Recent studies suggest that neurons in sensorimotor circuits involved in perceptual decision-making also play a role in decision confidence. In these studies, confidence is often considered to be an ...optimal readout of the probability that a decision is correct. However, the information leading to decision accuracy and the report of confidence often covaried, leaving open the possibility that there are actually two dissociable signal types in the brain: signals that correlate with decision accuracy (optimal confidence) and signals that correlate with subjects’ behavioral reports of confidence (subjective confidence). We recorded neuronal activity from a sensorimotor decision area, the superior colliculus (SC) of monkeys, while they performed two different tasks. In our first task, decision accuracy and confidence covaried, as in previous studies. In our second task, we implemented a motion discrimination task with stimuli that were matched for decision accuracy but produced different levels of confidence, as reflected by behavioral reports. We used a multivariate decoder to predict monkeys’ choices from neuronal population activity. As in previous studies on perceptual decision-making mechanisms, we found that neuronal decoding performance increased as decision accuracy increased. However, when decision accuracy was matched, performance of the decoder was similar between high and low subjective confidence conditions. These results show that the SC likely signals optimal decision confidence similar to previously reported cortical mechanisms, but is unlikely to play a critical role in subjective confidence. The results also motivate future investigations to determine where in the brain signals related to subjective confidence reside.
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Objective The inpatient treatment for anorexia nervosa (AN) is part of cross-sectoral networking. However, many patients relapse and need to be readmitted. To obtain a straightened improvement, a ...weight-mapping based treatment approach might help to improve the patients skills in dealing with symptoms and improve the cross-sectoral networking. Method Data of adult women with AN (N = 304) who received inpatient treatment and either received interval treatment (n = 179) or not (n = 125) were analyzed. Of these, 225 patient complete a follow-up measurement after an average of 25 months. Treatment outcome variables were body mass index and subscales of the Eating Disorder Inventory-2 at admission, discharge, and follow up. Results Across measurements, the interval treatment group had larger increases in body mass index and larger decreases in drive for thinness and binge/purge symptoms than the no interval Treatment Group. These differences did not to seem to be driven by longer treatment duration. Discussion Our data suggest that interval treatment for AN is effective and may even superior to conventional single inpatient treatment. Given the observational nature of this study, however, controled studies are necessary to corroborate these findings.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Reductive electrosynthesis has faced long-standing challenges in applications to complex organic substrates at scale. Here, we show how decades of research in lithium-ion battery materials, ...electrolytes, and additives can serve as an inspiration for achieving practically scalable reductive electrosynthetic conditions for the Birch reduction. Specifically, we demonstrate that using a sacrificial anode material (magnesium or aluminum), combined with a cheap, nontoxic, and water-soluble proton source (dimethylurea), and an overcharge protectant inspired by battery technology tris(pyrrolidino)phosphoramide can allow for multigram-scale synthesis of pharmaceutically relevant building blocks. We show how these conditions have a very high level of functional-group tolerance relative to classical electrochemical and chemical dissolving-metal reductions. Finally, we demonstrate that the same electrochemical conditions can be applied to other dissolving metal-type reductive transformations, including McMurry couplings, reductive ketone deoxygenations, and epoxide openings.
Current dominant views hold that perceptual confidence reflects the probability that a decision is correct. Although these views have enjoyed some empirical support, recent behavioral results ...indicate that confidence and the probability of being correct can be dissociated. An alternative hypothesis suggests that confidence instead reflects the magnitude of evidence in favor of a decision while being relatively insensitive to the evidence opposing the decision. We considered how this alternative hypothesis might be biologically instantiated by developing a simple neural network model incorporating a known property of sensory neurons: tuned inhibition. The key idea of the model is that the level of inhibition that each accumulator unit receives from units with the opposite tuning preference, i.e. its inhibition 'tuning', dictates its contribution to perceptual decisions versus confidence judgments, such that units with higher tuned inhibition (computing relative evidence for different perceptual interpretations) determine perceptual discrimination decisions, and units with lower tuned inhibition (computing absolute evidence) determine confidence. We demonstrate that this biologically plausible model can account for several counterintuitive findings reported in the literature where confidence and decision accuracy dissociate. By comparing model fits, we further demonstrate that a full complement of behavioral data across several previously published experimental results-including accuracy, reaction time, mean confidence, and metacognitive sensitivity-is best accounted for when confidence is computed from units without, rather than units with, tuned inhibition. Finally, we discuss predictions of our results and model for future neurobiological studies. These findings suggest that the brain has developed and implements this alternative, heuristic theory of perceptual confidence computation by relying on the diversity of neural resources available.
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Many believe that humans can 'perceive unconsciously' - that for weak stimuli, briefly presented and masked, above-chance discrimination is possible without awareness. Interestingly, an online survey ...reveals that most experts in the field recognize the lack of convincing evidence for this phenomenon, and yet they persist in this belief. Using a recently developed bias-free experimental procedure for measuring subjective introspection (confidence), we found no evidence for unconscious perception; participants' behavior matched that of a Bayesian ideal observer, even though the stimuli were visually masked. This surprising finding suggests that the thresholds for subjective awareness and objective discrimination are effectively the same: if objective task performance is above chance, there is likely conscious experience. These findings shed new light on decades-old methodological issues regarding what it takes to consider a neurobiological or behavioral effect to be 'unconscious,' and provide a platform for rigorously investigating unconscious perception in future studies.
