1,721,010 research outputs found
Sleep and metabolism: shared circuits, new connections.
No full textAssociation between sleep disturbances and hormonal imbalances can result in metabolic disorders, including obesity and diabetes. The hypothalamus is likely to play a part in these pathophysiological conditions because it contains sleep-wake circuits that are sensitive to metabolic hormones, including leptin and ghrelin. Thus, shared hypothalamic circuits such as the hypocretin and melanin-concentrating hormone systems are strong candidates for mediating both sleep and metabolic imbalances. This review reveals new roles for these systems as sensors and effectors of sleep and wakefulness, and discusses their plasticity in regulating sleep and energy balance. New optical tools that remotely control neuronal circuit activity provide an effective means to understand the cooperativity of shared circuits in regulating hypothalamic functions such as sleep and metabolism
A role for Melanin-Concentrating Hormone in learning and memory.
No full textThe neurobiological substrate of learning process and persistent memory storage involves multiple brain areas. The neocortex and hippocampal formation are known as processing and storage sites for explicit memory, whereas the striatum, amygdala, neocortex and cerebellum support implicit memory. Synaptic plasticity, long-term changes in synaptic transmission efficacy and transient recruitment of intracellular signaling pathways in these brain areas have been proposed as possible mechanisms underlying short- and long-term memory retention. In addition to the classical neurotransmitters (glutamate, GABA), experimental evidence supports a role for neuropeptides in modulating memory processes. This review focuses on the role of the Melanin-Concentrating Hormone (MCH) and receptors on memory formation in animal studies. Possible mechanisms may involve direct MCH modulation of neural circuit activity that support memory storage and cognitive functions, as well as indirect effect on arousal
The hypocretins as sensors for metabolism and arousal.
No full textSleep disturbances are associated with hormonal imbalances and may result in metabolic disorders including obesity and diabetes. Therefore, circuits controlling both sleep and metabolism are likely to play a role in these physiopathological conditions. The hypocretin (Hcrt) system is a strong candidate for mediating both sleep and metabolic imbalances because Hcrt neurons are sensitive to metabolic hormones, including leptin and ghrelin, and modulate arousal and goal-orientated behaviours. This review discusses the role of Hcrt neurons as a sensors of energy balance and arousal and proposes new ways of probing local hypothalamic circuits regulating sleep and metabolism with unprecedented cellular specificity and temporal resolution
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Optogenetics: opsins and optical interfaces in neuroscience.
No full textOptogenetics is defined as the integration of optics and genetics to control well-defined events within specified cells of living tissue. In this introduction, we focus on the basic techniques necessary for employing microbial opsins as optogenetic tools in mammalian brains. We provide a guide for the fundamentals of optogenetic application-selecting an opsin, implementing expression of opsins based on the neuroscientific experimental requirements, and adapting the corresponding optical hardware for delivery of light into mammalian brains
Variations on the Author
Full text link“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
Full text linkWe 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
Establishing a fiber-optic-based optical neural interface.
No full textSelective expression of opsins in genetically defined neurons makes it possible to control a subset of neurons without affecting nearby cells and processes in the intact brain, but light must still be delivered to the target brain structure. Light scattering limits the delivery of light from the surface of the brain. For this reason, we have developed a fiber-optic-based optical neural interface (ONI), which allows optical access to any brain structure in freely moving mammals. The ONI system is constructed by modifying the small animal cannula system from PlasticsOne. The system for bilateral stimulation consists of a bilateral cannula guide that has been stereotactically implanted over the target brain region, a screw cap for securing the optical fiber to the animal's head, a fiber guard modified from the internal cannula adapter, and a bare fiber whose length is customized based on the depth of the target region. For unilateral stimulation, a single-fiber system can be constructed using unilateral cannula parts from PlasticsOne. We describe here the preparation of the bilateral ONI system and its use in optical stimulation of the mouse or rat brain. Delivery of opsin-expressing virus and implantation of the ONI may be conducted in the same surgical session; alternatively, with a transgenic animal no opsin virus is delivered during the surgery. Similar procedures are useful for deep or superficial injections (even for neocortical targets, although in some cases surface light-emitting diodes or cortex-apposed fibers can be used for the most superficial cortical targets)
Shining light on wakefulness and arousal.
No full textAlterations in arousal states are associated with multiple neuropsychiatric disorders, including generalized anxiety disorders, addiction, schizophrenia, and depression. Therefore, elucidating the neurobiological mechanisms controlling the boundaries between arousal, hyperarousal, and hypoarousal is a crucial endeavor in biological psychiatry. Substantial research over several decades has identified distinct arousal-promoting neural populations in the brain; however, how these nuclei act individually and collectively to promote and maintain wakefulness and various arousal states is unknown. We have recently applied optogenetic technology to the repertoire of techniques used to study arousal. Here, we discuss the recent results of these experiments and propose future use of this approach as a way to understand the complex dynamics of neural circuits controlling arousal and arousal-related behaviors
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