Retinal metric: a stimulus distance measure derived from population neural responses

The ability of the organism to distinguish between various stimuli is limited by the structure and noise in the population code of its sensory neurons. Here we infer a distance measure on the stimulus space directly from the recorded activity of 100 neurons in the salamander retina. In contrast to previously used measures of stimulus similarity, this "neural metric" tells us how distinguishable a pair of stimulus clips is to the retina, given the noise in the neural population response. We show that the retinal distance strongly deviates from Euclidean, or any static metric, yet has a simple structure: we identify the stimulus features that the neural population is jointly sensitive to, and show the SVM-like kernel function relating the stimulus and neural response spaces. We show that the non-Euclidean nature of the retinal distance has important consequences for neural decoding.Comment: 5 pages, 4 figures, to appear in Phys Rev Let

Stillbirth is associated with perceived alterations in fetal activity - findings from an international case control study

Background Stillbirth after 28 weeks gestation affects between 1.3–8.8 per 1000 births in high-income countries. The majority of stillbirths in this setting occur in women without established risk factors. Identification of risk factors which could be identified and managed in pregnancy is a priority in stillbirth prevention research. This study aimed to evaluate women’s experiences of fetal movements and how these relate to stillbirth. Methods An international internet-based case–control study of women who had a stillbirth ≥28 weeks’ gestation within 30 days prior to completing the survey (n = 153) and women with an ongoing pregnancy or a live born child (n = 480). The online questionnaire was developed with parent stakeholder organizations using a mixture of categorical and open–ended responses and Likert scales. Univariate and multiple logistic regression was used to determine crude (unadjusted) and adjusted odds ratios (aOR) with 95% confidence intervals (CI). Summative content analysis was used to analyse free text responses. Results Women whose pregnancy ended in stillbirth were less likely to check fetal movements (aOR 0.54, 95% CI 0.35–0.83) and were less likely to be told to do so by a health professional (aOR 0.55, 95% CI 0.36–0.86). Pregnancies ending in stillbirth were more frequently associated with significant abnormalities in fetal movements in the preceding two weeks; this included a significant reduction in fetal activity (aOR 14.1, 95% CI 7.27–27.45) or sudden single episode of excessive fetal activity (aOR 4.30, 95% CI 2.25–8.24). Cases described their perception of changes in fetal activity differently to healthy controls e.g. vigorous activity was described as “frantic”, “wild” or “crazy” compared to “powerful” or “strong”. Conclusions Alterations in fetal activity are associated with increased risk of stillbirth. Pregnant women should be educated about awareness of fetal activity and reporting abnormal activity to health professionals

Maternal sleep practices and stillbirth: Findings from an international case‐control study

Background: Late stillbirth, which occurs ≥28 weeks’ gestation, affects 1.3‐8.8 per 1000 births in high‐income countries. Of concern, most occur in women without established risk factors. Identification of potentially modifiable risk factors that relate to maternal behaviors remains a priority in stillbirth prevention research. This study aimed to investigate, in an international cohort, whether maternal sleep practices are related to late stillbirth. Methods: An Internet‐based case‐control study of women who had a stillbirth ≥28 weeks’ gestation within 30 days before completing the survey (n = 153) and women with an ongoing third‐trimester pregnancy or who had delivered a live born child within 30 days (n = 480). Bivariate and multivariate logistic regressions were used to determine unadjusted and adjusted odds ratios (OR and aOR, respectively) with 95% confidence intervals (95% CIs) for stillbirth. Results: Sleeping >9 hours per night in the previous month was associated with stillbirth (aOR 1.75 [95% CI 1.10‐2.79]), as was waking on the right side (2.27 [1.31‐3.92]). Nonrestless sleep in the last month was also found to be associated with stillbirth (1.73 [1.03‐2.99]), with good sleep quality in the last month approaching significance (1.64 [0.98‐2.75]). On the last night of pregnancy, not waking more than one time was associated with stillbirth (2.03 [1.24‐3.34]). No relationship was found with going to sleep position during pregnancy, although very few women reported settling in the supine position (2.4%). Conclusions: Long periods of undisturbed sleep are associated with late stillbirth. Physiological studies of how the neuroendocrine and autonomic system pathways are regulated during sleep in the context of late pregnancy are warranted

An international internet survey of the experiences of 1,714 mothers with a late stillbirth: The STARS cohort study

Background: Stillbirth occurring after 28 weeks gestation affects between 1.5-4.5 per 1,000 births in high-income countries. The majority of stillbirths in this setting occur in women without risk factors. In addition, many established risk factors such as nulliparity and maternal age are not amenable to modification during pregnancy. Identification of other risk factors which could be amenable to change in pregnancy should be a priority in stillbirth prevention research. Therefore, this study aimed to utilise an online survey asking women who had a stillbirth about their pregnancy in order to identify any common symptoms and experiences. Methods: A web-based survey. Results: A total of 1,714 women who had experienced a stillbirth >3 weeks prior to enrolment completed the survey. Common experiences identified were: perception of changes in fetal movement (63 % of respondents), reports of a "gut instinct" that something was wrong (68 %), and perceived time of death occurring overnight (56 %). A quarter of participants believed that their baby's death was due to a cord issue and another 18 % indicated that they did not know the reason why their baby died. In many cases (55 %) the mother believed the cause of death was different to that told by clinicians. Conclusions: This study confirms the association between altered fetal movements and stillbirth and highlights novel associations that merit closer scrutiny including a maternal gut instinct that something was wrong. The potential importance of maternal sleep is highlighted by the finding of more than half the mothers believing their baby died during the night. This study supports the importance of listening to mothers' concerns and symptoms during pregnancy and highlights the need for thorough investigation of stillbirth and appropriate explanation being given to parents

