A cautionary note on evidence-accumulation models of response inhibition in the stop-signal paradigm

The stop-signal paradigm is a popular procedure to investigate responseinhibition–the ability to stop ongoing responses. It consists of a choice responsetime (RT) task that is occasionally interrupted by a stop stimulussignaling participants to withhold their response. Performance in the stopsignalparadigm is often formalized as race between a set of go runners triggeredby the choice stimulus and a stop runner triggered by the stop signal.We investigated whether evidence-accumulation processes, which have beenwidely used in choice RT analysis, can serve as the runners in the stop-signalrace model and support the estimation of psychologically meaningful parameters.We examined two types of the evidence-accumulation architectures:the racing Wald model (Logan, Van Zandt, Verbruggen, & Wagenmakers, 2014) and a novel proposal based on the Lognormal race (Heathcote & Love,2012). Using a series of simulation studies and fits to empirical data, wefound that these models are not measurement models in the sense that thedata-generating parameters cannot be recovered in realistic experimentaldesigns

Visual ecology of aphids – a critical review on the role of colours in host finding

We review the rich literature on behavioural responses of aphids (Hemiptera: Aphididae) to stimuli of different colours. Only in one species there are adequate physiological data on spectral sensitivity to explain behaviour crisply in mechanistic terms. Because of the great interest in aphid responses to coloured targets from an evolutionary, ecological and applied perspective, there is a substantial need to expand these studies to more species of aphids, and to quantify spectral properties of stimuli rigorously. We show that aphid responses to colours, at least for some species, are likely based on a specific colour opponency mechanism, with positive input from the green domain of the spectrum and negative input from the blue and/or UV region. We further demonstrate that the usual yellow preference of aphids encountered in field experiments is not a true colour preference but involves additional brightness effects. We discuss the implications for agriculture and sensory ecology, with special respect to the recent debate on autumn leaf colouration. We illustrate that recent evolutionary theories concerning aphid–tree interactions imply far-reaching assumptions on aphid responses to colours that are not likely to hold. Finally we also discuss the implications for developing and optimising strategies of aphid control and monitoring

Diffusion versus linear ballistic accumulation: different models but the same conclusions about psychological processes?

Quantitative models for response time and accuracy are increasingly used as tools to draw conclusions about psychological processes. Here we investigate the extent to which these substantive conclusions depend on whether researchers use the Ratcliff diffusion model or the Linear Ballistic Accumulator model. Simulations show that the models agree on the effects of changes in the rate of information accumulation and changes in non-decision time, but that they disagree on the effects of changes in response caution. In fits to empirical data, however, the models tend to agree closely on the effects of an experimental manipulation of response caution. We discuss the implications of these conflicting results, concluding that real manipulations of caution map closely, but not perfectly to response caution in either model. Importantly, we conclude that inferences about psychological processes made from real data are unlikely to depend on the model that is used

Primary biliary cirrhosis and autoimmune cholangitis are not associated with coeliac disease in Crete

BACKGROUND: An increased prevalence of coeliac disease in patients with primary biliary cirrhosis has been recently reported. However, in other studies the association has not been confirmed. There have been no formal attempts to systematically evaluate patients with autoimmune cholangitis for coeliac disease. METHODS: Sera from 62 patients with primary biliary cirrhosis, 17 with autoimmune cholangitis and 100 blood donors were screened for anti-gliadin, anti-endomysial, anti-reticulin, and IgA class antibodies to guinea pig liver-derived tissue transglutaminase. Eighteen untreated coeliacs served as methodological controls. Analyses were performed by using the χ(2) and Fischer's exact tests. RESULTS: Anti-gliadin antibodies were detected in 21% of patients with primary biliary cirrhosis, 35% of patients with autoimmune cholangitis, and 3% of controls (p < 0.001). IgA class gliadin antibodies positivity was more pronounced in patients with Scheuer's stage III-IV disease (p < 0.05). Anti-transglutaminase antibodies were detected in 10% and in 18% of patients with primary biliary cirrhosis and autoimmune cholangitis respectively (p < 0.001). Anti-reticulin and anti-endomysial antibodies were negative in all patients. Duodenal biopsies were performed in 59% and 71% of patients with primary biliary cirrhosis and autoimmune cholangitis respectively, tested positive for at least one antibody class. No histological features of coeliac disease were found. CONCLUSIONS: We were unable to demonstrate an increased risk of coeliac disease in patients with primary biliary cirrhosis and autoimmune cholangitis. Our results confirm the previously reported high prevalence of false-positive anti-gliadin and guinea pig liver-derived anti-tissue transglutaminase antibodies in patients with chronic liver disease

