Learning place cells, grid cells and invariances with excitatory and inhibitory plasticity

Neurons in the hippocampus and adjacent brain areas show a large diversity in their tuning to location and head direction, and the underlying circuit mechanisms are not yet resolved. In particular, it is unclear why certain cell types are selective to one spatial variable, but invariant to another. For example, place cells are typically invariant to head direction. We propose that all observed spatial tuning patterns – in both their selectivity and their invariance – arise from the same mechanism: Excitatory and inhibitory synaptic plasticity driven by the spatial tuning statistics of synaptic inputs. Using simulations and a mathematical analysis, we show that combined excitatory and inhibitory plasticity can lead to localized, grid-like or invariant activity. Combinations of different input statistics along different spatial dimensions reproduce all major spatial tuning patterns observed in rodents. Our proposed model is robust to changes in parameters, develops patterns on behavioral timescales and makes distinctive experimental predictions.BMBF, 01GQ1201, Lernen und Gedächtnis in balancierten Systeme

Obtención de diglicéridos a partir de subproductos del refinado de aceites vegetales mediante la esterificación catalizada por lipasas en ausencia de disolventes

Co-products of vegetable oil refining such as a mixed deodorizer distillate resulting from the refining of various vegetable oils, a crude distillate resulting from the physical refining of coconut oil and commercial mixtures of distilled sunflower and coconut fatty acids were used as starting materials for the enzymatic preparation of diglycerides. Reaction conditions (temperature, pressure, molar ratio) for the formation of diglycerides by lipase-catalyzed esterification/transesterification were studied using the mixed deodorizer distillate and glycerol as starting materials. The best results were obtained with the immobilized lipase B from Candida antarctica (Novozym 435) in vacuo at 60 °C leading to moderate proportions (~52%) of diglycerides. The proportion of diglycerides increased when residual acylglycerides of the co-products of vegetable oil refining were hydrolyzed prior to esterification. Thus, the esterification of hydrolyzed co-products of vegetable oil refining with glycerol led to high formation (62-72%) of diglycerides. Short-path vacuum distillation of the esterification products yielded distillation residues containing from 70% to 94% diglycerides. The proportions of fatty acids and monoglycerides in the distilled residues were quite low (≤ 1% and 1 to 3.9%, respectively). Immobilized lipases from Rhizomucor miehei and Thermomyces lanuginosus were less active as esterification biocatalysts.Subproductos del refinado de los aceites vegetales tales como el destilado obtenido en el desodorizador al refinar distintos aceites vegetales, el destilado crudo resultante de la refinación física del aceite de coco, y mezclas comerciales de los ácidos grasos obtenidos en la destilación de aceites de girasol y coco fueron utilizados como materiales de partida para la preparación enzimática de diglicéridos. Se estudiaron las condiciones de reacción (temperatura, presión, relación molar) para la formación de diglicéridos mediante esterificación/ transesterificación catalizada por lipasas usando la mezcla obtenida del desodorizador y glicerol como materiales de partida. Los mejores resultados se obtuvieron con lipasa B inmovilizada de Candida antarctica (Novozym 435) a vacío y 60 °C obteniéndose una concentración moderada (~52%) de diglicéridos. La proporción de diglicéridos aumentó cuando los aciglicéridos residuales de los subproductos de la refinación de los aceites vegetales fueron hidrolizados como paso previo a la esterificación. Así, la esterificación de subproductos hidrolizados del refinado de aceites vegetales con glicerol produjo una alta (62-72%) formación de diglicéridos. La posterior destilación a vacío de los productos de esta esterificación produjo destilados conteniendo del 70 al 94% de diglicéridos. Las proporciones de ácidos grasos y monoglicéridos en estos destilados fueron bastante bajas (≤ 1% y 1-3.9%, respectivamente). Las lipasas inmovilizadas de Rhizomucor miehei y Thermomyces lanuginosus fueron menos activas como biocatalizadores de esterificación

The Future of Human-AI Collaboration: A Taxonomy of Design Knowledge for Hybrid Intelligence Systems

Recent technological advances, especially in the field of machine learning, provide astonishing progress on the road towards artificial general intelligence. However, tasks in current real-world business applications cannot yet be solved by machines alone. We, therefore, identify the need for developing socio-technological ensembles of humans and machines. Such systems possess the ability to accomplish complex goals by combining human and artificial intelligence to collectively achieve superior results and continuously improve by learning from each other. Thus, the need for structured design knowledge for those systems arises. Following a taxonomy development method, this article provides three main contributions: First, we present a structured overview of interdisciplinary research on the role of humans in the machine learning pipeline. Second, we envision hybrid intelligence systems and conceptualize the relevant dimensions for system design for the first time. Finally, we offer useful guidance for system developers during the implementation of such applications

Exceptional Clinical Resistance and Variable Reservoir Competence

Cowpox virus (CPXV) is a zoonotic virus and endemic in wild rodent populations in Eurasia. Serological surveys in Europe have reported high prevalence in different vole and mouse species. Here, we report on experimental CPXV infections of bank voles (Myodes glareolus) from different evolutionary lineages with a spectrum of CPXV strains. All bank voles, independently of lineage, sex and age, were resistant to clinical signs following CPXV inoculation, and no virus shedding was detected in nasal or buccal swabs. In- contact control animals became only rarely infected. However, depending on the CPXV strain used, inoculated animals seroconverted and viral DNA could be detected preferentially in the upper respiratory tract. The highest antibody titers and virus DNA loads in the lungs were detected after inoculation with two strains from Britain and Finland. We conclude from our experiments that the role of bank voles as an efficient and exclusive CPXV reservoir seems questionable, and that CPXV may be maintained in most regions by other hosts, including other vole species. Further investigations are needed to identify factors that allow and modulate CPXV maintenance in bank voles and other potential reservoirs, which may also influence spill-over infections to accidental hosts

Pathogenic Fungi Regulate Immunity by Inducing Neutrophilic Myeloid-Derived Suppressor Cells

Peer reviewedPublisher PD

Association between exercise frequency with renal and cardiovascular outcomes in diabetic and non-diabetic individuals at high cardiovascular risk

Background: Guidelines recommend physical activity to reduce cardiovascular (CV) events. The association between physical activity and progression of chronic kidney disease (CKD) with and without diabetes is unknown. We assessed the association of self-reported physical activity with renal and CV outcomes in high-risk patients aged≥55 years over a median follow-up of 56 months in post-hoc analysis of a previously randomized trial program. Methods: Analyses were done with Cox regression analysis, mixed models for repeated measures, ANOVA and χ2 - test. 31,312 patients, among them 19,664 with and 11,648 without diabetes were analyzed. Results: Physical activity was inversely associated with renal outcomes (doubling of creatinine, end-stage kidney disease (ESRD)) and CV outcomes (CV death, myocardial infarction, stroke, heart failure hospitalization). Moderate activity (at least 2 times/week to every day) was associated with lower risk of renal outcomes and lower incidence of new albuminuria (p<0.0001 for both) compared to lower exercise levels. Similar results were observed for those with and without diabetes without interaction for renal outcomes (p=0.097–0.27). Physical activity was associated with reduced eGFR decline with a moderate association between activity and diabetes status (p=0.05). Conclusions: Moderate physical activity was associated with improved kidney outcomes with a threshold at two sessions per week. The association of physical activity with renal outcomes did not meaningfully difer with or without diabetes but absolute beneft of activity was even greater in people with diabetes. Thus, risks were similar between those with diabetes undertaking high physical activity and those without diabetes but low physical activity. Clinical trial registration: http://clinicaltrials.gov.uniqueidentifer:NCT00153101