Atypical coordination of cortical oscillations in response to speech in autism.

Subjects with autism often show language difficulties, but it is unclear how they relate to neurophysiological anomalies of cortical speech processing. We used combined EEG and fMRI in 13 subjects with autism and 13 control participants and show that in autism, gamma and theta cortical activity do not engage synergistically in response to speech. Theta activity in left auditory cortex fails to track speech modulations, and to down-regulate gamma oscillations in the group with autism. This deficit predicts the severity of both verbal impairment and autism symptoms in the affected sample. Finally, we found that oscillation-based connectivity between auditory and other language cortices is altered in autism. These results suggest that the verbal disorder in autism could be associated with an altered balance of slow and fast auditory oscillations, and that this anomaly could compromise the mapping between sensory input and higher-level cognitive representations

Brain oscillations and connectivity in autism spectrum disorders (ASD):new approaches to methodology, measurement and modelling

Although atypical social behaviour remains a key characterisation of ASD, the presence ofsensory and perceptual abnormalities has been given a more central role in recentclassification changes. An understanding of the origins of such aberrations could thus prove afruitful focus for ASD research. Early neurocognitive models of ASD suggested that thestudy of high frequency activity in the brain as a measure of cortical connectivity mightprovide the key to understanding the neural correlates of sensory and perceptual deviations inASD. As our review shows, the findings from subsequent research have been inconsistent,with a lack of agreement about the nature of any high frequency disturbances in ASD brains.Based on the application of new techniques using more sophisticated measures of brainsynchronisation, direction of information flow, and invoking the coupling between high andlow frequency bands, we propose a framework which could reconcile apparently conflictingfindings in this area and would be consistent both with emerging neurocognitive models ofautism and with the heterogeneity of the condition

Comparative analysis of the pathology of auditory temporal processing in autism spectrum disorder and dyslexia

Cette thèse a eu pour objectif de contribuer à la compréhension de deux troubles du langage: ceux associés aux troubles du spectre autistique et la dyslexie. Les récentes avancées sur les mécanismes neuraux de segmentation acoustique du signal de parole indiquent le rôle majeur des oscillations qui offrent des fenêtres d'intégration temporelle à l'échelle de la syllabe et du phonème, unités linguistiques ayant un sens. À l'aide d'enregistrements simultanés d'EEG et d'IRM fonctionnelle durant la visualisation d'un film et au repos, nous avons étudié les rythmes corticaux auditifs et leur topographie chez des sujets sains, autistes et dyslexiques. Nous avons montré que les sujets dyslexiques et les sujets autistes montrent une sensibilité atypique à la structure syllabique et à la structure phonémique. L'activité gamma et l'activité thêta ne s'engagent pas de façon synergique dans l'autisme. L'activité thêta dans le cortex auditif gauche échoue à suivre les modulations de l'enveloppe temporelle du signal de parole dans l'autisme et à potentialiser l'activité gamma qui encode les détails acoustiques. Les troubles du langage dans l'autisme résultent d'une altération du couplage des oscillations lentes et rapides, perturbant le décodage neural du signal de parole. Dans la dyslexie, l'activité corticale auditive thêta n'est pas altérée, et l'activité de modulation de l'activité gamma par l'activité thêta préservée, rendant possible le décodage phonémique, bien qu'atypique. Dans les deux pathologies, ces altérations de l'activité oscillatoire dans le cortex auditif entraînent une altération de la connectivité fonctionnelle entre le cortex auditif et les autres aires du langage.This research aimed to better understand two language disorders : those associated with autism spectrum disorder and dyslexia. Recent advances indicate how cortical collective neural behaviour intervene in speech segmentation and decoding. Cortical oscillations allow integration temporal windows at syllabic (4-7 Hz) and phonemic (25-35 Hz) time scale, resulting in chunking continuous speech signal into linguistically relevant units. We measured slow fluctuations of rhythmic cortical activity and their topography in healthy subjects, in subjects with autism spectrum disorder and in dyslexic subjects using combined fMRI and EEG. We showed that the sensitivity to syllabic and phonemic density is atypical in dyslexia and in autism. In autism gamma and theta activity do not engage synergistically in response to speech. Theta activity in left auditory cortex fails to track speech modulations and to down-regulate gamma oscillations that encode speech acoustic details. The language disorder in autism results from an altered coupling of slow and fast oscillations that disrupts the temporal organization of the speech neural code. In dyslexia, theta activity is not altered and theta-paced readout of gamma activity is preserved, enabling the phonemic decoding, even atypical (faster). In both pathologies, auditory oscillatory anomalies lead to atypical oscillation-based connectivity between auditory and other language cortices

Analyse comparée de la pathologie du traitement temporel auditif dans les troubles du spectre autistique et la dyslexie

