Afterimage duration depends on how deeply invisible stimuli were suppressed.

Quantifying visual responses to stimuli that are outside of awareness is a critical task for the study of visual consciousness. The current study psychophysically investigated whether afterimages reflect visual responses to stimuli that are not consciously visible throughout adaptation due to interocular suppression. A Gabor adaptor was presented to one eye of the observer, and a counterphase-flickering Gabor suppressor was presented to the other eye, thereby rendering the adaptor invisible during adaptation. To manipulate the depth of the suppression of the invisible adaptor, we varied the orientation difference between the adaptor and suppressor. We found that, even though the adaptor was not visible during adaptation, the afterimage duration varied depending on the orientation selectivity of interocular suppression. The duration was the shortest when the orientations of the adaptor and suppressor were identical and lengthened when the orientation differences increased. This finding could not be explained by confounding factors such as potential changes in contrast sensitivity that were caused by the suppressor. Our findings suggest that the magnitude of visual responses to stimuli suppressed below the threshold of awareness can be measured using the afterimage duration. Afterimages could be an effective tool for quantifying visual responses, irrespective of observers' conscious awareness of a presented stimulus.

Eye swapping temporally modulates potency of continuous flash suppression.

Continuous flash suppression (CFS) refers to a technique to render a monocular stimulus invisible by presenting a dynamic series of high-contrast patterns (such as Mondrian patterns) to the other eye. Despite its popularity as a tool to suppress stimulus from awareness, the suppression mechanisms underlying CFS remain not well understood. To further elucidate the suppression mechanisms, this study investigated the effects of eye swapping on CFS suppression by manipulating the eye of presentation of the suppressor and the target. Results showed that eye swapping of the suppressor and the target significantly reduced the strength of CFS suppression when swapping frequency was higher (3.5 Hz). However, strong suppression persisted at lower swapping frequency (1.2 Hz). Investigation of the time course of suppression revealed that suppression was weaker just after eye swapping but that it quickly regained strength over the monocular presentation period of the suppressor. However, this buildup seemed to not be fast enough to closely follow eye swapping at higher frequency. These findings can be better understood by the contribution of monocular processes to CFS suppression. They imply that interocular suppression caused by competition between monocular processes can mediate phenomenal suppression over multiple eye swaps when swapping frequency is low. The significance of the findings is discussed in relation to binocular rivalry and binocular switch suppression.

Averaging colors of multicolor mosaics.

The present study investigated how color information was summarized in multicolor mosaics. The mosaics were composed of small elements of 17 colors that roughly belonged to a single color category. We manipulated the degree of color variation around the mean by varying the proportion of different color elements. Observers matched the mean color of the multicolor mosaic by adjusting the color of a spatially uniform matching stimulus. Results showed that when the color variation was large, the matched color deviated from the colorimetric mean toward the most-saturated color, although the hue of the matched color was almost the same as that of the colorimetric mean. These findings together suggested differential processing of hue and saturation. The deviation of the matched color decreased, but did not disappear, when the color variation was reduced. The analysis of color metric underlying color averaging revealed differential color scaling in nearly orthogonal blue-orange and green-purple directions, implying that the visual system does not solely rely on linear cone-opponent codes when summarizing color signals. The deviation itself was consistently found regardless of different color metrics tested. The robustness of the deviation indicated an inherent bias of mean color judgments favoring highly saturated colors.

[Right Atrial Approach for the Surgical Repair of Delayed Ventricular Septal Rupture].

Ventricular septal rupture(VSR) after acute myocardial infarction(AMI) is a rare and serious complication that is associated with extremely high mortality. Delayed VSR is particularly uncommon and is difficult to diagnose and treat. A 68-year-old man presented with dyspnea on effort. Coronary angiography revealed subtotal occlusion of the right coronary artery(RCA) with collateral circulation to the chronically and totally occluded left anterior descending artery (LAD). Elective stenting of the RCA was successfully performed for a recent MI of the RCA, while percutaneous coronary intervention(PCI) in the LAD ended in failure. At 21 days after the 1st PCI, the patient developed acute heart failure with new pansystolic murmur. Cardiac catheterization showed a left to right ventricular shunting without new coronary artery lesions. Fortunately, the hemodynamic status was stable, and we could perform elective surgical repair by right atrial approach. Simultaneously, a left internal thoracic artery bypass to the LAD was performed. The postoperative course was uneventful. The patient is currently doing well at 5 years after the operation.

Integration of vascular systems between the brain and spinal cord in zebrafish.

