The luminal connection: From animal development to lumopathies

Interconnection of epithelial tubules is a crucial process during organogenesis. Organisms have evolved sets of molecular and cellular strategies to generate an interconnected tubular network during animal development. Spatiotemporal control of common cellular strategies includes dissolution of the basement membrane, apoptosis, rearrangements of cell adhesion junctions, and mesenchymal-like invasive cellular behaviors prior to tubular interconnection. Different model systems exhibit varying degrees of active invasive-like behaviors that precede tubular interconnection, which may reflect changes in cell polarity or differential adhesive cell states. Studies in this newly-emerging field of tubular interconnections will provide a greater understanding of pediatric diseases and cancer metastasis, as well as generate fundamentally new insights into lumen formation pathology, or lumopathies.     

Whole-cell recordings in freely moving rats

Intracellular recording, which allows direct measurement of the membrane potential and currents of individual neurons, requires a very mechanically stable preparation and has thus been limited to in vitro and head-immobilized in vivo experiments. This restriction constitutes a major obstacle for linking cellular and synaptic physiology with animal behavior. To overcome this limitation we have developed a method for performing whole-cell recordings in freely moving rats. We constructed a miniature head-mountable recording device, with mechanical stabilization achieved by anchoring the recording pipette rigidly in place after the whole-cell configuration is established. We obtain long-duration recordings (mean of approximately 20 min, maximum 60 min) in freely moving animals that are remarkably insensitive to mechanical disturbances, then reconstruct the anatomy of the recorded cells. This head-anchored whole-cell recording technique will enable a wide range of new studies involving detailed measurement and manipulation of the physiological properties of identified cells during natural behaviors.     

Dense and sparse aggregations in complex motion: Video coupled with simulation modeling

Investigations into the complex behaviors of aggregations of highly mobile animals have not used the link between image processing technology and simulation modeling fruitfully to address many fundamental ecological issues. Examples include population censusing, which remains difficult despite the demonstrated ecological importance of assessing abundance and density of organisms. We introduce a theoretical framework that connects thermal infrared video imaging with an individual-based simulation model—an approach that appears to be applicable to a diverse set of aggregated, highly mobile, nocturnal animals. To demonstrate the framework two applications are presented. The first is a dense aggregation of Brazilian free-tailed bats (Tadarida brasiliensis) that exhibits an emergence pattern that has complex dynamics and the second is a sparse local aggregation of agricultural pest moths whose dynamics are insipid. The first application uses individual-based modeling to mimic the behavior in the video of bats during a nightly emergence from a cave and to provide reliable estimates of the numbers, and associated error bounds. The second application uses video recordings of sparse aggregations to provide consistent estimates of the numbers of flying noctuid moths recorded over a corn and cotton-dominated agroecosystem in south-central Texas. This does not use a mathematical model because error estimates tend to be small.     

Out of thin air: sensory detection of oxygen and carbon dioxide

Oxygen (O?) and carbon dioxide (CO?) levels vary in different environments and locally fluctuate during respiration and photosynthesis. Recent studies in diverse animals have identified sensory neurons that detect these external variations and direct a variety of behaviors. Detection allows animals to stay within a preferred environment as well as identify potential food or dangers. The complexity of sensation is reflected in the fact that neurons compartmentalize detection into increases, decreases, and short-range and long-range cues. Animals also adjust their responses to these prevalent signals in the context of other cues, allowing for flexible behaviors. In general, the molecular mechanisms for detection suggest that sensory neurons adopted ancient strategies for cellular detection and coupled them to brain activity and behavior. This review highlights the multiple strategies that animals use to extract information about their environment from variations in O? and CO?.     

