Functional connectivity between medial pulvinar and cortical networks as a predictor of arousal to noxious stimuli during sleep.

The interruption of sleep by a nociceptive stimulus is favoured by an increase in the pre-stimulus functional connectivity between sensory and higher level cortical areas. In addition, stimuli inducing arousal also trigger a widespread electroencephalographic (EEG) response reflecting the coordinated activation of a large cortical network. Because functional connectivity between distant cortical areas is thought to be underpinned by trans-thalamic connections involving associative thalamic nuclei, we investigated the possible involvement of one principal associative thalamic nucleus, the medial pulvinar (PuM), in the sleeper's responsiveness to nociceptive stimuli. Intra-cortical and intra-thalamic signals were analysed in 440 intracranial electroencephalographic (iEEG) segments during nocturnal sleep in eight epileptic patients receiving laser nociceptive stimuli. The spectral coherence between the PuM and 10 cortical regions grouped in networks was computed during 5 s before and 1 s after the nociceptive stimulus and contrasted according to the presence or absence of an arousal EEG response. Pre- and post-stimulus phase coherence between the PuM and all cortical networks was significantly increased in instances of arousal, both during N2 and paradoxical (rapid eye movement [REM]) sleep. Thalamo-cortical enhancement in coherence involved both sensory and higher level cortical networks and predominated in the pre-stimulus period. The association between pre-stimulus widespread increase in thalamo-cortical coherence and subsequent arousal suggests that the probability of sleep interruption by a noxious stimulus increases when it occurs during phases of enhanced trans-thalamic transfer of information between cortical areas.

[Nociception pain and autism]. / Nociception, douleur et autisme.

Autistic subjects frequently display sensory anomalies. Those regarding nociception and its potential outcome, pain, are of crucial interest. Indeed, because of numerous comorbidities, autistic subjects are more often exposed to painful situation. Despite being often considered as less sensitive, experimental studies evaluating this point are failing to reach consensus. Using animal model can help reduce variability and bring, regarding autism, an overview of potential alterations of the nociceptive system at the cellular and molecular level.

TITLE: Nociception, douleur et autisme. ABSTRACT: Les sujets autistes présentent fréquemment des anomalies sensorielles. Celles concernant la nociception ainsi que sa potentielle résultante, la douleur, sont d'un intérêt capital. En effet, du fait de nombreuses comorbidités, les sujets autistes sont plus souvent exposés à des situations douloureuses que la population générale. Alors qu'ils sont souvent considérés comme moins sensibles, les études expérimentales sur ce point sont loin de faire consensus. Utiliser des modèles animaux pourrait permettre de s'affranchir de certaines sources de variabilité et d'apporter, dans le cadre de l'autisme, une vue d'ensemble des altérations potentielles du système nociceptif aux niveaux cellulaire et moléculaire.