Multistage model for binocular rivalry

Binocular rivalry is the alternating perception that occurs when incompatible stimuli are presented to the two eyes: one monocular stimulus dominates vision and then the other stimulus dominates, with a perceptual switch occurring every few seconds. There is a need for a binocular rivalry model that accounts for both well-established results on the timing of dominance intervals and for more recent evidence on the distributed neural processing of rivalry. The model for binocular rivalry developed here consists of four parallel visual channels, two driven by the left eye and two by the right. Each channel consists of several consecutive processing stages representing successively higher cortical levels, with mutual inhibition between the channels at each stage. All stages are architecturally identical. With n the number of stages, the model is implemented as 4n nonlinear differential equations using a total of eight parameters. Despite the simplicity of its architecture, the model accounts for a variety of experimental observations: 1) the increasing depth of rivalry at higher cortical areas, as shown in electrophysiological, imaging, and psychophysical experiments; 2) the unimodal probability density of dominance durations, where the mode is less than the mean; 3) the lack of correlation between successive dominance durations; 4) the effect of interocular stimulus differences on dominance duration; and 5) eye suppression, as opposed to feature suppression. The model is potentially applicable to issues of visual processing more general than binocular rivalry.     

Psychophysical evidence for two routes to suppression before binocular summation of signals in human vision

Visual mechanisms in primary visual cortex are suppressed by the superposition of gratings perpendicular to their preferred orientations. A clear picture of this process is needed to (i) inform functional architecture of image-processing models, (ii) identify the pathways available to support binocular rivalry, and (iii) generally advance our understanding of early vision. Here we use monoptic sine-wave gratings and cross-orientation masking (XOM) to reveal two cross-oriented suppressive pathways in humans, both of which occur before full binocular summation of signals. One is a within-eye (ipsiocular) pathway that is spatially broadband, immune to contrast adaptation and has a suppressive weight that tends to decrease with stimulus duration. The other pathway operates between the eyes (interocular), is spatially tuned, desensitizes with contrast adaptation and has a suppressive weight that increases with stimulus duration. When cross-oriented masks are presented to both eyes, masking is enhanced or diminished for conditions in which either ipsiocular or interocular pathways dominate masking, respectively. We propose that ipsiocular suppression precedes the influence of interocular suppression and tentatively associate the two effects with the lateral geniculate nucleus (or retina) and the visual cortex respectively. The interocular route is a good candidate for the initial pathway involved in binocular rivalry and predicts that interocular cross-orientation suppression should be found in cortical cells with predominantly ipsiocular drive.     

Binocular rivalry in half-occluded region is weakened by eye movement

To investigate the effect of eye movement on suppression of binocular rivalry in the half-occluded region, which is the monocular region made by occlusion, the amount of binocular rivalry in the half-occluded region was measured in the eye movement condition and the fixating condition. In the eye movement condition, the observer moved their eyes between the occluder and the occluded object. In the fixating condition, the observers fixated the occluder (the fixating-the-occluder condition) or the occluded object (the fixating-the-occluded-object condition). Following facts were found: (a) the amount of binocular rivalry in the half-occluded region reduced more in the eye movement condition than in the two fixating conditions, (b) there was no significant difference in the amount of binocular rivalry in the half-occluded region between the two fixating conditions. These results suggested that eye movement is one of the factors to suppress binocular rivalry in the half-occluded region in natural viewing situations.     

Traveling waves of activity in primary visual cortex during binocular rivalry

When the two eyes view large, dissimilar patterns that induce binocular rivalry, alternating waves of visibility are experienced as one pattern sweeps the other out of conscious awareness. Here we combine psychophysics with functional magnetic resonance imaging to show tight linkage between dynamics of perceptual waves during rivalry and neural events in human primary visual cortex (V1).     

Cortical responses to invisible objects in the human dorsal and ventral pathways

The primate visual system is believed to comprise two main pathways: a ventral pathway for conscious perception and a dorsal pathway that can process visual information and guide action without accompanying conscious knowledge. Evidence for this theory has come primarily from studies of neurological patients and animals. Using fMRI, we show here that even though observers are completely unaware of test object images owing to interocular suppression, their dorsal cortical areas demonstrate substantial activity for different types of visual objects, with stronger responses to images of tools than of human faces. This result also suggests that in binocular rivalry, substantial information in the suppressed eye can escape the interocular suppression and reach dorsal cortex.     