Functional imaging in freely moving animals

Uncovering the relationships between animal behavior and cellular activity in the brain has been one of the key aims of neuroscience research for decades, and still remains so. Electrophysiological approaches have enabled sparse sampling from electrically excitable cells in freely moving animals that has led to the identification of important phenomena such as place, grid and head-direction cells. Optical imaging in combination with newly developed labeling approaches now allows minimally invasive and comprehensive sampling from dense networks of electrically and chemically excitable cells such as neurons and glia during self-determined behavior. To achieve this two main imaging avenues have been followed: Optical recordings in head-restrained, mobile animals and miniature microscope-bearing freely moving animals. Here we review progress made toward functional cellular imaging in freely moving rodents, focusing on developments over the past few years. We discuss related challenges and biological applications.     

Neurophysiological recordings in freely moving monkeys

Recordings of neuronal activity in freely moving rats are common in experiments where electrical signals are transmitted using cables. Such techniques are not common in monkeys because their prehensile abilities are thought to preclude such techniques. However, analysis of brain mechanisms underlying spatial navigation and cognition require the subject to walk. We have developed techniques for recordings in freely moving monkeys in two different situations: a 5 x 5 m testing laboratory and in a 50 m2 open field environment. Neuronal signals are sent to amplifiers and data acquisition systems using cables or telemetry. These techniques provide high quality recordings of single neurons during behaviors such as foraging, walking, and the performance of memory tasks and thus provide a unique opportunity to study primate behavior in a semi-natural situation.     

Direct and indirect assessment of gamma-motor firing patterns

The study of the patterns of gamma-motor activity which accompany natural contractions has been long and difficult, and has not as yet led to general agreement. In this review we have simplified matters by considering the case of locomotion in the cat only, and we have avoided discussion of the various hypotheses which have been advanced to provide general schemes of gamma control for a wide range of movements. The development of the subject is shown to depend very much on devising ingenious methods applicable to reduced and intact animals. Direct recording from gamma-motoneurones has only been possible in reduced preparations, whereas indirect assessment of gamma activity from spindle afferent recordings was used in these and in intact animals. At this point in time, we still have no direct recordings from gamma-motoneurones in normally behaving animals, but those obtained in decerebrate animals show distinct patterns of modulation for static and dynamic types with particular temporal relation to the stepping movements. The spindle recordings in intact animals potentially provide the most important information, and the problems of interpretation, which have previously caused difficulties, are beginning to be solved through the insights obtained from the reduced preparations.     

The significance of plant growth-forms as "shelter" for terrestrial animals

Different plant growth-forms such as tussocks and rosettes, were selected as micro ecosystems in an area in which these structures were spatially isolated from each other. These growth forms are important during winter since they serve to regulate temperatures, which is important to invertebrate animals. This was shown with intensive temperature recordings in winter, correlated with numbers of animals. Plant growth-forms are more important in young bare areas where there are fewer plants to provide shelter, than in older areas, where a denser vegetation cover affords more possibilities for shelter. Such differences can be expected to influence the abundance as well as the occurrence of animals during the development of a community.     

Animal-Assisted Therapy Enhances Resident Social Interaction and Initiation in Long-Term Care Facilities

ABSTRACT

Social stimulation is a valuable aspect of therapeutic activities at long-term care facilities, designed to decrease social isolation, maintain or stimulate mental abilities, and increase awareness of the external environment. A study was undertaken at two such facilities to compare the effectiveness of Animal-Assisted Therapy (AAT) with Non-Animal Therapy (NAT) at providing social stimulation, that is, at providing opportunities for patients to engage in social interaction and to initiate social behaviors. While studies have indicated that AAT can improve resident outlook or affect, few have directly studied the social behaviors that might lead to such improvements, or the role the animals themselves might play. We observed 33 patients, both alert and semi- to non-alert, during regular recreational therapy sessions. Most patients were women (29 vs. four men), and geriatric (in their 70's and 80's). Non-Animal Therapies included Arts and Crafts and Snack Bingo, while AAT involved animals from local animal shelters being brought by volunteers to group sessions. Social behaviors naturally divided into Brief Conversations, Long Conversations, and Touch. We determined frequencies and rates of the behaviors, who initiated the behaviors and whether the behaviors were directed at other people or at the animals.

