1,720,957 research outputs found
Neural activity associated to joint-action during social cooperation in frontal and parietal cortex of macaque monkeys
No full textThe neural mechanisms related to the ability of humans and non-human primates to interact through joint-action are still poorly investigated. In the domain of motor functions, the study of goal-directed movement showed that no obligatory relationship exists between neural activity and movement, but rather movement-related activity is context-dependent and linked to different cognitive states. So far, neural activity in different cortical areas has been studied in a single brain in action, thus missing all information typical of interacting brains through a joint action task.
Two monkeys sat together in front of a display and they were trained in a center-out task in two intermingled conditions. In the first (SELF), each monkey had to move individually a visual cursor from a central position toward 8 different peripheral targets, by applying a force on an isometric joystick while its partner observed the action. In the second condition (cooperative joint action: COOP), both monkeys had to move their cursors together toward the same peripheral target, under the constraint of a maximum inter-cursor distance limit, which was visualized as an outlined circle incorporating the two cursors. Thus, in this context monkeys had to cooperate to reach a common goal.
Extracellular single-unit activity (SUA) was recorded from premotor cortex (PM) and inferior parietal lobule (IPL), simultaneously from homologous areas of both monkeys by using two multiple-electrode arrays.
Preliminary results showed that kinematic parameters, such as amplitude and direction of the force applied on the joystick, were overall similar in the COOP and SELF conditions. However, analysis of temporal aspects related to COOP trials showed a tendency of each monkey to adapt its own behavior in order to accommodate partner’s behaviour. In 540 PM and 258 IPL neurons studied during Reaction- and Movement Time, a 2-way ANOVA showed a significant difference of SUA between SELF and COOP conditions in 28.5 % PM and 22.1% IPL cells, and between final target directions in 42.6% PM and 39.2 % IPL cells with an interaction factor that resulted significant in 13.7% PM and 14.3% IPL cells. Therefore, in these areas similar actions performed in different social contexts (such as in absence or presence of social interactions), modulates SUA in a different way.
These findings represent a first step toward the description of the neural operations underlying motor functions in a cooperative context and suggest that within this action cooperation network different areas encode joint-action during different behavioural epochs
Local field potentials are influenced by cooperative joint-action in frontal and parietal cortex of macaque monkeys
No full textThe importance of social interaction in human and cultural evolution is οnly surpassed by the extreme complexity of social brain functions, making neural processes underlying social behavior difficult to study. Actions are identified as own or alien and in some cases alien actions trigger the same neural activity as own actions. However, evidence of neuronal activity associated to joint action in a social context is scant.
We studied extracellular local field potentials (LFPs:1-100 Hz) from premotor cortex (PM) and inferior parietal lobule (IPL) in two rhesus monkeys, during a joint-action task. Our goal was to determine not only the relationship between behavior and LFPs, but more importantly the context influence of an obligatory joint-action with a partner on neural activity.
Monkeys were trained in a center-out task in two conditions. In the first condition (SELF) each monkey, individually, had to move its cursor from the center toward a peripheral target, by applying a force on an isometric joystick, while the partner monkey observed the action. In the second condition (cooperative joint action: COOP), both monkeys had to move their cursors simultaneously toward the same peripheral target, constrained by a maximum inter-cursor distance limit visualized as an outlined circle encompassing the two cursors. Thus, in this condition they had to cooperate to reach a common goal.
We recorded neural activity from 236 PM and 166 IPL sites together with behavioral key events, simultaneously from homologous areas of both monkeys, by using two multiple-electrode arrays. Offline, we defined two epochs of interest, reaction time (RT: 0.2 s from target onset) and movement time (MT: 0.2 s from movement onset). For each trial we calculated the peak-to-peak LFP amplitude in each epoch. Finally we compared these values between the self-acting (SELF) and joint acting (COOP) and between peripheral target directions.
Behavioral analysis of reaction time and movement time showed that monkeys adapted their behavior during the joint-action condition in order to accommodate the partner’s behavior. A two way ANOVA showed a significant difference of LFP activity during RT or MT between SELF and COOP conditions in 25.8 % PM and 21.1% IPL sites and between peripheral target directions in 41.9% PM and 36.7 % IPL sites with an interaction factor that resulted significant in 11% PM and 13% IPL sites.
Our data show that there exists in the parieto-frontal system an action cooperation network which is set in motion during cooperative joint-action. We also show that LFP, reflecting cell assembly coordination, can disclose executive and higher-order neural processes
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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