C. elegans enteric motor neurons fire synchronized action potentials underlying the defecation motor program

The C. elegans nervous system was thought to be strictly analog, constituted solely by graded neurons. We recently discovered neuronal action potentials in the sensory neuron AWA; however, the extent to which the C. elegans nervous system relies on analog or digital neural signaling and coding is unclear. Here we report that the enteric motor neurons AVL and DVB fire all-or-none calcium-mediated action potentials that play essential roles in the rhythmic defecation behavior in C. elegans. Both AVL and DVB synchronously fire giant action potentials to faithfully execute all-or-none expulsion following the intestinal pacemaker. AVL fires unusual compound action potentials with each positive calcium-mediated spike followed by a potassium-mediated negative spike. The depolarizing calcium spikes in AVL are mediated by a CaV2 calcium channel UNC-2, while the negative potassium spikes are mediated by a repolarization-activated potassium channel EXP-2. Whole-body behavior tracking and simultaneous neural imaging in free-moving animals suggest that action potentials initiated in AVL in the head propagate along its axon to the tail and activate DVB through the INX-1 gap junction. Synchronized action potential spikes between AVL and DVB, as well as the negative spike and long-lasting afterhyperpolarization in AVL, play an important function in executing expulsion behavior. This work provides the first evidence that in addition to sensory coding, C. elegans motor neurons also use digital coding scheme to perform specific functions including long-distance communication and temporal synchronization, suggesting further, unforeseen electrophysiological diversity remains to be discovered in the C. elegans nervous system.

Impaired SARS-CoV-2 mRNA vaccine antibody response in chronic medical conditions: a real-world data analysis

This study is to investigate whether certain medical conditions may impair antibody response to the mRNA vaccines. In this unique study, participants were drawn from patients in National Jewish Health, a pulmonary specialty outpatient clinic.Our study highlights fact that 26% of our patients (n=226) who had spike protein ab measured at least 14 days post 2nd vaccine had negative spike protein ab testing. We found interstitial lung disease (ILD) to be an independent risk factor for impaired antibody response. While the exact antibody level that confers protection against SARS-CoV-2 is unknown and there may be other non-B cell-mediated protection (e.g. T cell-mediated), our study raises concerns that SARS-CoV-2 vaccination may not result in protective immunity in all populations and may have implications for some as masking and distancing strategies are abandoned.

Long-range coordination patterns in cortex change with behavioral context

Cortical connectivity mostly stems from local axonal arborizations, suggesting coordination is strongest between nearby neurons in the range of a few hundred micrometers. Yet multi-electrode recordings of resting-state activity in macaque motor cortex show strong positive and negative spike-count covariances between neurons that are millimeters apart. Here we show that such covariance patterns naturally arise in balanced network models operating close to an instability where neurons interact via indirect connections, giving rise to long-range correlations despite short-range connections. A quantitative theory explains the observed shallow exponential decay of the width of the covariance distribution at long distances. Long-range cooperation via this mechanism is not imprinted in specific connectivity structures but rather results dynamically from the network state. As a consequence, neuronal coordination patterns are not static but can change in a state-dependent manner, which we demonstrate by comparing different behavioral epochs of a reach-to-grasp experiment.

A scheme for forecasting severe space weather

<p>We have developed and tested a scheme for forecasting severe space weather (SvSW) that caused all known electric power outages and telecommunication system failures since 1957 and the Carrington event of 1859. The SvSW events of 04 August 1972 has puzzled the scientific community as it occurred during a moderate storm (DstMin = -124 nT) while all other SvSW events occurred during super storms (DstMin ≤ -250 nT). The solar wind velocity V and IMF Bz measured by ACE satellite at the L1 point since 1998 are used. For the earlier SvSW events such as the Carrington event of 1859, Quebec event of 1989, and the events in February 1958 and August 1972 we used the information from the literature. The coincidence of high ICME front (or shock) velocity ΔV (sudden increase in V over the background by over 275 km/s) and sufficiently large Bz southward at the time of the ΔV increase is associated with SvSW; and their product (ΔV×Bz) is found to exhibit a large negative spike at the speed increase. Such a product (ΔV×Bz) exceeding a threshold seems suitable for forecasting SvSW, with a maximum forecasting time of 35 minutes using ACE data. However, the coincidence of high V (not containing ΔV) and large Bz southward does not correspond to SvSW, indicating the importance of the impulsive action of high ΔV and large Bz southward coming through when they coincide. The need for the coincidence is verified using the CRCM.</p>

Novel Interaction between Prefrontal and Parietal Cortex during Memory Guided Saccades

Dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex (PPC) are linked to each other by direct reciprocal connections and by numerous pathways that traverse other areas. The nature of the functional coordination mediated by the interconnecting pathways is not well understood. To cast light on this issue, we simultaneously monitored neuronal activity in DLPFC (areas FEF and 8a) and PPC (areas LIP and 7a) while monkeys performed a memory guided saccade task. On measuring the spike-count correlation, a measure of the tendency for firing rates to covary across trials, we found that the DLPFC-PPC correlation became negative at the time of the saccade if and only if the neurons had matching spatial preferences and the target was at their mutually preferred location. The push-pull coordination underlying the negative spike-count correlation may help to ensure that saccadic commands emanating from DLPFC and PPC sum a constant value.SignificanceAnatomical pathways linking cortical areas that mediate executive control are thought to mediate coordination between them. We know very little, however, about the principles that govern this coordination. In the present study, we addressed this issue by recording simultaneously from neuronal populations in prefrontal and parietal cortex while monkeys performed memory guided saccades. We found a clear sign of coordination. Prefrontal and parietal neurons encoding a given saccade engage in a push-pull interaction during its execution. If parietal neurons are more active, prefrontal neurons are less active and vice versa. We suggest that this is a manifestation of a general principle whereby commands emanating from DLPFC and PPC are coordinated so as to sum a constant value.

