Synchrony Index Research Articles

Synchronous fruiting and common seed dispersers of two endemic columnar cacti in the Caatinga, a dry forest in Brazil

This study evaluates the fruiting phenology, fruit traits, and seed dispersal in two Pilosocereus (Cactaceae) species that are widely distributed in Caatinga vegetation. We monitored the fruiting phenology of Pilosocereus gounellei and Pilosocereus chrysostele on a monthly basis for a period of 4 years (45 months from March 2009 to November 2012), including 30 individuals of each species. We also carried out focal observations, captured dispersers, and conducted germination tests, to identify the effective seed dispersers of these species. Both species exhibited sub-annual fruiting patterns and high fruiting synchrony index (O jk 0.62), with peaks occurring from February to May for P. gounellei and February to April for P. chrysostele. In all, 248 visits by seven bird and two lizard species were recorded for P. gounellei, and 104 visits by five bird species were recorded for P. chrysostele. The two species shared five seed dispersers. The finch Lanio pileatus was the most frequently visiting bird species. The number of visits to the fruits of P. gounellei was higher than to the fruits of P. chrysostele. Passage of seeds through the digestive tracts of all bird species significantly increased the germination rate for P. chrysostele, whereas for P. gounellei, the birds Forpus xanthopterygius and L. pileatus decreased germination rates. Sub-annual fruiting patterns, similar fruit morphology, and high synchronous fruiting are factors that favor resource sharing among the dispersers of Pilosocereus in the Caatinga.

Reproductive phenology of understory species in anAbies religiosa(Pinaceae) forest in the Magdalena River Basin, Mexico City

Abstract Study of reproductive patterns of understory species is of great importance because they influence the regeneration dynamics of a forest, and the biogeographic origin of these species will also define their responses to environmental conditions. In this study, we answer the following questions: Are there temporal patterns in the reproductive phenology of understory species? If so, what are the variables that influence them? How do the reproductive patterns of the species differ according to their biogeographic origin? To answer these questions, in the Abies religiosa forest in the Magdalena River Basin, Mexico City, we determined the flowering and fruiting patterns of 55 species using multivariate analyses. Spearman's correlations were calculated between the patterns found and the environmental variables, and Augspurger's synchrony indexes were also calculated. Our results showed three flowering and three fruiting patterns. The correlations showed a significant and positive relationship between f...

Synaptic dynamics regulation in response to high frequency stimulation in neuronal networks

High frequency stimulation (HFS) has confirmed its ability in modulating the pathological neural activities. However its detailed mechanism is unclear. This study aims to explore the effects of HFS on neuronal networks dynamics. First, the two-neuron FitzHugh–Nagumo (FHN) networks with static coupling strength and the small-world FHN networks with spike-time-dependent plasticity (STDP) modulated synaptic coupling strength are constructed. Then, the multi-scale method is used to transform the network models into equivalent averaged models, where the HFS intensity is modeled as the ratio between stimulation amplitude and frequency. Results show that in static two-neuron networks, there is still synaptic current projected to the postsynaptic neuron even if the presynaptic neuron is blocked by the HFS. In the small-world networks, the effects of the STDP adjusting rate parameter on the inactivation ratio and synchrony degree increase with the increase of HFS intensity. However, only when the HFS intensity becomes very large can the STDP time window parameter affect the inactivation ratio and synchrony index. Both simulation and numerical analysis demonstrate that the effects of HFS on neuronal network dynamics are realized through the adjustment of synaptic variable and conductance.

