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Understanding the relation between cortical neuronal network structure and neuronal activity is a fundamental unresolved question in neuroscience, with implications to our understanding of the mechanism by which neuronal networks evolve over time, spontaneously or under stimulation. It requires a method for inferring the structure and composition of a network from neuronal activities. Tracking the evolution of networks and their changing functionality will provide invaluable insight into the occurrence of plasticity and the underlying learning process. We devise a probabilistic method for inferring the effective network structure by integrating techniques from Bayesian statistics, statistical physics, and principled machine learning. The method and resulting algorithm allow one to infer the effective network structure, identify the excitatory and inhibitory type of its constituents, and predict neuronal spiking activity by employing the inferred structure. We validate the method and algorithm's performance using synthetic data, spontaneous activity of an in silico emulator, and realistic in vitro neuronal networks of modular and homogeneous connectivity, demonstrating excellent structure inference and activity prediction. We also show that our method outperforms commonly used existing methods for inferring neuronal network structure. Inferring the evolving effective structure of neuronal networks will provide new insight into the learning process due to stimulation in general and will facilitate the development of neuron-based circuits with computing capabilities., (© The Author(s) 2024. Published by Oxford University Press on behalf of National Academy of Sciences.)

Background: The risks and benefits of preoperative aspirin continuation in patients undergoing isolated heart valve replacement surgery are unclear. We investigated the effect of aspirin continuation on the risk of bleeding and transfusion in these patients., Methods: In this single center, retrospective study, among 474 adult patients who underwent isolated heart valve surgery between April 2013 and June 2018, 269 continued aspirin within 5 days before surgery (aspirin group) and 205 patients did not take or stopped aspirin no later than 5 days before surgery (non-aspirin group). The chi-square test, the Mann-Whitney U -test, and the Student's T -test were used to compare data between the groups. Univariate and Multivariate logistic regressions were used to assess crude and adjusted relationships between outcome and exposure., Results: The primary outcome, red blood cell (RBC) transfusion, occurred in 59 patients (22%) of the aspirin group and in 24 patients (12%) of the non-aspirin group ( p  = 0.004). After adjustment for confounding factors, continuation of aspirin was no longer associated with RBC transfusion (aOR1.8;95%CI,0.98-3.2; p  = 0.06). The amount of allogenic blood products, the incidence of surgical re-exploration for bleeding, the volume of re-transfused cell-saved blood, and the cumulative chest tube drainage during the first 24 postoperative hours were similar between groups., Conclusion: Preoperative continuation of aspirin in patients undergoing isolated heart valve surgery is neither associated with a higher incidence of RBC transfusion, nor with larger perioperative blood loss, or more frequent surgical revision for bleeding., Trial Registration: Clinicaltrials.gov (NCT05151796).

The properties of complex networked systems arise from the interplay between the dynamics of their elements and the underlying topology. Thus, to understand their behavior, it is crucial to convene as much information as possible about their topological organization. However, in large systems, such as neuronal networks, the reconstruction of such topology is usually carried out from the information encoded in the dynamics on the network, such as spike train time series, and by measuring the transfer entropy between system elements. The topological information recovered by these methods does not necessarily capture the connectivity layout, but rather the causal flow of information between elements. New theoretical frameworks, such as Integrated Information Decomposition (Φ-ID), allow one to explore the modes in which information can flow between parts of a system, opening a rich landscape of interactions between network topology, dynamics, and information. Here, we apply Φ-ID on in silico and in vitro data to decompose the usual transfer entropy measure into different modes of information transfer, namely, synergistic, redundant, or unique. We demonstrate that the unique information transfer is the most relevant measure to uncover structural topological details from network activity data, while redundant information only introduces residual information for this application. Although the retrieved network connectivity is still functional, it captures more details of the underlying structural topology by avoiding to take into account emergent high-order interactions and information redundancy between elements, which are important for the functional behavior, but mask the detection of direct simple interactions between elements constituted by the structural network topology., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