This research aimed to better understand two language disorders : those associated with autism spectrum disorder and dyslexia. Recent advances indicate how cortical collective neural behaviour intervene in speech segmentation and decoding. Cortical oscillations allow integration temporal windows at syllabic (4-7 Hz) and phonemic (25-35 Hz) time scale, resulting in chunking continuous speech signal into linguistically relevant units. We measured slow fluctuations of rhythmic cortical activity and their topography in healthy subjects, in subjects with autism spectrum disorder and in dyslexic subjects using combined fMRI and EEG. We showed that the sensitivity to syllabic and phonemic density is atypical in dyslexia and in autism. In autism gamma and theta activity do not engage synergistically in response to speech. Theta activity in left auditory cortex fails to track speech modulations and to down-regulate gamma oscillations that encode speech acoustic details. The language disorder in autism results from an altered coupling of slow and fast oscillations that disrupts the temporal organization of the speech neural code. In dyslexia, theta activity is not altered and theta-paced readout of gamma activity is preserved, enabling the phonemic decoding, even atypical (faster). In both pathologies, auditory oscillatory anomalies lead to atypical oscillation-based connectivity between auditory and other language cortices.Cette thèse a eu pour objectif de contribuer à la compréhension de deux troubles du langage: ceux associés aux troubles du spectre autistique et la dyslexie. Les récentes avancées sur les mécanismes neuraux de segmentation acoustique du signal de parole indiquent le rôle majeur des oscillations qui offrent des fenêtres d'intégration temporelle à l'échelle de la syllabe et du phonème, unités linguistiques ayant un sens. À l'aide d'enregistrements simultanés d'EEG et d'IRM fonctionnelle durant la visualisation d'un film et au repos, nous avons étudié les rythmes corticaux auditifs et leur topographie chez des sujets sains, autistes et dyslexiques. Nous avons montré que les sujets dyslexiques et les sujets autistes montrent une sensibilité atypique à la structure syllabique et à la structure phonémique. L'activité gamma et l'activité thêta ne s'engagent pas de façon synergique dans l'autisme. L'activité thêta dans le cortex auditif gauche échoue à suivre les modulations de l'enveloppe temporelle du signal de parole dans l'autisme et à potentialiser l'activité gamma qui encode les détails acoustiques. Les troubles du langage dans l'autisme résultent d'une altération du couplage des oscillations lentes et rapides, perturbant le décodage neural du signal de parole. Dans la dyslexie, l'activité corticale auditive thêta n'est pas altérée, et l'activité de modulation de l'activité gamma par l'activité thêta préservée, rendant possible le décodage phonémique, bien qu'atypique. Dans les deux pathologies, ces altérations de l'activité oscillatoire dans le cortex auditif entraînent une altération de la connectivité fonctionnelle entre le cortex auditif et les autres aires du langage

Comparative analysis of the pathology of auditory temporal processing in autism spectrum disorder and dyslexia

Cette thèse a eu pour objectif de contribuer à la compréhension de deux troubles du langage: ceux associés aux troubles du spectre autistique et la dyslexie. Les récentes avancées sur les mécanismes neuraux de segmentation acoustique du signal de parole indiquent le rôle majeur des oscillations qui offrent des fenêtres d'intégration temporelle à l'échelle de la syllabe et du phonème, unités linguistiques ayant un sens. À l'aide d'enregistrements simultanés d'EEG et d'IRM fonctionnelle durant la visualisation d'un film et au repos, nous avons étudié les rythmes corticaux auditifs et leur topographie chez des sujets sains, autistes et dyslexiques. Nous avons montré que les sujets dyslexiques et les sujets autistes montrent une sensibilité atypique à la structure syllabique et à la structure phonémique. L'activité gamma et l'activité thêta ne s'engagent pas de façon synergique dans l'autisme. L'activité thêta dans le cortex auditif gauche échoue à suivre les modulations de l'enveloppe temporelle du signal de parole dans l'autisme et à potentialiser l'activité gamma qui encode les détails acoustiques. Les troubles du langage dans l'autisme résultent d'une altération du couplage des oscillations lentes et rapides, perturbant le décodage neural du signal de parole. Dans la dyslexie, l'activité corticale auditive thêta n'est pas altérée, et l'activité de modulation de l'activité gamma par l'activité thêta préservée, rendant possible le décodage phonémique, bien qu'atypique. Dans les deux pathologies, ces altérations de l'activité oscillatoire dans le cortex auditif entraînent une altération de la connectivité fonctionnelle entre le cortex auditif et les autres aires du langage.This research aimed to better understand two language disorders : those associated with autism spectrum disorder and dyslexia. Recent advances indicate how cortical collective neural behaviour intervene in speech segmentation and decoding. Cortical oscillations allow integration temporal windows at syllabic (4-7 Hz) and phonemic (25-35 Hz) time scale, resulting in chunking continuous speech signal into linguistically relevant units. We measured slow fluctuations of rhythmic cortical activity and their topography in healthy subjects, in subjects with autism spectrum disorder and in dyslexic subjects using combined fMRI and EEG. We showed that the sensitivity to syllabic and phonemic density is atypical in dyslexia and in autism. In autism gamma and theta activity do not engage synergistically in response to speech. Theta activity in left auditory cortex fails to track speech modulations and to down-regulate gamma oscillations that encode speech acoustic details. The language disorder in autism results from an altered coupling of slow and fast oscillations that disrupts the temporal organization of the speech neural code. In dyslexia, theta activity is not altered and theta-paced readout of gamma activity is preserved, enabling the phonemic decoding, even atypical (faster). In both pathologies, auditory oscillatory anomalies lead to atypical oscillation-based connectivity between auditory and other language cortices

