La perception des systèmes vocaliques étrangers: une étude inter-langues

International audienceL'objectif de ce papier est de comprendre si la "densité" du système vocalique d'une langue, en d'autres termes, le nombre de voyelles dans la langue, joue un rôle dans la perception vocalique. Les résultats d'une expérience d'identification dans trois langues (français, anglais et espagnol) tendent à montrer que les sujets espagnols sont capables, sans hésitation, de catégoriser des stimuli absents de leur espace de production. En revanche, les résultats des sujets anglais montrent une très grande difficulté dans la tâche de catégorisation. Les résultats des sujets français sont intermédiaires. Nous concluons qu'un nombre peu élevé de voyelles dans le système vocalique facilite la tâche de catégorisation des sujets. De plus, le système anglais semble être plus complexe en ce qui concerne le type d'indices nécessaires pour identification des voyelles

La perception des systèmes vocaliques étrangers: une étude inter-langues

International audienceL'objectif de ce papier est de comprendre si la "densité" du système vocalique d'une langue, en d'autres termes, le nombre de voyelles dans la langue, joue un rôle dans la perception vocalique. Les résultats d'une expérience d'identification dans trois langues (français, anglais et espagnol) tendent à montrer que les sujets espagnols sont capables, sans hésitation, de catégoriser des stimuli absents de leur espace de production. En revanche, les résultats des sujets anglais montrent une très grande difficulté dans la tâche de catégorisation. Les résultats des sujets français sont intermédiaires. Nous concluons qu'un nombre peu élevé de voyelles dans le système vocalique facilite la tâche de catégorisation des sujets. De plus, le système anglais semble être plus complexe en ce qui concerne le type d'indices nécessaires pour identification des voyelles

Modality effects in implicit artificial grammar learning: An EEG study

Recently, it has been proposed that sequence learning engages a combination of modality-specific operating networks and modality-independent computational principles. In the present study, we compared the behavioural and EEG outcomes of implicit artificial grammar learning in the visual vs. auditory modality. We controlled for the influence of surface characteristics of sequences (Associative Chunk Strength), thus focusing on the strictly structural aspects of sequence learning, and we adapted the paradigms to compensate for known frailties of the visual modality compared to audition (temporal presentation, fast presentation rate). The behavioural outcomes were similar across modalities. Favouring the idea of modality-specificity, ERPs in response to grammar violations differed in topography and latency (earlier and more anterior component in the visual modality), and ERPs in response to surface features emerged only in the auditory modality. In favour of modality-independence, we observed three common functional properties in the late ERPs of the two grammars: both were free of interactions between structural and surface influences, both were more extended in a grammaticality classification test than in a preference classification test, and both correlated positively and strongly with theta event-related-synchronization during baseline testing. Our findings support the idea of modality-specificity combined with modality-independence, and suggest that memory for visual vs. auditory sequences may largely contribute to cross-modal differences. (C) 2018 Elsevier B.V. All rights reserved.Max Planck Institute for Psycholinguistics; Donders Institute for Brain, Cognition and Behaviour; Fundacao para a Ciencia e Tecnologia [PTDC/PSI-PC0/110734/2009, UID/BIM/04773/2013, CBMR 1334, PEst-OE/EQB/1A0023/2013, UM/PSI/00050/2013

The P600 in Implicit Artificial Grammar Learning

The suitability of the artificial grammar learning (AGL) paradigm to capture relevant aspects of the acquisition of linguistic structures has been empirically tested in a number of EEG studies. Some have shown a syntax-related P600 component, but it has not been ruled out that the AGL P600 effect is a response to surface features (e. g., subsequence familiarity) rather than the underlying syntax structure. Therefore, in this study, we controlled for the surface characteristics of the test sequences (associative chunk strength) and recorded the EEG before (baseline preference classification) and after (preference and grammaticality classification) exposure to a grammar. After exposure, a typical, centroparietal P600 effect was elicited by grammatical violations and not by unfamiliar subsequences, suggesting that the AGL P600 effect signals a response to structural irregularities. Moreover, preference and grammaticality classification showed a qualitatively similar ERP profile, strengthening the idea that the implicit structural mere-exposure paradigm in combination with preference classification is a suitable alternative to the traditional grammaticality classification test.Max Planck Institute for Psycholinguistics; Donders Institute for Brain, Cognition and Behaviour; Fundacao para a Ciencia e a Tecnologia [PTDC/PSI-PCO/110734/2009, UID/BIM/04773/2013 CBMR 1334, PEst-OE/EQB/LA0023/2013, UID/PSI/00050/2013]info:eu-repo/semantics/publishedVersio

Medical image analysis methods in MR/CT-imaged acute-subacute ischemic stroke lesion:Segmentation, prediction and insights into dynamic evolution simulation models. A critical appraisal

