Experiences of Dutch Midwives Regarding the Quality of Care during the COVID-19 Pandemic.

This study assessed how the quality of care during the COVID-19 pandemic has been experienced by Dutch midwives. At the beginning of May 2020, 15 Dutch midwives were interviewed during the first wave of the pandemic. The interviews included questions based on the value-based healthcare framework by Porter. The interviews were transcribed verbatim, coded, and analyzed according to recurrent themes using the directed content analysis approach. Key themes identified included high quality midwifery care, information provision, costs, under/over treatment, interprofessional collaboration, and shared decision making. The quality of midwifery care during the COVID-19 pandemic was experienced to be sufficient, given the challenging circumstances. The midwives experienced the lack of face-to-face check-ups to be problematic. Unclear information and lack of personal protective equipment caused stress and confusion, and they worked an additional 2-4 h per working day. Some pregnant women were hesitant to call or visit them when they thought something was wrong. The midwives perceived some advantages in using video or telephone calls. Considerations for future pandemics include an additional face-to-face check-up between 16 and 27 weeks of pregnancy and one postpartum visit. For post-pandemic care, providing a check-up through telephone or video call could be offered in certain cases.

Barbed channels enhance unidirectional connectivity between neuronal networks cultured on multi electrode arrays.

Cultured neurons on multi electrode arrays (MEAs) have been widely used to study various aspects of neuronal (network) functioning. A possible drawback of this approach is the lack of structure in these networks. At the single cell level, several solutions have been proposed to enable directed connectivity, and promising results were obtained. At the level of connected sub-populations, a few attempts have been made with promising results. First assessment of the designs' functionality, however, suggested room for further improvement. We designed a two chamber MEA aiming to create a unidirectional connection between the networks in both chambers ("emitting" and "receiving"). To achieve this unidirectionality, all interconnecting channels contained barbs that hindered axon growth in the opposite direction (from receiving to emitting chamber). Visual inspection showed that axons predominantly grew through the channels in the promoted direction. This observation was confirmed by spontaneous activity recordings. Cross-correlation between the signals from two electrodes inside the channels suggested signal propagation at ≈2 m/s from emitting to receiving chamber. Cross-correlation between the firing patterns in both chambers indicated that most correlated activity was initiated in the emitting chamber, which was also reflected by a significantly lower fraction of partial bursts (i.e., a one-chamber-only burst) in the emitting chamber. Finally, electrical stimulation in the emitting chamber induced a fast response in that chamber, and a slower response in the receiving chamber. Stimulation in the receiving chamber evoked a fast response in that chamber, but no response in the emitting chamber. These results confirm the predominantly unidirectional nature of the connecting channels from emitting to receiving chamber.

Classification of motor imagery performance in acute stroke.

OBJECTIVE: Effective motor imagery performance, seen as strong suppression of the sensorimotor rhythm, is the key element in motor imagery therapy. Therefore, optimization of methods to classify whether the subject is performing the imagery task is a prerequisite. An optimal classification method should have high performance accuracy and use a small number of channels. We investigated the additional benefit of the common spatial pattern filtering (CSP) to a linear discriminant analysis (LDA) classifier, for different channel configurations. METHODS: Ten hemispheric acute stroke patients and 11 healthy subjects were included. EEGs were recorded using 60 channels. The classifier was trained with a motor execution task. For both healthy controls and patients, analysis of recordings was initially limited to 3 and 11 electrodes recording from the motor cortex area, and later repeated using 45 electrodes. RESULTS: No significant improvement on the addition of CSP to LDA was found (in both cases, the area under the receiving operating characteristic (AU-ROC) ≈ 0.70 (acceptable)). We then repeated the LDA+CSP method on recordings of 45 electrodes, since the use of imagery neuronal circuits may well extend beyond the motor area. AU-ROC rose to 0.90, but no virtual 'most responsible' electrode was observed. Finally, in mild-to-moderate stroke patients we could successfully use the EEG data recorded from the healthy hemisphere to train the classifier (AU-ROC ≈ 0.70). SIGNIFICANCE: Including only the channels on the unaffected motor cortex is sufficient to train a classifier.

