Movement Coordination or Movement Interference: Visual Tracking and Spontaneous Coordination Modulate Rhythmic Movement Interference

When an actor performs a rhythmic limb movement while observing a spatially incongruent movement he or she exhibits increased movement orthogonal to the instructed motion. Known as rhythmic movement interference, this phenomenon has been interpreted as a motor contagion effect, whereby observing the incongruent movement interferes with the intended movement and results in a motor production error. Here we test the hypothesis that rhythmic movement interference is an emergent property of rhythmic coordination. Participants performed rhythmic limb movements at a self-selected tempo while observing a computer stimulus moving in a congruent or incongruent manner. The degree to which participants visually tracked the stimulus was manipulated to influence whether participants became spontaneously entrained to the stimulus or not. Consistent with the rhythmic coordination hypothesis, participants only exhibited the rhythmic movement interference effect when they became spontaneously entrained to the incongruent stimulus.     

Microstructural Analysis of the Perception of form and Stroboscope Movement

The problem of analytical units for the visual image has been discussed for a long time. The classic dichotomies sensation/perception and figure/ground are no longer used by most investigators. It seems natural to take as analytical units the qualitatively and functionally different aspects of the visual image, such as color, space, movement, and form. Just as separate aspects of complex motor acts are provided by different levels of the structure of movement (1), so the real categories of perception, once identified, can be viewed as the result of the processing of information at different levels of the structure of the image. Actual recognition of this can be seen in the extensive individualization of the subdivisions of the psychology of perception that study the mechanisms of color vision or, for example, the metrics of visual space.     

运动对时距知觉的影响及其神经机制

在运动过程中,时距知觉的能力非常重要,能帮助个体对时长进行判断及对事件的发生做出预测和准备.近年来,越来越多的研究发现运动本身会直接影响个体的时距知觉.本文分别从运动参数、运动阶段、视觉运动刺激和运动有关的个体因素四个方面梳理了运动对时距知觉产生影响的行为学证据.目前已经有大量研究从不同角度证明,大脑运动系统组成了支持...     

Blood and Spleen Response to Isolation and Cold Stress in Little Brown Bats,Myotis lucifugus

Female bats were housed singly or in groups and maintained at 5° or 23 °C. Red blood cell life spans were determined utilizing the disappearance of labeled sodium chromate (Cr⁵¹). Red cell counts, hematocrits, reticulocyte percentages and diameters, white cell differentials, and spleen histology were determined for bats subjected to three weeks of stress treatment. Isolated animals (warm and cold) had significantly lower hematocrits and red cell counts and significantly higher reticulocyte diameters and percentages than grouped bats. Random destruction of erythrocytes was initially higher in isolated bats. In cold and isolated animals the white pulp of the spleen was most reduced in quantity and in proliferative activity. Red pulp became highly engorged with erythrocytes and showed a hypertrophy of reticuloendothelial elements. Higher rates of random destruction are closely correlated with increased splenic erythrophagocytosis. Gold or isolation imposed separately are mild stress factors in little brown bats, while a severe stress response occurs when the two stressors are imposed simultaneously.     

Independent Losses of Visual Perception Genes Gja10 and Rbp3 in Echolocating Bats (Order: Chiroptera)

A trade-off between the sensory modalities of vision and hearing is likely to have occurred in echolocating bats as the sophisticated mechanism of laryngeal echolocation requires considerable neural processing and has reduced the reliance of echolocating bats on vision for perceiving the environment. If such a trade-off exists, it is reasonable to hypothesize that some genes involved in visual function may have undergone relaxed selection or even functional loss in echolocating bats. The Gap junction protein, alpha 10 (Gja10, encoded by Gja10 gene) is expressed abundantly in mammal retinal horizontal cells and plays an important role in horizontal cell coupling. The interphotoreceptor retinoid-binding protein (Irbp, encoded by the Rbp3 gene) is mainly expressed in interphotoreceptor matrix and is known to be critical for normal functioning of the visual cycle. We sequenced Gja10 and Rbp3 genes in a taxonomically wide range of bats with divergent auditory characteristics (35 and 18 species for Gja10 and Rbp3, respectively). Both genes have became pseudogenes in species from the families Hipposideridae and Rhinolophidae that emit constant frequency echolocation calls with Doppler shift compensation at high-duty-cycles (the most sophisticated form of biosonar known), and in some bat species that emit echolocation calls at low-duty-cycles. Our study thus provides further evidence for the hypothesis that a trade-off occurs at the genetic level between vision and echolocation in bats.     

