1,721,030 research outputs found
Decoding sensorimotor information from superior parietal lobule of macaque via Convolutional Neural Networks
Full text linkDespite the well-recognized role of the posterior parietal cortex (PPC) in processing sensory information to guide action, the differential encoding properties of this dynamic processing, as operated by different PPC brain areas, are scarcely known. Within the monkey's PPC, the superior parietal lobule hosts areas V6A, PEc, and PE included in the dorso-medial visual stream that is specialized in planning and guiding reaching movements. Here, a Convolutional Neural Network (CNN) approach is used to investigate how the information is processed in these areas. We trained two macaque monkeys to perform a delayed reaching task towards 9 positions (distributed on 3 different depth and direction levels) in the 3D peripersonal space. The activity of single cells was recorded from V6A, PEc, PE and fed to convolutional neural networks that were designed and trained to exploit the temporal structure of neuronal activation patterns, to decode the target positions reached by the monkey. Bayesian Optimization was used to define the main CNN hyper-parameters. In addition to discrete positions in space, we used the same network architecture to decode plausible reaching trajectories. We found that data from the most caudal V6A and PEc areas outperformed PE area in the spatial position decoding. In all areas, decoding accuracies started to increase at the time the target to reach was instructed to the monkey, and reached a plateau at movement onset. The results support a dynamic encoding of the different phases and properties of the reaching movement differentially distributed over a network of interconnected areas. This study highlights the usefulness of neurons' firing rate decoding via CNNs to improve our understanding of how sensorimotor information is encoded in PPC to perform reaching movements. The obtained results may have implications in the perspective of novel neuroprosthetic devices based on the decoding of these rich signals for faithfully carrying out patient's intentions.(C) 2022 Published by Elsevier Ltd
Machine learning methods detect arm movement impairments in a patient with parieto-occipital lesion using only early kinematic information
Full text linkPatients with lesions of the parieto-occipital cortex typically misreach visual targets that they correctly perceive (optic ataxia). Although optic ataxia was described more than 30 years ago, distinguishing this condition from physiological behavior using kinematic data is still far from being an achievement. Here, combining kinematic analysis with machine learning methods, we compared the reaching performance of a patient with bilateral occipitoparietal damage with that of 10 healthy controls. They performed visually guided reaches toward targets located at different depths and directions. Using the horizontal, sagittal, and vertical deviation of the trajectories, we extracted classification accuracy in discriminating the reaching performance of patient from that of controls. Specifically, accurate predictions of the patient's deviations were detected after the 20% of the movement execution in all the spatial positions tested. This classification based on initial trajectory decoding was possible for both directional and depth components of the movement, suggesting the possibility of applying this method to characterize pathological motor behavior in wider frameworks
Introduzione
No full textQuesta raccolta di scritti di Mario Tronti, la prima a coprire l’intero periodo della sua produzione teorica, nasce dalla constatazione di un consolidato ritorno di interesse nei confronti del suo pensiero, oltre che dalla sostanziale irreperibilità di molte sue opere. Corredata da un’introduzione che ne storicizza il percorso politico e teorico, l’antologia offre una ricostruzione unitaria del pensiero di un intellettuale novecentesco tra i più conosciuti e internazionalmente citati, evidenziandone tanto le continuità quanto le fratture teoriche. Gli scritti selezionati sono raggruppati in quattro sezioni cronologiche, che individuano diversi periodi nel corso dell’evoluzione del pensiero di Tronti: Il punto di vista (1958-1967); Il politico e il movimento operaio (1968-1984); Realismo e trascendenza (1985-1998); Pensare il Novecento (1999-2015). In ciascuno di questi periodi l’autore sottopone a critica e in parte ripensa le proprie categorie, aprendo di volta in volta nuovi campi di ricerca e nuove prospettive per l’azione politica. Riproponendo i frutti più significativi del lavoro di Tronti, il volume risponde non solo a un’esigenza ricostruttiva e periodizzante, ma esprime una specifica natura interpretativa, caratterizzandosi come un utile strumento per la ricezione critica dell’intera opera trontiana.
Mario Tronti, filosofo e politico, negli anni Sessanta è stato tra i fondatori dell’operaismo italiano, poi professore di Filosofia morale e Filosofia politica all’Università di Siena, dirigente del Partito comunista italiano, più volte Senatore della Repubblica e presidente del Centro per la riforma dello Stato. Fra le sue opere più note ricordiamo «Operai e capitale» (1966), «Con le spalle al futuro» (1992), «La politica al tramonto» (1998), «Dello spirito libero» (2015)
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
The influence of action on perception spans different effectors
No full textPerception and action are fundamental processes that characterize our life and our possibility to modify the world around us. Several pieces of evidence have shown an intimate and reciprocal interaction between perception and action, leading us to believe that these processes rely on a common set of representations. The present review focuses on one particular aspect of this interaction: the influence of action on perception from a motor effector perspective during two phases,
action planning and the phase following execution of the action. The movements performed by eyes, hands, and legs have a different impact on object and space perception; studies that use different approaches and paradigms have formed an interesting general picture that demonstrates the existence of an action effect on perception, before as well as after its execution. Although the mechanisms of this
effect are still being debated, different studies have demonstrated thatmost of the time this effect pragmatically shapes and primes perception of relevant features of the object or environment which calls for action; at other times it improves our perception through motor experience and learning. Finally, a future perspective is provided, in which we suggest that thesemechanisms can be exploited to increase
trust in artificial intelligence systems that are able to interact with humans
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