Large-Scale Phase Synchrony Reflects Clinical Status After Stroke: An EEG Study

Background and Purpose. Stroke-induced focal brain lesions often exert remote effects via residual neural network activity. Electroencephalographic (EEG) techniques can assess neural network modifications after brain damage. Recently, EEG phase synchrony analyses have shown associations between the level of large-scale phase synchrony of brain activity and clinical symptoms; however, few reports have assessed such associations in stroke patients. Objective. The aim of this study was to investigate the clinical relevance of hemispheric phase synchrony in stroke patients by calculating its correlation with clinical status. Methods. This cross-sectional study included 19 patients with post-acute ischemic stroke admitted for inpatient rehabilitation. Interhemispheric phase synchrony indices (IH-PSIs) were computed in 2 frequency bands (alpha [α], and beta [β]), and associations between indices and scores of the Functional Independence Measure (FIM), the National Institutes of Health Stroke Scale (NIHSS), and the Fugl−Meyer Motor Assessment (FMA) were analyzed. For further assessments of IH-PSIs, ipsilesional intrahemispheric PSIs (IntraH-PSIs) as well as IH- and IntraH-phase lag indices (PLIs) were also evaluated. Results. IH-PSIs correlated significantly with FIM scores and NIHSS scores. In contrast, IH-PSIs did not correlate with FMA scores. IntraH-PSIs correlate with FIM scores after removal of the outlier. The results of analysis with PLIs were consistent with IH-PSIs. Conclusions. The PSIs correlated with performance on the activities of daily living scale but not with scores on a pure motor impairment scale. These results suggest that large-scale phase synchrony represented by IH-PSIs provides a novel surrogate marker for clinical status after stroke.

Flowering phenology and plant-pollinator interactions in a grassland community of Southern Brazil

Synchrony of phenological events at the community level is a critical aspect for plants. Distinct phenological patterns, such as aggregated and segregated, act in the establishment of plant-pollinator interactions and can play a fundamental role in plant community structure. Working in grazed subtropical grasslands in southern Brazil, our goals were to describe the plant-pollinator interactions in the grassland community and investigate the phenological patterns. The study was performed in a grassland community of Southern Brazil. In 12 sample plots (100m2 each) all flowering plant species with visually attractive flowers were recorded monthly during the period of six months. We used the Pianka index to estimate the flowering overlap, by comparison with 1000 pseudo-communities and a synchrony index to evaluate the phenological community pattern. All 82 flowering species present in the 12 study plots were observed monthly between six months. We observed that the community presented aggregated and non-synchronized flowering periods, which should reduce pollinator competition. We found no significant relationship between flowering synchrony and similarity of pollinators, that is, plant species that flower for a long time or together with many species did not share more pollinators than plants that flower for short time and alone. Some guilds of flowers visitors preferred flowers with a particular color, which indicated the important role of visual traits in plant-pollinator interactions. This study reports that flowering phenology could be structured by biotic components more than by random processes in these species-rich South Brazilian grasslands.

Left atrial strain assessed by three-dimensional speckle tracking echocardiography predicts atrial fibrillation recurrence after catheter ablation in patients with paroxysmal atrial fibrillation.

Several studies have shown the utility of left atrial (LA) function determined by two-dimensional or three-dimensional speckle tracking echocardiography (2D- or 3D-STE) for identifying patients with paroxysmal atrial fibrillation (AF). However, whether 3D-STE is applicable for prediction of the recurrence of AF after catheter ablation (CA) remains unknown. We examined whether any 3D-STE parameters are better than 2D-STE parameters for the prediction of AF recurrence. Forty-two patients with paroxysmal AF (58±10years old, 69% male) underwent 2D- and 3D-STE within 3days before first-time CA. The global peak LA longitudinal, circumferential, and area strains during systole (3D-GLSs, -GCSs, and -GASs, respectively) and those just before atrial contraction (3D-GLSa, -GCSa, and -GASa, respectively) were determined by 3D-STE and standard deviations of times to peaks of regional LA strains were calculated as indices of LA dyssynchrony. In 2D-STE, global LA longitudinal strains during systole and just before atrial contraction (2D-GLSs and -GLSa) were determined. During follow-up of 441±221days, 12 patients (29%) had AF recurrence. In the univariate Cox proportional hazard analysis, age [hazard ratio (HR): 1.08, p=0.04], 3D-GCSs (HR: 0.91, p=0.03), and 3D-GASs (HR: 0.95, p=0.01) were predictors of AF recurrence, though associations of recurrence with 2D-STE parameters, indices of LA synchrony, and LA volume were not significant. Multivariable analysis showed that 3D-GASs was an independent predictor of AF recurrence (HR: 0.96, p=0.048). LA strain determined by 3D-STE is a novel and better predictor of AF recurrence after CA than that determined by 2D-STE or other known predictors.

