Traditional test administration and proactive interference undermine visual-spatial working memory performance in schizophrenia-spectrum disorders.

Introduction Working-memory (WM) is a core cognitive deficit among individuals with Schizophrenia Spectrum Disorders (SSD). However, the underlying cognitive mechanisms of this deficit are less known. This study applies a modified version of the Corsi Block Test to investigate the role of proactive interference in visuospatial WM (VSWM) impairment in SSD. Methods Healthy and SSD participants completed a modified version of the Corsi Block Test involving both high (typical ascending set size from 4 to 7 items) and low (descending set size from 7 to 4 items) proactive interference conditions. Results The results confirmed that the SSD group performed worse overall relative to a healthy comparison group. More importantly, the SSD group demonstrated greater VSWM scores under low (Descending) versus high (Ascending) proactive interference; this pattern is opposite to that of healthy participants. Conclusions This differential pattern of performance supports that proactive interference associated with the traditional administration format contributes to VSWM impairment in SSD. Further research investigating associated neurocognitive mechanisms and the contribution of proactive interference across other domains of cognition in SSD is warranted.

Which came first: The lizard or the egg? Robustness in phylogenetic reconstruction of ancestral states.

Changes in parity mode between egg-laying (oviparity) and live-bearing (viviparity) have occurred repeatedly throughout vertebrate evolution. Oviparity is the ancestral amniote state, and viviparity has evolved many times independently within amniotes (especially in lizards and snakes), with possibly a few reversions to oviparity. In amniotes, the shelled egg is considered a complex structure that is unlikely to re-evolve if lost (i.e., it is an example of Dollo's Principle). However, a recent ancestral state reconstruction analysis concluded that viviparity was the ancestral state of squamate reptiles (lizards and snakes), and that oviparity re-evolved from viviparity many times throughout the evolutionary history of squamates. Here, we re-evaluate support for this provocative conclusion by testing the sensitivity of the analysis to model assumptions and estimates of squamate phylogeny. We found that the models and methods used for parity mode reconstruction are highly sensitive to the specific estimate of phylogeny used, and that the point estimate of phylogeny used to suggest that viviparity is the root state of the squamate tree is far from an optimal phylogenetic solution. The ancestral state reconstructions are also highly sensitive to model choice and specific values of model parameters. A method that is designed to account for biases in taxon sampling actually accentuates, rather than lessens, those biases with respect to ancestral state reconstructions. In contrast to recent conclusions from the same data set, we find that ancestral state reconstruction analyses provide highly equivocal support for the number and direction of transitions between oviparity and viviparity in squamates. Moreover, the reconstructions of ancestral parity state are highly dependent on the assumptions of each model. We conclude that the common ancestor of squamates was oviparous, and subsequent evolutionary transitions to viviparity were common, but reversals to oviparity were rare. The three putative reversals to oviparity with the strongest phylogenetic support occurred in the snakes Eryx jayakari and Lachesis, and the lizard, Liolaemus calchaqui. Our results emphasize that because the conclusions of ancestral state reconstruction studies are often highly sensitive to the methods and assumptions of analysis, researchers should carefully consider this sensitivity when evaluating alternative hypotheses of character-state evolution.

Multicolor dye-based flow structure visualization for seal-whisker geometry characterized by computer vision.

Pinniped vibrissae possess a unique and complex three-dimensional topography, which has beneficial fluid flow characteristics such as substantial reductions in drag, lift, and vortex induced vibration. To understand and leverage these effects, the downstream vortex dynamics must be studied. Dye visualization is a traditional qualitative method of capturing these downstream effects, specifically in comparative biological investigations where complex equipment can be prohibitive. High-fidelity numerical simulations or experimental particle image velocimetry are commonplace for quantitative high-resolution flow measurements, but are computationally expensive, require costly equipment, and can have limited measurement windows. This study establishes a method for extracting quantitative data from standard dye visualization experiments on seal whisker geometries by leveraging novel but intuitive computer vision techniques, which maintain simplicity and an advantageous large experimental viewing window while automating the extraction of vortex frequency, position, and advection. Results are compared to direct numerical simulation (DNS) data for comparable geometries. Power spectra and Strouhal numbers show consistent behavior between methods for a Reynolds number of 500, with minima at the canonical geometry wavelength of 3.43 and a peak frequency of 0.2 for a Reynolds number of 250. The vortex tracking reveals a clear increase in velocity from roll-up to 3.5 whisker diameters downstream, with a strong overlap with the DNS data but shows steady results beyond the limited DNS window. This investigation provides insight into a valuable bio-inspired engineering model while advancing an analytical methodology that can readily be applied to a broad range of comparative biological studies.