Cerebral and spinal vascular systems are organized individually, and they then conjugate at their border, through the integration of basilar artery and vertebral arteries. Zebrafish (Danio rerio) is an ideal organism for studying early vascular development, and the precise procedure of cranial and truncal vascular formation has been previously demonstrated using this model. However, the stepwise process of the integration between the brain and spinal cord has not been clearly elucidated. In this study, we describe the integration of the independent vascular systems for the brain and spinal cord, using transgenic zebrafish expressing enhanced green fluorescent protein in endothelial cells. Initially, basilar artery and primordial hindbrain channels, into which internal carotid arteries supplied blood, were connected with dorsal longitudinal anastomose vessels, via the first intersegmental artery. This initial connection was not influenced by flow dynamics, suggesting that vascular integration in this region is controlled by genetic cues. Vertebral arteries were formed individually as longitudinal vessels beneath the spinal cord, and became integrated with the basilar artery during subsequent remodeling. Furthermore, we confirmed the basal vasculature was well conserved in adult zebrafish. Observations of vascular integration presented herein will contribute to an understanding of regulatory mechanisms behind this process.

Application of infrared laser to the zebrafish vascular system: gene induction, tracing, and ablation of single endothelial cells.

OBJECTIVE: Infrared laser-evoked gene operator is a new microscopic method optimized to heat cells in living organisms without causing photochemical damage. By combining the promoter system for the heat shock response, infrared laser-evoked gene operator enables laser-mediated gene induction in targeted cells. We applied this method to the vascular system in zebrafish embryos and demonstrated its usability to investigate mechanisms of vascular morphogenesis in vivo. APPROACH AND RESULTS: We used double-transgenic zebrafish with fli1:nEGFP to identify the endothelial cells, and with hsp:mCherry to carry out single-cell labeling. Optimizing the irradiation conditions, we finally succeeded in inducing the expression of the mCherry gene in single targeted endothelial cells, at a maximum efficiency rate of 60%. In addition, we indicated that this system could be used for laser ablation under certain conditions. To evaluate infrared laser-evoked gene operator, we applied this system to the endothelial cells of the first intersegmental arteries, and captured images of the connection between the vascular systems of the brain and spinal cord. CONCLUSIONS: Our results suggest that the infrared laser-evoked gene operator system will contribute to the elucidation of the mechanisms underlying vascular morphogenesis by controlling spatiotemporal gene activation in single endothelial cells, by labeling or deleting individual vessels in living embryos.

Design, synthesis, and biological activities of 1-aryl-1,4-diazepan-2-one derivatives as novel triple reuptake inhibitors.

A novel series of triple reuptake inhibitors were explored by ligand-based drug design. A cyclic structure was designed from cyclopropane derivative 5 using the core structure of reported monoamine reuptake inhibitors, leading to the formation of the 1-aryl-1,4-diazepan-2-one derivative 23j-S. Compound 23j-S was shown to act as a potent TRI with an excellent ADME-Tox profile. Oral administration of 23j-S significantly enhanced norepinephrine, dopamine, and serotonin levels in the mouse prefrontal cortex and showed significant antidepressant-like activity in tail suspension tests in mouse.

Attenuation of the pupillary response to luminance and color changes during interocular suppression.

The present study investigated the effects of interocular suppression on the pupillary constriction to luminance and color changes. Stable interocular suppression was produced by presenting a flickering high-contrast grating to one eye and a spatially homogeneous field to the other eye. The results showed that the pupillary responses to luminance as well as color changes were clearly attenuated during interocular suppression; the pupillary constriction to stimulus changes was delayed and reduced in amplitude when those changes occurred in the suppressed eye. The attenuation of the pupillary response was observed over a wide range of test contrast extending to well above the threshold level. Moreover, the properties of the suppressive effect were very similar to those assessed psychophysically using both detection thresholds for weak stimuli and reaction times for suprathreshold stimuli. Overall, the present study provided converging evidence that the pupillary response can be a useful objective probe of interocular suppression in humans. The results are discussed in view of possible differential involvements of subcortical and cortical visual processing in driving the pupillary response as well as in interocular suppression.

Novel triple reuptake inhibitors with low risk of CAD associated liabilities: design, synthesis and biological activities of 4-[(1S)-1-(3,4-dichlorophenyl)-2-methoxyethyl]piperidine and related compounds.

