Protocol to image and analyze hippocampal network dynamics in non-anesthetized mouse pups.

Two-photon calcium imaging is a powerful technique that has revolutionized our understanding of how neural circuit dynamics supports different behaviors and cognitive processes. However, performing imaging during development remains challenging. Here, we provide a protocol to image CA1 neurons in mouse pups as well as a pipeline of analysis to analyze and share the data. We describe steps for intracerebroventricular injection, cranial window surgery, two-photon calcium imaging, and analysis of imaging data. For complete details on the use and execution of this protocol, please refer to Dard et al.1 and Denis et al.2.

The rapid developmental rise of somatic inhibition disengages hippocampal dynamics from self-motion.

Early electrophysiological brain oscillations recorded in preterm babies and newborn rodents are initially mostly driven by bottom-up sensorimotor activity and only later can detach from external inputs. This is a hallmark of most developing brain areas, including the hippocampus, which, in the adult brain, functions in integrating external inputs onto internal dynamics. Such developmental disengagement from external inputs is likely a fundamental step for the proper development of cognitive internal models. Despite its importance, the developmental timeline and circuit basis for this disengagement remain unknown. To address this issue, we have investigated the daily evolution of CA1 dynamics and underlying circuits during the first two postnatal weeks of mouse development using two-photon calcium imaging in non-anesthetized pups. We show that the first postnatal week ends with an abrupt shift in the representation of self-motion in CA1. Indeed, most CA1 pyramidal cells switch from activated to inhibited by self-generated movements at the end of the first postnatal week, whereas the majority of GABAergic neurons remain positively modulated throughout this period. This rapid switch occurs within 2 days and follows the rapid anatomical and functional surge of local somatic GABAergic innervation. The observed change in dynamics is consistent with a two-population model undergoing a strengthening of inhibition. We propose that this abrupt developmental transition inaugurates the emergence of internal hippocampal dynamics.

DeepCINAC: A Deep-Learning-Based Python Toolbox for Inferring Calcium Imaging Neuronal Activity Based on Movie Visualization.

Two-photon calcium imaging is now widely used to infer neuronal dynamics from changes in fluorescence of an indicator. However, state-of-the-art computational tools are not optimized for the reliable detection of fluorescence transients from highly synchronous neurons located in densely packed regions such as the CA1 pyramidal layer of the hippocampus during early postnatal stages of development. Indeed, the latest analytical tools often lack proper benchmark measurements. To meet this challenge, we first developed a graphical user interface (GUI) allowing for a precise manual detection of all calcium transients from imaged neurons based on the visualization of the calcium imaging movie. Then, we analyzed movies from mouse pups using a convolutional neural network (CNN) with an attention process and a bidirectional long-short term memory (LSTM) network. This method is able to reach human performance and offers a better F1 score (harmonic mean of sensitivity and precision) than CaImAn to infer neural activity in the developing CA1 without any user intervention. It also enables automatically identifying activity originating from GABAergic neurons. Overall, DeepCINAC offers a simple, fast and flexible open-source toolbox for processing a wide variety of calcium imaging datasets while providing the tools to evaluate its performance.

Arterial Spin Labeling and Central Precocious Puberty.

PURPOSE: To evaluate a non-invasive method to assess the progressivity of idiopathic central precocious puberty (CPP) by quantifying perfusion of the pituitary stalk with arterial spin labeling (ASL) and using the gonadotropin-releasing hormone (GnRH) test as a reference test to define progressive CPP. METHODS: In a single center retrospective study, 52 consecutive patients, observed between October 2015 and April 2017 and referred with early signs of puberty, were evaluated using the GnRH test and cerebral magnetic resonance imaging (MRI). Patients with peripheral or non-idiopathic puberty were excluded. The distribution of perfusion values between patients with progressive and non-progressive CPP was compared using a nonparametric Mann-Whitney U­test. RESULTS: In this study 35 patients were included and 29 had progressive CPP. These patients displayed significantly higher cerebral blood flow (CBF) values than the 6 patients with non-progressive CPP (p = 0.006). The median CBF for patients with non-progressive and progressive CPP was 45.25 ml/min/100 g (interquartile range 36.9-54) vs. 65 ml/min/100 g (interquartile range 55.5-74.5), respectively. To determine if the CPP was progressive, the best CBF threshold was 55.5 ml/min/100 g with a sensitivity of 76%, a specificity of 83% and an accuracy of 77%. There were strong significant correlations between CBF and LH peak (r = 0.67, p < 0.001) and between CBF and LH/FSH peaks ratio [r = 0.71, p < 0.001] during the GnRH test. CONCLUSION: Arterial spin labelling (ASL) offers a novel tool to assess the progressivity of idiopathic CPP.

