A temporal red-green opponent mechanism

A mechanistic model is presented that describes the temporal behaviour of a red-green colour opponent channel such as has been investigated for the macaque monkey. The model incorporates luminanceand chromaticity-adaptation mechanisms. Receptive field properties such as retardation and attenuation of the surround signals with respect to the center signals of the colour opponent channel are also included. The model predicts temporal psychophysical chromaticity thresholds and temporal electrophysiological red-green colour opponent ganglion cell behaviour with a reasonable degree of success.     

The ecological significance of time sense in animals

Time is a fundamental dimension of all biological events and it is often assumed that animals have the capacity to track the duration of experienced events (known as interval timing). Animals can potentially use temporal information as a cue during foraging, communication, predator avoidance, or navigation. Interval timing has been traditionally investigated in controlled laboratory conditions but its ecological relevance in natural environments remains unclear. While animals may time events in artificial and highly controlled conditions, they may not necessarily use temporal information in natural environments where they have access to other cues that may have more relevance than temporal information. Herein we critically evaluate the ecological contexts where interval timing has been suggested to provide adaptive value for animals. We further discuss attributes of interval timing that are rarely considered in controlled laboratory studies. Finally, we encourage consideration of ecological relevance when designing future interval-timing studies and propose future directions for such experiments.     

Long-range temporal correlations in the EEG bursts of human preterm babies

The electrical activity in the very early human preterm brain, as recorded by scalp EEG, is mostly discontinuous and has bursts of high-frequency oscillatory activity nested within slow-wave depolarisations of high amplitude. The temporal organisation of the occurrence of these EEG bursts has not been previously investigated. We analysed the distribution of the EEG bursts in 11 very preterm (23-30 weeks gestational age) human babies through two estimates of the Hurst exponent. We found long-range temporal correlations (LRTCs) in the occurrence of these EEG bursts demonstrating that even in the very immature human brain, when the cerebral cortical structure is far from fully developed, there is non-trivial temporal structuring of electrical activity.     

Temporal progress model of metabolic syndrome for clinical decision support system

The development of an integrated and personalized healthcare system is becoming an important issue in the modern healthcare industry. One of main objectives of integrated healthcare system is to effectively manage patients having chronic diseases that require long term care and its temporal information plays an important role to manage the statuses of diseases. Thus, a patient having chronic disease needs to visit the hospital periodically, which generates large volume of medical examination data. Among the various chronic diseases, metabolic syndrome (MS) has become a popular chronic disease in many countries. There have been efforts to develop an MS risk quantification and prediction model and to integrate it into personalized healthcare system, so as to predict the risk of having MS in the future. However, the development of methods for temporal progress management of metabolic syndrome has not been widely investigated. This paper proposes a method for identifying the temporal progress of MS patients' status based on the chronological clustering methodology. To investigate the temporal changes of disease status, we develop a chronological distance variance model that quantifies the difference of areal similarity degree (ASD) values between estimated and examined results of MS risk factors. We evaluate the clinical effectiveness of the temporal progress model by using sample subjects' examination results that have been measured for 10 years. We further elaborate the accuracy of the proposed temporal progress estimation method by using multiple linear regression method. Then, we develop a tier-based patients' MS status classification based on the chronological distance variance. The tier classification is based on the sensitivity for temporal change of MS status according to different values of control range of chronological distance variance. Our proposed temporal change identification method and patients' tier classification are expected to be incorporated with the integrated healthcare systems to help physicians with identifying the temporal progress of MS patients' health status and MS patients with self-management at home environments.     

Solvability of the electrocardiology inverse problem for a moving dipole

New formulations of the direct and inverse problems for the moving dipole are offered. It has been suggested to limit the study by a small area on the chest surface. This lowers the role of the medium inhomogeneity. When formulating the direct problem, irregular components are considered. The algorithm of simultaneous determination of the dipole and regular noise parameters has been described and analytically investigated. It is shown that temporal overdetermination of the equations offers a single solution of the inverse problem for the four leads.     