Neuronal cultures are a prominent experimental tool to understand complex functional organization in neuronal assemblies. However, neurons grown on flat surfaces exhibit a strongly coherent bursting behavior with limited functionality. To approach the functional richness of naturally formed neuronal circuits, here we studied neuronal networks grown on polydimethylsiloxane (PDMS) topographical patterns shaped as either parallel tracks or square valleys. We followed the evolution of spontaneous activity in these cultures along 20 days in vitro using fluorescence calcium imaging. The networks were characterized by rich spatiotemporal activity patterns that comprised from small regions of the culture to its whole extent. Effective connectivity analysis revealed the emergence of spatially compact functional modules that were associated with both the underpinned topographical features and predominant spatiotemporal activity fronts. Our results show the capacity of spatial constraints to mold activity and functional organization, bringing new opportunities to comprehend the structure-function relationship in living neuronal circuits., Competing Interests: The authors declare no competing interests., (© 2022 The Author(s).)

Neurons are connected to other neurons by axons and dendrites that conduct signals with finite velocities, resulting in delays between the firing of a neuron and the arrival of the resultant impulse at other neurons. Since delays greatly complicate the analytical treatment and interpretation of models, they are usually neglected or taken to be uniform, leading to a lack in the comprehension of the effects of delays in neural systems. This letter shows that heterogeneous transmission delays make small groups of neurons respond selectively to inputs with differing frequency spectra. By studying a single integrate-and-fire neuron receiving correlated time-shifted inputs, it is shown how the frequency response is linked to both the strengths and delay times of the afferent connections. The results show that incorporating delays alters the functioning of neural networks, and changes the effect that neural connections and synaptic strengths have., (© 2021 Massachusetts Institute of Technology.)

Hebbian plasticity means that if the firing of two neurons is correlated, then their connection is strengthened. Conversely, uncorrelated firing causes a decrease in synaptic strength. Spike-timing-dependent plasticity (STDP) represents one instantiation of Hebbian plasticity. Under STDP, synaptic changes depend on the relative timing of the pre- and post-synaptic firing. By inducing pre- and post-synaptic firing at different relative times the STDP curves of many neurons have been determined, and it has been found that there are different curves for different neuron types or synaptic sites. Biophysically, strengthening (long-term potentiation, LTP) or weakening (long-term depression, LTD) of glutamatergic synapses depends on the post-synaptic influx of calcium (Ca 2+ ): weak influx leads to LTD, while strong, transient influx causes LTP. The voltage-dependent NMDA receptors are the main source of Ca 2+ influx, but they will only open if a post-synaptic depolarisation coincides with pre-synaptic neurotransmitter release. Here we present a computational mechanism for Ca 2+ -dependent plasticity in which the interplay between the pre-synaptic neurotransmitter release and the post-synaptic membrane potential leads to distinct Ca 2+ time-courses, which in turn lead to the change in synaptic strength. It is shown that the model complies with classic STDP results, as well as with results obtained with triplets of spikes. Furthermore, the model is capable of displaying different shapes of STDP curves, as observed in different experimental studies.

Background: Laparoscopic cholecystectomy might be considered minor surgery, but it may result in severe postoperative pain. Subcostal transversus abdominis plane (TAP) block, which produces long-lasting supra-umbilical parietal analgesia, might improve analgesia after laparoscopic cholecystectomy., Objective: We investigated whether subcostal TAP block would reduce opioid consumption and pain after laparoscopic cholecystectomy in patients provided with multimodal analgesia., Design: A randomised, placebo-controlled, double-blind study., Setting: The study was conducted at a university teaching hospital from December 2017 to June 2018., Patients: Sixty patients scheduled for laparoscopic cholecystectomy were included. Anaesthesia and postoperative analgesia (etoricoxib, paracetamol, ketamine and dexamethasone) were standardised., Intervention: After induction of anaesthesia, patients were allocated into two groups: ultrasound-guided bilateral subcostal TAP block with 20 ml of levobupivacaine 0.375% and epinephrine 5 μg ml or 0.9% saline with epinephrine 5 μg ml., Main Outcome Measures: Opioid consumption in the recovery room and during the first 24 h after surgery were recorded. Postoperative somatic and visceral pain scores, fatigue and nausea were measured. Intra-operative end-tidal concentrations of sevoflurane (FETSEVO) were also recorded., Results: Twenty-four hour postoperative opioid consumption were similar in both groups: 21.2 mg (95% CI 15.3 to 27.1) vs. 25.2 (95% CI 15.1 to 35.5) oral morphine equivalent in the levobupivacaine and 0.9% saline groups, respectively; P = 0.48. No significant between-group differences were observed with regards to parietal (P = 0.56) and visceral (P = 0.50) pain scores, fatigue and nausea. FETSEVO was slightly lower in the levobupivacaine group (P < 0.01)., Conclusion: Subcostal TAP block does not improve the analgesia provided by multimodal analgesia after laparoscopic cholecystectomy. It allows for a small reduction in intra-operative sevoflurane requirements., Trial Registration: NCT0339153.