Predictors of clinically urgent intracranial pathology at neuroimaging in children with complex febrile seizures: a retrospective cross-sectional study.

AIM: To assess the prevalence of clinically urgent intracranial pathology (CUIP) in children visiting the emergency department with a complex febrile seizure (CFS). METHODS: Retrospective cohort review. We analysed the visits of patients for a CFS from January 2007 to December 2011 in seven paediatric emergency departments. Our main outcomes were the proportions of CUIP diagnosed between day 0 and 1 and within 30 days after the index visit. RESULTS: From 1 183 487 visits, 839 were for a CFS and 130 (15.5%) of these had a neuroimaging performed within 30 days (CT scan for 75 visits [8.9%], MRI for 30 visits [3.6%] and both for 25 visits [3.0%]). Three CUIP were diagnosed between day 0 and 1 (0.4% [CI-95%: 0.1-1.3]), 5 within 30 days after the index visit (0.7% [CI-95%: 0.2-1.7]) but none among the 630 visits of children presenting with a normal neurological clinical examination (0% [95% CI: 0.0-0.7]), nor among the 468 presenting only with multiple seizure (0% [95% CI: 0.0-1.0]). CONCLUSION: In children with a CFS, CUIP is rare event in the subgroup of children with a normal neurological clinical examination and in those with brief generalised multiple seizures.

Clinical study of 19 patients with SCN8A-related epilepsy: Two modes of onset regarding EEG and seizures.

OBJECTIVE: To describe the mode of onset of SCN8A-related severe epilepsy in order to facilitate early recognition, and eventually early treatment with sodium channel blockers. METHODS: We reviewed the phenotype of patients carrying a mutation in the SCN8A gene, among a multicentric cohort of 638 patients prospectively followed by several pediatric neurologists. We focused on the way clinicians made the diagnosis of epileptic encephalopathy, the very first symptoms, electroencephalography (EEG) findings, and seizure types. We made genotypic/phenotypic correlation based on epilepsy-associated missense variant localization over the protein. RESULTS: We found 19 patients carrying a de novo mutation of SCN8A, representing 3% of our cohort, with 9 mutations being novel. Age at onset of epilepsy was 1 day to 16 months. We found two modes of onset: 12 patients had slowly emerging onset with rare and/or subtle seizures and normal interictal EEG (group 1). The first event was either acute generalized tonic-clonic seizure (GTCS; Group 1a, n = 6) or episodes of myoclonic jerks that were often mistaken for sleep-related movements or other movement disorders (Group 1b, n = 6). Seven patients had a sudden onset of frequent tonic seizures or epileptic spasms with abnormal interictal EEG leading to rapid diagnosis of epileptic encephalopathy. Sodium channel blockers were effective or nonaggravating in most cases. SIGNIFICANCE: SCN8A is the third most prevalent early onset epileptic encephalopathy gene and is associated with two modes of onset of epilepsy.

Do All Children Who Present With a Complex Febrile Seizure Need a Lumbar Puncture?