Genetic, geographic, and environmental correlates of human temporal bone variation

Temporal bone shape has been shown to reflect molecular phylogenetic relationships among hominoids and offers significant morphological detail for distinguishing taxa. Although it is generally accepted that temporal bone shape, like other aspects of morphology, has an underlying genetic component, the relative influence of genetic and environmental factors is unclear. To determine the impact of genetic differentiation and environmental variation on temporal bone morphology, we used three-dimensional geometric morphometric techniques to evaluate temporal bone variation in 11 modern human populations. Population differences were investigated by discriminant function analysis, and the strength of the relationships between morphology, neutral molecular distance, geographic distribution, and environmental variables were assessed by matrix correlation comparisons. Significant differences were found in temporal bone shape among all populations, and classification rates using cross-validation were relatively high. Comparisons of morphological distances to molecular distances based on short tandem repeats (STRs) revealed a significant correlation between temporal bone shape and neutral molecular distance among Old World populations, but not when Native Americans were included. Further analyses suggested a similar pattern for morphological variation and geographic distribution. No significant correlations were found between temporal bone shape and environmental variables: temperature, annual rainfall, latitude, or altitude. Significant correlations were found between temporal bone size and both temperature and latitude, presumably reflecting Bergmann's rule. Thus, temporal bone morphology appears to partially follow an isolation by distance model of evolution among human populations, although levels of correlation show that a substantial component of variation is unexplained by factors considered here.     

Stimulus repetition and the perception of time: the effects of prior exposure on temporal discrimination, judgment, and production

It has been suggested that repeated stimuli have shorter subjective duration than novel items, perhaps because of a reduction in the neural response to repeated presentations of the same object. Five experiments investigated the effects of repetition on time perception and found further evidence that immediate repetition reduces apparent duration, consistent with the idea that subjective duration is partly based on neural coding efficiency. In addition, the experiments found (a) no effect of repetition on the precision of temporal discrimination, (b) that the effects of repetition disappeared when there was a modest lag between presentations, (c) that, across participants, the size of the repetition effect correlated with temporal discrimination, and (d) that the effects of repetition suggested by a temporal production task were the opposite of those suggested by temporal judgments. The theoretical and practical implications of these results are discussed.     

Statistical analysis of a small set of time-ordered gene expression data using linear splines

MOTIVATION: Recently, the temporal response of genes to changes in their environment has been investigated using cDNA microarray technology by measuring the gene expression levels at a small number of time points. Conventional techniques for time series analysis are not suitable for such a short series of time-ordered data. The analysis of gene expression data has therefore usually been limited to a fold-change analysis, instead of a systematic statistical approach. METHODS: We use the maximum likelihood method together with Akaike's Information Criterion to fit linear splines to a small set of time-ordered gene expression data in order to infer statistically meaningful information from the measurements. The significance of measured gene expression data is assessed using Student's t-test. RESULTS: Previous gene expression measurements of the cyanobacterium Synechocystis sp. PCC6803 were reanalyzed using linear splines. The temporal response was identified of many genes that had been missed by a fold-change analysis. Based on our statistical analysis, we found that about four gene expression measurements or more are needed at each time point.     

Whole mitochondrial DNA variations in hippocampal surgical specimens and blood samples with high-throughput sequencing: A case of mesial temporal lobe epilepsy with hippocampal sclerosis

Introduction

Hippocampal sclerosis is the most common lesion in patients with mesial temporal lobe epilepsy. Recently, there has been growing evidence on the involvement of mitochondria also in sporadic forms of epilepsy. In addition, it has been increasingly argued that mitochondrial dysfunction has an important role in epileptogenesis and seizure generation in temporal lobe epilepsy. Although mtDNA polymorphisms have been identified as potential risk factors for neurological diseases, the link between homoplasmy and heteroplasmy within tissues is not clear. We investigated whether mitochondrial DNA (mtDNA) polymorphisms are involved in a case report of a patient with mesial temporal lobe epilepsy-hippocampal sclerosis (MTLE-HS).

Design

We report the whole genome mtDNA deep sequencing results and clinical features of a 36-year-old woman with MTLE-HS. We used pyrosequencing technology to sequence a whole mitochondrial genome isolated from six different regions of her brain and blood. To assess the possible role of mitochondrial DNA variations in affected tissues, we compared all specimens from different regions of the hippocampus and blood.

Results

In total, 35 homoplasmic and 18 heteroplasmic variations have been detected in 6 different regions of the hippocampus and in blood samples. While the samples did not display any difference in homoplasmic variations, it has been shown that hippocampus regions contain more heteroplasmic variations than blood. The number of heteroplasmic variations was highest in the CA2 region of the brain and accumulated in ND2, ND4 and ND5 genes. Also, dentate and subiculum regions of the hippocampus had similar heteroplasmic variation profiles.

Discussion

We present a new rare example of parallel mutation at 16223 position. Our case suggests that defects in mitochondrial function might be underlying the pathogenesis of seizures in temporal lobe epilepsy.     