Six taxa of limnoterrestrial rhabdocoels are discussed, two of them, both belonging to Typhloplanidae Graff, 1905, are new to science. Adenoplea reisingeri n. sp. can be distinguished from its congeners by the absence of a separate seminal receptacle, the presence of a copulatory bursa and the fact that it has an unarmed copulatory organ. Carcharodopharynx schlitzensis n. sp. can be distinguished from C. arcanus (Reisinger, 1924) Poche, 1926, the only other species within the genus, by the fact that the cirrus bears spines. For four other taxa: Adenoplea perigraptopera Reisinger, 1924, A. meridionalis Kolasa, 1981, C. arcanus (Reisinger, 1924) Poche, 1926 and Archivortex silvestris Reisinger, 1924, new data on morphology and distribution are provided. Neotypes are designated for A. perigraptopera and C. arcanus.

A morphological and taxonomical account of the taxon Phaenocora is provided. An effort was made to locate and study all available material and, where possible, species are briefly re-described. We also describe two new species: Phaenocora gilberti sp. nov. from Cootes Paradise, Ontario, Canada and Phaenocora aglobulata sp. nov. from Prairie Grove, Alabama, USA. Species recognition is based on a combination of both male and female morphology. A comparison of and discussion on all species is given, resulting in a total of 28 valid species, three species inquirendae, five species dubiae, and one nomen nudum. An identification key is provided.

An overview of the morphology, taxonomy and distribution of all known species of the rhabdocoel taxon Acrochordonoposthia is provided. One new species A. vandeputae n. sp. is described from Graz (Austria). This new species can easily be distinguished from its congeners by the morphology of its copulatory organ, which contains a straight cirrus lined with spines. All species of Acrochordonoposthia are compared with one another, and an updated identification key is provided.

In a cooperative study on the efficiency of isolation and decontamination in patients with acute leukaemia performed in seven hospitals in Europe, faecal samples and oral washings were collected twice weekly and shipped for culturing to a Central Bacteriological Laboratory. In this laboratory the Enterobacteriaceae species isolated from these samples were biotyped as well as those isolated from infections that occurred in these patients during treatment. Enterobacteriaceae biotypes isolated for the first time during the isolation phase of the patient indicated a leak in the isolation system. The "colonizing" (newly resident) biotypes of Enterobacteriaceae species were found to be more often involved in infections and to be more commonly distributed among the patients in the participating hospitals than the "contaminating" (transient) Enterobacteriaceae biotypes. Furthermore, a linear correlation was found between the incidence of gram-negative infections and the number of cases in which these Enterobacteriaceae biotypes colonized the gastro-intestinal tract of patients. The majority of the infections was caused by Enterobacteriaceae biotypes that had settled in the gastro-intestinal tract during treatment and consequently were of nosocomial origin.

Lethally irradiated conventional mice were killed at daily intervals after irradiation. A high correlation was found between the occurrence of bacterial overgrowth in the digestive tract and invasion into the regional lymph nodes the spleen and the blood. By oral contamination of mice with quite high doses of either an exogenous or an endogenous biotype of an Enterobacteriaceae species at day 4 after irradiation, it was attempted to induced such condition of intestinal overgrowth. In all animals such an abnormal colonization of the contaminant was indeed achieved in this way and the mice died from an infection caused by the biotype used for the contamination. The interval between contamination and death was different when different biotypes were used for contamination and occurred sooner after irradiation when an endogenous biotype was used for (re)contamination. It is concluded that oral contamination with exogenous as well as with endogenous potentially pathogenic bacteria during a period of severely decreased resistance to infections must be avoided. The colonization resistance of the digestive tract of these animals should be maintained as high as possible.