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Abstract Maximizing healthy life expectancy is essential for enhancing well-being. Optimal exercise intensity is crucial in promoting health and ensuring safe rehabilitation. Since heart rate is related to exercise intensity, the required exercise intensity is achieved by controlling the heart rate. This study aims to control heart rate during exercise by dynamically adjusting the load on a bicycle ergometer using a proportional-integral (PI) control. The choice of PI parameters is very important because the PI parameters significantly affect the performance of heart rate control. Since the dynamic characteristics of heart rate relative to work rate vary widely from subject to subject, the PI parameters for each subject must be determined individually. In this study, PI parameters are optimized directly from exercise data using a data-driven design approach. Thus, the proposed method does not require excessive exercise of the subject to model heart rate dynamics. Using the proposed method, the heart rate can be controlled to follow a designed reference model so that the heart rate is safely increased to the desired value. The quantitative evaluation of the control results of fifteen healthy volunteers confirmed that the proposed method improved the control error of the target heart rate trajectory by approximately 40%, regardless of gender or age. In addition, it was shown that control parameters from the exercise experiment also indicate that females are more likely than males to have an elevated heart rate at the same load.

Sika deer (Cervus nippon) is the most abundant ruminant in the Japanese archipelago and has been the primary hunting target, including during the prehistoric ages. Abundant skeletal remains of sika deer have been excavated from archeological sites of the Jomon periods (ca. 15,000–2,400 BP). We reconstructed the feeding habits of sika deer from the Torihama Shell Midden site in Fukui Prefecture, western Japan. The Torihama site is one of the most well-preserved archeological sites of the Jomon period, and we investigated materials from the layers of the Early Jomon period (ca. 6,000 BP). In this study, we obtained three-dimensional tooth surface texture from the lower molars of excavated deer and measured microwear texture using international surface roughness parameters (ISO 25178-2) to infer their habitat use. Next, we estimated the percentage of grasses in the diet by using the reference dataset for extant sika deer with known diets. The results show that the Torihama deer overlapped with mixed feeding and grazing sika deer populations. Moreover, the proportion of grasses in the diet was estimated to be 50.7% on average but showed a wide range among the Torihama deer. This result implied that Torihama deer were mixed feeders of dicot leaves and grasses and had a flexible diet adapted to the vegetation of its habitat. Our results support the paleoenvironmental estimation that the Torihama Shell Midden site contained mixed vegetation of evergreen, deciduous, and coniferous trees around the Mikata Five Lakes in the Early Jomon period. These findings provide insights into the highly plastic diets of the extant sika deer in the Japanese archipelago.

Abstract Background Cytomegalovirus (CMV) is an important pathogen among immunocompromised hosts. Typically, CMV in human immunodeficiency virus (HIV) infection causes diseases of the retina, digestive tract, lungs and liver, but there are few cases of CMV infection of the pharynx and larynx. Case presentation A 57-year-old man with HIV infection was admitted because of pharyngeal pain. Before and after admission, pharyngeal biopsies guided by laryngeal endoscopy were performed four times, but pathological examination showed nonspecific inflammation, and the cause of pharyngeal ulceration was unclear. Additionally, the ulceration deteriorated after initiation of retroviral therapy. Laryngomicrosurgery was conducted under general anesthesia to remove tissue, and pathological diagnosis confirmed CMV infection. Pathological features included enlargement of the cytoplasm and nucleus in infected cells, and intranuclear bodies called owl’s eye inclusions. Ganciclovir dramatically improved the symptoms and laryngoscopic findings. Conclusions This case was diagnosed as pharyngitis and pharyngeal ulceration caused by CMV infection, related to immune reconstitution inflammatory syndrome. In previous reports of CMV-induced pharyngeal or laryngeal ulceration in HIV infection, we found six cases similar to our present case. All cases were diagnosed by biopsy. The present case indicates the importance of biopsy for definitive diagnosis. CMV infection should be considered as a differential diagnosis of pharyngeal ulceration in patients with HIV infection.

