Experience Does Not Equal Expertise in Recognizing Infrequent Incoming Gunfire: Neural Markers for Experience and Task Expertise at Peak Behavioral Performance

For a soldier, decisions to use force can happen rapidly and sometimes lead to undesired consequences. In many of these situations, there is a rapid assessment by the shooter that recognizes a threat and responds to it with return fire. But the neural processes underlying these rapid decisions are largely unknown, especially amongst those with extensive weapons experience and expertise. In this paper, we investigate differences in weapons experts and non-experts during an incoming gunfire detection task. Specifically, we analyzed the electroencephalography (EEG) of eleven expert marksmen/soldiers and eleven non-experts while they listened to an audio scene consisting of a sequence of incoming and non-incoming gunfire events. Subjects were tasked with identifying each event as quickly as possible and committing their choice via a motor response. Contrary to our hypothesis, experts did not have significantly better behavioral performance or faster response time than novices. Rather, novices indicated trends of better behavioral performance than experts. These group differences were more dramatic in the EEG correlates of incoming gunfire detection. Using machine learning, we found condition-discriminating EEG activity among novices showing greater magnitude and covering longer periods than those found in experts. We also compared group-level source reconstruction on the maximum discriminating neural correlates and found that each group uses different neural structures to perform the task. From condition-discriminating EEG and source localization, we found that experts perceive more categorical overlap between incoming and non-incoming gunfire. Consequently, the experts did not perform as well behaviorally as the novices. We explain these unexpected group differences as a consequence of experience with gunfire not being equivalent to expertise in recognizing incoming gunfire.     

Determinants of the hierarchy of humoral immune responsiveness during ontogeny.

A model system of ontogeny was utilized to investigate the development of humoral immunity in both AKR and BALB/c mice. Lethally irradiated adult mice were reconstituted with syngeneic fetal or neonatal liver. These mice were immunized at various times after reconstitution with a series of eight antigens: the bacteriophages F2, phiX-174, and T4; the hapten carrier complexes 2,4 dinitrophenyl-bovine serum albumin and fluorescein-bovine serum albumin; and the small proteins: hen egg lysozyme, sperm whale myoglobin, and bovine pancreatic ribonuclease. Subsequent antibody production to the antigens was assayed with either a direct or a modified bacteriophage neutralization technique. Individual mice responded to the various antigens in a sequential pattern which was basically the same for all mice within each strain. However, there was a marked difference between the two strains in the time at which they developed responsiveness to myoglobin. In order to begin to delineate the separate roles played by B and T cells in the generation of this hierarchical response pattern during ontogeny, the development of anti-DNP and anti-FTC activity was examined in carrier-primed mice. Results of this experiment indicated that functional B cell specificities for the two haptens arise at different times during ontogeny. Further studies are needed to determine whether the hierarchical pattern of immune responsiveness observed for the other antigens is a function of sequential appearance of B cell specificities, T cell specificities, or both.     

Haematological observations on a hibernating tuatara,Sphenodon punctatus

Abstract

Quantitative and biochemical observations were made on the peripheral blood of a hibernating female tuatara. The packed red cell volume (haematocrit) was 30%. There were about 260 000 erythrocytes and 5000 leucocytes per mm³ blood. Lymphocytes and neutrophils were the predominant leucocytes, followed by monocytes, eosinophils, and basophils. Haemoglobin, plasma protein, glucose, sodium, potassium, cholesterol, and triglyceride levels were determined. These haematological data are compared with data from the same animal obtained during the active summer period.     

High genetic diversity is not essential for successful introduction

Some introduced populations thrive and evolve despite the presumed loss of diversity at introduction. We aimed to quantify the amount of genetic diversity retained at introduction in species that have shown evidence of adaptation to their introduced environments. Samples were taken from native and introduced ranges of Arctotheca populifolia and Petrorhagia nanteuilii. Using microsatellite data, we identified the source for each introduction, estimated genetic diversity in native and introduced populations, and calculated the amount of diversity retained in introduced populations. These values were compared to those from a literature review of diversity in native, confamilial populations and to estimates of genetic diversity retained at introduction. Gene diversity in the native range of both species was significantly lower than for confamilials. We found that, on average, introduced populations showing evidence of adaptation to their new environments retained 81% of the genetic diversity from the native range. Introduced populations of P. nanteuilii had higher genetic diversity than found in the native source populations, whereas introduced populations of A. populifolia retained only 14% of its native diversity in one introduction and 1% in another. Our literature review has shown that most introductions demonstrating adaptive ability have lost diversity upon introduction. The two species studied here had exceptionally low native range genetic diversity. Further, the two introductions of A. populifolia represent the largest percentage loss of genetic diversity in a species showing evidence of substantial morphological change in the introduced range. While high genetic diversity may increase the likelihood of invasion success, the species examined here adapted to their new environments with very little neutral genetic diversity. This finding suggests that even introductions founded by small numbers of individuals have the potential to become invasive.     

LRP6 Enhances Glucose Metabolism by Promoting TCF7L2-Dependent Insulin Receptor Expression and IGF Receptor Stabilization in Humans

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Highlights? Nondiabetic LRP6 mutation carriers are hyperinsulinemic and insulin resistant ? IR expression is reduced in skeletal muscles of the LRP6 mutation carriers ? Wnt/LRP6 regulate the insulin receptor and IGFR expression ? The LRP6 mutation reduces TCF7L2-dependent IR expression and enhances mTOR activity     

Is MHC diversity a better marker for conservation than neutral genetic diversity? A case study of two contrasting dolphin populations

Genetic diversity is essential for populations to adapt to changing environments. Measures of genetic diversity are often based on selectively neutral markers, such as microsatellites. Genetic diversity to guide conservation management, however, is better reflected by adaptive markers, including genes of the major histocompatibility complex (MHC). Our aim was to assess MHC and neutral genetic diversity in two contrasting bottlenose dolphin (Tursiops aduncus) populations in Western Australia—one apparently viable population with high reproductive output (Shark Bay) and one with lower reproductive output that was forecast to decline (Bunbury). We assessed genetic variation in the two populations by sequencing the MHC class II DQB, which encompasses the functionally important peptide binding regions (PBR). Neutral genetic diversity was assessed by genotyping twenty‐three microsatellite loci. We confirmed that MHC is an adaptive marker in both populations. Overall, the Shark Bay population exhibited greater MHC diversity than the Bunbury population—for example, it displayed greater MHC nucleotide diversity. In contrast, the difference in microsatellite diversity between the two populations was comparatively low. Our findings are consistent with the hypothesis that viable populations typically display greater genetic diversity than less viable populations. The results also suggest that MHC variation is more closely associated with population viability than neutral genetic variation. Although the inferences from our findings are limited, because we only compared two populations, our results add to a growing number of studies that highlight the usefulness of MHC as a potentially suitable genetic marker for animal conservation. The Shark Bay population, which carries greater adaptive genetic diversity than the Bunbury population, is thus likely more robust to natural or human‐induced changes to the coastal ecosystem it inhabits.