40 research outputs found

    Functional architecture of reward learning in mushroom body extrinsic neurons of larval Drosophila.

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    The brain adaptively integrates present sensory input, past experience, and options for future action. The insect mushroom body exemplifies how a central brain structure brings about such integration. Here we use a combination of systematic single-cell labeling, connectomics, transgenic silencing, and activation experiments to study the mushroom body at single-cell resolution, focusing on the behavioral architecture of its input and output neurons (MBINs and MBONs), and of the mushroom body intrinsic APL neuron. Our results reveal the identity and morphology of almost all of these 44 neurons in stage 3 Drosophila larvae. Upon an initial screen, functional analyses focusing on the mushroom body medial lobe uncover sparse and specific functions of its dopaminergic MBINs, its MBONs, and of the GABAergic APL neuron across three behavioral tasks, namely odor preference, taste preference, and associative learning between odor and taste. Our results thus provide a cellular-resolution study case of how brains organize behavior

    Confidence in uncertainty: Error cost and commitment in early speech hypotheses

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    © 2018 Loth et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Interactions with artificial agents often lack immediacy because agents respond slower than their users expect. Automatic speech recognisers introduce this delay by analysing a user’s utterance only after it has been completed. Early, uncertain hypotheses of incremental speech recognisers can enable artificial agents to respond more timely. However, these hypotheses may change significantly with each update. Therefore, an already initiated action may turn into an error and invoke error cost. We investigated whether humans would use uncertain hypotheses for planning ahead and/or initiating their response. We designed a Ghost-in-the-Machine study in a bar scenario. A human participant controlled a bartending robot and perceived the scene only through its recognisers. The results showed that participants used uncertain hypotheses for selecting the best matching action. This is comparable to computing the utility of dialogue moves. Participants evaluated the available evidence and the error cost of their actions prior to initiating them. If the error cost was low, the participants initiated their response with only suggestive evidence. Otherwise, they waited for additional, more confident hypotheses if they still had time to do so. If there was time pressure but only little evidence, participants grounded their understanding with echo questions. These findings contribute to a psychologically plausible policy for human-robot interaction that enables artificial agents to respond more timely and socially appropriately under uncertainty

    The Open Anchoring Quest Dataset: Anchored Estimates from 96 Studies on Anchoring Effects

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    People’s estimates are biased toward previously considered numbers (anchoring). We have aggregated all available data from anchoring studies that included at least two anchors into one large dataset. Data were standardized to comprise one estimate per row, coded according to a wide range of variables, and are available for download and analyses online (https://metaanalyses.shinyapps.io/OpAQ/). Because the dataset includes both original and meta-data it allows for fine-grained analyses (e.g., correlations of estimates for different tasks) but also for meta-analyses (e.g., effect sizes for anchoring effects)

    Serotonin Reduction in Post-acute Sequelae of Viral Infection

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    Post-acute sequelae of COVID-19 (PASC, Long COVID ) pose a significant global health challenge. The pathophysiology is unknown, and no effective treatments have been found to date. Several hypotheses have been formulated to explain the etiology of PASC, including viral persistence, chronic inflammation, hypercoagulability, and autonomic dysfunction. Here, we propose a mechanism that links all four hypotheses in a single pathway and provides actionable insights for therapeutic interventions. We find that PASC are associated with serotonin reduction. Viral infection and type I interferon-driven inflammation reduce serotonin through three mechanisms: diminished intestinal absorption of the serotonin precursor tryptophan; platelet hyperactivation and thrombocytopenia, which impacts serotonin storage; and enhanced MAO-mediated serotonin turnover. Peripheral serotonin reduction, in turn, impedes the activity of the vagus nerve and thereby impairs hippocampal responses and memory. These findings provide a possible explanation for neurocognitive symptoms associated with viral persistence in Long COVID, which may extend to other post-viral syndromes

    Quantitative sensorische Testung bei Handdenervierung

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    Postoperative long-term developments after surgical wrist denervation have already been investigated several times. The evaluation of the operation has so far been focused on the development of pain and strength as well as mobility. On the other hand, possible changes in sensitivity after the elimination of nerve branches have not yet been quantified. This study mainly assesses sensory loss of function. The study group comprises 42 patients. In a postoperative interval between 4.4 and 13.5 years the group was evaluated and examined after denervation according to Wilhelm at chronic pain. A survey was established in order to compare the results of the examination to a clinical context. The protocol of quantitative sensory testing (QST) of the German Research Association for Neuropathic Pain (DFNS was used to measure somatosensory changes over the operated wrist. In 7 tests, 13 different thermal and mechanical perception and pain thresholds above the denervated hand were determined. For further data analysis, an intraindividual comparison of the operated side with the control area of the non-operated hand and a somatosensory phenotype of the investigated of the subject collectives. This phenotype was characterized by a statistically significant sensitive deficit only for the detection of non-painful stimuli mediated by thick, thin and non-myelinated nerve fibers. A central or peripheral sensitization could not be proven by the QST of the investigated collective. In a gender- and age-adapted group comparison with published QST reference data (Magerl et al. 2010), the results showed that the tactile detection mediated by A-beta fibers differs most frequently in the present study. As a result of the subjective questioning, a large part of the collective was found to have an improved postoperative pain situation in the long term. With the present study, both the concordance of the long-term results of the examination as well as the long-term effect of the operation can also be confirmed. Larger follow-up studies would be desirable in order to further investigate the significance of QST in denervation surgery and to establish it as a helpful tool as part of the course diagnosis

    Highly Active Superbulky Alkaline Earth Metal Amide Catalysts for Hydrogenation of Challenging Alkenes and Aromatic Rings

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    Two series of bulky alkaline earth (Ae) metal amide complexes have been prepared: Ae[N(TRIP)2]2 (1‐Ae) and Ae[N(TRIP)(DIPP)]2 (2‐Ae) (Ae=Mg, Ca, Sr, Ba; TRIP=SiiPr3, DIPP=2,6‐diisopropylphenyl). While monomeric 1‐Ca was already known, the new complexes have been structurally characterized. Monomers 1‐Ae are highly linear while the monomers 2‐Ae are slightly bent. The bulkier amide complexes 1‐Ae are by far the most active catalysts in alkene hydrogenation with activities increasing from Mg to Ba. Catalyst 1‐Ba can reduce internal alkenes like cyclohexene or 3‐hexene and highly challenging substrates like 1‐Me‐cyclohexene or tetraphenylethylene. It is also active in arene hydrogenation reducing anthracene and naphthalene (even when substituted with an alkyl) as well as biphenyl. Benzene could be reduced to cyclohexane but full conversion was not reached. The first step in catalytic hydrogenation is formation of an (amide)AeH species, which can form larger aggregates. Increasing the bulk of the amide ligand decreases aggregate size but it is unclear what the true catalyst(s) is (are). DFT calculations suggest that amide bulk also has a noticeable influence on the thermodynamics for formation of the (amide)AeH species. Complex 1‐Ba is currently the most powerful Ae metal hydrogenation catalyst. Due to tremendously increased activities in comparison to those of previously reported catalysts, the substrate scope in hydrogenation catalysis could be extended to challenging multi‐substituted unactivated alkenes and even to arenes among which benzene
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