Barrett's oesophagus: Microsatellite analysis provides evidence to support the proposed metaplasia-dysplasia-carcinoma sequence

The development of adenocarcinoma in Barrett's oesophagus is proposed to occur via a stepwise progression recognised histologically as a metaplasia-dysplasia-carcinoma sequence. In order to identify chromosomal loci involved in the malignant transformation of Barrett's epithelium and the development of oesophageal adenocarcinoma, microsatellite analysis was carried out on 17 cases of Barrett's-associated oesophageal adenocarcinoma. Samples of premalignant Barrett's epithelium adjacent to adenocarcinoma were obtained from seven of these cases. Allelic imbalance was detected in >45% of informative cases of oesophageal adenocarcinoma on chromosome arms 3q (65%), 4q (71%), 5q (59%), 6q (59%), 9p (50%), 9q (47%), 12p (47%), 12q (65%), 17p (76%), and 18q (75%). Allelic imbalance at 4q, 17p, and 18q was significantly higher than the upper 95% confidence interval for background allelic imbalance. Allelic imbalance was detected at several loci in the premalignant epithelium from five of the seven cases studied. These loci included several chromosomal arms that had demonstrated high levels of allelic imbalance in oesophageal adenocarcinoma, namely, 4q (one case), 5q (two cases), 9 (three cases), 12q (five cases), 17p (four cases), and 18q (two cases). Novel microsatellite alleles were detected in both premalignant and malignant Barrett's epithelium. In three cases, dysplastic Barrett's epithelium and adjacent adenocarcinoma demonstrated the same pattern of novel microsatellite alleles at a number of loci. In conclusion, these data indicate chromosomal loci which may be specifically involved in the histological progression of Barrett's epithelium. The detection of shared novel microsatellite alleles in premalignant and malignant Barrett's epithelium is consistent with a process of clonal expansion underlying this progression. Genes Chromosomes Cancer 21:49–60, 1998. © 1998 Wiley-Liss, Inc.     

Neural correlates of binocular rivalry in the human lateral geniculate nucleus

When dissimilar images are presented to the two eyes, they compete for perceptual dominance so that only one image is visible at a time while the other one is suppressed. Neural correlates of such binocular rivalry have been found at multiple stages of visual processing, including striate and extrastriate visual cortex. However, little is known about the role of subcortical processing during binocular rivalry. Here we used fMRI to measure neural activity in the human LGN while subjects viewed contrast-modulated gratings presented dichoptically. Neural activity in the LGN correlated strongly with the subjects' reported percepts, such that activity increased when a high-contrast grating was perceived and decreased when a low-contrast grating was perceived. Our results provide evidence for a functional role of the LGN in binocular rivalry and suggest that the LGN, traditionally viewed as the gateway to the visual cortex, may be an early gatekeeper of visual awareness.     

Statin-induced rhabdomyolysis in patient with renal failure and underlying undiagnosed hypothyroidism

Rhabdomyolysis is a syndrome characterized by muscle necrosis which causes the release of myoglobin into the bloodstream. The manifestations of this syndrome range from asymptomatic elevation of serum muscle enzymes to life-threatening cases associated with extremely high enzyme levels, electrolyte imbalance, and acute renal failure. Symptoms of rhabdomyolysis include dark urine, muscle weakness, and fatigue. Statins are commonly used drugs for the prevention and management of dyslipidemia. We present an interesting and critical case on statin-induced rhabdomyolysis with renal failure and previously undiagnosed idiopathic hypothyroidism.     

Neuronal activity in human primary visual cortex correlates with perception during binocular rivalry

During binocular rivalry, two incompatible monocular images compete for perceptual dominance, with one pattern temporarily suppressed from conscious awareness. We measured fMRI signals in early visual cortex while subjects viewed rival dichoptic images of two different contrasts; the contrast difference served as a 'tag' for the neuronal representations of the two monocular images. Activity in primary visual cortex (V1) increased when subjects perceived the higher contrast pattern and decreased when subjects perceived the lower contrast pattern. These fluctuations in V1 activity during rivalry were about 55% as large as those evoked by alternately presenting the two monocular images without rivalry. The rivalry-related fluctuations in V1 activity were roughly equal to those observed in other visual areas (V2, V3, V3a and V4v). These results challenge the view that the neuronal mechanisms responsible for binocular rivalry occur primarily in later visual areas.     