植物水分胁迫信号识别与转导

植物对水分胁迫信号作出反应,需要经过信号的识别,转导和胞间信使传递等过程,该文从胁迫感觉,第二信使系统及蛋白质可逆磷酸化等方面,介绍了植物细胞对水分胁迫（原初 ）信号和胁迫信号分子（脱落酸）识别转导的研究进展。     

Involvement of Ethylene in Picloram-induced Leaf Movement Response

The relationship of root-applied 4-amino-3,5,6-trichloropicolinic acid (picloram) to ethylene production and the leaf movement response in honey mesquite (Prosopis juliflora [Swartz] DC. var. glandulosa [Torr.] Cockerell) and huisache (Acacia farnesiana [L.] Willd.) was studied in detail. The threshold and saturation levels of exogenous ethylene and root-applied picloram necessary to inhibit leaf movement were determined. Internal levels of ethylene in excess of those necessary to saturate the leaf movement inhibition response occurred in tops of treated plants before and after symptom expression. These internal levels of ethylene, while averages for the entire plant tops, probably occur at the specific site of action and thus account for the action of picloram in inhibition of leaf movement and related responses. Quantitative differences in the leaf movement response of both species to picloram and ethylene were observed. In huisache alone, a very small change in ethylene levels was necessary to produce a major blockage of the leaf movement response, suggesting that the gas may have a natural function in that species.     

The Effect of Expertise on Eye Movement Behaviour in Medical Image Perception

The present eye-movement study assessed the effect of expertise on eye-movement behaviour during image perception in the medical domain. To this end, radiologists, computed-tomography radiographers and psychology students were exposed to nine volumes of multi-slice, stack-view, axial computed-tomography images from the upper to the lower part of the abdomen with or without abnormality. The images were presented in succession at low, medium or high speed, while the participants had to detect enlarged lymph nodes or other visually more salient abnormalities. The radiologists outperformed both other groups in the detection of enlarged lymph nodes and their eye-movement behaviour also differed from the other groups. Their general strategy was to use saccades of shorter amplitude than the two other participant groups. In the presence of enlarged lymph nodes, they increased the number of fixations on the relevant areas and reverted to even shorter saccades. In volumes containing enlarged lymph nodes, radiologists’ fixation durations were longer in comparison to their fixation durations in volumes without enlarged lymph nodes. More salient abnormalities were detected equally well by radiologists and radiographers, with both groups outperforming psychology students. However, to accomplish this, radiologists actually needed fewer fixations on the relevant areas than the radiographers. On the basis of these results, we argue that expert behaviour is manifested in distinct eye-movement patterns of proactivity, reactivity and suppression, depending on the nature of the task and the presence of abnormalities at any given moment.     

回声定位蝙蝠及其声通讯

综述了回声定位蝙蝠种类及其发声方式,回声定位信号的主要类型及回声定位信号声学特征,多普勒频移对长CF／FM蝙蝠的主要作用,简介了蝙蝠求偶和母婴识别等内声通讯行为,提出了一些尚待解决的重要问题。     

Size Constancy in Bat Biosonar? Perceptual Interaction of Object Aperture and Distance

Perception and encoding of object size is an important feature of sensory systems. In the visual system object size is encoded by the visual angle (visual aperture) on the retina, but the aperture depends on the distance of the object. As object distance is not unambiguously encoded in the visual system, higher computational mechanisms are needed. This phenomenon is termed “size constancy”. It is assumed to reflect an automatic re-scaling of visual aperture with perceived object distance. Recently, it was found that in echolocating bats, the ‘sonar aperture’, i.e., the range of angles from which sound is reflected from an object back to the bat, is unambiguously perceived and neurally encoded. Moreover, it is well known that object distance is accurately perceived and explicitly encoded in bat sonar. Here, we addressed size constancy in bat biosonar, recruiting virtual-object techniques. Bats of the species Phyllostomus discolor learned to discriminate two simple virtual objects that only differed in sonar aperture. Upon successful discrimination, test trials were randomly interspersed using virtual objects that differed in both aperture and distance. It was tested whether the bats spontaneously assigned absolute width information to these objects by combining distance and aperture. The results showed that while the isolated perceptual cues encoding object width, aperture, and distance were all perceptually well resolved by the bats, the animals did not assign absolute width information to the test objects. This lack of sonar size constancy may result from the bats relying on different modalities to extract size information at different distances. Alternatively, it is conceivable that familiarity with a behaviorally relevant, conspicuous object is required for sonar size constancy, as it has been argued for visual size constancy. Based on the current data, it appears that size constancy is not necessarily an essential feature of sonar perception in bats.     

