Active intrinsic conductances in recurrent networks allow for long-lasting transients and sustained activity with realistic firing rates as well as robust plasticity.

Recurrent neural networks of spiking neurons can exhibit long lasting and even persistent activity. Such networks are often not robust and exhibit spike and firing rate statistics that are inconsistent with experimental observations. In order to overcome this problem most previous models had to assume that recurrent connections are dominated by slower NMDA type excitatory receptors. Usually, the single neurons within these networks are very simple leaky integrate and fire neurons or other low dimensional model neurons. However real neurons are much more complex, and exhibit a plethora of active conductances which are recruited both at the sub and supra threshold regimes. Here we show that by including a small number of additional active conductances we can produce recurrent networks that are both more robust and exhibit firing-rate statistics that are more consistent with experimental results. We show that this holds both for bi-stable recurrent networks, which are thought to underlie working memory and for slowly decaying networks which might underlie the estimation of interval timing. We also show that by including these conductances, such networks can be trained to using a simple learning rule to predict temporal intervals that are an order of magnitude larger than those that can be trained in networks of leaky integrate and fire neurons.

Prediction of Pouch of Douglas Obliteration: Point-of-care Ultrasound Versus Pelvic Examination.

STUDY OBJECTIVE: To evaluate the point-of-care preoperative transvaginal ultrasound (TVUS) sliding sign in comparison with palpation of a nodule on digital pelvic examination for the prediction of pouch of Douglas (POD) obliteration. DESIGN: Analysis of data from a prospective data registry (Canadian Task Force classification II-2). SETTING: A tertiary referral center. PATIENTS: Women with suspected endometriosis who had preoperative pelvic examination and point-of-care TVUS followed by laparoscopic surgery between August 2015 and December 2016. INTERVENTIONS: Women were preoperatively assessed for the prediction of POD obliteration with pelvic examination for a nodule and point-of-care TVUS uterine/cervix sliding sign. MEASUREMENTS AND MAIN RESULTS: The study included 269 women, 15.2% (41/269) of whom had POD obliteration at the time of surgery. A preoperative negative sliding sign had a sensitivity of 73.2% (95% confidence interval, 57.1%-85.8%) and a specificity of 93.9% (95% CI, 89.9%-96.6%) in the prediction of POD obliteration compared with preoperative palpation of a nodule on pelvic examination, which had a sensitivity of 24.4% (95% CI, 12.4%-40.3%) and a specificity of 93.4% (95% CI, 89.4%-96.3%). The difference in sensitivity was statistically significant (McNemar test, p <.001). A negative sliding sign was also associated with longer operating times and more difficult surgery including the need for ureterolysis. CONCLUSION: The point-of-care TVUS sliding sign showed significantly improved sensitivity compared with palpation of a nodule on pelvic examination for the prediction of POD obliteration. Therefore, the point-of-care TVUS sliding sign improves the preoperative assessment of POD disease and thus may lead to more optimal surgical planning in women with suspected endometriosis.

Preeclampsia biomarkers: An assessment of maternal cardiometabolic health.

Preeclampsia is a serious pregnancy condition defined as new-onset hypertension and proteinuria, commonly characterized as either early, 'placental', or late onset, 'maternal', using a cut-off of 34 weeks gestation. However, it may be more useful to differentiate between the vascular remodelling and placental invasion vs. inflammation and metabolic pathophysiology that underlie these forms of preeclampsia. Due to rising rates of obesity, the late-onset, maternal form is increasingly occurring earlier in pregnancy. Predictive tests for preeclampsia typically include biophysical markers such as maternal body mass index and mean arterial pressure, indicating the importance of cardiovascular and metabolic health in its pathophysiology. In contrast, the placental, inflammatory, endothelial and/or metabolic biomarkers used in these tests are generally thought to indicate an abnormal response to placentation and predict the disease. However, many of these non-placental biomarkers are known to predict impaired metabolic health in non-pregnant subjects with obesity (metabolically unhealthy obesity) and coronary artery disease or stroke in people at risk for cardiovascular events. Similarities between the performance of these markers in the prediction of cardiovascular and metabolic health outside of pregnancy suggests that they may be more indicative of maternal health than predictive for preeclampsia. This paper reviews the biophysical and biochemical markers in preeclampsia prediction and compares their performance to tests assessing metabolic health and risk of cardiovascular disease, particularly in the obese population.

Apoptosis in the Ovine Fetal Brain Following Placental Embolization and Intermittent Umbilical Cord Occlusion.

The purpose of this study was to compare the regional distribution of apoptotic cells in the near term ovine fetal brain caused by prolonged moderate hypoxia, as seen in placental insufficiency, and intermittent severe hypoxia, as seen in umbilical cord compression, which may then contribute to adverse neurodevelopment in the postnatal life. We hypothesized that apoptosis in the fetal brain will be increased in response to both prolonged moderate hypoxia and intermittent severe hypoxia. Twenty-one near term (126-127 days) sheep were divided into 3 groups: control (CON; n = 7), placental embolization (EMB; n = 7), and umbilical cord occlusion (UCO; n = 8). The EMB group had microsphere injections into the umbilical arterial circulation until the oxygen content was at 50% of baseline value. The UCO group had complete cord occlusion for 2 minutes every hour, 6 times a day for 2 consecutive days. At 4 pm on day 2, the animals were euthanized; fetal brains were fixed and prepared for apoptosis staining using the terminal uridine deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay method. In the cerebellar white matter, there was a 3-fold increase in the number of TUNEL positive cells per 1000 cells in both EMB and UCO animals as compared to CON (P = .017). There was also a significant increase in the frontal cortical grey matter (layers 1-3) in EMB animals as compared to CON (P = .014). As such, apoptosis in the near term fetal sheep brain is altered with both sustained moderate hypoxia and intermittent severe hypoxia in the latter part of pregnancy, with potential for long-term neurological sequelae.