1,720,980 research outputs found
A Neuroplastic Network Underlying Behaviour and Seasonal Change in Lymnaea stagnalis: A Neuroecological Standpoint
No full textThe gastropod mollusc Lymnaea stagnalis (L.) is an advantageous model system for neureothological studies and is a suitable model for studying Neuroecology. Here we describe its well organised nervous system many of whose ganglia have been mapped, both electrophysiologically and morphologically, to characterise individual giant neurons and neuronal clusters. This has allowed us to speculate on the evolution and reorganisation of the brain in relation to torsion and detorsion and to show that many behavioural networks remain virtually intact during these processes, but reflect the evolutionary changes that the nervous system has undergone in adaptation of the animal to its environment.
We also describe the Lymnaea behavioural hierarchy in which the defensive whole body withdrawal reflex takes precedence over all other behaviours, all of which appear to be organised on a multiganglionic basis and underlain by a complex neural network in which several central pattern generators (CPGs) are embedded. The interactions of the CPGs with one another and with a number of wide-acting synaptic inputs are discussed with particular reference to the locomotor and respiratory systems of the animal. Knowledge of these cellular interactions has allowed us to demonstrate seasonal changes within the respiratory CPG (RCPG) of Lymnaea with a loss of connectivity as winter approaches and a restoration of synaptic connectivity and the behavioural programme during the spring.
With its flexible and adaptable behavioural repertoire Lymnaea is well adapted to its freshwater environment. We suggest that it will prove to be a useful and sensitive model for studying the neuroecological effects of climate change with particular respect to invasive freshwater species (IFS) such as predators, freshwater plans or microbial species
Neuroecology and neuroethology in Molluscs The interface between behaviour and environment
No full textThe term neuroecology was first coined in the 1980s and describes the ways in which species adapt to their environment both in the short term and in evolutionary time. Here, we focus on molluscan neuroecology to show how it interfaces with neuroethology and how animal behaviour adapts to environmental cues. neuroecology is thus meeting point between ethology, neuroscience, evolution, ecology, physics and chemistry. In this book, our contributors examine the concept of Neuroecology as applied to molluscs for the first time with particular reference to the areas of chemical ecology, predator prey relationships, neuroethology and evolution.
Significant neuroecological progress has been made with a number of molluscan groups in terms of neurotoxic peptides, complex defensive ink alarm pheromones, bioaccumulation of shellfish toxins and the evolution of chemical defence mechanisms in species with reduced physical protection. Many molluscs inhabit a world of olfactory cues and their perceptions of the outside world are largely chemically driven, leading to odorant driven behavioural responses. This is important to both molluscan predators and prey and this area is explored in some detail with particular reference to gastropod molluscs. It is also true for cephalopod molluscs which although they have excellent vision, rely on distance chemoreception particularly prey perception, thus demonstrating their significance in affecting marine populations and communities. A better understanding the interactions of chemical cues between predator and prey molluscs will be important in future studies in the area of chemical ecology.
Within the immune and neuroendocrine systems of molluscs the primary signalling molecules are exceptionally well-conserved and the pool of molecules used is similar to those in advanced vertebrates. This conservation of molecular systems is important in neuroecology and underlies the conservation of neural mechanisms underlying behaviours as organ systems alter under evolutionary pressure. Indeed, studies on pulmonates have shown that behavioural networks remain virtually intact during these processes, although reflecting the evolutionary changes that adapt the animal to its environment. Such networks exhibit plastic responses to allow for behavioural selection and seasonal change. However, studies on respiratory behaviour lead to the conclusion that many molluscs and other invertebrates are facing extinction because they cannot adapt their respiratory behaviour to the rapidly changing environmental conditions currently occurring particularly where hypoxia threatens the health of ecosysystems due to human activity. Such animals may prove to be sensitive models for studying the neuroecological effects of climate change with particular respect to invasive freshwater species such as predators, freshwater plans or microbial species.
The challenge for the future is to utilise molluscan species research to illuminate the effects of environmental change on the neuroecology of these species, using them wherever possible to evaluate the degree of ecological change taking place. (Imprint: Nova Biomedica
Dose-Dependent Effects of the Clinical Anesthetic Isoflurane onOctopus vulgaris: A Contribution to Cephalopod Welfare
No full textRecent progress in animal welfare legislation relating to invertebrates has provoked interest in methods for the anesthesia of cephalopods, for which different approaches to anesthesia have been tried but in most cases without truly anesthetizing the animals. For example, several workers have used muscle relaxants or hypothermia as forms of “anesthesia.” Several inhalational anesthetics are known to act in a dose-dependent manner on the great pond snail Lymnaea stagnalis, a pulmonate mollusk. Here we report, for the first time, on the effects of clinical doses of the well-known inhalational clinical anesthetic isoflurane on the behavioral responses of the common octopus Octopus vulgaris. In each experiment, isoflurane was equilibrated into a well-aerated seawater bath containing a single adult O. vulgaris. Using a web camera, we recorded each animal’s response to touch stimuli eliciting withdrawal of the arms and siphon and observed changes in the respiratory rate and the chromatophore pattern over time (before, during, and after application of the anesthetic). We found that different animals of the same size responded with similar behavioral changes as the isoflurane concentration was gradually increased. After gradual application of 2% isoflurane for a maximum of 5 min (at which time all the responses indicated deep anesthesia), the animals recovered within 45–60 min in fresh aerated seawater. Based on previous findings in gastropods, we believe that the process of anesthesia induced by isoflurane is similar to that previously observed in Lymnaea. In this study we showed that isoflurane is a good, reversible anesthetic for O. vulgaris, and we developed a method for its use
Bahavioral effects of clinical doses of the general anesthetic isofluorane on Octopus vulgaris
No full textHere, we report, for the first time, on the effects clinical doses of inhalational anesthetic isofluorane on the behavioral responses of Octopus vulgari
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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