Stimulus-dependent maximum entropy models of neural population codes

Neural populations encode information about their stimulus in a collective fashion, by joint activity patterns of spiking and silence. A full account of this mapping from stimulus to neural activity is given by the conditional probability distribution over neural codewords given the sensory input. To be able to infer a model for this distribution from large-scale neural recordings, we introduce a stimulus-dependent maximum entropy (SDME) model---a minimal extension of the canonical linear-nonlinear model of a single neuron, to a pairwise-coupled neural population. The model is able to capture the single-cell response properties as well as the correlations in neural spiking due to shared stimulus and due to effective neuron-to-neuron connections. Here we show that in a population of 100 retinal ganglion cells in the salamander retina responding to temporal white-noise stimuli, dependencies between cells play an important encoding role. As a result, the SDME model gives a more accurate account of single cell responses and in particular outperforms uncoupled models in reproducing the distributions of codewords emitted in response to a stimulus. We show how the SDME model, in conjunction with static maximum entropy models of population vocabulary, can be used to estimate information-theoretic quantities like surprise and information transmission in a neural population.Comment: 11 pages, 7 figure

Rehabilitation via HOMe Based gaming exercise for the Upper-limb post Stroke (RHOMBUS): a qualitative analysis of participants’ experience

Objective To report participants’ experiences of trial processes and use of the Neurofenix platform for home-based rehabilitation following stroke. The platform, consisting of the NeuroBall device and Neurofenix app, is a non-immersive virtual reality tool to facilitate upper limb rehabilitation following stroke. The platform has recently been evaluated and demonstrated to be safe and effective through a non-randomised feasibility trial (RHOMBUS). Design Qualitative approach using semistructured interviews. Interviews were audio recorded, transcribed verbatim and analysed using the framework method. Setting Participants’ homes, South-East England. Participants Purposeful sample of 18 adults (≥18 years), minimum 12 weeks following stroke, not receiving upper limb rehabilitation prior to the RHOMBUS trial, scoring 9–25 on the Motricity Index (elbow and shoulder), with sufficient cognitive and communicative abilities to participate. Results Five themes were developed which explored both trial processes and experiences of using the platform. Factors that influenced participant’s decision to take part in the trial, their perceptions of support provided during the trial and communication with the research team were found to be important contextual factors effecting participants’ overall experience. Specific themes around usability and comfort of the NeuroBall device, factors motivating persistence and perceived effectiveness of the intervention were highlighted as being central to the usability and acceptability of the platform. Conclusion This study demonstrated the overall acceptability of the platform and identified areas for enhancement which have since been implemented by Neurofenix. The findings add to the developing literature on the interface between virtual reality systems and user experience. Trial registration number ISRCTN60291412.Innovate UK (grant number: 104188

Hepatic leptospiral infections in dogs without obvious renal involvement.

BACKGROUND: Reports of chronic hepatitis in dogs caused by Leptospira spp. are confined to small case series. Fluorescence in situ hybridization (FISH) allows the identification of spirochetes in liver samples. Consequently, this technique may help elucidate the role of Leptospira spp. in cases of chronic hepatitis. OBJECTIVES: To describe cases of hepatic leptospirosis in dogs diagnosed by FISH and subsequent polymerase chain reaction (PCR) speciation, with the absence of clinically relevant renal involvement. ANIMALS: Ten client-owned dogs. METHODS: Retrospective case series from the University of Cambridge presented between 2013 and 2016 or cases consulted by telephone advice during this time period. Cases were selected based on histopathologically confirmed granulomatous hepatitis and leptospiral organisms identified by FISH and PCR speciation (Leptospira interrogans/kirschneri). RESULTS: All cases had increased liver enzyme activities, and FISH in combination with PCR speciation-confirmed infection with L. interrogans/kirschneri. Four dogs underwent repeat liver biopsy, FISH and PCR speciation 4-15 months after initial presentation and doxycycline treatment with 1 dog undergoing repeat sampling at necropsy. Three dogs that underwent repeat biopsy remained positive for L. interrogans/kirschneri infection. Six dogs were alive at the time of manuscript preparation and 4 dogs were euthanized as a result of progressive liver disease. CONCLUSIONS AND CLINICAL IMPORTANCE: The presence of hepatic leptospiral organisms may be associated with chronic granulomatous hepatitis without clinical evidence of renal involvement. Further studies are necessary to elucidate the etiological role of these organisms in the disease

Rehabilitation via home based gaming exercise for the upper-limb post stroke (RHOMBUS): results of an intervention feasibility trial

Innovate UK grant number 10418

CRLF3 plays a key role in the final stage of platelet genesis and is a potential therapeutic target for thrombocythemia.

The process of platelet production has so far been understood to be a 2-stage process: megakaryocyte maturation from hematopoietic stem cells followed by proplatelet formation, with each phase regulating the peripheral blood platelet count. Proplatelet formation releases into the bloodstream beads-on-a-string preplatelets, which undergo fission into mature platelets. For the first time, we show that preplatelet maturation is a third, tightly regulated, critical process akin to cytokinesis that regulates platelet count. We show that deficiency in cytokine receptor-like factor 3 (CRLF3) in mice leads to an isolated and sustained 25% to 48% reduction in the platelet count without any effect on other blood cell lineages. We show that Crlf3-/- preplatelets have increased microtubule stability, possibly because of increased microtubule glutamylation via the interaction of CRLF3 with key members of the Hippo pathway. Using a mouse model of JAK2 V617F essential thrombocythemia, we show that a lack of CRLF3 leads to long-term lineage-specific normalization of the platelet count. We thereby postulate that targeting CRLF3 has therapeutic potential for treatment of thrombocythemia