In this study, a data-driven design method is proposed for a dual-rate system, where the sampling interval of a plant output is restricted and is an integer multiple of the holding interval of a control input. In our proposed method, single-rate virtual reference feedback tuning (S-VRFT), where the holding interval is the same as the sampling interval, is extended to the dual-rate virtual reference feedback tuning (D-VRFT) system. In D-VRFT, a controller is decided using a set of input/output data used in S-VRFT, and it is easy to extend S-VRFT to D-VRFT and implement D-VRFT. In this study, intersample oscillations caused in such a dual-rate control system is prevented because a weighting filter is introduced for penalizing the control input deviation between the sampling instants. The filter is designed as an integrator for weighting the low-frequency domain. The improvement in fast-tracking performance as well as the ripple-free property are demonstrated through both the numerical and experimental results.

Abstract A new approach to the active fault diagnosis (AFD) for input redundant plants is presented in this paper. A test signal which helps the diagnosis is injected to the plant in addition to nominal control input in the AFD typically. One feature of the proposed AFD is adaptive allocation of the test signal. The adaptive allocator which distributes the test signal and injects it to the redundant actuators is introduced in this paper. A fault-diagnosis (FD) system that estimates fault location and its magnitude from adaptive parameter of the adaptive allocator is constructed with a simple neural network (NN) model. Furthermore, a A fault-tolerant adaptive control system which includes the adaptive test signal allocator is designed based on the model reference adaptive control (MRAC) technique. The adaptive laws of the adaptive allocator and controller are derived by using a suitable Lyapunov function. By performing experiments using a two-input redundant plant, we show the effectiveness and applicability of the proposed AFD and MRAC system.

This paper proposes a design method of model predictive control (MPC) for multi-input multi-output (MIMO) plants with time-delay by using an interactor matrix and a sequential procedure to solve the matrix polynomial Diophantine equations required to be solved in the design. The equations are of matrix polynomials, and matrix calculations are not commutative; hence it is not easy to solve the equations, and it is necessary to obtain a sequential solving procedure. Also, the difficulty in the design of MPC of MIMO plants comes from the fact that a plant transfer function is a matrix, which is not commutative in multiplication. This paper avoids this difficulty by deriving a plant transfer function with a scalar polynomial denominator. And to handle the time-delay in MIMO plants, an interactor matrix is used to shift the outputs by time-delay steps. Then the design problem with time-delay is reduced to a problem without time-delay. There exist designs of MPC for time-delay plants by using a longer horizon than the time-delay steps. In this paper, it is shown by simulations that MPC having a long horizon is sensitive to disturbances and that the proposed MPC is less sensitive.

The present study discusses the consensus control of dual-rate multi-agent systems, where the sampling/communication interval of quantized data is an integer multiple of the control interval. A conventional multi-agent system uses a dynamic quantizer which is designed in a single-rate system where the intervals are equal, i.e., the control interval length is the same as the communication interval length. However, a dynamic quantizer designed in a dual-rate system is expected to have improved control performance. In the present study, an objective function is divided into a quantization term, which is related to the quantization error, and the remaining term. The proposed dual-rate dynamic quantizer is designed such that the quantization term is minimized. Finally, in numerical examples, the proposed dual-rate method is quantitatively evaluated by comparing with the conventional single-rate method, and the effectiveness of the proposed method is demonstrated.

This paper considered a new nonlinear state estimation method based on the Kalman filter. In this method, we employed a state-dependent linear representation which is rewritten the system nonlinear equation into pseudo linear equation without any approximation, then applied a linear kalman filter to estimate the system state using the observed output. The method is inspired by a method based on the state-dependent Riccati equation (SDRE), which is a method for designing controllers or observers for nonlinear systems. Our filter approach is very simple and can be implemented more easily than the conventional methods of similar nonlinear state estimation methods such as extended Kalman filter (EKF) and unscented Kalman filter (UKF). The effectiveness of the proposed method was verified by numerical simulations. As a result, we confirmed that the proposed method is faster in computation time and easier in design than the SDRE-based observer. In addition, from the comparison between the estimation results by the proposed method and the estimation results of EKF and UKF, it was confirmed that the proposed method can be applied to the same state estimation problems as EKF and UKF.