A novel triple reuptake inhibitor with low potential of liabilities associated with cationic amphiphilic drug (CAD) was identified following an analysis of existing drugs. Low molecular weight (MW < ca. 300), low aromatic ring count (number = 1) and reduced lipophilicity (ClogP < 3.5) were hypothesized to be key factors to avoid the CAD associated liabilities (CYP2D6 inhibition, hERG inhibition and phospholipidosis). Based on the hypothesis, a series of piperidine compounds was designed with consideration of the common characteristic features of CNS drugs. Optimization of the side chain by adjusting overall lipophilicity suggested that incorporation of a methoxymethyl group could provide compounds with a balance of both potent reuptake inhibition and low liability potential. Compound (S)-3a showed a potent antidepressant-like effect in the mice tail suspension test (MED = 10 mg/kg, p.o.), proportional monoamine transporter occupancies and enhancement of monoamine concentrations in mouse prefrontal cortex.

Spatial organization affects lightness perception on articulated surrounds.

The articulation effect refers to a change in lightness contrast induced by adding small patches of different luminances to a uniform background surrounding a target in a lightness contrast display. This study investigated how local luminance signals are integrated to generate the articulation effect. We asked whether spatial organization due to perceptual grouping can influence the articulation effect even when the spatially averaged luminance of the surrounds is held constant. Grouping factors used were common-fate motion (Experiment 1), similarity of orientation (Experiment 2), and synchrony (Experiment 3). Results of all experiments consistently showed that the articulation effect was larger when the target was strongly grouped with the articulation patches. These findings provide converging evidence for the effects of spatial organization on the articulation effect. Moreover, they suggest that lightness computation underlying the articulation effect depends on a middle-level representation in which perceptual organization is at least partially established. The changes in lightness perception due to spatial organization could be accounted for by the double-anchoring theory of lightness (Bressan, 2006b).

Two distinct types of color spreading induced by different luminance and color conditions in static flank transparency displays.

Flank transparency refers to illusory, phenomenally transparent color spreading induced when narrow colored flanks are added to line segments located within a virtual region. We investigated whether the luminance conditions that induced flank transparency were consistent with predictions based on luminance-contrast-based boundary interactions and the episcotister model for perceptual transparency. Examination of the requirements for the boundary interaction and perceptual transparency revealed that similar luminance conditions are necessary for both; that is, the flank luminance needs to be intermediate between the line and background luminances. We used green and achromatic flanks and systematically varied the luminance of the flanks, line segments, and background. We then asked the observers to rate the subjective certainty of color spreading using a five-point scale. The results showed that the perception of color spreading depended on color as well as luminance conditions. Generally, color spreading was convincing and phenomenally transparent when luminance conditions were consistent with the requirements for boundary interaction and perceptual transparency. In addition, color conditions worked in a facilitatory and inhibitory manner. Moreover, the results revealed that another convincing color spreading could be observed when the flank luminance was lower than the line or background luminance, that is, when the luminance condition for perceptual transparency was not satisfied. The observers' verbal reports indicated that phenomenal transparency was not evident in this color spreading. Overall, the present findings demonstrate that typical transparent color spreading is not the only one observed in the flank transparency display. Different color and luminance conditions can modulate the phenomenal appearance of color spreading, resulting in distinct types of color spreading.

The apelin­apelin receptor signaling pathway in fibroblasts is involved in tumor growth via p53 expression of cancer cells.

Cancer­associated fibroblasts (CAFs) are pivotal in tumor progression. TP53­deficiency in cancer cells is associated with robust stromal activation. The apelin­apelin receptor (APJ) system has been implicated in suppressing fibroblast­to­myofibroblast transition in non­neoplastic organ fibrosis. The present study aimed to elucidate the oncogenic role of the apelin­APJ system in tumor fibroblasts. APJ expression and the effect of APJ suppression in fibroblasts were investigated for p53 status in cancer cells using human cell lines (TP53­wild colon cancer, HCT116, and Caco­2; TP53­mutant colon cancer, SW480, and DLD­1; and colon fibroblasts, CCD­18Co), resected human tissue samples of colorectal cancers, and immune­deficient nude mouse xenograft models. The role of exosomes collected by ultracentrifugation were also analyzed as mediators of p53 expression in cancer cells and APJ expression in fibroblasts. APJ expression in fibroblasts co­cultured with p53­suppressed colon cancer cells (HCT116sh p53 cells) was significantly lower than in control colon cancer cells (HCT116sh control cells). APJ­suppressed fibroblasts treated with an antagonist or small interfering RNA showed myofibroblast­like properties, including increased proliferation and migratory abilities, via accelerated phosphorylation of Sma­ and Mad­related protein 2/3 (Smad2/3). In addition, xenografts of HCT116 cells with APJ­suppressed fibroblasts showed accelerated tumor growth. By contrast, apelin suppressed the upregulation of phosphorylated Smad2/3 in fibroblasts. MicroRNA 5703 enriched in exosomes derived from HCT116sh p53 cells inhibited APJ expression, and inhibition of miR­5703 diminished APJ suppression in fibroblasts caused by cancer cells. APJ suppression from a specific microRNA in cancer cell­derived exosomes induced CAF­like properties in fibroblasts. Thus, the APJ system in fibroblasts in the tumor microenvironment may be a promising therapeutic target.