Flowering phenology of Catopsis compacta (Bromeliaceae), a dioecious epiphyte in an oak forest

Background: Knowledge of the flowering phenology of species with an epiphytic habit and a dioecious sexual system is scarce.
 Questions: We studied the flowering phenology of a population of the dioecious epiphytic bromeliad, Catopsis compacta , in an oak forest in Oaxaca, Mexico, to answer the following questions: 1) what type of flowering period is exhibited by this population of C. compacta ? 2) what is the degree of synchrony between the male and female flowering periods? and 3) what is the flowering synchrony index of the population?
 Methods: In February 2006, in a 20 m × 20 m plot, we marked and measured 151 individuals of C. compacta ? 10 cm in height (minimum reproductive size). We recorded the number of flowers and fruits present in each individual every month for one year.
 Results: Our results showed that the flowering period in both sexes lasted for three months (May–July). Only 23 marked individuals flowered (15.23 %): of these 12 (52.17 %) were female and 11 (47.83 %) were male. The index of synchrony between females and males was 0.958 ± 0.013 and the flowering synchrony index of the population was 0.833 ± 0.189.
 Conclusions: The high flowering synchrony between the sexes, together with a flowering season that coincided with the period of highest rainfall when the number of arthropods (potential pollinators) is the highest, could favor breeding and, therefore, reproductive success.

Unravelling the inheritance, QST and reproductive phenology attributes of the tetraploid tropical grass Brachiaria ruziziensis (Germain et Evrard)

AbstractThe autotetraploid forage Congo signal grass (Brachiaria ruziziensis) is an important component in the Brachiaria breeding programme. As with other tropical forage grass species, the association between flowering and seed yield components, the mode of inheritance and the effects of population structure on phenotypic breeding are lacking. Seventeen characteristics evaluated in 59 half‐sib progeny of seven subpopulations were analysed using a mixed model methodology. According to the commonality analysis, the total seed yield (0.67) and number of days to flowering (0.22) had a greater influence on the filled‐seed yield. The flowering synchrony, total number of panicles, filled‐seed yield, green matter yield and dry matter yield presented statistically significant additive genetic variance between and within the subpopulations. The QST estimates ranged from 0.09 for the flowering synchrony index to 0.31 for the filled‐seed yield. The effects of population structure and its use in breeding programmes are further discussed.

Functional synchrony and stimulus selectivity of visual cortical units: Comparison between cats and mice

In spite of the fact that the functional organization of primary visual cortices (V1) differs across species, the dynamic of orientation selectivity is highly structured within neuronal populations. In fact, neurons functionally connect each other in an organized Hebbian process, wherein their wiring and firing are intimately related. Moreover, neuronal ensembles have been suggested to be strongly implicated in sensory processing. Within these ensembles, neurons may be sharply or broadly tuned in relation to the stimulus. Therefore, it is important to determine the relationship between the response selectivity of neurons and their functional connectivity pattern across species. In the present investigation, we sought to compare the stimulus-evoked functional connectivity between the broadly tuned and the sharply tuned neurons in two species exhibiting different cortical organization for orientation selectivity: cats (columnar-organized) and mice (salt-and-pepper organization). In addition, we examined the distribution of connectivity weights within cell-assemblies in the visual cortex during visual adaptation. First, we report that the sharply tuned neurons exhibited higher synchrony index than the broadly tuned cells in the cat visual cortex. On the contrary, in mice, the broadly tuned cells displayed higher connectivity index. Second, a significant correlation was found between the connectivity strength and the difference of preferred orientations of neurons for both species. Finally, we observed a systematic adjustment of the connectivity weights within neuronal ensembles in mouse primary visual cortex similarly to the cat V1.

Utility of Equilibrium Radionuclide Angiogram-Derived Measures of Dyssynchrony to Predict Outcomes in Heart Failure Patients Undergoing Cardiac Resynchronization Therapy.