In the present study, a data-driven ripple-free design is proposed for a dual-rate sampled-data control system in which the sampling interval of the plant output is longer than the holding interval of the control input. The objective of the present study is to improve the steady-state intersample response without changing the sampled response and without using the plant model. To achieve the objective directly from controlled data, an add-on input based on the null space of steady-state step responses to an existing control system is used. The open-loop or closed-loop system to obtain the step response is assumed to be stable. In the present study, a two-degree-of-freedom design is given that redesigns the intersample output response independently of the steady-state sampled output response. In a numerical example, the proposed method is applied to a linear time-invariant single-input single-output stable system, where intersample ripples are eliminated using the add-on input that is independent of the existing sample output response in steady state.

Background. The saline-induced distal coronary pressure/aortic pressure ratio predicted fractional flow reserve (FFR). The resting full-cycle ratio (RFR) represents the maximal relative pressure difference in a cardiac cycle. Therefore, the present study aimed to compare the results of saline-induced RFR (sRFR) with FFR. Methods. Seventy consecutive lesions with only moderate stenosis were included. The FFR, RFR, and sRFR values were compared. The sRFR was assessed using an intracoronary bolus infusion of saline (2 mL/s) for five heartbeats. The FFR was obtained after an intravenous injection of papaverine. Results. Overall, the FFR, sRFR, and RFR values were 0.78 ± 0.12, 0.79 ± 0.13, and 0.83 ± 0.14, respectively. With regard to anatomical morphology were 40, 18, and 12 cases of focal, diffuse, and tandem lesion. There was a significant correlation between the sRFR and FFR (R = 0.96, p

Early detection of pancreatic ductal adenocarcinoma (PDAC) in the general population is difficult due to unknown clinical characteristics. This study was conducted to clarify the factors associated with early stage PDAC. Well-known symptoms and factors associated with PDAC were classified into clinical indicators, risk factors, and imaging findings concomitant with early stage PDAC. To analyze these factors for the detection of patients with early stage PDAC compared to patients without PDAC, we constructed new diagnostic strategies. The factors of 35 patients with early stage PDAC (stage 0 and IA) and 801 patients without PDAC were compared retrospectively. Clinical indicators; presence and number of indicators, elevated pancreatic enzyme level, tumor biomarker level, acute pancreatitis history, risk factors; familial pancreatic cancer, diabetes mellitus, smoking history, imaging findings; presence and number of findings, and main pancreatic duct dilation were significant factors for early stage PDAC detection. A new screening strategy to select patients who should be examined by imaging modalities from evaluating clinical indicators and risk factors and approaching a definitive diagnosis by evaluating imaging findings had a relatively high sensitivity, specificity, and areas under the curve of 80.0%, 80.8%, and 0.80, respectively. Diagnosis based on the new category and strategy may be reasonable for early stage PDAC detection.

