Measuring asymmetric temporal interdependencies in simulated and biological networks

We use a newly developed metric to characterize asymmetric temporal interdependencies in networks of coupled dynamical elements. We studied the formation of temporal ordering in a system of coupled Rössler oscillators for different connectivity ratios and network topologies and also applied the metric to investigate the functional structure of a biological network (cerebral ganglia of Helix snail). In the former example we show how the local ordering evolves to the global one as a function of structural parameters of the network, while in the latter we show spontaneous emergence of functional interdependence between two groups of electrodes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87883/2/043121_1.pd

Electrophysiological Properties of Motor Neurons in a Mouse Model of Severe Spinal Muscular Atrophy: In Vitro versus In Vivo Development

We examined the electrophysiological activity of motor neurons from the mouse model of severe spinal muscular atrophy (SMA) using two different methods: whole cell patch clamp of neurons cultured from day 13 embryos; and multi-electrode recording of ventral horns in spinal cord slices from pups on post-natal days 5 and 6. We used the MED64 multi-electrode array to record electrophysiological activity from motor neurons in slices from the lumbar spinal cord of SMA pups and their unaffected littermates. Recording simultaneously from up to 32 sites across the ventral horn, we observed a significant decrease in the number of active neurons in 5–6 day-old SMA pups compared to littermates. Ventral horn activity in control pups is significantly activated by serotonin and depressed by GABA, while these agents had much less effect on SMA slices. In contrast to the large differences observed in spinal cord, neurons cultured from SMA embryos for up to 21 days showed no significant differences in electrophysiological activity compared to littermates. No differences were observed in membrane potential, frequency of spiking and synaptic activity in cells from SMA embryos compared to controls. In addition, we observed no difference in cell survival between cells from SMA embryos and their unaffected littermates. Our results represent the first report on the electrophysiology of SMN-deficient motor neurons, and suggest that motor neuron development in vitro follows a different path than in vivo development, a path in which loss of SMN expression has little effect on motor neuron function and survival

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

The Use of Arbuscular Mycorrhizal Fungi to Improve Strawberry Production in Coir Substrate.

Strawberry is an important fruit crop within the UK. To reduce the impact of soil-borne diseases and extend the production season, more than half of the UK strawberry production is now in substrate (predominantly coir) under protection. Substrates such as coir are usually depleted of microbes including arbuscular mycorrhizal fungi (AMF) and consequently the introduction of beneficial microbes is likely to benefit commercial cropping systems. Inoculating strawberry plants in substrate other than coir has been shown to increase plants tolerance to soil-borne pathogens and water stress. We carried out studies to investigate whether AMF could improve strawberry production in coir under low nitrogen input and regulated deficit irrigation. Application of AMF led to an appreciable increase in the size and number of class I fruit, especially under either deficient irrigation or low nitrogen input condition. However, root length colonisation by AMF was reduced in strawberry grown in coir compared to soil and Terragreen. Furthermore, the appearance of AMF colonising strawberry and maize roots grown in coir showed some physical differences from the structure in colonised roots in soil and Terragreen: the colonization structure appeared to be more compact and smaller in coir

No difference in spiking activity in motor neurons cultured from wild type and SMA embryos.

<p><b>A</b>. Sample of cells from a ventral horn culture from an E13 embryo (wild type, 7 days in culture) showing the large somas and extensive network of cell processes. <b>B</b>. Sample genotyping result using the protocol from the Jackson Lab. Wild type band is 800 bp. Band from SMN1 knock-out is 500 bp. <b>C</b>. Sample traces showing the membrane potential and action potentials from control and SMA mice. <b>D</b>. Summary data of the resting membrane potential comparing the 2^nd and 3^rd week culture in control and SMA mice. <b>E</b>. Summary data of the frequency of action potential comparing the 2^nd week and 3^rd week culture in control and SMA mice. We did not find any significant difference between the average membrane potential or action potential frequency between the control and SMA cultures (<i>p</i>>0.05, One-way ANOVA).</p

Pharmacological agents cause little change in activity of control or SMA slices.

<p>Acetylcholine (100 µM), bicuculline (10 µM) or GABA (20 µM) were bath applied to the slice and recording was resumed after 2 minutes. For wash, slices were perfused with aCSF for 10 minutes before recording was resumed. Averages are calculated for 12 slices from 3 control mice and 11 slices from 3 SMA mice.</p><p>*p<0.05 (One-way ANOVA). Active electrodes are those electrodes recording spiking activity of at least 1 Hz over a 50 second period. Number of spikes per minute totals the number of spikes recorded on all electrodes recording neural activity from a slice.</p

Sample traces show the reduced activity recorded from the ventral horns of SMA mice.

<p>Sample traces showing spike activity recorded from all active electrodes in a single slice from a control and an SMA mouse showing activity in both basal and serotonin-stimulated conditions. Slices from SMA mice had many fewer active electrodes than controls, and showed fewer neurons active after serotonin treatment.</p

Neural activity is significantly reduced in the spinal cords of SMA mice.

<p><b>A</b>. Example of a slice from the lumbar spine with only the ventral horn positioned over the electrodes of the MED probe. <b>B</b>. Two littermates from the Smn^−/−;SMN2 strain of mice at P4 showing the difference in size of the wild type and mutant pups. <b>C</b>. Average number of active electrodes recorded for each slice. One Way ANOVA, p<0.0001 <b>D</b>. Average spike frequency recorded by each active electrode. <i>p</i> = 0.46, One way ANOVA.</p

Motor neuron activity in both control and SMA slices is stimulated by serotonin.

<p>50 µM of serotonin was added to the bath and neuronal activity was recorded after 2 minutes. For the wash condition, slices were perfused with aCSF for 10 minutes before recording resumed. <b>A</b>. Average number of active electrodes/slice (active electrodes are those that recorded more than 50 spikes in 50 seconds). One way ANOVA, p<0.0001 for both control and SMA. <b>B</b>. Average frequency of spikes recorded on active electrodes. One way ANOVA, p<0.0001 for control, p = 0.137 for SMA.</p