Temporal processing in sensory systems

The idea that sensory information is represented by the temporal firing patterns of neurons or entire networks, rather than by firing rates measured over long integration times, has recently gained increasing experimental support. A number of mechanisms that help to preserve temporal information in ascending sensory systems have been identified, and the role of inhibition in these processes has been characterized. Furthermore, it has become obvious that temporal processing and the representation of sensory events by temporal spike patterns are highly dependent upon the behavioral state of the animal or experimental subject.     

Curve of labeled mitoses in different kinetic states of cell proliferation. III. Experiments with a mathematical model]

By means of computer simulation, the dynamic structure of labeled mitoses curve (LMC) has been investigated. Experiments using computer demonstrated the dependence of LMC form not only on the values of temporal parameters of the mitotic cycle, but also on the state of cell proliferation kinetics before and after pulse labeling. Of particular interest was a case of a temporal block of cell entry into the S period which has been studied in a greater detail. The results of modelling experiments have shown that the universally accepted graphic procedures for the evaluation of mean durations of S- and G2-periods (using 50%-level of LMC) yield the satisfactory estimates only for systems with stationary age distribution for cells in the mitotic cycle (steady, in the strict sense, and exponential states of cell proliferation kinetics). The paper presents also the kinetic interpretation of certain abnormalities in LMC form arising from some peculiarities of cell population kinetics in the real biological experiment.     

Temporal changes in native-exotic richness correlations during early post-fire succession

The relationship between native and exotic richness has mostly been studied with respect to space (i.e., positive at larger scales, but negative or more variable at smaller scales) and its temporal patterns have rarely been investigated. Although some studies have monitored the temporal trends of both native and exotic richness, how these two groups of species might be related to each other and how their relative proportions vary through time in a local community remains unclear. Re-analysis of early post-fire successional data for a California chaparral community shows that, in the same communities and at small spatial scales, the native-exotic correlations varied through time. Both exotic richness and exotic fraction (i.e., the proportion of exotic species in the flora) quickly increased and then gradually declined, during the initial stages of succession following fire disturbance. This result sheds new light on habitat invasibility and has implications for timing the implementation of effective management actions to prevent and/or mitigate species invasions.     

Creating morphological diversity in reptilian temporal skull region: A review of potential developmental mechanisms

Reptilian skull morphology is highly diverse and broadly categorized into three categories based on the number and position of the temporal fenestrations: anapsid, synapsid, and diapsid. According to recent phylogenetic analysis, temporal fenestrations evolved twice independently in amniotes, once in Synapsida and once in Diapsida. Although functional aspects underlying the evolution of tetrapod temporal fenestrations have been well investigated, few studies have investigated the developmental mechanisms responsible for differences in the pattern of temporal skull region. To determine what these mechanisms might be, we first examined how the five temporal bones develop by comparing embryonic cranial osteogenesis between representative extant reptilian species. The pattern of temporal skull region may depend on differences in temporal bone growth rate and growth direction during ontogeny. Next, we compared the histogenesis patterns and the expression of two key osteogenic genes, Runx2 and Msx2, in the temporal region of the representative reptilian embryos. Our comparative analyses suggest that the embryonic histological condition of the domain where temporal fenestrations would form predicts temporal skull morphology in adults and regulatory modifications of Runx2 and Msx2 expression in osteogenic mesenchymal precursor cells are likely involved in generating morphological diversity in the temporal skull region of reptiles.     

Masking release for gap detection.

In random noise, masking is influenced almost entirely by noise components in a narrow band around the signal frequency. However, when the noise is not random, but has a modulation pattern which is coherent across frequency, noise components relatively remote from the signal frequency can actually produce a release from masking. This masking release has been called comodulation masking release (CMR). The present research investigated whether a similar release from masking occurs in the analysis of a suprathreshold signal. Specifically, the ability to detect the presence of a temporal gap was investigated in conditions which do and do not result in CMR for detection threshold. Similar conditions were investigated for the masking level difference (a binaural masking release phenomenon). The results indicated that suprathreshold masking release for gap detection occurred for both the masking-level difference (MLD) and for CMR. However, masking release for gap detection was generally smaller than that obtained for detection threshold. The largest gap detection masking release effects obtained corresponded to relatively low levels of stimulation, where gap detection was relatively poor.     

Synchronization of activity of rhythm-forming neurons in the respiratory center

The method of determination of the basic parameter of the mathematical model of respiratory centre using temporal characteristics of respiratory neurons has been suggested. The model's behaviour depending on the meaning of this parameter and possibility of respiratory neuron's activity sinchronization have been investigated. The influence of feedback shorting on the mechanico-receptor outline on this process has been described.     