Fast nonconvex deconvolution of calcium imaging data

Summary Calcium imaging data promises to transform the field of neuroscience by making it possible to record from large populations of neurons simultaneously. However, determining the exact moment in time at which a neuron spikes, from a calcium imaging data set, amounts to a non-trivial deconvolution problem which is of critical importance for downstream analyses. While a number of formulations have been proposed for this task in the recent literature, in this article, we focus on a formulation recently proposed in Jewell and Witten (2018. Exact spike train inference via $\ell_{0} $ optimization. The Annals of Applied Statistics12(4), 2457–2482) that can accurately estimate not just the spike rate, but also the specific times at which the neuron spikes. We develop a much faster algorithm that can be used to deconvolve a fluorescence trace of 100 000 timesteps in less than a second. Furthermore, we present a modification to this algorithm that precludes the possibility of a “negative spike”. We demonstrate the performance of this algorithm for spike deconvolution on calcium imaging datasets that were recently released as part of the $\texttt{spikefinder}$ challenge (http://spikefinder.codeneuro.org/). The algorithm presented in this article was used in the Allen Institute for Brain Science’s “platform paper” to decode neural activity from the Allen Brain Observatory; this is the main scientific paper in which their data resource is presented. Our $\texttt{C++}$ implementation, along with $\texttt{R}$ and $\texttt{python}$ wrappers, is publicly available. $\texttt{R}$ code is available on $\texttt{CRAN}$ and $\texttt{Github}$, and $\texttt{python}$ wrappers are available on $\texttt{Github}$; see https://github.com/jewellsean/FastLZeroSpikeInference.

Thermal Response of Gas Pipeline Metal to Gas Decompression

During natural gas pipeline processes that involve severe depressurization (e.g. blowdown), the gas experiences very significant cooling. The general impression in the industry has been that the adjacent pipeline metal also experiences cooling to a comparable extent. Should this actually be the case, the metal would be rendered susceptible to embrittlement. This would increase the possibility of fracture, thus compromising the integrity of the pipeline. To avoid the perceived possibility of fracture, pipeline design specifications tend to recommend special materials that can withstand low temperature. Such materials are often very expensive. However, recent experimental and analytical investigations into the heat transfer effects during pipeline decompression have shown that although the gas does undergo considerable cooling during events such as blowdowns, the metal is not cooled to nearly the same extent. These investigations resulted in a model of the blowdown. The model was based on the finding that the thermal response of the pipeline metal at a particular location is largely determined by the formation of a sharp negative spike in the gas temperature as the decompression wave passes that location. The present paper offers a more detailed version of the blowdown model, taking into account the transient temperature variations through the thickness of the pipe wall. The additional investigations offer insight into the phenomenon of ‘thermal shock’ in the pipeline metal. It is found that the metal response to a thermal ‘spike’ differs markedly from that to a thermal ‘shock’ imposed on the surface of the metal. It is shown that the possibility of damage due to unequal expansion/contraction in the material across the pipe wall thickness is minimal during a blowdown.

Transient Latch-Up Analysis of Power Control Device with Combined Light Emission and Backside Transient Interferometric Mapping Methods

A case study of a transient induced latch-up (TLU) problem is presented, which was identified during the development of a 60 V, 0.8 µm BiCMOS power control device. The mechanism was characterized by controlled transient latch-up testing and found to be fairly unusual, being triggered by a fast decreasing not necessarily negative spike or glitch on the positive supply pin. Emission Microscopy (EMMI) and Transient Interferometric Mapping (TIM) successfully located the parasitic silicon controlled rectifiers (SCR) structure. TIM is an infra-red laser beam based technique for back side analysis. TIM analysis enables concurrent imaging of carrier injection and heating in nanosecond timescale providing more detailed information on the SCR action than more often used static photon emission or dynamic TLP / PICA imaging.

Novel Sample Preparation Technique for Backside Analysis of Singulated Die

A case study of a transient induced latch-up (TLU) problem is presented, which was identified during the development of a 60 V, 0.8 µm BiCMOS power control device. The mechanism was characterized by controlled transient latch-up testing and found to be fairly unusual, being triggered by a fast decreasing not necessarily negative spike or glitch on the positive supply pin. Emission Microscopy (EMMI) and Transient Interferometric Mapping (TIM) successfully located the parasitic silicon controlled rectifiers (SCR) structure. TIM is an infra-red laser beam based technique for back side analysis. TIM analysis enables concurrent imaging of carrier injection and heating in nanosecond timescale providing more detailed information on the SCR action than more often used static photon emission or dynamic TLP / PICA imaging.