. We have therefore investigated verbal memory and learning in a large sample of newly diagnosed, drug na?ve, non-demented patients with PD. Method: From a sample of patients with PD from the Norwegian ParkWest study, 133 PD patients and 133 controls matched on sex, age, and education were included. The California Verbal Learning Test-2 (CVLT-2) was used to assess verbal memory. Results: Patients performed significantly worse than controls on free and cued recall as well as on recognition memory. Patients used the semantic clustering learning strategy significantly less extensively than the controls and the learning slope of the PD patients was significantly less steep. There was no difference in retention when controlling for encoding. Patients did not perform better on the recognition measure or on cued recall (d-prime), as compared to free recall. Executive functions explained a substantial part of the memory deficits. Conclusions: This study suggests that memory impairment in drug na?ve early PD to a large degree is a deficit of learning/ encoding and not of retention or retrieval. An implication is that the retrieval deficit hypothesis should be moderated in its general form. Executive deficits and less extensive use of the efficient semantic clustering learning strategy had a strong impact on learning and memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental renewal in human participants.

Two experiments with human participants are presented that differentiate renewal from other behavioral effects that can produce a response after extinction. Participants played a video game and learned to suppress their behavior when sensor stimuli predicted an attack. Contexts (A, B, & C) were provided by fictitious galaxies where the game play took place. In Experiment 1, participants who received conditioning in A, extinction in B, and testing in A showed some context specificity of conditioning during extinction and a recovery of suppression on test. Experiment 2 demonstrated recovery of extinguished responding when participants were conditioned in A, extinguished in B, and tested in C, a third, neutral context. The experiment also demonstrated that the context of extinction did not control performance by becoming inhibitory. Results are discussed in terms of mechanisms that can produce a response recovery after extinction. The experiments demonstrated a renewal effect: a response recovery that was not attributable to the contexts acting as simple conditioned stimuli and is the first work with human participants to conclusively do so. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding modality can affect memory accuracy via retrieval orientation.

Research indicates that false memory is lower following visual than auditory study, potentially because visual information is more distinctive. In the present study we tested the extent to which retrieval orientation can cause a modality effect on memory accuracy. Participants studied unrelated words in different modalities, followed by criterial recollection tests that selectively oriented retrieval toward one study modality at a time. Memory errors were lower when oriented toward visual than toward auditory information, thereby generalizing the modality effect to an explicit source memory task. Moreover, these effects persisted independent of the test presentation modality, indicating that retrieval orientation overrode the potential cuing properties of the test stimulus. An independent manipulation check confirmed that visual recollections were subjectively experienced as more distinctive than auditory recollections. These results suggest that retrieval orientation is sufficient to cause a modality effect on memory accuracy by focusing monitoring processes on the recollection of studied features that are diagnostic of prior presentation. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Retrieval during learning facilitates subsequent memory encoding.

In multiple-list learning, retrieval during learning has been suggested to improve recall of the single lists by enhancing list discrimination and, at test, reducing interference. Using electrophysiological, oscillatory measures of brain activity, we examined to what extent retrieval during learning facilitates list encoding. Subjects studied 5 lists of items in anticipation of a final cumulative recall test and did either a retrieval or a no-retrieval task between study of the lists. Retrieval was from episodic memory (recall of the previous list), semantic memory (generation of exemplars from an unrelated category), or short-term memory (2-back task). Behaviorally, all 3 forms of retrieval enhanced recall of both previously and subsequently studied lists. Physiologically, the results showed an increase of alpha power (8–14 Hz) from List 1 to List 5 encoding when no retrieval activities were interpolated but no such increase when any of the 3 retrieval activities occurred. Brain–behavior correlations showed that alpha-power dynamics from List 1 to List 5 encoding predicted subsequent recall performance. The results suggest that, without intermittent retrieval, encoding becomes ineffective across lists. In contrast, with intermittent retrieval, there is a reset of the encoding process for each single list that makes encoding of later lists as effective as encoding of early lists. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

基于本体和云模型的电能质量信息状态监测平台

提出了一种适用于智能电网的电能质量信息状态监测平台。将本体技术引入到该平台建设中,建立了电能质量信息状态监测领域的领域本体,借助该领域本体可以实现电能质量信息的快速检索。建立的电能质量信息状态监测检索引擎可以在领域本体的指导下从电能质量数据库中提取出符合条件的数据集合,再将定制处理后的检索结果返回给用户。平台引入了云模型技术,基于云模型完成对电能质量信息的诊断,以实现电能质量信息的状态诊断和实时监测。实例展示介绍了平台的操作界面和具体实现界面,可见该平台具有一定的工程实用价值。     

基于移动Agent的电能质量监测数据管理方案

针对传统电能质量监测数据管理模式对网络条件要求高、检索效率低、可靠性差等问题,提出并实现了一种基于移动Agent的电能质量监测数据管理方案。将实现数据管理功能的程序封装为移动Agent,并从监测主站迁移到存储原始监测数据的子站,就地执行数据处理任务,仅将结果返回监测主站。利用Aglets平台实现所提方案并进行测试,结果表明此方案可以有效减少检索耗时,提高系统的网络适应性和可靠性,同时,方案无需对现有系统进行大量改造。     

基于形状特征的图像检索系统的设计

基于图像形状特征的图像检索方法已成为一个研究热点。为了便于在众多的图像信息库中快速、准确的检索出所需图像,研究了基于形状特征图像检索的主要步骤,且对步骤中所涉及的算法做了比较、选取、改进。利用MATLAB语言开发了一个基于形状特征的图像检索系统。并对该系统进行了测试,通过测试表明该系统可以有效的检索出相似的图像,且对于实验结果做了查全率和查准率的计算与分析,结果证明该系统切实可行具有一定的推广价值和使用价值。     

改进的强度相干成像室内实验方法

设计了一种新的强度相干成像室内实验方法,以简化现有强度相干实验过程,获取接近实际观测的测量数据。首先,分析了强度相干成像原理及影响成像质量的因素;介绍了现有强度相干成像实验方法并分析其存在的不足。然后,利用赝热光源和CCD设计了一种新的强度相干成像方法;介绍了利用此种方法模拟强度相干成像的原理及特点。最后,进行了室内强度相干成像实验,验证了提出方法的可行性。实验结果表明:利用提出的实验方法能够较好地测量目标的空间功率谱,测量噪声主要分布在高频部分;当测量信噪比大于20时,利用相位恢复方法可恢复获得较好的目标光强分布图像。实验显示,提出的成像方法能够较好地模拟强度相干成像,实验中能够较为方便地调节光强随机涨落并观测基线参数,实现对小角直径目标的有效成像。     

Evaluation of novelty metrics for sentence-level novelty mining

This work addresses the problem of detecting novel sentences from an incoming stream of text data, by studying the performance of different novelty metrics, and proposing a mixed metric that is able to adapt to different performance requirements. Existing novelty metrics can be divided into two types, symmetric and asymmetric, based on whether the ordering of sentences is taken into account. After a comparative study of several different novelty metrics, we observe complementary behavior in the two types of metrics. This finding motivates a new framework of novelty measurement, i.e. the mixture of both symmetric and asymmetric metrics. This new framework of novelty measurement performs superiorly under different performance requirements varying from high-precision to high-recall as well as for data with different percentages of novel sentences. Because it does not require any prior information, the new metric is very suitable for real-time knowledge base applications such as novelty mining systems where no training data is available beforehand.