Background: Third-generation stents with abluminal biodegradable polymer (BP) might facilitate early healing. Therefore, we compared early healing between second-generation and third-generation stents using coronary angioscopy (CAS) and optical frequency domain imaging [OFDI]. Methods: We prospectively enrolled 30 consecutive patients with stent implantation for acute coronary syndrome (cobalt‑chromium [CoCr] everolimus-eluting stent [EES] [n = 10], BP-EES [n = 10], and BP-sirolimus eluting stent [SES] [n = 10]). All patients underwent CAS and OFDI 1 month after initial percutaneous coronary intervention. On OFDI, the stent coverage (SC), thrombus, and peri-strut low intensity area (PLIA) were assessed. CAS findings were recorded for the grade of SC, grade of yellow color (YC), and grade of the thrombus (TG). Results: On OFDI, the incidences of any thrombus at the 1-month follow-up were 70%, 80%, and 80% in the CoCr-EES, BP-EES, and BP-SES groups, respectively. The percentage of coverage was comparable among the groups (CoCr-EES 79.8 vs. BP-EES 79.9 vs. BP-SES 80.1%, P = 0.96). However, the number of struts with PLIA was numerically higher in the BP-SES group than in the CoCr-EES and BP-EES groups (46.4 ± 25.1 vs. 21.6 ± 13.2 vs. 22.0 ± 7.2%, P = 0.08). In the CoCr-EES, BP-EES, and BP-SES groups, mean grades of SC were 1.25 ± 0.5, 1.25 ± 0.5, and 0.85 ± 0.70 (P = 0.60); mean grades of YC were 0.75 ± 0.5, 0.80 ± 0.45, and 0.88 ± 0.37 (P = 0.65), and mean grades of TG were 1.00 ± 1.00, 1.20 ± 0.83, and 0.88 ± 0.64 (P = 0.75), respectively. Conclusion: Third-generation stents are not inferior to second-generation stents regarding stent coverage. However, PLIA on OFDI was often observed with BP-SESs, indicating involvement of the fibrin component. Keywords: Early healing, Coronary angioscopy, Optical frequency domain imaging

Abstract Background Glycosuria produced by sodium–glucose co-transporter-2 (SGLT-2) inhibitors is associated with weight loss. SGLT-2 inhibitors reportedly might reduce the occurrence of cardiovascular events. Epicardial adipose tissue (EAT) is a pathogenic fat depot that may be associated with coronary atherosclerosis. The present study evaluated the relationship between an SGLT-2 inhibitor (dapagliflozin) and EAT volume. Methods In 40 diabetes mellitus patients with coronary artery disease (10 women and 30 men; mean age of all 40 patients was 67.2 ± 5.4 years), EAT volume was compared prospectively between the dapagliflozin treatment group (DG; n = 20) and conventional treatment group (CTG; n = 20) during a 6-month period. EAT was defined as any pixel that had computed tomography attenuation of − 150 to − 30 Hounsfield units within the pericardial sac. Metabolic parameters, including HbA1c, tumor necrotic factor-α (TNF-α), and plasminogen activator inhibitor-1 (PAI-1) levels, were measured at both baseline and 6-months thereafter. Results There were no significant differences at baseline of EAT volume and HbA1c, PAI-1, and TNF-α levels between the two treatment groups. After a 6-month follow-up, the change in HbA1c levels in the DG decreased significantly from 7.2 to 6.8%, while body weight decreased significantly in the DG compared with the CTG (− 2.9 ± 3.4 vs. 0.2 ± 2.4 kg, p = 0.01). At the 6-month follow-up, serum PAI-1 levels tended to decline in the DG. In addition, the change in the TNF-α level in the DG was significantly greater than that in the CTG (− 0.5 ± 0.7 vs. 0.03 ± 0.3 pg/ml, p = 0.03). Furthermore, EAT volume significantly decreased in the DG at the 6-month follow-up compared with the CTG (− 16.4 ± 8.3 vs. 4.7 ± 8.8 cm3, p = 0.01). Not only the changes in the EAT volume and body weight, but also those in the EAT volume and TNF-α level, showed significantly positive correlation. Conclusion Treatment with dapagliflozin might improve systemic metabolic parameters and decrease the EAT volume in diabetes mellitus patients, possibly contributing to risk reduction in cardiovascular events.

In this study, we examined the operation of first- and second-order motion mechanisms with respect to object tracking using dichoptic presentation. A bistable apparent motion stimulus composed of four rectangles arranged in square- and diamond-shapes in every other frame was presented binocularly, monocularly, or dichoptically using a stereoscope. Since past motion studies showed that the first-order motion mechanism cannot function under dichoptic stimulation, we evaluated the upper temporal frequency limits of object tracking with dichoptic presentation and compared these results with those obtained with ordinary binocular or monocular (nondichoptic) presentation. We found that the temporal limits were 4 -5 Hz, regardless of the viewing conditions. These limits are similar to those for within-attribute (first- and second-order) object tracking (4 -5 Hz) obtained in our previous study. Thus, this putative mechanism may be responsible for object tracking, based only on second-order components, even in the case of first-order stimuli.

