Improved brain pattern recovery through ranking approaches

International audienceInferring the functional specificity of brain regions from functional Magnetic Resonance Images (fMRI) data is a challenging statistical problem. While the General Linear Model (GLM) remains the standard approach for brain mapping, supervised learning techniques (a.k.a.} decoding) have proven to be useful to capture multivariate statistical effects distributed across voxels and brain regions. Up to now, much effort has been made to improve decoding by incorporating prior knowledge in the form of a particular regularization term. In this paper we demonstrate that further improvement can be made by accounting for non-linearities using a ranking approach rather than the commonly used least-square regression. Through simulation, we compare the recovery properties of our approach to linear models commonly used in fMRI based decoding. We demonstrate the superiority of ranking with a real fMRI dataset

Traitement des structures syntaxiques dans le langage et dans la musique

Ce travail de thèse porte sur la structure syntaxique des phrases. La première partie de ce travail examine dans quelle mesure les mots grammaticaux et la prosodie sont utilisés pour identifier les catégories syntaxiques (Nom et Verbe). Nous montrons, grâce à une expérience comportementale avec des enfants de 18 mois, qu'ils savent déjà que les déterminants précèdent les noms et que les pronoms précèdent les verbes. Les enfants, à l'âge où ils apprennent le sens des mots, ne disposent que des informations syntaxiques et prosodiques. Trois expériences comportementales prouvent que les adultes utilisent ces indices pour déterminer automatiquement la catégorie grammaticale de pseudo-mots. Ces données nous conduisent à proposer un modèle d'accès lexical s'appuyant sur la prosodie et les mots grammaticaux pour sélectionner les mots les plus probables. Ce modèle rend également compte de l'apprentissage de nouveaux mots. La deuxième partie de ce travail explore les réseaux cérébraux impliqués dans le traitement de la structure syntaxique. Nous examinons si les traitements des structures dans le langage et dans la musique partagent les mêmes réseaux. Deux expériences d'IRMf utilisant la langue parlée montrent que les aires inféro-frontales (BA45 et BA47), temporales (pôle temporal, aSTS et pSTS) et temporo-pariétale sont recrutées pour le traitement de la structure syntaxique linguistique. Dans une seconde étude, nous montrons qu'un sous-ensemble de ces régions est impliqué dans le traitement de la structure musicale.This dissertation deals with syntactic structures. In the first part of this work, we examine how function words and prosody are exploited to recognize syntactic categories (nouns and verbs). With a behavioral experiment testing 18-months-olds, we showed that toddlers already know that determiners precede nouns and that pronouns occur before verbs in the case of known words. Furthermore, our behavioral experiments on adults proved that adult speakers use prosodic cues and function words to compute online syntactic categories for pseudowords. Those data lead us to propose a model which rely on prosody and function words to constrain lexical access. This model would also explain the acquisition of new words. In the second part of our work, we explored cerebral networks processing syntactic structure. We questioned if those networks involved in syntactic processing in lnaguage were shared with other domains such as music. Two fMRI experiments using spoken language showed that infero-frontal regions (BA45 and BA47), temporal regions (temporal pole, aSTS, pSTS) and the temporo-parietal junction are recruted to process syntactic structure in language. In a second study, we showed that a part of these networks is involved in syntactic structure processing in music.PARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Discovering word forms and word meanings: The role of phrasal prosody and function words

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Early bootstrapping of syntactic acquisition

International audienceInfants acquiring language have to learn about the lexicon, the phonology, and the syntax of their native language, among others. For each of these domains, being able to rely on knowledge from the other domains would simplify the learner’s task. For instance, having access to words and their meaning should help infants to learn about syntax, but learning about the meaning of words would be greatly facilitated if infants had access to some aspects of syntactic structure (Gleitman 1990). This chapter focuses on how phrasal prosody and function words may interact during early acquisition. Experimental results show that infants have access to intermediate prosodic phrases (phonological phrases) during the first year of life, and use these to constrain lexical segmentation. In addition, by two years of age they can exploit function words to infer the syntactic category of unknown content words (nouns vs verbs) and guess their plausible meaning (object vs action). We speculate on how infants may build a partial syntactic structure, the ‘syntactic skeleton’, by relying on both phonological phrase boundaries and function words, and present adult results strengthening the plausibility of this hypothesis

Function Words Constrain On-Line Recognition of Verbs and Nouns in French 18-Month-Olds

In this experiment using the conditioned head-turn procedure, 18-month-old French-learning toddlers were trained to respond to either a target noun (“la balle”/the ball) or a target verb (“je mange”/I eat). They were then tested on target word recognition in two syntactic contexts: the target word was preceded either by a correct function word (“une balle”/a ball or “on mange”/they eat), or by an incorrect function word, signaling a word from the other category (∗“on balle”/they ball or ∗“une mange”/a eat). We showed that 18-month-old s exploit the syntactic context on-line to recognize the target word: verbs were recognized when preceded by a personal pronoun but not when preceded by a determiner and vice-versa for nouns. These results suggest that 18-month-olds already know noun and verb contexts. As a result, they might be able to exploit them to categorize unknown words and constrain their possible meaning (nouns typically refer to objects whereas verbs typically refer to actions)

Sex Differences Along the Autism Continuum: A Twin Study of Brain Structure

International audienceFemales might possess protective mechanisms regarding autism spectrum disorder (ASD) and require a higher detrimental load, including structural brain alterations, before developing clinically relevant levels of autistic traits. This study examines sex differences in structural brain morphology in autism and autistic traits using a within-twin pair approach. Twin design inherently controls for shared confounders and enables the study of gene-independent neuroanatomical variation. N = 148 twins (62 females) from 49 monozygotic and 25 dizygotic same-sex pairs were included. Participants were distributed along the whole continuum of autism including twin pairs discordant and concordant for clinical ASD. Regional brain volume, surface area, and cortical thickness were computed. Within-twin pair increases in autistic traits were related to decreases in cortical volume and surface area of temporal and frontal regions specifically in female twin pairs, in particular regions involved in social communication, while only two regions were associated with autistic traits in males. The same pattern was detected in the monozygotic twin pairs only. Thus, non-shared environmental factors seem to impact female more than male cerebral architecture associated with autistic traits. Our results are in line with the hypothesis of a female protective effect in autism and highlights the need to study ASD in females separately from males