AbstractOver the last 15years, basic thresholding techniques in combination with standard statistical correlation-based data analysis tools have been widely used to investigate different aspects of evolution of acute or subacute to late stage ischemic stroke in both human and animal data. Yet, a wave of biology-dependent and imaging-dependent issues is still untackled pointing towards the key question: “how does an ischemic stroke evolve?” Paving the way for potential answers to this question, both magnetic resonance (MRI) and CT (computed tomography) images have been used to visualize the lesion extent, either with or without spatial distinction between dead and salvageable tissue. Combining diffusion and perfusion imaging modalities may provide the possibility of predicting further tissue recovery or eventual necrosis. Going beyond these basic thresholding techniques, in this critical appraisal, we explore different semi-automatic or fully automatic 2D/3D medical image analysis methods and mathematical models applied to human, animal (rats/rodents) and/or synthetic ischemic stroke to tackle one of the following three problems: (1) segmentation of infarcted and/or salvageable (also called penumbral) tissue, (2) prediction of final ischemic tissue fate (death or recovery) and (3) dynamic simulation of the lesion core and/or penumbra evolution. To highlight the key features in the reviewed segmentation and prediction methods, we propose a common categorization pattern. We also emphasize some key aspects of the methods such as the imaging modalities required to build and test the presented approach, the number of patients/animals or synthetic samples, the use of external user interaction and the methods of assessment (clinical or imaging-based). Furthermore, we investigate how any key difficulties, posed by the evolution of stroke such as swelling or reperfusion, were detected (or not) by each method. In the absence of any imaging-based macroscopic dynamic model applied to ischemic stroke, we have insights into relevant microscopic dynamic models simulating the evolution of brain ischemia in the hope to further promising and challenging 4D imaging-based dynamic models. By depicting the major pitfalls and the advanced aspects of the different reviewed methods, we present an overall critique of their performances and concluded our discussion by suggesting some recommendations for future research work focusing on one or more of the three addressed problems

COGNITION SEQUENTIELLE ET LANGAGE (ETUDE DU TRAITEMENT DES STRUCTURES)

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Not an aspirin: No evidence for acute anti-nociception to laser-evoked pain after motor cortex rTMS in healthy humans

Background High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) has shown efficacy in relieving neuropathic pain. Whether its analgesic effect also applies to acute physiological nociception remains unclear due to previous contradictory findings. Objective To provide an in-depth investigation of the effects of motor cortex HF-rTMS on acute laser-evoked pain and excitability of nociceptive networks in healthy subjects. Methods Randomized, placebo-controlled, double-blind, cross-over study in 20 healthy participants. Laser heat stimuli at nociceptive threshold were delivered to the right hand, allowing assessment of: (a) subjective pain intensity and unpleasantness; (b) laser-evoked potentials (LEPs, 128 electrodes) and their source model; (c) sympathetic skin responses, and (d) spino-thalamic pathway excitability. Data were collected before and 20 minutes after a session of neuro-navigated 20 Hz rTMS to the contralateral motor cortex. Results Subjective pain reports to thermal laser pulses, amplitude of late cortical potentials and sympathetic skin responses were decreased after cortical stimulation, to a similar extent whether it was active or placebo. Early cortical potentials and nociceptive network excitability remained identical before and after rTMS, as did anatomical sources of LEPs. Conclusions Our results do not provide evidence for a genuine anti-nociceptive effect of rTMS on acute physiological pain. We suggest that motor cortex rTMS may act upon high-order networks linked to the emotional and cognitive appraisal of chronic pain, and/or modulate pathologically sensitized networks, rather than change the physiological transmission within an intact nervous system. Such dichotomy is reminiscent of that observed with most drugs used for neuropathic pain

Production and perception of vowels: does the density of the system play a role?

International audienceThe objective of the present paper is to understand whether the "density" of the vowel system of a language, in other words the large or small number of vowels in the language, plays a significant role in the production and perception of vowels. Three languages (French, English and Spanish) are analysed. This work rests upon the comparison between speech production and the cognitive processing of linguistic units. Two different methodologies were employed in this aim : observation of phonetic productions and analyses of behavioural measures. First results lead us to hypothese that perception units can be larger than production units. In other words, the density of a vowel system seems to influence vowel perception but not vowel production

Exploration of beneficial and deleterious effects of inflammation in stroke: dynamics of inflammation cells.

International audienceThe inflammatory process during stroke consists of activation of resident brain microglia and recruitment of leucocytes, namely neutrophils and monocytes/macrophages. During inflammation, microglial cells, neutrophils and macrophages secrete inflammatory cytokines and chemokines, and phagocytize dead cells. The recruitment of blood cells (neutrophils and macrophages) is mediated by the leucocyte-endothelium interactions and more specifically by cell adhesion molecules. A mathematical model is proposed to represent the dynamics of various brain cells and of immune cells (neutrophils and macrophages). This model is based on a set of six ordinary differential equations and explores the beneficial and deleterious effects of inflammation, respectively phagocytosis by immune cells and the release of pro-inflammatory mediators and nitric oxide (NO). The results of our simulations are qualitatively consistent with those observed in experiments in vivo and would suggest that the increase of phagocytosis could contribute to the increase of the percentage of living cells. The inhibition of the production of cytokines and NO and the blocking of neutrophil and macrophage infiltration into the brain parenchyma led also to the improvement of brain cell survival. This approach may help to explore the respective contributions of the beneficial and deleterious roles of the inflammatory process in stroke, and to study various therapeutic strategies in order to reduce stroke damage