This paper discusses a design method for controlling a single-input single-output linear time-invariant sampled-data multi-rate control system, where the sampling interval of a plant output is longer than the holding interval of a control input. In such a sampled-data control system, the control input can be changed between the sampling instants. Hence, even if the sampled output converges to the reference input, the intersample output may oscillate. Such an intersample oscillation is eliminated when the control input is constant. In a conventional method, a control law is extended using an additional signal which is independent of the reference response in the discrete time, and the additional signal is designed so that the control input is constant in the steady state. The conventional method is designed based on the transfer function model, on the other hand, the proposed method is designed using the state-space model. Furthermore, a new design method of the additional input is proposed using the input redundancy which is defined by strongly input redundant or weakly input redundant. Finally, the effectiveness of the proposed method is demonstrated through numerical examples.

The present study proposes a novel proportional-integral-derivative (PID) control design method in discrete time. In the proposed method, a PID controller is designed for first-order plus dead-time (FOPDT) systems so that the prescribed robust stability is accomplished. Furthermore, based on the control performance, the relationship between the servo performance and the regulator performance is a trade-off relationship, and hence, these items are not simultaneously optimized. Therefore, the proposed method provides an optimal design method of the PID parameters for optimizing the reference tracking and disturbance rejection performances, respectively. Even though such a trade-off design method is being actively researched for continuous time, few studies have examined such a method for discrete time. In conventional discrete time methods, the robust stability is not directly prescribed or available systems are restricted to systems for which the dead-time in the continuous time model is an integer multiple of the sampling interval. On the other hand, in the proposed method, even when a discrete time zero is included in the controlled plant, the optimal PID parameters are obtained. In the present study, as well as the other plant parameters, a zero in the FOPDT system is newly normalized, and then, a universal design method is obtained for the FOPDT system with the zero. Finally, the effectiveness of the proposed method is demonstrated through numerical examples.

The present study proposes a new design method for a proportional-integral-derivative (PID) control system for first-order plus dead-time (FOPDT) and over-damped second-order plus dead-time (SOPDT) systems. What is presented is an optimal PID tuning constrained to robust stability. The optimal tuning is defined for each one of the two operation modes the control system may operate in: servo (reference tracking) and regulation (disturbance rejection). The optimization problem is stated for a normalized second-order plant that unifies FOPDT and SOPDT process models. Different robustness levels are considered and for each one of them, the set of optimal controller parameters is obtained. In a second step, suitable formulas are found that provide continuous values for the controller parameters. Finally, the effectiveness of the proposed method is confirmed through numerical examples.

Heat shock protein 27 (HSP27) is a member of the small molecular weight HSP family. Upon treatment with transforming growth factor β1 (TGF-β1), we observed upregulation of HSP27 along with that of α-smooth muscle actin (α-SMA), a marker of myofibroblast differentiation, in cultured human and mouse lung fibroblasts. Furthermore, by using siRNA knockdown, we demonstrated that HSP27 was involved in cell survival and upregulation of fibronectin, osteopontin (OPN) and type 1 collagen, all functional markers of myofibroblast differentiation, in TGF-β1-treated MRC-5 cells. In lung tissues of bleomycin-treated mice, HSP27 was strongly upregulated and substantially co-localized with α-SMA, OPN and type I collagen but not with proSP-C (a marker of type II alveolar epithelial cells), E-cadherin (a marker of epithelial cells) or F4/80 (a marker of macrophages). A similar co-localization of HSP27 and α-SMA was observed in lung tissues of patients with idiopathic pulmonary fibrosis. Furthermore, airway delivery of HSP27 siRNA effectively suppressed bleomycin-induced pulmonary fibrosis in mice. Collectively, our findings indicate that HSP27 is critically involved in myofibroblast differentiation of lung fibroblasts and may be a promising therapeutic target for lung fibrotic diseases.