Sixty-six advanced heart failure patients referred for CRT with an LV ejection fraction (EF) of < 35% and QRS ≥ 120 ms were studied. We performed equilibrium radionuclide angiography (ERNA) before and 6 mo after CRT. We assessed ventricular dyssynchrony with parameters derived from the first harmonic phase (Ø) analysis of the ERNA time-activity curve and evaluated change in these parameters after 6 mo of CRT. These parameters include novel indices of synchrony (S), a measure of intraventricular contraction order, and entropy (E), a measure of intraventricular contraction disorder, and interventricular synchrony (IVS), a measure of synchronous biventricular function. Forty-seven (71%) patients improved clinically (responders) at 6 mo after CRT whereas 19 (28.8%) showed no change in New York Heart Association class or worsened (nonresponders). The post-CRT changes in QRS duration (P = 0.006), echocardiographic (P = 0.03) and ERNA LVEF (P = 0.0007), LVS (P = 0.004), LVE (P = 0.006), LV standard deviation of ventricular phase (LVSDØ) (P = 0.004), and IVS (P = 0.05) were significantly different between responders and nonresponders. Sixty-two percent of responders had either an LVS < 0.84 or an IVS ≥ 18.8° as opposed to only 16% of nonresponders (P = 0.001). Twenty-nine of 32 (91%) patients with either of these measures responded to CRT (P < 0.01). LVS and IVS are novel measures of LV dyssynchrony derived from ERNA planar analysis. A baseline value of LVS < 0.84 or IVS ≥ 18.8° predicts a positive response to CRT.

A Measure of Multivariate Phase Synchrony Using Hyperdimensional Geometry

Phase synchrony has been used to investigate the dynamics of subsystems that make up a complex system. Current measures of phase synchrony are mostly bivariate focusing on the synchrony between pairs of time series. Bivariate measures do not necessarily lead to a complete picture of the global interactions within a complex system. Current multivariate synchrony measures are based on either averaging all possible pairwise synchrony values or eigendecomposition of the pairwise bivariate synchrony matrix. These approaches are sensitive to the accuracy of the bivariate synchrony indices, computationally complex and indirect ways of quantifying the multivariate synchrony. Recently, we had proposed a method to compute the multivariate phase synchrony using a hyperdimensional coordinate system. This method, referred to as Hyperspherical Phase Synchrony (HPS), has been found to be dependent on the ordering of the phase differences. In this paper, we propose a more general hyperspherical coordinate system along with a new higher-dimensional manifold representation to eliminate the dependency on the ordering of the signals’ phases. This new framework, referred to as Hyper-Torus Synchrony (HTS), is shown to be equivalent to the root-mean-square of a sufficient set of squared phase-locking values whose phase differences contain information about all oscillators in the network. The statistical properties of HTS are given analytically and its performance is evaluated thoroughly for both synthetic and real signals.

Padrão Fenológico de Attalea maripa (Aubl.) Mart. em Áreas de Pastagens na Amazônia Oriental

RESUMO A pesquisa avaliou a fenologia de Attalea maripa (inajá), relacionando os eventos fenológicos com a precipitação pluviométrica. Os dados foram obtidos em 100 palmeiras adultas provenientes de regeneração natural, em 3,25 hectares de área de pastagens em Bonito, PA, no período de agosto de 2009 a dezembro de 2011. Os dados foram analisados por meio de fenogramas, índice de sincronia e análise fatorial. Pelo que a pesquisa evidenciou, o padrão fenológico do inajá não é sazonal. A floração e a frutificação ocorrem durante todo o ano; são eventos de longa duração, que sofrem oscilações ao longo do ano. A fenofase espata fechada é altamente sincrônica. A frutificação é um evento fenológico pouco sincrônico. A precipitação é um fator climático importante para a fenologia do inajá, pois afeta negativamente a produção de espata aberta com flores e a queda de folhas e positivamente a queda de frutos maduros.

Early development of synchrony in cortical activations in the human

Early intermittent cortical activity is thought to play a crucial role in the growth of neuronal network development, and large scale brain networks are known to provide the basis for higher brain functions. Yet, the early development of the large scale synchrony in cortical activations is unknown. Here, we tested the hypothesis that the early intermittent cortical activations seen in the human scalp EEG show a clear developmental course during the last trimester of pregnancy, the period of intensive growth of cortico-cortical connections. We recorded scalp EEG from altogether 22 premature infants at post-menstrual age between 30 and 44weeks, and the early cortical synchrony was quantified using recently introduced activation synchrony index (ASI). The developmental correlations of ASI were computed for individual EEG signals as well as anatomically and mathematically defined spatial subgroups. We report two main findings. First, we observed a robust and statistically significant increase in ASI in all cortical areas. Second, there were significant spatial gradients in the synchrony in fronto-occipital and left-to-right directions. These findings provide evidence that early cortical activity is increasingly synchronized across the neocortex. The ASI-based metrics introduced in our work allow direct translational comparison to in vivo animal models, as well as hold promise for implementation as a functional developmental biomarker in future research on human neonates.