Overall, during AAT residents were involved in as much or more conversation with others, including the animals, as residents in Non-Animal Therapy, and were more likely to initiate and participate in longer conversations. The finding that different kinds of therapies seem to encourage different kinds of conversation might be an important consideration when investigating health benefits. The most dramatic differences between therapy types were found in rates of touch: touching the animals during AAT added significantly to resident engagement in, and initiation of, this behavior. Since touch is considered an important part of social stimulation and therapy, the enhancement of this social behavior by the animals is an important, and perhaps undervalued, effect.     

Invasive recordings from the human brain: clinical insights and beyond

Although non-invasive methods such as functional magnetic resonance imaging, electroencephalograms and magnetoencephalograms provide most of the current data about the human brain, their resolution is insufficient to show physiological processes at the cellular level. Clinical approaches sometimes allow invasive recordings to be taken from the human brain, mainly in patients with epilepsy or with movement disorders, and such recordings can sample neural activity at spatial scales ranging from single cells to distributed cell assemblies. In addition to their clinical relevance, these recordings can provide unique insights into brain functions such as movement control, perception, memory, language and even consciousness.     

Research progress on Drosophila visual cognition in China

Visual cognition,as one of the fundamental aspects of cognitive neuroscience,is generally associated with high-order brain functions in animals and human.Drosophila,as a model organism,shares certain features of visual cognition in common with mammals at the genetic,molecular,cellular,and even higher behavioral levels.From learning and memory to decision making,Drosophila covers a broad spectrum of higher cognitive behaviors beyond what we had expected.Armed with powerful tools of genetic manipulation in Drosophila,an increasing number of studies have been conducted in order to elucidate the neural circuit mechanisms underlying these cognitive behaviors from a genes-brain-behavior perspective.The goal of this review is to integrate the most important studies on visual cognition in Drosophila carried out in mainland China during the last decade into a body of knowledge encompassing both the basic neural operations and circuitry of higher brain function in Drosophila.Here,we consider a series of the higher cognitive behaviors beyond learning and memory,such as visual pattern recognition,feature and context generalization,different feature memory traces,salience-based decision,attention-like behavior,and cross-modal leaning and memory.We discuss the possible general gain-gating mechanism implementing by dopamine-mushroom body circuit in fly's visual cognition.We hope that our brief review on this aspect will inspire further study on visual cognition in flies,or even beyond.     

Mapping behaviorally relevant neural circuits with immediate-early gene expression

Immediate-early genes have gained widespread popularity as activity markers for mapping neuronal circuits involved in specific behaviors in many different species. In situ immediate early gene detection methods provide cellular level resolution, a major benefit for mapping neuronal networks. Recent advances using fluorescence in situ hybridization also afford temporal resolution, enabling within-animal activity maps for two distinct behaviors. Moreover, use of transgenic mice with fluorescent reporter proteins driven by immediate early gene promoters is enabling repeated measurements, over long time scales, of cortical activity within the same animal. These methodological innovations, coupled with recent advances in fluorescence imaging and probe development, will enable large scale mapping of behaviorally relevant circuits with temporal and three-dimensional spatial resolution in experimental animals.     

Lipid polymorphisms and membrane shape

Morphological plasticity of biological membrane is critical for cellular life, as cells need to quickly rearrange their membranes. Yet, these rearrangements are constrained in two ways. First, membrane transformations may not lead to undesirable mixing of, or leakage from, the participating cellular compartments. Second, membrane systems should be metastable at large length scales, ensuring the correct function of the particular organelle and its turnover during cellular division. Lipids, through their ability to exist with many shapes (polymorphism), provide an adequate construction material for cellular membranes. They can self-assemble into shells that are very flexible, albeit hardly stretchable, which allows for their far-reaching morphological and topological behaviors. In this article, we will discuss the importance of lipid polymorphisms in the shaping of membranes and its role in controlling cellular membrane morphology.     

