1,720,965 research outputs found
Molecular Logic of Spinocerebellar Tract Neuron Diversity and Connectivity
Get PDFCoordinated motor behaviors depend on feedback communication between peripheral sensory systems and central circuits in the brain and spinal cord. Relay of muscle- and tendon-derived sensory information to the CNS is facilitated by functionally and anatomically diverse groups of spinocerebellar tract neurons (SCTNs), but the molecular logic by which SCTN diversity and connectivity is achieved is poorly understood. We used single-cell RNA sequencing and genetic manipulations to define the mechanisms governing the molecular profile and organization of SCTN subtypes. We found that SCTNs relaying proprioceptive sensory information from limb and axial muscles are generated through segmentally restricted actions of specific Hox genes. Loss of Hox function disrupts SCTN-subtype-specific transcriptional programs, leading to defects in the connections between proprioceptive sensory neurons, SCTNs, and the cerebellum. These results indicate that Hox-dependent genetic programs play essential roles in the assembly of neural circuits necessary for communication between the brain and spinal cord. © 2019 The Author(s)Baek et al. show that Hox-transcription-factor-dependent programs govern the specification and connectivity of spinal interneurons that relay muscle-derived sensory information to the cerebellum. These findings shed light on the development of neural circuits required for proprioception—the perception of body position. © 2019 The Author(s)1
Investigating Whole Brain Activation Patterns During Complex Movement Sequences
Get PDFVoluntary planning and execution of motor sequences rely not just on one brain area but on a distributed motor circuit. This brain-wide network includes both cortical and subcortical regions such as the supplementary motor area (SMA), basal ganglia, and the primary motor cortex (M1). Activity in each of these regions has proven necessary to both motor initiation and execution in both mice and monkeys. Still, technological limits have constrained the ability of previous experiments to simultaneously record activity from multiple brain areas, preventing the extension of these findings to ethologically relevant sequences. As a result of these limitations, prior work has resorted to either simplified movement sequences, such as finger tapping, or highly localized recordings from neural subpopulations. Here, we utilized a novel fMRI recording approach to acquire whole-brain images during a reach-to-grasp task. Using this technique, we were able to acquire motor network activity during both self-initiated and externally cued movement sequences, allowing for the appreciation of unique network signatures associated with either paradigm. These findings both demonstrate the validity of our fMRI method in eliminating movement artifact and shed light on the network dynamics necessary for self-initiated movement generation.Bachelor of Scienc
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
Mapping and modulating whole-brain motor circuits using ultrasound
Get PDFThe primary motor cortex (M1) plays a critical role in motor control in mice. However, our previous work has shown that mice are still able to perform a reach-grab-eat motor task even when M1 is optogenetically inhibited. We hypothesize that, during M1 inhibition, mice engage compensatory neural circuits to successfully complete the task. To investigate this, we used functional ultrasound (fUS) to map whole-brain activity during the motor task and used transcranial focused ultrasound (tFUS) to noninvasively suppress M1 activity, providing a more translationally relevant approach for neural modulation.
In this study, we present the first protocol for mapping and modulating whole-brain motor circuits in awake, head-fixed mice using fUS and tFUS. We compare two headpost materials - Clear Resin V4 and TPX polymethylpentene - to optimize whole-brain imaging quality. Using fUS, we measured cerebral blood volume (CBV) during resting-state scans (when the mouse was awake but not engaged in the task) and during the reach-grab-eat task, providing insights into whole-brain activity patterns associated with motor execution. Additionally, we applied tFUS to reduce CBV and modulate M1 activity during the task, aiming to impair motor performance by reducing dexterity, accuracy, and the overall ability to successfully complete the reach task.
We found that TPX polymethylpentene provided the best imaging quality, making fUS suitable for whole-brain imaging in awake, head-fixed mice. We observed a correlation between CBV and reach-related activity, and while neuromodulation effects on motor performance were noted, further studies are needed to assess their significance. These findings have clinical implications for understanding compensatory neural mechanisms and functional recovery in patients recovering from stroke or other neurological disorders affecting limb movement.Bachelor of Scienc
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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