Brain dynamics in ASD during movie-watching show idiosyncratic functional integration and segregation

To refine our understanding of autism spectrum disorders (ASD), studies of the brain in dynamic, multimodal and ecological experimental settings are required. One way to achieve this is to compare the neural responses of ASD and typically developing (TD) individuals when viewing a naturalistic movie, but the temporal complexity of the stimulus hampers this task, and the presence of intrinsic functional connectivity (FC) may overshadow movie-driven fluctuations. Here, we detected inter-subject functional correlation (ISFC) transients to disentangle movie-induced functional changes from underlying resting-state activity while probing FC dynamically. When considering the number of significant ISFC excursions triggered by the movie across the brain, connections between remote functional modules were more heterogeneously engaged in the ASD population. Dynamically tracking the temporal profiles of those ISFC changes and tying them to specific movie subparts, this idiosyncrasy in ASD responses was then shown to involve functional integration and segregation mechanisms such as response inhibition, background suppression, or multisensory integration, while low-level visual processing was spared. Through the application of a new framework for the study of dynamic experimental paradigms, our results reveal a temporally localized idiosyncrasy in ASD responses, specific to short-lived episodes of long-range functional interplays

Dynamic Inter-subject Functional Connectivity Reveals Moment-to-Moment Brain Network Configurations Driven by Continuous or Communication Paradigms

Task-based functional magnetic resonance imaging bears great potential to understand how our brain reacts to various types of stimulation; however, this is often achieved without considering the dynamic facet of functional processing, and analytical outputs typically account for merged influences of task-driven effects and underlying spontaneous fluctuations of brain activity. Here, we introduce a novel methodological pipeline that can go beyond these limitations: the use of a sliding-window analytical scheme permits tracking of functional changes over time, and through cross-subject correlational measurements, the approach can isolate purely stimulus-related effects. Thanks to a rigorous thresholding process, significant changes in inter-subject functional correlation can be extracted and analyzed. On a set of healthy subjects who underwent naturalistic audio-visual stimulation, we demonstrate the usefulness of the approach by tying the unraveled functional reconfigurations to particular cues of the movie. We show how, through our method, one can capture either a temporal profile of brain activity (the evolution of a given connection), or focus on a spatial snapshot at a key time point. We provide a publicly available version of the whole pipeline, and describe its use and the influence of its key parameters step by step

Time-resolved effective connectivity in task fMRI: Psychophysiological interactions of Co-Activation patterns

Investigating context-dependent modulations of Functional Connectivity (FC) with functional magnetic resonance imaging is crucial to reveal the neurological underpinnings of cognitive processing. Most current analysis methods hypothesise sustained FC within the duration of a task, but this assumption has been shown too limiting by recent imaging studies. While several methods have been proposed to study functional dynamics during rest, task-based studies are yet to fully disentangle network modulations. Here, we propose a seed-based method to probe task-dependent modulations of brain activity by revealing Psychophysiological Interactions of Co-activation Patterns (PPI-CAPs). This point process-based approach temporally decomposes task-modulated connectivity into dynamic building blocks which cannot be captured by current methods, such as PPI or Dynamic Causal Modelling. Additionally, it identifies the occurrence of co-activation patterns at single frame resolution as opposed to window-based methods. In a naturalistic setting where participants watched a TV program, we retrieved several patterns of co-activation with a posterior cingulate cortex seed whose occurrence rates and polarity varied depending on the context; on the seed activity; or on an interaction between the two. Moreover, our method exposed the consistency in effective connectivity patterns across subjects and time, allowing us to uncover links between PPI-CAPs and specific stimuli contained in the video. Our study reveals that explicitly tracking connectivity pattern transients is paramount to advance our understanding of how different brain areas dynamically communicate when presented with a set of cues