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Background Sequential effects of environmental stimuli are ubiquitous in most behavioral tasks involving magnitude estimation, memory, decision making, and emotion. The human visual system exploits continuity in the visual environment, which induces two contrasting perceptual phenomena shaping visual perception. Previous work reported that perceptual estimation of a stimulus may be influenced either by attractive serial dependencies or repulsive aftereffects, with a number of experimental variables suggested as factors determining the direction and magnitude of sequential effects. Recent studies have theorized that these two effects concurrently arise in perceptual processing, but empirical evidence that directly supports this hypothesis is lacking, and it remains unclear whether and how attractive and repulsive sequential effects interact in a trial. Here we show that the two effects concurrently modulate estimation behavior in a typical sequence of perceptual tasks. Results We first demonstrate that observers’ estimation error as a function of both the previous stimulus and response cannot be fully described by either attractive or repulsive bias but is instead well captured by a summation of repulsion from the previous stimulus and attraction toward the previous response. We then reveal that the repulsive bias is centered on the observer’s sensory encoding of the previous stimulus, which is again repelled away from its own preceding trial, whereas the attractive bias is centered precisely on the previous response, which is the observer’s best prediction about the incoming stimuli. Conclusions Our findings provide strong evidence that sensory encoding is shaped by dynamic tuning of the system to the past stimuli, inducing repulsive aftereffects, and followed by inference incorporating the prediction from the past estimation, leading to attractive serial dependence.

Background Falls are the leading cause of accidental injury and death among older adults. One of three adults over the age of 65 years falls annually. As the size of elderly population increases, falls become a major concern for public health and there is a pressing need to understand the causes of falls thoroughly. Main body of the abstract While it is well documented that visual functions such as visual acuity, contrast sensitivity, and stereo acuity are correlated with fall risks, little attention has been paid to the relationship between falls and the ability of the visual system to perceive motion in the environment. The omission of visual motion perception in the literature is a critical gap because it is an essential function in maintaining balance. In the present article, we first review existing studies regarding visual risk factors for falls and the effect of ageing vision on falls. We then present a group of phenomena such as vection and sensory reweighting that provide information on how visual motion signals are used to maintain balance. Conclusion We suggest that the current list of visual risk factors for falls should be elaborated by taking into account the relationship between visual motion perception and balance control.

This study examines the Environmental Kuznets Curve (EKC) hypothesis by adopting a country’s ecological footprint as an indicator of environmental degradation in three East Asian countries: Japan, Korea, and China. During the development process, countries intend to balance between stabilizing export demand and maintaining sustainable economic improvement in the context of deteriorating global warming and climate change. The Environmental Kuznets Curve (henceforth, EKC) was originally developed to estimate the correlation between environment condition and economic development. In this paper, we started from the EKC model and adopted an Error Correction Methodology (henceforth, ECM) to estimate the EKC relationships in Japan, Korea (two developed countries), and China (a developing country) over the period of 1990 to 2013. Besides this, instead of only using Gross Domestic Product (henceforth, GDP), two subdivisions of trade diversification—export product diversification and export market diversification—are introduced as proxy variables for economic development in rectification of the EKC. The results demonstrate that both Korea and Japan satisfy the EKC theory by demonstrating an inverted U-shaped relationship between economic development and ecological footprint, while analysis based on data from China does not display the same tendency. For both export product diversification and market diversification, the more diversified the country’s export is, the bigger its ecological footprint. The policy implications of this econometric outcome are also discussed.

The ability of a moving observer to accurately perceive their heading direction is essential for effective locomotion and balance control. While previous studies have shown that observers integrate visual and vestibular signals collected during movement, it remains unclear whether and how observers use visual signals collected before their movement to perceive heading direction. Here we investigate the effect of environmental motion that occurred ahead of self-motion on the perception of self-motion. Human observers sat on a motion platform, viewed visual motion stimuli, and then reported their perceived heading after the platform moved. The results reveal that environmental motion presented before the observers’ movement significantly modulates their heading perception. We account for this effect using a normative computational model that takes into account the causal relationship between visual signals generated before and during the observers’ movement. Overall, our study highlights the crucial role of environmental motion presented before self-motion in heading perception, broadening the current perspective on the computational mechanisms behind heading estimation.

Despite growing evidence for perceptual interactions between motion and position, no unifying framework exists to account for these two key features of our visual experience. We show that percepts of both object position and motion derive from a common object-tracking system—a system that optimally integrates sensory signals with a realistic model of motion dynamics, effectively inferring their generative causes. The object-tracking model provides an excellent fit to both position and motion judgments in simple stimuli. With no changes in model parameters, the same model also accounts for subjects’ novel illusory percepts in more complex moving stimuli. The resulting framework is characterized by a strong bidirectional coupling between position and motion estimates and provides a rational, unifying account of a number of motion and position phenomena that are currently thought to arise from independent mechanisms. This includes motion-induced shifts in perceived position, perceptual slow-speed biases, slowing of motions shown in visual periphery, and the well-known curveball illusion. These results reveal that motion perception cannot be isolated from position signals. Even in the simplest displays with no changes in object position, our perception is driven by the output of an object-tracking system that rationally infers different generative causes of motion signals. Taken together, we show that object tracking plays a fundamental role in perception of visual motion and position. Significance In our visual environment, object motion is strongly correlated with changes in object position. However, there is no unifying computational framework that can account for both motion and position perception and their interactions. Here, we propose and test an object-tracking model that optimally integrates sensory signals with a realistic model of motion dynamics. The model accounts for several well-known visual illusions, including motion-induced position shifts, slow speed biases, and the curveball illusion. Moreover, the model also makes several novel and, in some cases, counterintuitive predictions about interdependencies between position and motion. In summary, we provide a unifying framework that reconceptualizes how the human visual system constructs coherent percepts from noisy position and motion signals.

