Adaptation Accelerating Sampling-based Bayesian Inference in Attractor Neural Networks

The brain performs probabilistic Bayesian inference to interpret the external world. The sampling-based view assumes that the brain represents the stimulus posterior distribution via samples of stochastic neuronal responses. Although the idea of sampling-based inference is appealing, it faces a critical challenge of whether stochastic sampling is fast enough to match the rapid computation of the brain. In this study, we explore how latent feature sampling can be accelerated in neural circuits. Specifically, we consider a canonical neural circuit model called continuous attractor neural networks (CANNs) and investigate how sampling-based inference of latent continuous variables is accelerated in CANNs. Intriguingly, we find that by including noisy adaptation in the neuronal dynamics, the CANN is able to speed up the sampling process significantly. We theoretically derive that the CANN with noisy adaptation implements the efficient sampling method called Hamiltonian dynamics with friction, where noisy adaption effectively plays the role of momentum. We theoretically analyze the sampling performances of the network and derive the condition when the acceleration has the maximum effect. Simulation results validate our theoretical analyses. We further extend the model to coupled CANNs and demonstrate that noisy adaptation accelerates the sampling of the posterior distribution of multivariate stimuli. We hope that this study enhances our understanding of how Bayesian inference is realized in the brain

First two cases of living related liver transplantation with complicated anatomy of blood vessels in Beijing

Aim: Living related liver transplantation (LRLT) has been developed in response to the paediatric organ donor shortage. Though it has been succeeded in many centers worldwide, the safety of the donor is still a major concern, especially in donors with anatomy variation. We succeeded in performing the first two cases of living related liver transplantation with complicated anatomy of blood vessels as a way to overcome cadaveric organ shortage in Beijing. Methods: Two patients, with congenital liver fibrosis and congenital biliary atresia were performed with living donor liver transplantation in our hospital and then followed up from November 12 to December 13, 2001. The two living donors, mother and father, were healthy aged 34 and 35 years. One right lobe (segment V, VI, VII, VIII) and one left lateral lobe (segment II and III) were used. The grafts weighed 394 g and 300 g. The ratio of graff weight to the standard liver volume (SLV) of donors was 68% and 27%. The graft weight to recipient body weight ratio was 3.2% and 4.4%. The graft weight to recipient estimated standard liver mass (ESLM) ratio was 63% and 85%. The two donors had complicated blood vessel variation. Results: Two patients undergone living donor liver transplantation had good results. Abnormal liver function with high bilirubin level appeared in a few days after operation, bur liver function returned to normal one month after operation with bilirubin level almost decreased to near normal. No bleeding, thrombosis, infection and bile leakage occurred. One had an acure rejection and recovered. The two donors recovered in two weeks. One had slight fever because of a little collection in abdomen and recovered after paracentesis and drainage. Conclusion: Living donor liver transplantation has been proved to be a good way that offers a unique opportunity of getting a timely liver graft as a response to shortage of pediatric donors, though it could be a technically difficult operation if there is anatomical variation. Copyright © 2004 by The WJG Press.published_or_final_versio

Head-to-head comparison of H2-receptor antagonists and proton pump inhibitors in the treatment of erosive esophagitis: A meta-analysis

Aim: To systematically evaluate the efficacy of H2-receptor antagonists (H2RAs) and proton pump inhibitors in healing erosive esophagitis (EE). Methods: A meta-analysis was performed. A literature search was conducted in PubMed, Medline, Embase, and Cochrane databases to include randomized controlled head-to-head comparative trials evaluating the efficacy of H2RAs or proton pump inhibitors in healing EE. Relative risk (RR) and 95% confidence interval (CI) were calculated under a random-effects model. Results: RRs of cumulative healing rates for each comparison at 8 wk were: high dose vs standard dose H2RAs, 1.17 (95%CI, 1.02-1.33); standard dose proton pump inhibitors vs standard dose H2RAs, 1.59 (95%CI, 1.44-1.75); standard dose other proton pump inhibitors vs standard dose omeprazole, 1.06 (95%CI, 0.98-1.06). Proton pump inhibitors produced consistently greater healing rates than H2RAs of all doses across all grades of esophagitis, including patients refractory to H2RAs. Healing rates achieved with standard dose omeprazole were similar to those with other proton pump inhibitors in all grades of esophagitis. Conclusion: H2RAs are less effective for treating patients with erosive esophagitis, especially in those with severe forms of esophagitis. Standard dose proton pump inhibitors are significantly more effective than H2RAs in healing esophagitis of all grades. Proton pump inhibitors given at the recommended dose are equally effective for healing esophagitis. © 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio

Oscillatory Tracking of Continuous Attractor Neural Networks Account for Phase Precession and Procession of Hippocampal Place Cells

Hippocampal place cells of freely moving rodents display an intriguing temporal organization in their responses known as 'theta phase precession', in which individual neurons fire at progressively earlier phases in successive theta cycles as the animal traverses the place fields. Recent experimental studies found that in addition to phase precession, many place cells also exhibit accompanied phase procession, but the underlying neural mechanism remains unclear. Here, we propose a neural circuit model to elucidate the generation of both kinds of phase shift in place cells' firing. Specifically, we consider a continuous attractor neural network (CANN) with feedback inhibition, which is inspired by the reciprocal interaction between the hippocampus and the medial septum. The feedback inhibition induces intrinsic mobility of the CANN which competes with the extrinsic mobility arising from the external drive. Their interplay generates an oscillatory tracking state, that is, the network bump state (resembling the decoded virtual position of the animal) sweeps back and forth around the external moving input (resembling the physical position of the animal). We show that this oscillatory tracking naturally explains the forward and backward sweeps of the decoded position during the animal's locomotion. At the single neuron level, the forward and backward sweeps account for, respectively, theta phase precession and procession. Furthermore, by tuning the feedback inhibition strength, we also explain the emergence of bimodal cells and unimodal cells, with the former having co-existed phase precession and procession, and the latter having only significant phase precession. We hope that this study facilitates our understanding of hippocampal temporal coding and lays foundation for unveiling their computational functions