Continuous flash suppression reduces negative afterimages

Illusions that produce perceptual suppression despite constant retinal input are used to manipulate visual consciousness. Here we report on a powerful variant of existing techniques, continuous flash suppression. Distinct images flashed successively at approximately 10 Hz into one eye reliably suppress an image presented to the other eye. The duration of perceptual suppression is at least ten times greater than that produced by binocular rivalry. Using this tool we show that the strength of the negative afterimage of an adaptor was reduced by half when it was perceptually suppressed by input from the other eye. The more completely the adaptor was suppressed, the more strongly the afterimage intensity was reduced. Paradoxically, trial-to-trial visibility of the adaptor did not correlate with the degree of reduction. Our results imply that formation of afterimages involves neuronal structures that access input from both eyes but that do not correspond directly to the neuronal correlates of perceptual awareness.     

Accelerated binocular rivalry with anxious personality

When dissimilar figures are presented to the two eyes individually, perception alternates spontaneously between each monocular view. This phenomenon, designated binocular rivalry, has been used by many scientists as a tool for investigating visual awareness. Some recent studies have suggested involvement of serotonergic neural systems in this phenomenon. We explored the relationship between binocular rivalry and anxiety, a state thought to be associated with serotonergic neural activity. Perceptual alternation rate in dominance of binocular rivalry were compared between normal volunteers with high and low general anxiety as measured using the harm avoidance (HA) scale of the Tridimensional Personality Questionnaire. Perceptual alternation rate and rhythmicity in the high-HA group was significantly greater than that in the low-HA group. The perceptual alternation rate in binocular rivalry was accelerated in anxious subjects, suggesting that binocular rivalry and anxiety may share some common serotonergic neural substrates.     

A cytogenetic study of nonpolymalformed patients with mental retardation of clinically undefined etiology: application of a high resolution banding technique

We performed a cytogenetic study on 140 nonpolymalformed patients with mental retardation of clinically undefined origin, using a high resolution banding technique, to determine how much chromosome abnormalities contribute to the etiology of this condition. A total of 15 patients (10.7%) were found to have autosomal or sex chromosomal abnormalities. Autosomal abnormalities included partial monosomy (5 cases), reciprocal translocation (one case), 13/14 robertsonian translocation (3 cases), unbalanced translocation (one case), inverted duplication of 15q (one case) and mosaic trisomy 21 (one case). Sex chromosomal abnormalities comprised structural rearrangement of the short arm of the X chromosome (one case) and 47, XXY in a pure or mosaic form (two cases). It should be noted that four out of the 5 cases of partial monosomy had subtle interstitial deletions, which might have been unidentified by the conventional G-banding method alone. In one case of the robertsonian translocation 46,XY,t(13;14)/45,XY,t(13;14), a small deletion was thought to have occurred in the cells with a chromosome number of 45. Comparison of clinical features of the 15 chromosomally abnormal patients with those of patients with normal karyotypes did not show any clinical parameter indicative of chromosome imbalance. These results suggest that a subtle chromosomal deletion is specific to mental retardation associated with few malformations. We believe that diagnostic evaluation of mentally retarded patients, even if nonmalformed, should include chromosome analysis using a high resolution banding technique.     

Situation of the envenomations by snakebites in Congo-Brazzaville: epidemiological, clinical and therapeutic approaches

A retrospective study was carried out in six areas of Congo and in the town of Brazzaville for the period between 2000 and 2004 in order to evaluate the incidence, lethality, treatments and the used drugs in cases of snakebites. We associated a retrospective survey using health centre registers (11 centres) and a retrospective survey based on the staff statements of village communities (42) and private pharmacies and drug centrals. The questionnaire related to the snakebites (identification of victims, place of bite, symptoms and treatment) was used in communities. The total case fatality rate was relatively low (3,11%). The incidence of the estimated snakebites was higher in villages (221) than in health centres (165). But, lethality was equal in the two study clusters (6 cases versus 6 cases). There was no difference of cases rate between male and female subjects. Around urban areas, many victims consulted health centre and in rural area, many victims resorted systematically to traditional practitioners. In drug centrals and private pharmacies of Brazzaville, drugs against envenomations were proposed, respectively, by one and two structures. In health centres these drugs were not available. This evaluation could be underestimated as many victims consulted traditional practitioners. This explains why collecting data from health centre registers is not sufficient to evaluate the importance of envenomations in our study area.     