M cells in the follicle-associated epithelium (FAE) of Peyer's patches (PPs) serve as a main portal for external antigens and function as a sentinel in mucosal immune responses. The scarcity of these cells has hampered identification of M cell-specific molecules. Recent efforts have begun to provide insight into antigen transcytosis and differentiation of M cells; however, the molecular mechanisms underlying these processes are not fully elucidated. Small non-coding RNAs including microRNA (miRNA) have been reported to regulate gene expression and control various biological processes such as cellular differentiation and function. To evaluate the expression of miRNAs in FAE, including M cells, we previously performed microarray analysis comparing intestinal villous epithelium (VE) and PP FAE. Here we confirmed FAE specific miRNA expression levels by quantitative PCR. To gain insight into miRNA function, we generated mice with intestinal epithelial cell-specific deletion of Dicer1 (DicerΔIEC) and analyzed intestinal phenotypes, including M-cell differentiation, morphology and function. DicerΔIEC mice had a marked decrease in M cells compared to control floxed Dicer mice, suggesting an essential role of miRNAs in maturation of these cells. Furthermore, transmission electron microscopic analysis revealed that depletion of miRNA caused the loss of endosomal structures in M cells. In addition, antigen uptake by M cells was impaired in DicerΔIEC mice. These results suggest that miRNAs play a significant role in M cell differentiation and help secure mucosal immune homeostasis.

Previous studies have demonstrated that the serotonin transporter gene-linked polymorphic region (5-HTTLPR) affects the recognition of facial expressions and attention to them. However, the relationship between 5-HTTLPR and the perceptual detection of others' facial expressions, the process which takes place prior to emotional labeling (i.e., recognition), is not clear. To examine whether the perceptual detection of emotional facial expressions is influenced by the allelic variation (short/long) of 5-HTTLPR, happy and sad facial expressions were presented at weak and mid intensities (25% and 50%). Ninety-eight participants, genotyped for 5-HTTLPR, judged whether emotion in images of faces was present. Participants with short alleles showed higher sensitivity (d') to happy than to sad expressions, while participants with long allele(s) showed no such positivity advantage. This effect of 5-HTTLPR was found at different facial expression intensities among males and females. The results suggest that at the perceptual stage, a short allele enhances the processing of positive facial expressions rather than that of negative facial expressions.

A person depicted in portrait paintings does not appear slanted even when observers move around. The gaze is also fixed to the observer. This constancy in angle of face/body orientation or gaze direction is called the Mona Lisa effect. Do observers realize the portrait was physically slanted when the effect occurs? What is the relationship between the effect for face/body and gaze? To answer these questions, we separately measured the perceived angle of face, gaze, and background while varying the physical slant of portrait itself. The stimulus was a computer generated face (19 × 12 deg) presented on a 3D LCD display. It was surrounded by a 24 × 24 deg black-contour frame filled with a noise texture. There were also no-frame and/or no-texture conditions. The slant was varied between ±30 deg. The observer was asked to judge the direction of gaze and the orientation of face or background in separate sessions. It was found that the perceived gaze almost always directed toward the observer regardless of slant angle or existence of frame or background. In contrast, the face orientation was judged facing the observer only in 40–50% of trials, and it was facing at the correct angle in 50–60% of trials. The background was perceived correctly in most trials. These results demonstrate special characteristics of eyes. The gaze is always directed to you even when the portrait is slanted and the background is perceived slanted. The face has intermediate characteristics: it is sometimes directed to you, but sometimes it appears slanted.