Modelling the effects of beverage substitution during adolescence on later obesity outcomes in early adulthood: results from the Raine study

High sugar-sweetened beverage (SSB) consumption has been linked with obesity. The present study examined the associations between adolescent SSB intake and body mass index (BMI), waist circumference (WC), and overweight status in early adulthood, and modelled the association of alternative beverage substitution with BMI and WC. Data of offspring from the Western Australian Pregnancy Cohort (Raine) Study at ages 14 and 22 years were used (n = 667). SSB intake at 14 years (100 g/day) was associated with higher BMI (β = 0.19 kg/m2, 95% CI 0.04, 0.33), WC (β = 0.41cm, 95% CI 0.04, 0.78), and being overweight at 22 years (OR 1.10, 95% CI 1.02, 1.18). Every 100g modelled substitution of SSB with milk at age 14 years was associated with lower BMI (-0.19 kg/m2) and WC (-0.52 cm) at age 22 years. Replacement of SSB with diet drink was associated with higher BMI and WC. No association was found for substitutions of SSB with water, tea/coffee, or 100% fruit juice with BMI or WC. SSB intake during adolescence was associated with higher BMI, WC, and being overweight in early adulthood. Milk as an alternative to SSB was associated with less adiposity. Caution is necessary in recommending diet drinks as a SSB alternative

N-Acetyl-seryl-aspartyl-lysyl-proline Alleviates Renal Fibrosis Induced by Unilateral Ureteric Obstruction in BALB/C Mice

To expand the armamentarium of treatment for chronic kidney disease (CKD), we explored the utility of boosting endogenously synthesized N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), which is augmented by inhibition of the angiotensin converting enzyme. Male BALB/c mice underwent unilateral ureteral ligation (UUO) or sham operation and received exogenously administered Ac-SDKP delivered via a subcutaneous osmotic minipump or Captopril treatment by oral gavage. Seven days after UUO, there were significant reductions in the expression of both collagen 1 and collagen 3 in kidneys treated with Ac-SDKP or Captopril, and there was a trend towards reductions in collagen IV, alpha-SMA, and MCP-1 versus control. However, no significant attenuation of interstitial injury or macrophage infiltration was observed. These findings are in contrary to observations in other models and underscore the fact that a longer treatment time frame may be required to yield anti-inflammatory effects in BALB/c mice treated with Ac-SDKP compared to untreated mice. Finding an effective treatment regimen for CKD requires fine-tuning of pharmacologic protocols.published_or_final_versio

Counterflow dielectrophoresis for trypanosome enrichment and detection in blood

Human African trypanosomiasis or sleeping sickness is a deadly disease endemic in sub-Saharan Africa, caused by single-celled protozoan parasites. Although it has been targeted for elimination by 2020, this will only be realized if diagnosis can be improved to enable identification and treatment of afflicted patients. Existing techniques of detection are restricted by their limited field-applicability, sensitivity and capacity for automation. Microfluidic-based technologies offer the potential for highly sensitive automated devices that could achieve detection at the lowest levels of parasitemia and consequently help in the elimination programme. In this work we implement an electrokinetic technique for the separation of trypanosomes from both mouse and human blood. This technique utilises differences in polarisability between the blood cells and trypanosomes to achieve separation through opposed bi-directional movement (cell counterflow). We combine this enrichment technique with an automated image analysis detection algorithm, negating the need for a human operator

Optical coherence tomography: an assessment of current training across all levels of seniority in 8 ophthalmic units in the united kingdom

BACKGROUND: Optical Coherence Tomography (OCT) is becoming an increasingly integral part of ophthalmological clinical practice. The accurate interpretation of OCT images is important both in terms of diagnosis and in directing subsequent management. The aim of this study was to determine the clinical competence in OCT image interpretation of ophthalmologists in different subspecialties and grades. METHODS: Eight OCT images demonstrating a single macular pathology and two normal scans were selected by case notes review. These ten images were shown to thirty doctors and 10 non-medical staff from eight units. They were asked to identify each lesion, the average thickness of the lesion, and the axis at which the OCT was taken. One point was awarded for each correct answer. RESULTS: The mean scores for the correct qualitative identification of the OCT lesion (with a maximum score of 10) for different grades of doctors and non-medical staff were as follows: medical retinal consultants (MRC), 9 (range, 8–10); vitreoretinal consultants (VRC), 7 (range, 6–9); non-retinal consultants (NRC), 4 (range, 2–6); vitreoretinal fellows (VRF), 4 (range, 3–7); specialist registrars (SpR), 3 (range, 2–5); senior house officers (SHO), 4 (range, 3–6); orthoptists, 1 (range, 0–1); ancillary staff, 2 (range, 0–3). CONCLUSION: A wide range in the ability to accurately interpret OCT images has been demonstrated. All doctors would thereby benefit from further training in the interpretation of OCT scans

ERα inhibits epithelial-mesenchymal transition by suppressing Bmi1 in breast cancer

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ERα inhibits epithelial-mesenchymal transition by suppressing Bmi1 in breast cancer

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