Early development of the pulmonary vascular system: An anatomical and histochemical reinvestigation of the pulmonary venous return development in mice.

Pulmonary venous return development establishes the fetal circulation and is critical for the formation of pulmonary circulation independent of systemic circulation at birth. Anomalous returns lead to inappropriate drainage of blood flow, sometimes resulting in neonatal cyanosis and cardiac failure. While many classical studies have discussed the anatomical features of the pulmonary venous system development, the cellular dynamics of the endothelia based on the molecular marker expression remain unknown. In the present study, we examined the expression of several endothelial markers during early pulmonary vascular system development of murine embryos. We show that Endomucin and CD31 are expressed early in endothelial cells of the splanchnic plexus, which is the precursor of the pulmonary vascular system. Three-dimensional analyses of the expression patterns revealed the spatiotemporal modification of the venous returns to systemic venous systems or sinoatrial canal during the formation of the pulmonary plexus. We herein report the results of spatiotemporal analyses of the early pulmonary venous system development with histochemistry as well as a delineation of the anatomical features of the tentative drainage pathways.

Molecular mechanism of the wake-promoting agent TAK-925.

The OX2 orexin receptor (OX2R) is a highly expressed G protein-coupled receptor (GPCR) in the brain that regulates wakefulness and circadian rhythms in humans. Antagonism of OX2R is a proven therapeutic strategy for insomnia drugs, and agonism of OX2R is a potentially powerful approach for narcolepsy type 1, which is characterized by the death of orexinergic neurons. Until recently, agonism of OX2R had been considered 'undruggable.' We harness cryo-electron microscopy of OX2R-G protein complexes to determine how the first clinically tested OX2R agonist TAK-925 can activate OX2R in a highly selective manner. Two structures of TAK-925-bound OX2R with either a Gq mimetic or Gi reveal that TAK-925 binds at the same site occupied by antagonists, yet interacts with the transmembrane helices to trigger activating microswitches. Our structural and mutagenesis data show that TAK-925's selectivity is mediated by subtle differences between OX1 and OX2 receptor subtypes at the orthosteric pocket. Finally, differences in the polarity of interactions at the G protein binding interfaces help to rationalize OX2R's coupling selectivity for Gq signaling. The mechanisms of TAK-925's binding, activation, and selectivity presented herein will aid in understanding the efficacy of small molecule OX2R agonists for narcolepsy and other circadian disorders.

A novel glycogen synthase kinase-3 inhibitor 2-methyl-5-(3-{4-[(S )-methylsulfinyl]phenyl}-1-benzofuran-5-yl)-1,3,4-oxadiazole decreases tau phosphorylation and ameliorates cognitive deficits in a transgenic model of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder leading to a progressive loss of cognitive function and is pathologically characterized by senile plaques and neurofibrillary tangles. Glycogen synthase kinase-3 (GSK-3) is involved in AD pathogenesis. GSK-3 is reported not only to phosphorylate tau, a major component of neurofibrillary tangles, but also to regulate the production of amyloid ß, which is deposited in senile plaques. Therefore, pharmacological inhibition of GSK-3 is considered an attractive therapeutic approach. In this study, we report the pharmacological effects of a novel GSK-3 inhibitor, 2-methyl-5-(3-{4-[(S)-methylsulfinyl]phenyl}-1-benzofuran-5-yl)-1,3,4-oxadiazole (MMBO), which displays high selectivity for GSK-3 and brain penetration following oral administration. MMBO inhibited tau phosphorylation in primary neural cell culture and also in normal mouse brain. When administered to a transgenic mouse model of AD, MMBO significantly decreased hippocampal tau phosphorylation at GSK-3 sites. Additionally, chronic MMBO administration suppressed tau pathology as assessed by AT8-immunoreactivity without affecting amyloid ß pathology. Finally, in behavioral assessments, MMBO significantly improved memory and cognitive deficits in the Y-maze and in novel object recognition tests in the transgenic AD mouse model. These results indicate that pharmacological GSK-3 inhibition ameliorates behavioral dysfunction with suppression of tau phosphorylation in an AD mouse model, and that MMBO might be beneficial for AD treatment.