BACKGROUND: When a second sound follows a long first sound, its location appears to be perceived away from the first one (the localization/lateralization aftereffect). This aftereffect has often been considered to reflect an efficient neural coding of sound locations in the auditory system. To understand determinants of the localization aftereffect, the current study examined whether it is induced by an interaural temporal difference (ITD) in the amplitude envelope of high frequency transposed tones (over 2 kHz), which is known to function as a sound localization cue. METHODOLOGY/PRINCIPAL FINDINGS: In Experiment 1, participants were required to adjust the position of a pointer to the perceived location of test stimuli before and after adaptation. Test and adapter stimuli were amplitude modulated (AM) sounds presented at high frequencies and their positional differences were manipulated solely by the envelope ITD. Results showed that the adapter's ITD systematically affected the perceived position of test sounds to the directions expected from the localization/lateralization aftereffect when the adapter was presented at ±600 µs ITD; a corresponding significant effect was not observed for a 0 µs ITD adapter. In Experiment 2, the observed adapter effect was confirmed using a forced-choice task. It was also found that adaptation to the AM sounds at high frequencies did not significantly change the perceived position of pure-tone test stimuli in the low frequency region (128 and 256 Hz). CONCLUSIONS/SIGNIFICANCE: The findings in the current study indicate that ITD in the envelope at high frequencies induces the localization aftereffect. This suggests that ITD in the high frequency region is involved in adaptive plasticity of auditory localization processing.

Presenting luminance contours surrounding the adapted areas in test phase enhances color afterimages in both duration and color appearance. The presence of surrounding contour is crucial to some color phenomenon such as van Lier's afterimage, but the contour-effect itself has not been seriously examined. In this paper, we compared the contour-effect to color afterimages and to actually colored patches to examine the nature of color information subserving color-aftereffect. In the experiment, observers were adapted for 1 sec to a small colored square (red, green, yellow, or blue) presented on a gray background. Then, a test field either with or without surrounding contour was presented. Observers matched the color of a test-patch located near the afterimage to the color of afterimage. It was found that the saturation of negative afterimage was almost doubled by the presence of surrounding contours. There was no effect of luminance contrast or polarity of contours. In contrast, no enhancement of saturation by surrounding contours was observed for actually colored patches even though the colors of patches were equalized to that of afterimage without contours. This dissociation in the contour-effect demonstrates the crucial difference between the color information for aftereffects and for ordinary bottom-up color perception.

The apparent contrast of a texture is reduced when it is surrounded by another texture with high contrast. This contrast-contrast illusion has been thought to be a result of spatial interactions between visual channels that encode contrast energy. In the present study, we show that the contrast-contrast is selective to the luminance polarity by using texture patterns composed of sparse elongated blobs. The apparent contrast of a texture of bright (dark) elements was substantially reduced only when it was surrounded by a texture of elements with the same polarity. This polarity specificity was not found for textures of dense elements, which was similar to those used in previous studies, probably because such stimuli should inevitably activate both on- and off-type sensors. The polarity selective suppression decreased as the difference in orientation between the centre and surround elements increased, but still remained as for orthogonally-oriented elements. These results suggest that the contrast-contrast illusion largely depends on spatial interactions between visual channels that are selective to the luminance polarity and partially to the orientation.

It is known that moving stimuli perceptually dominate over static stimuli during binocular rivalry. Recent evidence shows that visual motions can be processed in spatiotopic, or object-based as well as retinotopic coordinates. Here we examined which spatial coordinate determines the motion dominance in binocular rivalry. Observers viewed a dichoptic pair of stimuli, each consisting of a fixation marker, a gray square background, and a diagonal grating (45 deg in one eye and 135 deg in the other). The observer judged which grating appeared dominant. Drifting gratings were dominant over static gratings when observers maintained stationary fixation. However, when they tracked the fixation marker that moved together with the drifting grating, the physically drifting but retinotopically stationary grating became dominant. When observers tracked fixation marker and stimulus background both moving together, the gratings that were physically stationary but moving in retinotopic and object-based coordinates were perceptually dominant. Subsequent quantitative analyses revealed that spatiotopic and object-based motions contribute equally with or even more than retinotopic motion. These results demonstrate a significant role of nonretinotopic motion signals in triggering the conscious awareness of visual stimuli.