Bicyclic hydrocarbons, and bicyclo1.1.1pentanes (BCPs) in particular, are playing an emerging role as saturated bioisosteres in pharmaceutical, agrochemical and materials chemistry. Taking advantage ...of strain-release strategies, prior synthetic studies have featured the synthesis of bridgehead-substituted (C1, C3) BCPs from 1.1.1propellane. Here, we describe an approach to access multisubstituted BCPs via intramolecular cyclization. In addition to C1,C3-disubstituted BCPs, this method also enables the construction of underexplored multisubstituted (C1, C2 and C3) BCPs from readily accessible cyclobutanones. The broad generality of this method has also been examined through the synthesis of a variety of other caged bicyclic molecules, ranging from 2.1.1 to 3.2.1 scaffolds. The modularity afforded by the pendant bridgehead boron pinacol esters generated during the cyclization reaction has been demonstrated through several downstream functionalizations, highlighting the ability of this approach to enable the programmed and divergent synthesis of multisubstituted bicyclic hydrocarbons.
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Abstract Since 2005, the standard of care for patients with newly diagnosed glioblastoma (GBM) has consisted of maximal resection followed by radiotherapy plus daily temozolomide (TMZ), followed by ...maintenance TMZ. In patients selected for clinical trials, median overall survival (OS) and progression-free survival (PFS) with this regimen is 15 to 17 months and 6 to 7 months, respectively. There have been various, largely unsuccessful attempts to improve on this standard of care. With the FDA approval of the tumor-treating fields (TTFields) device, Optune, for recurrent GBM (2011), and the more recent EF-14 interim trial results and approval for newly diagnosed GBM patients, several questions have arisen. A roundtable of experts was convened at the 2015 ASCO meeting to engage in an open conversation and debate of the EF-14 results presented at that meeting and their implications for neuro-oncology practice and clinical research. In October 2015, subsequent to the roundtable discussion, TTFields received FDA approval for newly diagnosed GBM.
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Dynamic functional connectivity investigates how the interactions among brain regions vary over the course of an fMRI experiment. Such transitions between different individual connectivity states can ...be modulated by changes in underlying physiological mechanisms that drive functional network dynamics, e.g., changes in attention or cognitive effort. In this paper, we develop a multi-subject Bayesian framework where the estimation of dynamic functional networks is informed by time-varying exogenous physiological covariates that are simultaneously recorded in each subject during the fMRI experiment. More specifically, we consider a dynamic Gaussian graphical model approach where a non-homogeneous hidden Markov model is employed to classify the fMRI time series into latent neurological states. We assume the state-transition probabilities to vary over time and across subjects as a function of the underlying covariates, allowing for the estimation of recurrent connectivity patterns and the sharing of networks among the subjects. We further assume sparsity in the network structures via shrinkage priors, and achieve edge selection in the estimated graph structures by introducing a multi-comparison procedure for shrinkage-based inferences with Bayesian false discovery rate control. We evaluate the performances of our method vs alternative approaches on synthetic data. We apply our modeling framework on a resting-state experiment where fMRI data have been collected concurrently with pupillometry measurements, as a proxy of cognitive processing, and assess the heterogeneity of the effects of changes in pupil dilation on the subjects' propensity to change connectivity states. The heterogeneity of state occupancy across subjects provides an understanding of the relationship between increased pupil dilation and transitions toward different cognitive states.
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Zylberberg et al. Zylberberg, Barttfeld, & Sigman (Frontiers in Integrative Neuroscience, 6; 79,
2012
),
Frontiers in Integrative Neuroscience 6
:79 found that confidence decisions, but not ...perceptual decisions, are insensitive to evidence against a selected perceptual choice. We present a signal detection theoretic model to formalize this insight, which gave rise to a counter-intuitive empirical prediction: that depending on the observer’s perceptual choice, increasing task performance can be associated with
decreasing
metacognitive sensitivity (i.e., the trial-by-trial correspondence between confidence and accuracy). The model also provides an explanation as to why metacognitive sensitivity tends to be less than optimal in actual subjects. These predictions were confirmed robustly in a psychophysics experiment. In a second experiment we found that, in at least some subjects, the effects were replicated even under performance feedback designed to encourage optimal behavior. However, some subjects did show improvement under feedback, suggesting the tendency to ignore evidence against a selected perceptual choice may be a heuristic adopted by the perceptual decision-making system, rather than reflecting inherent biological limitations. We present a Bayesian modeling framework that explains why this heuristic strategy may be advantageous in real-world contexts.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, ODKLJ, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Aim: Identifying traits that enhance the success of animals in unhospitable climates helps to understand biogeographical patterns and to predict the consequences of climatic changes. On temperate ...mountains, traits that increase cold performance potentially allow species to colonize higher elevations. We first tested the importance of morphological traits for the cold performance of bees. Second, we assessed the relevance of these traits for species distributional patterns by analysing intraspecific and interspecific trait shifts along elevational gradients. Location: National Park Berchtesgaden, Germany; Würzburg, Germany. Methods: We determined thermal activity thresholds by measuring signs of immobility along temperature gradients under laboratory conditions and related them to morphometric traits. We sampled bee communities at 34 sites along an elevation gradient in the northern Alps, measured for all species morphometric traits and thermal activity limits in the field, and analysed how trait measures changed with elevation within and across species. Results: Laboratory and field experiments revealed that bees with larger body size, longer hair and relatively short wings tolerated lower temperatures before reaching immobility and started being active in the field at lower temperatures than small, short-haired and long-winged species. In correspondence to these results, we found that morphometric traits increased (body size, hair length) or decreased (relative wing length) with increasing elevation in communities and, in case of body size, also within species. Main conclusions: Results of laboratory and field experiments and their reflectance in community- and species-level trends of morphological traits along elevational gradients underscore the adaptive nature of large body size, long hair and short wings for bees' thermal performance. Morphological traits expanding lower thermal limits probably contribute to the fitness of bees in cold environments and may simultaneously be under selection in a warming world.
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