Type I Interferon Response Is Delayed in Human Astrovirus Infections

Type I interferon (IFN) activation and its subsequent effects are important in the response to viral infections. Here we show that human astroviruses (HAstVs), which are important agents of acute gastroenteritis in children, induce a mild and delayed IFN response upon infecting CaCo-2 cells. Although IFN-β mRNA is detected within infected cells and supernatant from infected cells show antiviral activity against the replication of other well-known IFN-sensitive viruses, these responses occur at late stages of infection once genome replication has taken place. On the other hand, HAstV replication can be partially reduced by the addition of exogenous IFN, and inhibition of IFN activation by BX795 enhances viral replication, indicating that HAstVs are IFN-sensitive viruses. Finally, different levels of IFN response were observed in cells infected with different HAstV mutants with changes in the hypervariable region of nsP1a/4, suggesting that nsP1a/4 genotype may potentially have clinical implications due to its correlation with the viral replication phenotype and the antiviral responses induced within infected cells.     

Signaling Organogenesis in Parasitic Angiosperms: Xenognosin Generation, Perception, and Response

Abstract Parasitic strategies within the angiosperms generally succeed by tightly coupling developmental transitions with host recognition signals in a process referred to as xenognosis. Within the Scrophulariaceae, Striga asiatica is among the most studied and best understood parasitic member with respect to the processes of host recognition. Specific xenognosins regulate seed germination, the development of the host attachment organ, the haustorium, and several later stages of host-parasite integration. Here we discuss the signals regulating the development of the haustorium, the critical vegetative/parasitic transition in the life cycle of this obligate parasite. We provide evidence for the localized production of H₂O₂ at the Striga root tip and suggest how this oxidant is used to exploit host peroxidases and cell wall pectins to generate a simple benzoquinone signal. This benzoquinone xenognosin proves to be both necessary and sufficient for haustorial induction in cultured seedlings. Furthermore, evidence is provided that benzoquinone binding to a redox active site completes a ``redox circuit' to mediate signal perception. This redox reaction regulates the time-dependent expression of specific marker genes critical for the development of the mature host attachment organ. These studies extend the emerging series of events necessary for the molecular regulation of organogenesis within the parasitic plants and suggest novel signaling features and molecular mechanisms that may be common across higher plants.     

Individual Differences in the Frequency-Following Response: Relation to Pitch Perception

The scalp-recorded frequency-following response (FFR) is a measure of the auditory nervous system’s representation of periodic sound, and may serve as a marker of training-related enhancements, behavioural deficits, and clinical conditions. However, FFRs of healthy normal subjects show considerable variability that remains unexplained. We investigated whether the FFR representation of the frequency content of a complex tone is related to the perception of the pitch of the fundamental frequency. The strength of the fundamental frequency in the FFR of 39 people with normal hearing was assessed when they listened to complex tones that either included or lacked energy at the fundamental frequency. We found that the strength of the fundamental representation of the missing fundamental tone complex correlated significantly with people''s general tendency to perceive the pitch of the tone as either matching the frequency of the spectral components that were present, or that of the missing fundamental. Although at a group level the fundamental representation in the FFR did not appear to be affected by the presence or absence of energy at the same frequency in the stimulus, the two conditions were statistically distinguishable for some subjects individually, indicating that the neural representation is not linearly dependent on the stimulus content. In a second experiment using a within-subjects paradigm, we showed that subjects can learn to reversibly select between either fundamental or spectral perception, and that this is accompanied both by changes to the fundamental representation in the FFR and to cortical-based gamma activity. These results suggest that both fundamental and spectral representations coexist, and are available for later auditory processing stages, the requirements of which may also influence their relative strength and thus modulate FFR variability. The data also highlight voluntary mode perception as a new paradigm with which to study top-down vs bottom-up mechanisms that support the emerging view of the FFR as the outcome of integrated processing in the entire auditory system.     