Fatal Cardiac Arrhythmia and Long-QT Syndrome in a New Form of Congenital Generalized Lipodystrophy with Muscle Rippling (CGL4) Due to PTRF-CAVIN Mutations

We investigated eight families with a novel subtype of congenital generalized lipodystrophy (CGL4) of whom five members had died from sudden cardiac death during their teenage years. ECG studies revealed features of long-QT syndrome, bradycardia, as well as supraventricular and ventricular tachycardias. Further symptoms comprised myopathy with muscle rippling, skeletal as well as smooth-muscle hypertrophy, leading to impaired gastrointestinal motility and hypertrophic pyloric stenosis in some children. Additionally, we found impaired bone formation with osteopenia, osteoporosis, and atlanto-axial instability. Homozygosity mapping located the gene within 2 Mbp on chromosome 17. Prioritization of 74 candidate genes with GeneDistiller for high expression in muscle and adipocytes suggested PTRF-CAVIN (Polymerase I and transcript release factor/Cavin) as the most probable candidate leading to the detection of homozygous mutations (c.160delG, c.362dupT). PTRF-CAVIN is essential for caveolae biogenesis. These cholesterol-rich plasmalemmal vesicles are involved in signal-transduction and vesicular trafficking and reside primarily on adipocytes, myocytes, and osteoblasts. Absence of PTRF-CAVIN did not influence abundance of its binding partner caveolin-1 and caveolin-3. In patient fibroblasts, however, caveolin-1 failed to localize toward the cell surface and electron microscopy revealed reduction of caveolae to less than 3%. Transfection of full-length PTRF-CAVIN reestablished the presence of caveolae. The loss of caveolae was confirmed by Atomic Force Microscopy (AFM) in combination with fluorescent imaging. PTRF-CAVIN deficiency thus presents the phenotypic spectrum caused by a quintessential lack of functional caveolae

The host range of beet yellowing viruses among common arable weed species

Twenty common arable weed species were inoculated using Myzus persicae to transmit beet yellows virus (BYV), beet mild yellowing virus (BMYV), and an isolate of beet western yellows viruses (BWYV) that did not infect beet. The viruses were detected by enzyme-linked immunosorbent assay (ELISA), in which monoclonal antibodies distinguished between BMYV and BWYV, and by aphid transmissions to indicator host plants. Spergula arvensis, Stellaria media, Lamium purpureum and Papaver rhoeas were susceptible to all three viruses whereas Senecio vulgaris, Capsella bursa-pastoris, Anagallis arvensis and Chrysanthemum segetum were susceptible to both BMYV and BWYV, and Matricaria perforata, Raphanus raphanistrum, Veronica persica, Urtica urens and Viola arvensis were susceptible to BWYV only. Atriplex patula, Chenopodium album and Portulaca oleracea were susceptible to BW only. Myosotis arvensis, Silene alba, Poa annua and Solanum nigrum were not susceptible to any of the viruses. Portulaca oleracea was shown for the first time to be a host of BW, and C. segetum a host of BMYV and BWYV. In spring 1991, 8% of weeds sampled in a field of autumn-sown oilseed rape contained BWYV. Tests on weeds collected from an area of 'set-side' adjacent to sugar beet showed that 3% contained BMYV and 3% BWYV. No sampled weeds were infected with BYV. The role of weeds in the epidemiology of sugar beet virus yellows is discussed