Temporal evolution of event-related desynchronization in acute stroke: a pilot study.

OBJECTIVE: Assessment of event-related desynchronization (ERD) may assist in predicting recovery from stroke and rehabilitation, for instance in BCI applications. Here, we explore the temporal evolution of ERD during stroke recovery. METHODS: Ten stroke patients and eleven healthy controls were recruited to participate in a hand movement task while EEG was being recorded. Four measurements were conducted in eight patients within four months. We quantified changes of ERD using a modulation strength measure, S(m), which represents an area and amplitude of ERD. RESULTS: 7/8 patients showed good recovery. Absence-or-reduction of ipsilesional modulation was initially found in stroke patients but not in the healthy controls. In the patient group, two evolutions were found in 6/8 patients: a significant increase in ipsilesional S(m); and a decreasing trend in contralesional S(m). In the only non-recovery patient, absence of ipsilesional modulation was observed, while his contralesional S(m) increased with time after stroke. CONCLUSION: The two evolutions presumably reflect the reorganization of brain networks and functional recovery after acute stroke. The significant increase of ipsilesional S(m) in patients with a good recovery suggests an important role of this hemisphere during recovery. SIGNIFICANCE: Improved understanding of ERD in acute stroke may assist in prognostication and rehabilitation.

In vivo testing of a 3D bifurcating microchannel scaffold inducing separation of regenerating axon bundles in peripheral nerves.

Artificial nerve guidance channels enhance the regenerative effectiveness in an injured peripheral nerve but the existing design so far has been limited to basic straight tubes simply guiding the growth to bridge the gap. Hence, one of the goals in development of more effective neuroprostheses is to create bidirectional highly selective neuro-electronic interface between a prosthetic device and the severed nerve. A step towards improving selectivity for both recording and stimulation have been made with some recent in vitro studies which showed that three-dimensional (3D) bifurcating microchannels can separate neurites growing on a planar surface and bring them into contact with individual electrodes. Since the growing axons in vivo have the innate tendency to group in bundles surrounded by connective tissue, one of the big challenges in neuro-prosthetic interface design is how to overcome it. Therefore, we performed experiments with 3D bifurcating guidance scaffolds implanted in the sciatic nerve of rats to test if this new channel architecture could trigger separation pattern of ingrowth also in vivo. Our results showed that this new method enabled the re-growth of neurites into channels with gradually diminished width (80, 40 and 20 µm) and facilitated the separation of the axonal bundles with 91% success. It seems that the 3D bifurcating scaffold might contribute towards conveying detailed neural control and sensory feedback to users of prosthetic devices, and thus could improve the quality of their daily life.

Ghrelin stimulates synaptic formation in cultured cortical networks in a dose-dependent manner.

Ghrelin was initially related to appetite stimulation and growth hormone secretion. However, it also has a neuroprotective effect in neurodegenerative diseases and regulates cognitive function. The cellular basis of these processes is related to synaptic efficacy and plasticity. Previous studies indicated that ghrelin has an excitatory effect on neuronal activity, and stimulates synaptic plasticity in vivo. Plasticity in the adult brain occurs in many different ways, including changes in synapse morphology and number. Therefore, we used in vitro neuronal cultures to investigate how ghrelin affects synaptogenesis. We used dissociated cortical cultures of newborn rats, chronically treated with different doses of ghrelin (0.5, 1, 1.5 and 2µM). After one-, two-, three- or four weeks cultures were immunostained for the presynaptic marker synaptophysin. In parallel, additional groups of non-treated cultures were immunostained for detection of ghrelin receptor (GHSR1). During development, GHSR1was increasingly expressed in all type of neurons, as well as the synaptophysin. Synaptic density depended on ghrelin concentration, and was much higher than in controls in all age groups. In conclusion, ghrelin leads to earlier network formation in dissociated cortical networks and an increase in number of synapses. The effect is probably mediated by GHSR1. These findings suggest that ghrelin may provide a novel therapeutic strategy for the treatment of disorders related to synaptic impairment.

Importance of baseline in event-related desynchronization during a combination task of motor imagery and motor observation.