Synchrony in Leafing, Flowering, and Fruiting Phenology ofSenegalia senegalwithin Lake Baringo Woodland, Kenya: Implication for Conservation and Tree Improvement

Leafing, flowering, and fruiting patterns ofSenegalia senegalwere studied over a period of 24 months from January 2014 to December 2015. The phenological events of the species are bimodal and follow the rainfall patterns. The leafing phase starts during the onset of rains and lasts for 18 weeks. New leaves continued to appear on the new shoots while old leaves persisted to the leaf fall period. Flowering event takes 12 weeks and is concentrated in the months of high relative humidity (April and October) with one-month peak flowering period. Fruiting phase starts at the peak of the rainy seasons (May and November) and peaks in June and December. This phase lasted for 14 weeks. The fruits mature towards the end of the rainy season (January/February and July/August). The fruits open for dispersal mainly in February/March and September during the peak dry season. High synchrony index (SI) was found in leafing (SI: 0.87), flowering (SI: 0.75), and fruiting (SI: 0.85) events among the populations. Temperature, precipitation, and soil moisture content were significantly correlated with the phenological events. Significant variations in floral morphology and fruits traits were also evident. Seed collections should be undertaken in the months of January/February and July/August.

Sugar apple (&lt;i&gt;Annona squamosa&lt;/i&gt; L.) seed germination affected by the application of gibberellins

This research sought to establish the response of the germination percentage (PG), synchrony index (E), mean germination time (MGT) and mean germination rate (MGR) of Annona squamosa L. seeds from Apulo (province of Cundinamarca) and Castilla (province of Tolima), Colombia, to treatments with 0, 50, 100, 200, 400, 600, or 800 mg L-1 of gibberellic acid (GA). All of the treatments with GA increased the PG at each point of time of seed incubation. The 600 mg L-1 GA treatment resulted in higher PGs (92.3% at 16 days for Apulo and 95% at 24 days for Castilla) and lower MGTs (8.75 and 5.38 days for Apulo and Castilla, respectively) than those found with the concentration of 0 mg L-1 GA (17.68 and 10.88 days for Apulo and Castilla, respectively). Also, treating the seeds with 600 mg L-1 GA generated higher MGRs (0.18 and 0.12 germinated seeds/day for Castilla and Apulo, respectively) than those obtained with 0 mg L-1 GA (Castilla = 0.09 and Apulo = 0.06 germinated seeds/ day). Likewise, the germination was synchronized with the application of any concentration of GA. The results evidenced a positive response to the GA application, which provided a tool for the characterization of the phenomenon of dormancy in the A. squamosa seeds.

Normal values of cardiac mechanical synchrony parameters using gated myocardial perfusion single-photon emission computed tomography: Impact of population and study protocol

Purpose of the Study:Normal values of cardiac mechanical synchrony parameters in gated myocardial perfusion single-photon emission computed tomography (GMPS) are well established in literature from the Western population. The aim of the study is to establish normal values of mechanical synchrony with GMPS in Indian population and to find out whether it differs significantly from established values.Procedure:We retrospectively analyzed 1 day low-dose stress/high-dose rest GMPS studies of 120 patients (sixty males, 52 ± 11.7 years) with low pretest likelihood of coronary artery disease and having normal GMPS study. In GMPS, first-harmonic fast Fourier transform was used to extract a phase array using commercially available software. Phase standard deviation (PSD) and phase histogram bandwidth (PHB) were used to quantify cardiac mechanical dyssynchrony.Results:The values obtained were as follows, PSD: In men, 14.3 ± 4.7 (stress) and 8.9 ± 2.9 (rest), in women 11 ± 4 (stress) and 7.7 ± 2.7 (rest), and PHB: In men, 40.1 ± 11.9 (stress) and 30.6 ± 7.6 (rest), in women, 34.7 ± 12.6 (stress) and 25.3 ± 8.6 (rest). The value of PSD and PHB was significantly less in Indian population as compared with established values in literature. We also observed that synchrony indices derived from the low-dose stress studies are higher than high-dose rest studies.Conclusions:The value of synchrony parameters differs significantly according to population and methodology suggesting that specific population and methodology-based normal database for assessment of cardiac mechanical dyssynchrony should be established.