Origins of Balance Disorders during a Daily Living Movement in Obese: Can Biomechanical Factors Explain Everything?

Obese people suffer from postural deficits and are more subject to falls than their lean counterpart. To improve prevention and post-fall rehabilitation programs, it seems important to better understand the posturo-kinetic disorders in daily life situations by determining the contribution of some key factors, mainly morphological characteristics and physical activity level, in the apparition of these disorders.Twelve severe android obese and eight healthy non obese adults performed a reaching task mobilizing the whole body. To further determine the origin of the postural and motor behavior differences, non obese individuals also performed an experimental session with additional constraints which simulated some of the obese morphological characteristics. Impact of the sedentary lifestyle was also studied by dissociation of the obese in two subgroups: physically « active » and physically « inactive ». Movement kinetics and kinematics were characterized with an optoelectronic system synchronized to a force platform. The mechanical equilibrium pattern was evaluated through the displacements of the Centre of Mass (CoM) and the centre of foot pressure within the Base of Support (BoS).Results showed that obesity decreased movement speed (≈−23%, p<0.01), strongly increased CoM displacement (≈+30%, p<0.05) and induced an important spatio-temporal desynchronization (≈+40%, p<0.05) of the focal and postural components of the movement during the transition between the descending and ascending movements.The role of some morphological characteristics and of physical activity on obese patients'' postural control disorder is discussed and set back in the more general context of overall factors contributing to postural deficits with obesity.     

Movement of Cicindela hirticollis Say Larvae in Response to Moisture and Flooding

The larvae of the tiger beetle, Cicindela hirticollis Say, inhabit sandy shoreline areas that flood periodically. This species has declined over much of its range and at least one subspecies is near extinction, possibly as a result of human alteration of waterways. In addition to physiological tolerance for anoxia, the larvae have physical and behavioral adaptations to avoid drowning. We hypothesized that C. hirticollis larvae would exhibit behavioral responses to soil moisture change and flooding because, unlike most other tiger beetles, they frequently relocate their burrows. Our laboratory studies demonstrated that larvae select surface soil moisture levels of 7–50% saturation in which to dig new burrows. Within 96 h of immersion, most larvae abandon burrows and larvae do not form new burrows in darkness. Larvae may relocate when flooded, suggesting a previously undocumented mechanism for dispersal; however, dams often eliminate suitable habitat areas downstream, suggesting that this behavior may be detrimental in riverine populations. Because larvae move during daylight hours, they also are likely to suffer mortality from trampling due to human recreational activity.     

Dark Stomatal Movement in Sunflowers in Response to Illumination under Nitrogen

Experiments were performed on intact sunflowers (Helianthus annuus) placed in a specially designed experimental chamber which allows instantaneous modifications of the atmospheric composition without changing any other conditions. After one night in normal conditions, the plant was illuminated under pure nitrogen atmosphere; the opening stomatal movement, measured as a transpiration rate variation, was inhibited. After an anoxia time period not exceeding one hour, the light was turned off and normal air restored. The stomatal movement was no longer inhibited, and a transient increase in the transpiration rate, referred to here as the postillumination transpiration peak (PITP), was observed.     

The Polarity of Movement of Endogenously Produced IAA in Relation to a Gravity Perception Mechanism

The polarity of radioactive IAA transport in segments of theleaf sheath base of Avena fatua L. is reversed upon their inversionthrough 180° transport towards the apex being greater thantowards the base. Changes in rates of transport leading to thisreversal can be detected within 10–20 min, correlatingwith the timing of statolith movements from the base to theapex of statocyte cells and conforming to a proposed model forthe gravity control of auxin transport. Transport of H³-trytophan-derived H³-IAA was found to undergosimilar changes in polarity upon re-orientation as did exogenouslyapplied H³ or C¹⁴ IAA. It is concluded that the proposed modelalso relates to the movement of endogenously produced IAA.