Synthetic cell biology

Synthesis of data into formal models of cellular function is rapidly becoming a necessary industry. The complexity of the interactions among cellular constituents and the quantity of data about these interactions hinders the ability to predict how cells will respond to perturbation and how they can be engineered for industrial or medical purposes. Models provide a systematic framework to describe and analyze these complex systems. In the past few years, models have begun to have an impact on mainstream biology by creating deeper insight into the design rules of cellular signal processing, providing a basis for rational engineering of cells, and for resolving debates about the root causes of certain cellular behaviors. This review covers some of the recent work and challenges in developing these "synthetic cell" models and their growing practical applications.     

Motor inactivity in hibernating frogs: Linking plasticity that stabilizes neuronal function to behavior in the natural environment

All animals must generate reliable neuronal activity to produce adaptive behaviors in an ever‐changing environment. Neural systems are thought to achieve this goal, in part, through cellular and synaptic plasticity mechanisms that stabilize electrophysiological functions. Despite strong evidence for a role in regulating neuronal properties, these plasticity mechanisms have been difficult to link to natural behaviors in animals. In this review, I discuss how animals that inhabit extreme environments can address this challenge. As an example, I highlight recent work from frogs that stop breathing for several months during hibernation and, in response, use classic mechanisms of stabilizing plasticity to support respiratory motor output shortly after emergence. Furthermore, I describe problems for neuronal stability that may benefit from the study of hibernators: how circuits with variable modes of output control stabilizing mechanisms over long time scales and why some neural systems mount robust compensatory responses and others do not. By continuing to appreciate how diverse animal groups overcome challenges in the natural environment, we will broaden our view of the role that plasticity mechanisms play in stabilizing the nervous system.     

Energy conservation characterizes sleep in sharks

Sharks represent the earliest group of jawed vertebrates and as such, they may provide original insight for understanding the evolution of sleep in more derived animals. Unfortunately, beyond a single behavioural investigation, very little is known about sleep in these ancient predators. As such, recordings of physiological indicators of sleep in sharks have never been reported. Reduced energy expenditure arising from sustained restfulness and lowered metabolic rate during sleep have given rise to the hypothesis that sleep plays an important role for energy conservation. To determine whether this idea applies also to sharks, we compared metabolic rates of draughtsboard sharks (Cephaloscyllium isabellum) during periods ostensibly thought to be sleep, along with restful and actively swimming sharks across a 24 h period. We also investigated behaviours that often characterize sleep in other animals, including eye closure and postural recumbency, to establish relationships between physiology and behaviour. Overall, lower metabolic rate and a flat body posture reflect sleep in draughtsboard sharks, whereas eye closure is a poorer indication of sleep. Our results support the idea for the conservation of energy as a function of sleep in these basal vertebrates.     

Cellular processes associated with germ band retraction in Drosophila

Large-scale movements of epithelial sheets are necessary for most embryonic and regenerative morphogenetic events. We have characterized the cellular processes associated with germ band retraction (GBR) in the Drosophila embryo. During GBR, the caudal end of the embryo retracts to its final posterior position. We show using time-lapse recordings that, in contrast to germ band extension, cells within the lateral germ band do not intercalate. In addition, the germ band and amnioserosa move as one coherent sheet, and the amnioserosa strongly shortens along its dorsal-ventral axis. Furthermore, during GBR, the amnioserosa adheres to and migrates over the caudal end of the germ band via lamellipodia. Expression of both dominant-negative and constitutively active RhoA in the amnioserosa disrupts GBR. As RhoA acts on both actomyosin contractility and cell-matrix adhesion, it suggests a role for such processes in the amnioserosa during GBR. The results establish the cellular movements and shape changes occurring during GBR and provide the basis for an analysis of the forces acting during GBR.