Eye- and feature-based modulation of onset rivalry caused by the preceding stimulus.

Pre-exposure to a stimulus can modulate initial perceptual dominance experienced in binocular rivalry with brief test stimuli (onset rivalry). This study investigated this modulating effect using both color and pattern stimuli. We confirmed separate contributions of eye- and feature-based suppressions and showed that their relative strength varied with temporal parameters. Eye-based suppression was stronger with a short test duration (10 ms) and shorter ISIs between the preceding and test stimuli. On the other hand, feature-based suppression grew with ISI and was more pronounced with a longer test duration (200 ms). We also investigated the nature of the modulating effect associated with feature-based suppression using chromatic gratings of high luminance contrast. Results revealed that different features of the preceding stimulus (i.e., color and orientation) exerted nearly independent effects on onset rivalry. However, different features shared their fate in competitive interactions for perceptual dominance; when one feature became dominant, the other also dominated. These findings suggest that competitive interactions for perceptual dominance and the modulation of these interactions are mediated at least partially by different mechanisms. Overall, the present findings are consistent with a theoretical view that initial dominance is established through competitive interactions at multiple levels of processing.

Statistical test of VEP waveform equality.

The aim of the study was to describe a theory and method for inferring the statistical significance of a visually evoked cortical potential (VEP) recording. The statistical evaluation is predicated on the pre-stimulus VEP as estimates of the cortical potentials expected when the stimulus does not produce an effect, a mathematical transform to convert the voltages into standard deviations from zero, and a time-series approach for estimating the variability of between-session VEPs under the null hypothesis. Empirical and Monte Carlo analyses address issues concerned with testability, statistical validity, clinical feasibility, as well as limitations of the proposed method. We conclude that visual electrophysiological recordings can be evaluated as a statistical study of n = 1 subject using time-series analysis when confounding effects are adequately controlled. The statistical test can be performed on either a single VEP or the difference between pairs of VEPs.

Enantioselective synthesis of the novel chiral sulfoxide derivative as a glycogen synthase kinase 3beta inhibitor.

Glycogen synthase kinase 3beta (GSK-3beta) inhibitors are expected to be attractive therapeutic agents for the treatment of Alzheimer's disease (AD). Recently we discovered sulfoxides (S)-1 as a novel GSK-3beta inhibitor having in vivo efficacy. We investigated practical asymmetric preparation methods for the scale-up synthesis of (S)-1. The highly enantioselective synthesis of (S)-1 (94% ee) was achieved by titanium-mediated oxidation with D-(-)-diethyl tartrate on gram scale.

Task-driven and flexible mean judgment for heterogeneous luminance ensembles.

Spatial averaging of luminances over a variegated region has been assumed in visual processes such as light adaptation, texture segmentation, and lightness scaling. Despite the importance of these processes, how mean brightness can be computed remains largely unknown. We investigated how accurately and precisely mean brightness can be compared for two briefly presented heterogeneous luminance arrays composed of different numbers of disks. The results demonstrated that mean brightness judgments can be made in a task-dependent and flexible fashion. Mean brightness judgments measured via the point of subjective equality (PSE) exhibited a consistent bias, suggesting that observers relied strongly on a subset of the disks (e.g., the highest- or lowest-luminance disks) in making their judgments. Moreover, the direction of the bias flexibly changed with the task requirements, even when the stimuli were completely the same. When asked to choose the brighter array, observers relied more on the highest-luminance disks. However, when asked to choose the darker array, observers relied more on the lowest-luminance disks. In contrast, when the task was the same, observers' judgments were almost immune to substantial changes in apparent contrast caused by changing the background luminance. Despite the bias in PSE, the mean brightness judgments were precise. The just-noticeable differences measured for multiple disks were similar to or even smaller than those for single disks, which suggested a benefit of averaging. These findings implicated flexible weighted averaging; that is, mean brightness can be judged efficiently by flexibly relying more on a few items that are relevant to the task.

Design, synthesis and structure-activity relationships of 1,3,4-oxadiazole derivatives as novel inhibitors of glycogen synthase kinase-3beta.

Glycogen synthase kinase-3beta (GSK-3beta) is implicated in abnormal hyperphosphorylation of tau protein and its inhibitors are expected to be a promising therapeutic agents for the treatment of Alzheimer's disease. Here we report design, synthesis and structure-activity relationships of a novel series of oxadiazole derivatives as GSK-3beta inhibitors. Among these inhibitors, compound 20x showed highly selective and potent GSK-3beta inhibitory activity in vitro and its binding mode was determined by obtaining the X-ray co-crystal structure of 20x and GSK-3beta.