OBJECTIVE: Event-related desynchronization (ERD) or synchronization (ERS) refers to the modulation of any EEG rhythm in response to a particular event. It is typically quantified as the ratio between a baseline and a task condition (the event). Here, we focused on the sensorimotor mu-rhythm. We explored the effects of different baselines on mu-power and ERD of the mu-rhythm during a motor imagery task. METHODS: Eighteen healthy subjects performed motor imagery tasks while EEGs were recorded. Five different baseline movies were shown. For the imagery task a right-hand opening/closing movie was shown. Power and ERD of the mu-rhythm recorded over C3 and C4 for the different baselines were estimated. MAIN RESULTS: 50% of the subjects showed relatively high mu-power for specific baselines only, and ERDs of these subjects were strongly dependent on the baseline used. In 17% of the subjects no preference was found. Contralateral ERD of the mu-rhythm was found in about 67% of the healthy volunteers, with a significant baseline preference in about 75% of that subgroup. SIGNIFICANCE: The sensorimotor ERD quantifies activity of the brain during motor imagery tasks. Selection of the optimal baseline increases ERD.

Growth dynamics explain the development of spatiotemporal burst activity of young cultured neuronal networks in detail.

A typical property of isolated cultured neuronal networks of dissociated rat cortical cells is synchronized spiking, called bursting, starting about one week after plating, when the dissociated cells have sufficiently sent out their neurites and formed enough synaptic connections. This paper is the third in a series of three on simulation models of cultured networks. Our two previous studies [26], [27] have shown that random recurrent network activity models generate intra- and inter-bursting patterns similar to experimental data. The networks were noise or pacemaker-driven and had Izhikevich-neuronal elements with only short-term plastic (STP) synapses (so, no long-term potentiation, LTP, or depression, LTD, was included). However, elevated pre-phases (burst leaders) and after-phases of burst main shapes, that usually arise during the development of the network, were not yet simulated in sufficient detail. This lack of detail may be due to the fact that the random models completely missed network topology .and a growth model. Therefore, the present paper adds, for the first time, a growth model to the activity model, to give the network a time dependent topology and to explain burst shapes in more detail. Again, without LTP or LTD mechanisms. The integrated growth-activity model yielded realistic bursting patterns. The automatic adjustment of various mutually interdependent network parameters is one of the major advantages of our current approach. Spatio-temporal bursting activity was validated against experiment. Depending on network size, wave reverberation mechanisms were seen along the network boundaries, which may explain the generation of phases of elevated firing before and after the main phase of the burst shape.In summary, the results show that adding topology and growth explain burst shapes in great detail and suggest that young networks still lack/do not need LTP or LTD mechanisms.

Orexin a in cortical cultures: expression and effect on synaptogenesis during development.

Orexin A (OXA) is an excitatory hypothalamic neurotransmitter and ligand for Orexin Receptor-1 (OR1), isolated from a small group of hypothalamic neurons. OXA orchestrates different brain functions, and at the cognitive level some of the effects of insufficiency of OXA are well-known, for example in Parkinson's disease. It is widely assumed that deteriorated cognitive processes are related to impaired network connectivity. However, little is known about the effects of OXA in network connectivity and synaptogenesis. Therefore, to obtain insight into this problem we designed experiments with two groups of networks of dissociated cortical neurons: one group incubated in a plain medium and another chronically treated with OXA. After 1, 2, 3 or 4 weeks in vitro we applied immunocytochemistry for detection of OXA, OR1, and synaptic marker synaptophysin. Shortly after plating, 91 ± 8% of the neurons cultivated in a plain medium expressed OXA-immunoreactivity, which does normally not occur in vivo indicating that neurons may change their phenotype under non-natural culture conditions to develop synaptically coupled networks. The fraction of orexinergic neurons decreased to 33 ± 21% after 4 weeks in vitro. OXA expression was highest in the first week of network formation, the period of maximum synaptogenesis, and then decreased and stabilized in the weeks thereafter. Our hypothesis that OXA plays a role in the network development as a synaptogenic factor was supported by higher levels, earlier onset, and sustained increase of synaptophysin expression in experiments with chronic OXA application to the culture medium.

Phase-dependent effects of stimuli locked to oscillatory activity in cultured cortical networks.