The role of superior temporal cortex in auditory timing

Recently, there has been upsurge of interest in the neural mechanisms of time perception. A central question is whether the representation of time is distributed over brain regions as a function of stimulus modality, task and length of the duration used or whether it is centralized in a single specific and supramodal network. The answers seem to be converging on the former, and many areas not primarily considered as temporal processing areas remain to be investigated in the temporal domain. Here we asked whether the superior temporal gyrus, an auditory modality specific area, is involved in processing of auditory timing. Repetitive transcranial magnetic stimulation was applied over left and right superior temporal gyri while participants performed either a temporal or a frequency discrimination task of single tones. A significant decrease in performance accuracy was observed after stimulation of the right superior temporal gyrus, in addition to an increase in response uncertainty as measured by the Just Noticeable Difference. The results are specific to auditory temporal processing and performance on the frequency task was not affected. Our results further support the idea of distributed temporal processing and speak in favor of the existence of modality specific temporal regions in the human brain.     

Novel features of radiation-induced bystander signaling in Arabidopsis thaliana demonstrated using root micro-grafting

Radiation-induced bystander effects (RIBE) have been well demonstrated in whole organisms, as well as in single-cell culture models in vitro and multi-cellular tissues models in vitro, however, the underlying mechanisms remain unclear, including the temporal and spatial course of bystander signaling. The RIBE in vivo has been shown to exist in the model plant Arabidopsis thaliana (A. thaliana). Importantly, the unique plant grafting provides a delicate approach for studying the temporal and spatial course of bystander signaling in the context of whole plants. In our previous study, the time course of bystander signaling in plants has been well demonstrated using the root micro-grafting technique. In this study, we further investigated the temporal cooperation pattern of multiple bystander signals, the directionality of bystander signaling, and the effect of bystander tissues on the bystander signaling. The results showed that the bystander response could also be induced efficiently when the asynchronously generated bystander signals reached the bystander tissues in the same period, but not when they entered into the bystander tissues in an inversed sequence. The absence of bystander response in root-inversed grafting indicated that the bystander signaling along roots might be of directionality. The bystander signaling was shown to be independent of the bystander tissues.     

Recent greening of grasslands in northern China driven by increasing precipitation

近年中国北方草地变绿受降水增加的驱动 中国北方的暖湿化是近期的热点话题,然而其对植被生长的影响仍不清楚。本研究基于长时间序列(1982–2018年)数据,研究了归一化植被指数(NDVI)的时间动态及其气候驱动因子之间的关系,以探索近年来气候的暖湿化是否会导致该区植被变绿。我们采用分段回归探测了NDVI的变化趋势是否存在转变点,用Pearson相关分析描述了植被指数与气候因子的关系。最后,采用逐步多元回归方法研究了气候因子对NDVI时间变化的贡献率。研究结果表明,NDVI时间变化趋势的转变点出现在2008年,GIMMS NDVI在1982–2008年略有增加,上升速率为0.00022 yr⁻¹,在2008–2015年上升速率达到0.002 yr⁻¹,MODIS NDVI在2008–2018年上升速率为0.0018 yr⁻¹。降水是NDVI变化的主要驱动因子,气温和饱和水汽压差(VPD)对NDVI的变化影响较小。总体看来,NDVI时间序列变化趋势存在转变点,并且近期气候的暖湿化主导了中国北方草地植被变绿,这为今后更好地预测该地区气候变化下的植被覆盖变化提供了依据。     

Organization of work in the honeybee: a compromise between division of labour and behavioural flexibility

Although the caste concept has been central to our understanding of the organization of work in social insect colonies, the concept has been the subject of considerable recent criticism. Theoretically, it has been suggested that temporal castes are too inflexible to allow a colony to rapidly reallocate labour in response to changing conditions. In addition, several authors have suggested that task switching is so prevalent that it precludes even the possibility of a rigidly controlled temporal caste system. This study addresses these two criticisms by presenting and testing a revision of the temporal caste concept that recognizes two categories of tasks: those that require a physiological specialization for their efficient performance, and those that all workers are equally able to perform. Only those tasks requiring a physiological specialization are relevant to the temporal caste concept. Two castes of honeybees were shown to vary in response to increased nectar influx, which requires a physiological specialization, but not to heat stress, which requires no specialization. This work suggests that the organization of work in social insect colonies reflects a compromise between selection for the benefits of division of labour and opposing selection for flexibility in task allocation.