Neural correlates of true and false memory in mild cognitive impairment

The goal of this research was to investigate the changes in neural processing in mild cognitive impairment. We measured phase synchrony, amplitudes, and event-related potentials in veridical and false memory to determine whether these differed in participants with mild cognitive impairment compared with typical, age-matched controls. Empirical mode decomposition phase locking analysis was used to assess synchrony, which is the first time this analysis technique has been applied in a complex cognitive task such as memory processing. The technique allowed assessment of changes in frontal and parietal cortex connectivity over time during a memory task, without a priori selection of frequency ranges, which has been shown previously to influence synchrony detection. Phase synchrony differed significantly in its timing and degree between participant groups in the theta and alpha frequency ranges. Timing differences suggested greater dependence on gist memory in the presence of mild cognitive impairment. The group with mild cognitive impairment had significantly more frontal theta phase locking than the controls in the absence of a significant behavioural difference in the task, providing new evidence for compensatory processing in the former group. Both groups showed greater frontal phase locking during false than true memory, suggesting increased searching when no actual memory trace was found. Significant inter-group differences in frontal alpha phase locking provided support for a role for lower and upper alpha oscillations in memory processing. Finally, fronto-parietal interaction was significantly reduced in the group with mild cognitive impairment, supporting the notion that mild cognitive impairment could represent an early stage in Alzheimer’s disease, which has been described as a ‘disconnection syndrome’.

Research practices that can prevent an inflation of false-positive rates

Recent studies have indicated that research practices in psychology may be susceptible to factors that increase false-positive rates, raising concerns about the possible prevalence of false-positive findings. The present article discusses several practices that may run counter to the inflation of false-positive rates. Taking these practices into account would lead to a more balanced view on the false-positive issue. Specifically, we argue that an inflation of false-positive rates would diminish, sometimes to a substantial degree, when researchers (a) have explicit a priori theoretical hypotheses, (b) include multiple replication studies in a single paper, and (c) collect additional data based on observed results. We report findings from simulation studies and statistical evidence that support these arguments. Being aware of these preventive factors allows researchers not to overestimate the pervasiveness of false-positives in psychology and to gauge the susceptibility of a paper to possible false-positives in practical and fair ways.

Optimized hash for network path encoding with minimized false positives

The Bloom filter is a space efficient randomized data structure for representing a set and supporting membership queries. Bloom filters intrinsically allow false positives. However, the space savings they offer outweigh the disadvantage if the false positive rates are kept sufficiently low. Inspired by the recent application of the Bloom filter in a novel multicast forwarding fabric, this paper proposes a variant of the Bloom filter, the optihash. The optihash introduces an optimization for the false positive rate at the stage of Bloom filter formation using the same amount of space at the cost of slightly more processing than the classic Bloom filter. Often Bloom filters are used in situations where a fixed amount of space is a primary constraint. We present the optihash as a good alternative to Bloom filters since the amount of space is the same and the improvements in false positives can justify the additional processing. Specifically, we show via simulations and numerical analysis that using the optihash the false positives occurrences can be reduced and controlled at a cost of small additional processing. The simulations are carried out for in-packet forwarding. In this framework, the Bloom filter is used as a compact link/route identifier and it is placed in the packet header to encode the route. At each node, the Bloom filter is queried for membership in order to make forwarding decisions. A false positive in the forwarding decision is translated into packets forwarded along an unintended outgoing link. By using the optihash, false positives can be reduced. The optimization processing is carried out in an entity termed the Topology Manger which is part of the control plane of the multicast forwarding fabric. This processing is only carried out on a per-session basis, not for every packet. The aim of this paper is to present the optihash and evaluate its false positive performances via simulations in order to measure the influence of different parameters on the false positive rate. The false positive rate for the optihash is then compared with the false positive probability of the classic Bloom filter.