骨重建失衡导致骨质疏松发生的作用机制及其药物治疗策略

背景:目前骨重建失衡被认为是造成骨质疏松的关键因素,如在骨质疏松发生过程中干预重建失衡,则可一定程度逆转骨质疏松状态并改善预后。破骨抑制和成骨诱导性药物则是针对此致病机制的靶点药物。因此综述性回顾骨质疏松的骨重建失衡机制对于骨质疏松药物治疗具有指导意义,破骨抑制和成骨诱导性药物的临床应用现状和治疗效果也急需进行系统性总结,以起到临床用药指导的作用。目的:综述骨质疏松的骨重建失衡发生机制,并总结破骨抑制药物和成骨诱导药物针对骨重建失衡的调节作用机制,对比2种药物的临床作用效果,为骨质疏松的药物治疗选择进行指导。方法:检索PubMed、WebofScience、中国知网数据库建库至2020年2月发表的相关文献,英文检索词为"osteoporosis,bone remodeling,antiresorptive,anabolic,bisphosphonate,RANKL inhibitor,PTH analogue,anti-sclerostin antibody",中文检索词为"骨质疏松,骨重建,破骨抑制,成骨诱导,双膦酸盐,RANKL抑制剂,甲状旁腺素类似物,抗硬化素抗体"。共检索到相关文献144篇,按照纳入与排除标准,最终纳入84篇文献进行总结。结果与结论:①骨质破坏发生后,可引起机体发生骨重塑,而骨重塑则会导致可逆性非可逆性两种类型的骨缺失发生;②可逆性骨缺失约历时3个月,依次经历骨吸收、骨重填和新骨矿化过程,修复后的骨量和骨质均优;③而不可逆性骨缺失则存在破骨-成骨失衡,虽然也有一定的新骨形成,但新生的骨质较差,易再次发生骨结构破坏;④双膦酸盐、RANKL抑制性抗体属于破骨抑制药物,其作用机制为减慢骨重建速率以减少逆转期骨吸收量,但新生骨量和质量也会相应减少;⑤而特里帕肽、甲状旁腺素类似物等成骨诱导类药物则利于缺损骨质修复,完善破坏的哈弗氏管系统结构,使得新生骨质获得优良的力学强度。     

Place of surgery in the prevention of recurrences of digestive haemorrhages at the patients presenting a portal hypertension due to Schistosoma mekongi

In spite of a decrease of the prevalence of hepato-splenic schistosomiasis thanks to mass-treatment with Praziquentel from December 1994 till now (CNM - MSF - WHO - Health Provincial Director) of target-populations in Kratie Province, severe cases of portal hypertension are not exceptional (digestive bleedings, after rupture of oesophageal varices). Out of 106 cases of portal hypertension: alI patients have had clinical survey biological tests (liver function, haematology and serology). Most of them had ultrasonography (Aloka 55,500 Sound 3.5 MHz). Nearly half of the group of 153 patients has never had bleedings. More than 45 were not eligible for surgery for different reasons: severe anaemia (few possibilities for massive transfusion in Cambodia), serology (S. mekongi) + but also hepatitis B or C +, hepatic biological exams (hepatic insufficiency). So we decided for eleven of them to use a surgical decompression procedure in order to decrease portal hypertension and the porto-systemic gradient. After defining portal hypertension, specific clinical features of portal hypertension (secondary to Schistosomiasis) the authors report eleven cases who were operated on (2000-2002): 4 mesenterico-cave shunt with interposition of a graft (Drapanas' procedure), 1 operation of HASSAB (after splenectomy), 6 proximal spleno-renal diversion (after splenectomy). After studying the results of the eleven patients, discussion with other surgical procedures, particularly endoscopic procedures is developed. The follow-up of these patients during at least five years is mandatory to give guidelines for post-systemic shunts to prevent rebleeding (near other methods). Treated too late, schistosomiasis has no benefit from drugs (Praziquentel). After a mean period of forty two months, the following results are: mortality: one case (10 days after operation): hepatic insufficiency (group Child B/C). morbidity: one occlusion of the small intestine, after 4 months (debridment), operated at the Provincial hospital of Kratie (case no1). Ten patients resume work, family and social life between Kratie and Sambor in 2002. No rebleeding. No encephalopathy.     