The suppression curve as a new representation of the premature EEG maturation

Automated analysis of premature electroencephalogram (EEG) for diagnosis is a crucial step to reduce the workload of neurologists. The grade of gives important information about the maturation [1]. For normal maturation, the discontinuous pattern gradually evolves into a more continuous pattern. This means, interburst intervals (IBI), periods of low activity, become shorter. We have defined the suppression curve (SC), which is a measure of discontinuity [2] (Figure ​(Figure1A).1A). All data for this study were recorded at the Neonatal Intensive Care Unit, University Hospital Gasthuisberg, Leuven, Belgium. The dataset consisted of 170 EEG recordings (8 channels, 250 Hz) of 93 preterm infants with a postmenstrual age (PMA) of 24-40 weeks. Some maturational features are extracted from the discontinuous periods, like the IBI length and the synchrony index. However, the SC on itself gives also relevant information about the maturation. Taking the mean of every SC, we can find a correlation with the age till 34 weeks PMA (Figure ​(Figure1B).1B). Few outliers (abnormal EEG) are excluded. After that age, the patient is called late preterm or even term, and the EEG pattern is in normal condition mostly continuous (low values of the SC). Figure 1 A Suppression curve example, containing 2 periods of 20-30 minutes of discontinuous pattern, B Evolution of the mean of the suppression curve in function of the age, · represents a patient with normal EEG, * patient with abnormal EEG In conclusion, this research adds another valuable feature for the automated analysis of premature background EEG, which would improve the overall assessment in the NICU for EEG diagnosis

Neural synchrony indexes impaired motor slowing after errors and novelty following white matter damage

In humans, action errors and perceptual novelty elicit activity in a shared frontostriatal brain network, allowing them to adapt their ongoing behavior to such unexpected action outcomes. Healthy and pathologic aging reduces the integrity of white matter pathways that connect individual hubs of such networks and can impair the associated cognitive functions. Here, we investigated whether structural disconnection within this network because of small-vessel disease impairs the neural processes that subserve motor slowing after errors and novelty (post-error slowing, PES; post-novel slowing, PNS). Participants with intact frontostriatal circuitry showed increased right-lateralized beta-band (12–24 Hz) synchrony between frontocentral and frontolateral electrode sites in the electroencephalogram after errors and novelty, indexing increased neural communication. Importantly, this synchrony correlated with PES and PNS across participants. Furthermore, such synchrony was reduced in participants with frontostriatal white matter damage, in line with reduced PES and PNS. The results demonstrate that behavioral change after errors and novelty result from coordinated neural activity across a frontostriatal brain network and that such cognitive control is impaired by reduced white matter integrity.

Editorial: Bridging the gap before and after birth: methods and technologies to explore the functional neural development in humans.

Editorial: Bridging the gap before and after birth: methods and technologies to explore the functional neural development in humans.

A BREATHING SYNCHRONIZATION STRATEGY FOR THE NON-INVASIVE VENTILATOR SYSTEM

The study presents a method to achieve a subject-ventilator synchronic pressure supply for a non-invasive ventilator (NIV) used for obstructive sleep apnea syndrome (OSAS), solely through controlling the blower instead of using expiratory relief valves. The controller used air flow signal to distinguish inspiratory and expiratory phases, and used a fast auto-forecast (AF) algorithm to predict the current inspiratory duration based on respiration periods distinguished previously. Then in a patient's late inspiration the mechanical expiratory state was triggered to release pressure in advance. Afterward, when the beginning of a patient's actual expiration was detected, a timer was used to trigger the end-expiratory state. As the index of patient-ventilator synchrony, subject's chest movement was detected by electrical impedance signal in experiments. The experimental results indicated that the previous state transition based on the prediction of inspiratory duration can eliminate the pressure overshoot spike, and then avoid excessive expiratory pressure to subjects. The fast auto-forecast with end expiratory positive airway pressure (AF-EEPAP) controlling strategy presented in this paper provided a mild pressure curve, which is consistent with the subject's respiratory physiology, and thus improved respiratory synchrony between subject and ventilator.