The archetypal activity pattern in cultures of dissociated neurons is spontaneous network-wide bursting. Bursts may interfere with controlled activation of synaptic plasticity, but can be suppressed by the application of stimuli at a sufficient rate. We sinusoidally modulated (4 Hz) the pulse rate of random background stimulation (RBS) and found that cultures were more active, burst less frequently, and expressed oscillatory activity. Next, we studied the effect of phase-locked tetani (four pulses, 200 s(-1)) on network activity. Tetani were applied to one electrode at the peak or trough of mRBS stimulation. We found that when tetani were applied at the peak of modulated RBS (mRBS), a significant potentiation of poststimulus histograms (PSTHs) occurred. Conversely, tetani applied at the trough resulted in a small but insignificant depression of PSTHs. In addition to PSTHs, electrode-specific firing rate profiles within spontaneous bursts before and after mRBS were analyzed. Here, significant changes in firing rate profiles were found only for stimulation at the peak of mRBS. Our study shows that rhythmic activity in culture is possible, and that the network responds differentially to strong stimuli depending on the phase at which they are delivered. This suggests that plasticity mechanisms may be differentially accessible in an oscillatory state.

The effect of slow electrical stimuli to achieve learning in cultured networks of rat cortical neurons.

Learning, or more generally, plasticity may be studied using cultured networks of rat cortical neurons on multi electrode arrays. Several protocols have been proposed to affect connectivity in such networks. One of these protocols, proposed by Shahaf and Marom, aimed to train the input-output relationship of a selected connection in a network using slow electrical stimuli. Although the results were quite promising, the experiments appeared difficult to repeat and the training protocol did not serve as a basis for wider investigation yet. Here, we repeated their protocol, and compared our 'learning curves' to the original results. Although in some experiments the protocol did not seem to work, we found that on average, the protocol showed a significantly improved stimulus response indeed. Furthermore, the protocol always induced functional connectivity changes that were much larger than changes that occurred after a comparable period of random or no stimulation. Finally, our data shows that stimulation at a fixed electrode induces functional connectivity changes of similar magnitude as stimulation through randomly varied sites; both larger than spontaneous connectivity fluctuations. We concluded that slow electrical stimulation always induced functional connectivity changes, although uncontrolled. The magnitude of change increased when we applied the adaptive (closed-loop) training protocol. We hypothesize that networks develop an equilibrium between connectivity and activity. Induced connectivity changes depend on the combination of applied stimulus and initial connectivity. Plain stimuli may drive networks to the nearest equilibrium that accommodates this input, whereas adaptive stimulation may direct the space for exploration and force networks to a new balance, at a larger distance from the initial state.

Orexin-A and orexin-B during the postnatal development of the rat brain.

Orexin-A and orexin-B are hypothalamic neuropeptides isolated from a small group of neurons in the hypothalamus, which project their axons to all major parts of the central nervous system. Despite the extensive information about orexin expression and function at different parts of the nervous system in adults, data about the development and maturation of the orexin system in the brain are a bit contradictory and insufficient. A previous study has found expression of orexins in the hypothalamus after postnatal day 15 only, while others report orexins detection at embryonic stages of brain formation. In the present study, we investigated the distribution of orexin-A and orexin-B neuronal cell bodies and fibers in the brain at three different postnatal stages: 1-week-, 2-week-old and adult rats. By means of immunohistochemical techniques, we demonstrated that a small subset of cells in the lateral hypothalamus, and the perifornical and periventricular areas were orexin-A and orexin-B positive not only in 2-week-old and adult rats but also in 1-week-old animals. In addition, orexin-A and orexin-B expressing neuronal varicosities were found in many other brain regions. These results suggest that orexin-A and orexin-B play an important role in the early postnatal brain development. The widespread distribution of orexinergic projections through all these stages may imply an involvement of the two neurotransmitters in a large variety of physiological and behavioral processes also including higher brain functions like learning and memory.

Time-dependent changes in ghrelin-immunoreactivity in dissociated neuronal cultures of the newborn rat neocortex.