Despite the fundamental importance of visual motion processing, our understanding of how the brain represents basic aspects of motion is incomplete. While it is generally believed that direction is the main representational feature of motion, motion processing is also influenced by nondirectional orientation signals that are present in most motion stimuli. Here, we aimed to test whether this nondirectional motion axis contributes motion perception even when orientation is completely absent from the stimulus. Using stimuli with and without orientation signals, we found that serial dependence in a simple motion direction estimation task was predominantly determined by the orientation of the previous motion stimulus. Moreover, the observed attraction profiles closely matched the characteristic pattern of serial attraction found in orientation perception. Evidently, the sequential integration of motion signals strongly depends on the orientation of motion, indicating a fundamental role of nondirectional orientation in the coding of visual motion direction.

Acinetobacter baumannii is an important nosocomial pathogen that causes a high morbidity and mortality rate in infected patients, but pathogenic mechanisms of this microorganism regarding the secretion and delivery of virulence factors to host cells have not been characterized. Gram-negative bacteria naturally secrete outer membrane vesicles (OMVs) that play a role in the delivery of virulence factors to host cells. A. baumannii has been shown to secrete OMVs when cultured in vitro, but the role of OMVs in A. baumannii pathogenesis is not well elucidated. In the present study, we evaluated the secretion and delivery of virulence factors of A. baumannii to host cells via the OMVs and assessed the cytotoxic activity of outer membrane protein A (AbOmpA) packaged in the OMVs. A. baumannii ATCC 19606(T) secreted OMVs during in vivo infection as well as in vitro cultures. Potential virulence factors, including AbOmpA and tissue-degrading enzymes, were associated with A. baumannii OMVs. A. baumannii OMVs interacted with lipid rafts in the plasma membranes and then delivered virulence factors to host cells. The OMVs from A. baumannii ATCC 19606(T) induced apoptosis of host cells, whereas this effect was not detected in the OMVs from the ΔompA mutant, thereby reflecting AbOmpA-dependent host cell death. The N-terminal region of AbOmpA(22-170) was responsible for host cell death. In conclusion, the OMV-mediated delivery of virulence factors to host cells may well contribute to pathogenesis during A. baumannii infection.

Ecklonia cava (E. cava) and Chrysanthemum indicum Linne (C. indicum) are natural raw materials known to have beneficial effects on inflammatory-related diseases, as evidenced by various sources in the literature. This study aimed to investigate the airway-protective effects of a formulation called ED, comprising E. cava and C. indicum, by evaluating its potential anti-inflammatory properties. Methods: The major components of ED were analyzed using high-performance liquid chromatography (HPLC) and its anti-inflammatory activity was assessed in RAW 264.7 cells through measurements of nitric oxide’s (NO) inhibitory effect, cyclooxygenase (COX)-2 protein expression, and the mitogen-activated protein kinase (MAPK) signaling pathway. Additionally, the anti-inflammatory effect of ED was evaluated in an ovalbumin-induced asthma model by measuring cytokine levels in serum, bronchoalveolar lavage fluid (BALF), and lung tissue. Through HPLC analysis, the major components of ED, dieckol and luteolin, were identified. ED demonstrated no cytotoxicity and effectively reduced NO production in lipopolysaccharide (LPS)-induced RAW 264.7 cells. Moreover, ED downregulated COX-2 expression through the MAPK signaling pathway in LPS-induced RAW 264.7 cells. In the ovalbumin-induced asthma model, the ED-treated group exhibited reduced levels of inflammatory cytokines in lung tissue. Furthermore, the ED-treated group showed a decrease in the number of inflammatory cells in BALF and lower serum interleukin (IL)-6 levels compared to the ovalbumin-treated group. These results suggest that ED has the potential to be a novel therapeutic agent for improving inflammatory respiratory diseases.

The secretion of outer membrane vesicles (OMVs) is one of the major mechanisms by which Gram-negative bacteria deliver effector molecules to host cells. Acinetobacter baumannii is an important opportunistic pathogen in hospital-acquired infections, but the secretion system for effector molecules to induce host cell damage has not been characterized. In the present study, we investigated the secretion of OMVs from a clinical A. baumannii isolate and analyzed the comprehensive proteome of A. baumannii-derived OMVs. Acinetobacter baumannii secreted OMVs into the extracellular milieu during in vitro growth. Using 1-DE and LC-MS/MS protein identification and assignment analysis, 132 different proteins associated with OMVs were identified. These proteins were derived from outer membranes (n=26), periplasmic space (n=6), inner membranes (n=8), cytoplasm (n=43), and unknown localization or multiple localization sites (n=49) according to the cell location prediction programs. Among the proteins associated with OMVs, a potent cytotoxic molecule, outer membrane protein A, was highly enriched and several putative virulence-associated proteins were also identified. These results suggest that OMVs from A. baumannii are an important vehicle designed to deliver effector molecules to host cells.