1,721,006 research outputs found
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Signatures of cortical multisensory integration in mice performing a novel visuotactile evidence accumulation task
No full textMuch effort has been focused on studying how the brain processes information from our individual senses. However, the neural mechanisms, that allow the effortless integration of unisensory inputs into multisensory percepts, are largely unknown. To study how neural circuits integrate visual and tactile information, we developed a multisensory discrimination task for head-fixed mice. Here, two sequences of visual, tactile or combined visuotactile stimuli are presented on both sides of the mouse, which has to indicate the higher-rate target-side to obtain a water reward. To ensure integration of sensory information over the entire stimulus period, a short delay was added before the response. Mice achieved high accuracy in all conditions, with improved performance in the multisensory condition. This behavioral task gave us the opportunity to investigate the neural circuits that allow mice to synergistically use both the visual and tactile sensory information to solve the behavioral task. We then used widefield imaging to measure cortex-wide activity in transgenic mice expressing the Ca2+-indicator GCaMP6s in all cortical excitatory neurons. Here, we found that multisensory stimuli evoked higher neuronal activity compared to unisensory stimulation. This was most evident in the rostrolateral association area RL and parts of medial frontal cortex (mFC), which reliably responded to both visual and tactile stimuli. To better isolate sensory responses from co-occurring task- or behavior-related activity, we used a linear encoding model. Including a multisensory interaction-term significantly improved the predictions of cortical activity. With this approach we identified two key features of sensory evoked responses, depending on the stimulus condition. First, in unisensory trials mice display cross-modal inhibition. Here, in addition to the main sensory responses in the corresponding sensory cortex, robust inhibition of activity in the non-matching sensory cortex was found. Second, we found additional superadditive responses in multisensory trials, likely representing the absence of cross-modal inhibition as well as increased activity in areas RL and mFC. To understand how sensory information is used to guide behavioral decisions, we first investigated which brain areas displayed activity that reliably reflected the target stimulus side. Here, the medial motor cortex more faithfully reflected the target-side in tactile trials, while secondary visual areas were more reliable in visual trials. In multisensory trials, both regions accurately reflected the target-side, likely resulting in higher certainty and improved performance in multisensory trials. Finally, using a choice-decoder we identified choice-related neural activity in the anterolateral motor cortex (ALM), as well as in licking-related regions of the primary motor and somatosensory cortex. With this approach, we found no clear modality-specific differences, suggesting that the same neural circuits form decisions in all stimulus conditions. Our results demonstrate that multisensory stimulation cause widespread cortical activation in mice, which leads to improved task performance. Here, cross-modal inhibition in unisensory trials and superadditive multisensory integration especially in RL and mFC were found in multisensory trials, likely aiding mice in performing the individual task condition. Sensory information is then accumulated over the stimulus period in secondary visual areas and medial motor cortex and this information converges in the secondary motor cortex to form modality-unspecific decisions. These findings give us a much deeper understanding of how the brain processes and generalizes sensory information in order to guide behavioral decisions
Projection-specific information coding in frontal cortical networks
No full textLearning to make decisions is a fundamental cognitive process that animals use to adapt their behaviour to the surrounding environment. System neuroscience has achieved great progress in studying how animals learn task rules via the use of sophisticated decision-making tasks. These tasks are used in combination with physiological recordings of neuronal activity in order to understand the neural underpinnings of sensory information, motor planning, and cognitive flexibility, which depend on a distributed network of brain regions. The frontal cortex, along with subcortical structures, such as the basal ganglia and the thalamus, play critical roles in attention, sensory processing, action selection, habit formation, and working memory. Closely following the activity of interconnected brain regions involved in decision making is crucial to understand how decisions are learned upon different environmental requests. The anterior lateral motor cortex (ALM) integrates sensory information to drive behavior, relying on long-range projections to subcortical regions, particularly the striatum, which receives strong inputs from cortico-striatal (CStr) neurons. This specific pathway has been thought to be critical for forming new sensorimotor associations during learning, but its precise role remains unclear.To investigate this, we anatomically mapped ALM terminals in the striatum and found a conserved anteroposterior gradient across ipsilateral and contralateral projections. We then trained mice in tasks of increasing cognitive demand. First, mice underwent an innate behavior, collecting a reward from two available water spouts, requiring no novel stimulus-response associations. Second, mice learned to associate the location of click sounds to the side of a water reward (task learning). After achieving expert performance, mice had to additionally retain their choice for a short delay period (task expert). After the auditory tasks, the innate task was repeated. Optogenetic inhibition of ALM and CStr neurons during these tasks revealed that CStr activity was most influential early in training and during the auditory task but not in the second innate task.To track learning-related changes, we retrogradely labeled CStr neurons and performed functional two-photon imaging of all excitatory neurons in the superficial layers of the ALM. Choice selectivity increased across all ALM neurons during the auditory task and remained stable in the expert phase, indicating a restructuring of choice-related circuits. However, no clear activity differences emerged between CStr and non-CStr neurons. Since CStr neurons are located in both superficial and deep layers, we decided to directly measure ALM output signal using fiber photometry to record axonal signals in the striatum. Trial averages of both CStr and motion energy activities revealed strong learning-related increases in both neural and motor activity. A generalized linear model (GLM) further isolated task-related signals, showing heightened ALM axonal activity during stimulus and choice periods, supporting the role of CStr neurons in sensorimotor association and choice formation.To confirm this, we used eOPN3-mediated synaptic silencing to inactivate ALM projections to the striatum. The inhibition significantly impaired task performance early in training, in the first innate task and during the learning of the auditory task. We next explored whether other projection pathways became more relevant later in learning. At first we used a triple retrograde approach to study the proportion of divergent projections to one or multiple target regions for each subpopulation of projecting neurons. Then, we used fiber photometry to record signals from ALM terminals in SC and thalamus and showed increased pre-stimulus inactivation, implicating these pathways in attention-driven sensorimotor associations. Furthermore, their synaptic inhibition confirmed their increasing relevance in the expert stage of training. Finally, optogenetic inhibition of the striatum reduced behavioral performance across all tasks and increased the number of missed trials, highlighting the central role in motor response execution of this region.Overall, our findings reveal that task learning induces long-lasting changes in ALM choice-related circuitry, with distinct subcortical pathways playing specialized roles in behavior acquisition and execution. In particular, we found a switch in the importance of subcortical projection pathways where CStr projections appear to be most important during early learning while other subcortical projection pathways increase their importance during expert performance
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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