Ghrelin is a hormone, initially described as a gastric peptide stimulating appetite and growth hormone secretion, which also has an important role in the regulation of many other processes, including higher brain functions. Ghrelin has been described in situ in different parts of the brain, but so far there has been no data about its expression in cell cultures. Therefore, we aimed in this study to investigate the levels of ghrelin in dissociated cortical neurons at various times in culture. We applied the ABC immunocytochemical method for the detection of ghrelin in one-day-, one-week-, and two-week-old cultures. Our results clearly show that at the early stages after plating the cultures 86.2% (+/-8.93) of the neurons are ghrelin-positive and their number decreases during the culturing period. As ghrelin is present in the majority of cultured newborn neurons, when the neuronal differentiation and network formation take place, it may also influence the early synaptic formation and cell-to-cell interactions, which are both very important for network functions like learning and memory.

The effect of learning on bursting.

We have studied the effect that learning a new stimulus-response (SR) relationship had within a neuronal network cultured on a multielectrode array. For training, we applied repetitive focal electrical stimulation delivered at a low rate (<1/s). Stimulation was withdrawn when a desired SR success ratio was achieved. It has been shown elsewhere, and we verified that this training algorithm, named conditional repetitive stimulation (CRS), can be used to strengthen an initially weak SR. So far, it remained unclear what the role of the rest of the network during learning was. We therefore studied the effect of CRS on spontaneously occurring network bursts. To this end, we made profiles of the firing rates within network bursts. We have earlier shown that these profiles change shape on a time base of several hours during spontaneous development. We show here that profiles of summed activity, called burst profiles, changed shape at an increased rate during CRS. This suggests that the whole network was involved in making the changes necessary to incorporate the desired SR relationship. However, a local (path-specific) component to learning was also found by analyzing profiles of single-electrode-activity phase profiles. Phase profiles that were not part of the SR relationship changed far less during CRS than the phase profiles of the electrodes that were part of the SR relationship. Finally, the manner in which phase profiles changed shape varied and could not be linked to the SR relationship.

Single pulse and pulse train modulation of cutaneous electrical stimulation: a comparison of methods.

SUMMARY: : Changing the amplitude of single rectangular pulse stimuli (SP) has the disadvantage of recruiting tactile and nociceptive fibers in a changing, unknown proportion. Keeping the amplitude constant, but applying a varying number of pulses in a train is another way of stimulus variation, keeping the proportion constant. So, pulse trains (PT) with a variable number of pulses but fixed amplitude might be more suitable to study nonperipheral aspects of processing of stimuli. In this study, we compared the effects of PT and SP stimulation on subjective Numeric Rating Scale scores of perceived stimulus strength and evoked potentials (EP). A total of 41 healthy subjects were electrically stimulated at the left forearm or left middle fingertip using SP and PT stimuli. Numeric Rating Scale scores and EPs were averaged from 105 randomized stimuli at 5 stimulus amplitudes or number of pulses for each subject. The relationships between stimulus amplitudes or number of pulses, EP components and Numeric Rating Scale scores differed depending on the stimulation method and stimulus location. Although the repeatedly reported Numeric Rating Scale-EP (N150-P200) correlation was reproduced for SP at the fingertip, no significant correlation was found for SP stimulation at the forearm. For PT this correlation was found for both stimulus locations. These findings demonstrate that SP and PT involve different ways of processing. The two methods result in different Numeric Rating Scale scores and EP components. Furthermore, PT stimulation is less dependent on stimulus location.

Analysis of cultured neuronal networks using intraburst firing characteristics.

It is an open question whether neuronal networks, cultured on multielectrode arrays, retain any capability to usefully process information (learning and memory). A necessary prerequisite for learning is that stimulation can induce lasting changes in the network. To observe these changes, one needs a method to describe the network in sufficient detail, while stable in normal circumstances. We analyzed the spontaneous bursting activity that is encountered in dissociated cultures of rat neocortical cells. Burst profiles (BPs) were made by estimating the instantaneous array-wide firing frequency. The shape of the BPs was found to be stable on a time scale of hours. Spatiotemporal detail is provided by analyzing the instantaneous firing frequency per electrode. The resulting phase profiles (PPs) were estimated by aligning BPs to their peak spiking rate over a period of 15 min. The PPs reveal a stable spatiotemporal pattern of activity during bursts over a period of several hours, making them useful for plasticity and learning studies. We also show that PPs can be used to estimate conditional firing probabilities. Doing so, yields an approach in which network bursting behavior and functional connectivity can be studied.