Comparative study of the sorption of clomipramine and viloxazine hydrochlorides in Stedim 6 and PVC bags

The stability of two antidepressant drugs, clomipramine and viloxazine hydrochlorides, was studied as was their possible sorption on Stedim 6, a new multilayer polyethylene-lined film, which was considered comparatively to polyvinyl chloride (PVC) and glass surfaces. Appropriate amounts of the drugs were added to 500 ml of 5% dextrose and 0.9% sodium chloride solutions in Stedim 6 and PVC bags, and in glass flasks, in order to obtain the concentrations currently used in clinical practice. All the containers were stored at room temperature in daylight for 72 hours. Samples were taken at various times and evaluated for remaining drug concentrations by UV spectrometry. The two drugs appeared stable under the given conditions. No concentration decrease was observed in glass flasks. Viloxazine hydrochloride showed an excellent compatibility with the PVC bags, but a slight concentration decrease (about 6-7% in 72 hours) was observed for clomipramine hydrochloride, depending on the contact duration. The compatibility of the two drugs with the new material Stedim 6 was found to be perfect. The behavioral differences observed between the two drugs with regard to PVC are explained in terms of differences of lipophilicity of the drugs. Those observed for a given drug with regard to the two materials are due to the crystalline structure of polyethylene and the amorphous one of PVC.     

The temporal dynamics of two response-focused forms of emotion regulation: experiential, expressive, and autonomic consequences

This study examines the early affective consequences of two close forms of suppression. Participants (N=37) were shown negative, positive, and neutral pictures and cued either to attend to the pictures, or to perform expressive or physiological suppression (i.e., reduce body reactions). Continuous measures of experience, expressivity, and autonomic responses showed that both suppression strategies produced rapid response modulation. Common effects of the two strategies included a transient increase in negative feeling, a durable decrease in positive feeling, and a decrease in expressivity, cardiovascular activity, and oxygenation. The two strategies were significantly different only in response to positive stimuli, with physiological suppression showing a larger decrease in experience intensity and blood pressure. These results suggest a strong overlap between the two suppression strategies in terms of their early impact on emotional responses.     

Effect of some physiologically important drugs on the skin impedance

The impedance of rabbit skin has been measured in the frequency range 1–60 kHz using a simple a.c. bridge method and stainless steel electrodes. The effect of four important drugs, namely, adrenaline, noradrenaline, atropine and histamine, has been examined. It was found that all these drugs produced a decrease in the skin impedance in varying degrees, suggesting a penetration of the ions through the underlying layers of the skin. For the purpose of analysis, all these data are compared with their own controls. The order of applying the two drugs adrenaline and noradrenaline at the same site on the skin of an animal does not produce a change in the nature of the relative impedance variation. It was observed that the effect produced by noradrenaline is more pronounced than that by adrenaline. The effect produced by these drugs was compared with that produced by pure hydration of the skin. It was found that the change produced in the latter case is much less than that produced by drugs, thus showing a clear difference between the two effects.     

Immune thrombocytopenia in Hodgkin's disease

Thrombocytopenic purpura of the idiopathic thrombocytopenic purpura (ITP) type is an unusual and poorly documented complication of Hodgkin's disease. In an eight year period, three patients out of 140 with Hodgkin's disease developed thrombocytopenia; two of them presented a clinical picture undistinguishable from classic ITP. In both platelet antibody could be demonstrated. The third patient developed thrombocytopenia during an acute exacerbation of the underlying disease. Successful therapy of thrombocytopenia was achieved by methylprednisolone alone in one case and by cyclophosphamide in combination with methylprednisolone in the other two cases. These case reports demonstrate again that thrombocytopenia in Hodgkin's disease take place in active phases as well as in periods of complete remission; in the latter thrombocytopenia may reflect a part of immunological imbalance closely related to the pathophysiological background of Hodgkin's disease.     

阿立哌唑与利培酮治疗精神分裂症疗效比较

目的比较阿立哌唑与利培酮治疗精神分裂症的疗效。方法将我院2012年10月-2013年6月收治的40例精神分裂症患者按随机数字表法随机分为阿立哌唑组和利培酮组各20例,分别使用阿立哌唑和利培酮对两组患者进行治疗,将两组治疗效果按照CCMD-3精神分裂症的诊断标准进行评价,依据副反应量表(TESS)评定副反应,以阳性与阴性症状量表(PANSS)减分率对疗效进行评定。结果阿立哌唑组痊愈9例,7例显著好转,3例好转,1例无效;利培酮组痊愈10例,5例显著好转,3例好转,2例无效。两组间的疗效比较无显著性差异。阿立哌唑组5例出现不良反应,占25%;利培酮组出现不良反应的有12例,占60%,阿立哌唑组不良反应总发生率显著低于利培酮组(χ2=5.013,P0.05)。结论阿立哌唑与利培酮治疗精神分裂症的疗效显著,在治疗过程中,两种药物各有千秋,但在不良反应发生率方面,阿立哌唑低于利培酮,阿立哌唑的安全性高于利培酮。