Targeted training: Converging evidence against the transferable benefits of online brain training on cognitive function.

There is strong incentive to improve our cognitive abilities, and brain training has emerged as a promising approach for achieving this goal. While the idea that extensive 'training' on computerized tasks will improve general cognitive functioning is appealing, the evidence to support this remains contentious. This is, in part, because of poor criteria for selecting training tasks and outcome measures resulting in inconsistent definitions of what constitutes transferable improvement to cognition. The current study used a targeted training approach to investigate whether training on two different, but related, working memory tasks (across two experiments, with 72 participants) produced transferable benefits to similar (quantified based on cognitive and neural profiles) untrained test tasks. Despite significant improvement on both training tasks, participants did not improve on either test task. In fact, performance on the test tasks after training were nearly identical to a passive control group. These results indicate that, despite maximizing the likelihood of producing transferable benefits, brain training does not generalize, even to very similar tasks. Our study calls into question the benefit of cognitive training beyond practice effects, and provides a new framework for future investigations into the efficacy of brain training.

Taxonomic revision of Ectyphus Gerstaecker, 1868 and Parectyphus Hesse, 1972 with a key to world Ectyphinae (Insecta, Diptera, Mydidae).

The Afrotropical Mydidae genera Ectyphus Gerstaecker, 1868 and Parectyphus Hesse, 1972 are revised. Six species of Ectyphus are recognised (Ectyphus abdominalis Bezzi, 1924, Ectyphus armipes Bezzi, 1924, Ectyphus capillatus Hesse, 1969, Ectyphus pinguis Gerstaecker, 1868, and Ectyphus pretoriensis Bezzi, 1924), of which one is newly described from Kenya, Ectyphus amboselisp. n. Two species, Ectyphus bitaeniatus Hesse, 1969 and Ectyphus flavidorsalis Hesse, 1969, are newly synonymised with Ectyphus pinguis. The monotypic genus Parectyphus Hesse, 1972 and the male of its type species Parectyphus namibiensis Hesse, 1972 are re-described while the female is described for the first time. Comments on the distribution of all species within biodiversity hotspots are given. A dichotomous identification key to the genera and species of world Ectyphinae is provided and illustrated keys to the world Ectyphinae are made available online in both dichotomous and multi-access, matrix-based formats.

Heterogeneity in the physiological states and pharmacological responses of differentiating 3T3-L1 preadipocytes.

Increases in key components of adipogenesis and lipolysis pathways correlate at the population-averaged level during adipogenesis. However, differentiating preadipocytes are highly heterogeneous in cellular and lipid droplet (LD) morphologies, and the degree to which individual cells follow population-averaged trends is unclear. In this study, we analyze the molecular heterogeneity of differentiating 3T3-L1 preadipocytes using immunofluorescence microscopy. Unexpectedly, we only observe a small percentage of cells with high simultaneous expression of markers for adipogenesis (peroxisome proliferator-activated receptor gamma [PPARgamma], CCAAT/enhancer-binding protein alpha, and adiponectin) and lipid accumulation (hormone-sensitive lipase, perilipin A, and LDs). Instead, we identify subpopulations of cells with negatively correlated expressions of these readouts. Acute perturbation of adipocyte differentiation with PPARgamma agonists, forskolin, and fatty acids induced subpopulation-specific effects, including redistribution of the percentage of cells in observed subpopulations and differential expression levels of PPARgamma. Collectively, our results suggested that heterogeneity observed during 3T3-L1 adipogenesis reflects a dynamic mixture of subpopulations with distinct physiological states.