Changes within bursts during learning in dissociated neural networks.

We have studied the effect of imprinting a new stimulus-response (SR) relationship into a neuronal network cultured on a multi electrode array (MEA). We have used the Conditional Repetitive Stimulation (CRS) algorithm introduced by Shahaf et al in 2004. In this algorithm focal electrical stimulation is delivered at a low rate (<<1 Hz) and is withdrawn when a desired response is observed. We confirmed that CRS could train the network to strengthen an initially weak SR relationship. With the acquisition of a new SR relationship, we studied its effect on network activity. Specifically, spontaneously occurring network bursts measured before, during and after training were analyzed. The total firing rate within bursts was estimated with a temporal resolution of milliseconds (burst profiles). We have shown earlier that these profiles change shape on a time base of several hours during spontaneous development. We show that the rate of change of the profiles during training (i.e. CRS) was higher than when no stimulation was applied.

Do external stimuli, applied to train cultured cortical networks, disturb the balance between activity and connectivity?

Learning, or more generally, plasticity may be studied using cultured neuronal networks on multi electrode arrays. Many protocols have been proposed to change connectivity in such networks. So far, only one of these protocols, proposed by Shahaf and Marom, aimed to change the input-output relationship of a selected connection in the network. Although the results were quite promising, the experiments appeared difficult to repeat and the protocol did not serve as a basis for wider investigation yet. Here, we repeated their protocol, and compared our 'learning curves' to the original results. Although in some experiments the protocol did not seem to work, we found that on average, the protocol showed a significant learning effect indeed. We frequently found learning curves that initially declined as in the original results, but then increased again before finally settling at a low level.

Latency dependent development of related firing patterns of cultured cortical neurons.

Networks of cortical neurons were grown over multi electrode arrays to enable simultaneous measurement of signals from multiple neurons. We described functional connectivity in these networks by relationships between individual electrodes, based on conditional firing probabilities. In this study we investigated periods in which the strength of a relationship monotonously increased (strengthening) or decreased (weakening) during periods of 24 or 10 hours. We observed a slightly increased incidence of latencies up to 25 ms during strengthening, while these latencies rarely occurred during weakening. Next, it appeared that relationships tended to strengthen more than average in periods with latencies in the range 5-30 ms, whereas strengthening was significantly less than average in latencies 40-65 ms.

Heritabilities, apolipoprotein E, and effects of inbreeding on plasma lipids in a genetically isolated population: the Erasmus Rucphen Family Study.

Despite considerable progress in unravelling the genetic basis of dyslipidemias, most findings are based on families with extreme phenotypes. We studied lipid levels in an extended pedigree ascertained irrespective of phenotype from the population of a recent genetic isolate in the Netherlands. Heritabilities of plasma lipid measures were examined; this analysis also included estimates of the proportion of variance attributable to ApoE genotype. The association between inbreeding and lipids was also considered, as a substantial fraction of the population had known inbreeding. A total of 868 individuals from this pedigree, containing more than 60,000 people over 15 generations, were investigated in this study. Laboratory analysis of these subjects included the determination of fasting plasma lipids. ApoE epsilon2/3/4 status was ascertained using TaqMan assays. Heritabilities for plasma lipids were estimated with adjustments for multiple covariates using SOLAR. Heritabilities for total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), triglycerides (TG), TC/HDL ratio, and TG/HDL ratio were found to be 0.35, 0.56, 0.30, 0.24, 0.49, and 0.39, respectively. The addition of ApoE genotype in the model significantly decreased these estimates (Deltah(2) = -0.030, -0.004, -0.054, and -0.006 for TC, HDL, LDL, and TG). In a further analysis, TC and LDL were positively associated with the extent of inbreeding (p (trend) = 0.02 and p (trend) = 0.05, respectively). These data provide estimates of lipid heritability unbiased due to selection and suggest that this population represents a good opportunity to localize novel genes influencing plasma lipid levels.