STUDY OBJECTIVE: We assess the prevalences of bacterial meningitis and herpes simplex virus meningoencephalitis (HSV-ME) in children with a complex febrile seizure and determine these prevalences in the subgroup of children with a clinical examination result not suggestive of meningitis or encephalitis. METHODS: This multicenter retrospective study was conducted in 7 pediatric emergency departments (EDs) in the region of Paris, France. Visits of patients aged 6 months to 5 years for a complex febrile seizure from January 2007 to December 2011 were analyzed. We defined a subgroup of patients whose clinical examination result was not suggestive of meningitis or encephalitis. Bacterial meningitis and HSV-ME were sequentially sought for by analyzing bacteriologic and viral data at the visit, looking for data from a second visit to the hospital after the index visit, and telephoning the child's parents. RESULTS: From a total of 1,183,487 visits in the 7 pediatric EDs, 839 patients presented for a complex febrile seizure, of whom 260 (31.0%) had a lumbar puncture. The outcomes bacterial meningitis and HSV-ME were ascertainable for 715 (85%) and 657 (78.3%) visits, respectively, and we found 5 cases of bacterial meningitis (0.7% [95% confidence interval [CI] 0.2% to 1.6%]) and no HSV-ME (0% [95% CI 0% to 0.6%]). Among the 630 visits of children with a clinical examination result not suggesting meningitis or encephalitis, we found no bacterial meningitis (0% [95% CI 0% to 0.7%]) and no HSV-ME (0% [95% CI 0% to 0.8%]). CONCLUSION: In children with a complex febrile seizure, bacterial meningitis and HSV-ME are unexpected events when the clinical examination after complex febrile seizure is not suggestive of meningitis or encephalitis.

Activation of kinin B1 receptor evokes hyperthermia through a vagal sensory mechanism in the rat.

BACKGROUND: Kinins are mediators of pain and inflammation. Their role in thermoregulation is, however, unknown despite the fact the B1 receptor (B1R) was found implicated in lipopolysaccharide (LPS)-induced fever. The aim of this study was to investigate the mechanism by which peripheral B1R affects body core temperature in a rat model known to show up-regulated levels of B1R. METHODS: Male Sprague-Dawley rats received streptozotocin (STZ, 65 mg/kg; i.p.) to enhance B1R expression. Control rats received the vehicle only. One week later, rectal temperature was measured in awake rats after i.p. injection of increasing doses (0.01 to 5 mg/kg) of des-Arg(9)-Bradykinin (BK) and Sar-[D-Phe(8)]des-Arg(9)-BK (B1R agonists) or BK (B2R agonist). The mechanism of B1R-induced hyperthermia was addressed using specific inhibitors and in rats subjected to subdiaphragmatic vagal nerve ligation. B1R mRNA level was measured by quantitative Real Time-polymerase chain reaction (qRT-PCR) and B1R was localized by confocal microscopy. RESULTS: B1R agonists (0.1 to 5 mg/kg) showed transient (5- to 30-minute) and dose-dependent increases of rectal temperature (+1.5°C) in STZ-treated rats, but not in control rats. BK caused no effect in STZ and control rats. In STZ-treated rats, B1R agonist-induced hyperthermia was blocked by antagonists/inhibitors of B1R (SSR240612), cyclooxygenase-2 (COX-2) (niflumic acid) and nitric oxide synthase (NOS) (L-NAME), and after vagal nerve ligation. In contrast, COX-1 inhibition (indomethacin) had no effect on B1R agonist-induced hyperthermia. In STZ-treated rats, B1R mRNA was significantly increased in the hypothalamus and the vagus nerve where it was co-localized with calcitonin-gene-related peptide in sensory C-fibers. CONCLUSION: B1R, which is induced in inflammatory diseases, could contribute to hyperthermia through a vagal sensory mechanism involving prostaglandins (via COX-2) and nitric oxide.

Delta-viniferin, a resveratrol dehydrodimer: one of the major stilbenes synthesized by stressed grapevine leaves.

Delta-viniferin is a resveratrol dehydrodimer, an isomer of epsilon-viniferin. This compound has been reported as a molecule produced in vitro by the oxidative dimerization of resveratrol by plant peroxidases or fungal laccases. It was also recently identified in wines and in grape cell cultures. We have now identified this dimer by NMR, high-performance liquid chromatography-diode array detection (HPLC-DAD), and HPLC-mass spectrometry (MS) in grapevine leaves infected by Plasmopara viticola (downy mildew) or UV-C irradiated. Its concentration was higher than that of epsilon-viniferin and constitutes one of the most important phytoalexins derived from resveratrol.