False-positive results of a rapid K39-based strip test and Chagas disease

Background: The definitive diagnosis of visceral. leishmaniasis (VL) requires invasive procedures with demonstration of amastigotes in tissue or promastigotes in culture. Unfortunately, these approaches require laboratory materials not available in poor countries where the disease is endemic. The correct diagnosis of VL is important, and made more difficult by the fact that several common tropical diseases such as malaria, disseminated tuberculosis, and enteric fever share the same clinical presentation. Serological tests have been developed to replace parasitological diagnosis in the field. A commercially available K39-based strip test for VL has been developed for this purpose. The endemic area of leishmaniasis in Brazil overlaps the endemic area of Chagas disease, a disease that can cause false-positive serological test results. The aim of this study was to evaluate the incidence of false-positive exams using a rapid test for VL in patients with Chagas disease. Methods: A rapid test based on the recombinant K39 antigen of Leishmania was used in: (1) 30 patients with confirmed Chagas disease, (2) 30 patients with a serological diagnosis of Chagas disease by ELISA, indirect immunofluorescence, indirect hemagglutination, and chemiluminescence, (3) 30 healthy patients from a non-endemic area as the control group, (4) 30 patients with confirmed VL, and (5) 20 patients with proved cutaneous leishmaniasis. Results: The sensitivity and specificity of the rapid strip test were 100% when compared with healthy volunteers and those with confirmed Chagas disease. One false-positive result occurred in the group with Chagas disease diagnosed by serological tests (specificity of 96%). Conclusion: The rapid test based on recombinant K39 is a useful diagnostic assay, and a false-positive result rarely occurs in patients with a serological diagnosis of Chagas disease. (C) 2008 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Uncovering false positives on a virtual screening search for cruzain inhibitors

Some unexpected promiscuous inhibitors were observed in a virtual screening protocol applied to select cruzain inhibitors from the ZINC database. Physical-chemical and pharmacophore model filters were used to reduce the database size. The selected compounds were docked into the cruzain active site. Six hit compounds were tested as inhibitors. Although the compounds were designed to be nucleophilically attacked by the catalytic cysteine of cruzain, three of them showed typical promiscuous behavior, revealing that false positives are a prevalent concern in VS programs. (C) 2007 Elsevier Ltd. All rights reserved.

Directors' duties to stakeholders : a reform proposal based on three false assumptions

The Corporations and Markets Advisory Committee has been asked to consider whether the duties of directors under the Corporations Act 2001 (Cth) should be broadened to require directors to take into account the interests of stakeholder groups other than shareholders when making corporate decisions. In this article, the author argues that the existing statutory duties of directors in Australia should remain unchanged. The existing duties of directors, in particular the overriding duty of directors to act in the best interests of the company, already accommodates consideration of stakeholder interests by directors if the decision is justifiable as being in the company's best interests. Furthermore, corporate culture and norms are moving towards embracing stakeholder engagement, again with the implicit recognition that integrating stakeholder considerations within the decision-making processes of companies is integral to achieving long-term sustainable growth.

The consistency of false suggestions moderates children`s reports of a single instance of a repeated event: predicting increases and decreases in suggestibility.

Participants (6- and 7-year-olds, N = 130) participated in classroom activities four times. Children were interviewed about the final occurrence (target event) either 1 week or 4 weeks later, during which half of the event items were described inaccurately. Half of these suggestions were consistent with the theme of the detail across the occurrences (e.g., always sat on a kind of floor mat) or were inconsistent (e.g., sat on a chair). When memory for the target event was tested 1 day later, children falsely recognized fewer inconsistent suggestions than consistent suggestions, especially compared with a control group of children who experienced the event just one time. Furthermore, the longer delay reduced accuracy only for consistent suggestions. Source-monitoring ability was strongly and positively related to resistance to suggestions, and encouraging children to identify the source of false suggestions allowed them to retract a significant proportion of their reports of inconsistent suggestions but not of consistent suggestions. The results suggest that the gist consistency of suggestions determines whether event repetition increases or decreases suggestibility.

How well does the gudjonsson suggestibility scale for children, version 2 predict the recall of false details among children with and without intellectual disabilities?

Purpose. This study explored the effectiveness of the Gudjonsson Suggestibility Scale for Children, version 2 in predicting the tendency of older school-aged children (with and without intellectual disabilities) to generate errors in an independent suggestibility paradigm.

Method. Sixty-nine children with an intellectual disability (aged 9-14 years) and 50 mainstream children matched for chronological age participated in a 30-minute magic show that was staged at their school. Three days later, the children participated in a separate biasing interview that provided seven true and seven false details about the magic show. The following day, the children participated in a second interview where they were required to recall the magic show in their own words and answer a series of cued-recall questions. Between 1 and 2 weeks later, the children were administered the Gudjonsson Suggestibility Scale-2 (GSS-2).

Results. While there was no significant association between performance on the GSS-2 and the independent suggestibility paradigm for the children with an intellectual disability, the chronological age-matched children's yield scores predicted their reporting of both false-new details and false-interviewer suggestions for the independent event.

Conclusion. When predicting children's recall of false details, the GSS-2 appears to be more useful with mainstream school-aged children compared with children who have an intellectual disability.

The usefulness of suggestibility scales in predicting children's false reports of events

This thesis examined the nature and strength of the relationship between children's performance on suggestibility scales and their recall of independent events. It demonstrated that whilst standardised scales of suggestibility may be useful in predicting children's reporting of false information, there are clear boundaries to their usefulness. The clinical portfolio examines and discusses the impact that exposure to family violence has on children's functioning across development.