Sustained synchronized neuronal network activity in a human astrocyte co-culture system

Impaired neuronal network function is a hallmark of neurodevelopmental and neurodegenerative disorders such as autism, schizophrenia, and Alzheimer's disease and is typically studied using genetically modified cellular and animal models. Weak predictive capacity and poor translational value of these models urge for better human derived in vitro models. The implementation of human induced pluripotent stem cells (hiPSCs) allows studying pathologies in differentiated disease-relevant and patient-derived neuronal cells. However, the differentiation process and growth conditions of hiPSC-derived neurons are non-trivial. In order to study neuronal network formation and (mal) function in a fully humanized system, we have established an in vitro co-culture model of hiPSC-derived cortical neurons and human primary astrocytes that recapitulates neuronal network synchronization and connectivity within three to four weeks after final plating. Live cell calcium imaging, electrophysiology and high content image analyses revealed an increased maturation of network functionality and synchronicity over time for co-cultures compared to neuronal monocultures. The cells express GABAergic and glutamatergic markers and respond to inhibitors of both neurotransmitter pathways in a functional assay. The combination of this co-culture model with quantitative imaging of network morphofunction is amenable to high throughput screening for lead discovery and drug optimization for neurological diseases

Glycine and Glycine Receptor Signalling in Non-Neuronal Cells

Glycine is an inhibitory neurotransmitter acting mainly in the caudal part of the central nervous system. Besides this neurotransmitter function, glycine has cytoprotective and modulatory effects in different non-neuronal cell types. Modulatory effects were mainly described in immune cells, endothelial cells and macroglial cells, where glycine modulates proliferation, differentiation, migration and cytokine production. Activation of glycine receptors (GlyRs) causes membrane potential changes that in turn modulate calcium flux and downstream effects in these cells. Cytoprotective effects were mainly described in renal cells, hepatocytes and endothelial cells, where glycine protects cells from ischemic cell death. In these cell types, glycine has been suggested to stabilize porous defects that develop in the plasma membranes of ischemic cells, leading to leakage of macromolecules and subsequent cell death. Although there is some evidence linking these effects to the activation of GlyRs, they seem to operate in an entirely different mode from classical neuronal subtypes

Multimodal stance-taking in interaction—A systematic literature review

Stance-taking, the public act of positioning oneself toward objects, people or states of affairs, has been studied in many fields of research. Recently, its multimodal realization in interaction has received increasing attention. The current contribution aims to take stock of research on multimodal stance-taking so far, and to present possible avenues for future research. We systematically gathered and appraised 76 articles that investigate the involvement of bodily-visual resources in stance-taking in interaction. The critical appraisal focused on two dimensions of the stance act: form-function relations constituting it, and its dynamic organization in interaction. Regarding form-function relations, we found systematic involvement of specific bodily-visual resources in different stance acts, as well as patterns of multimodal intensification and mitigation of stances. As for its dynamic organization, the review discusses how stance-taking is organized temporally throughout an interaction, with all participants involved carefully negotiating and adapting their stances to one another. Finally, attention is paid to the broader context of stance-taking, including its role in different social and societal contexts. Based on this review, we were able to identify several gaps in the literature, and avenues for future research. We argue that much potential for broadening the scope of research lies in increasing the methodological diversity in approaching multimodal stance-taking, as well as in cross-linguistic studies and varying settings and participant constellations. In conclusion, research into multimodal stance-taking is vibrant, with ample opportunities for future work. This review can be considered as a call to action to move beyond the premise that stance-taking is multimodal, and further investigate this intriguing and fundamental human capacity

The effects of urolithin A on poly I:C-induced microglial activation

Neuroinflammation can be triggered by various stimuli, including viral infections. Viruses can directly invade the brain and infect neuronal cells or indirectly trigger a “cytokine storm” in the periphery that eventually leads to microglial activation in the brain. While this initial activation of microglial cells is important for viral clearance, chronic activation leads to excessive inflammation and oxidative stress, which can be neurotoxic. Remarkebly, recent studies have shown that certain viruses such as influenza A virus, coronavirus, herpes virus and Epstein–Barr virus may be involved in the development of neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, and multiple sclerosis. Therefore, it is important to find therapeutic strategies against chronic neuroinflammation triggered by viral infections. Here, we investigated the effects of urolithin A (UA) on microglial activation in vitro induced by a viral mimetic, poly I:C, in a triple co-culture system of neurons, astrocytes and microglial cells. Immunocytochemistry was used to perform a comprehensive single-cell analysis of the morphological changes of microglia as an indicator of their reactive state. Treatment with UA significantly prevented the poly I:C-induced reactive state of microglia, which was characterized by increased expression of the microglial activation markers CD68 and IBA-1. UA restored the poly I:C-induced morphology by restoring microglial ramification. In addition, UA was able to reduce the release of the pro-inflammatory mediators CCL2, TNF-α, and IL-1β and showed a trend toward attenuation of cellular ROS production in poly I:C-treated cultures. Overall, this study suggests that UA as a component of a healthy diet may help prevent virus-induced neuroinflammation and may have therapeutic potential for future studies to prevent or treat neurodegenerative diseases by targeting the associated neuroinflammatory processes

Alpha2-Containing Glycine Receptors Promote Neonatal Spontaneous Activity of Striatal Medium Spiny Neurons and Support Maturation of Glutamatergic Inputs

Glycine receptors (GlyRs) containing the α2 subunit are highly expressed in the developing brain, where they regulate neuronal migration and maturation, promote spontaneous network activity and subsequent development of synaptic connections. Mutations in GLRA2 are associated with autism spectrum disorder, but the underlying pathophysiology is not described yet. Here, using Glra2-knockout mice, we found a GlyR-dependent effect on neonatal spontaneous activity of dorsal striatum medium spiny neurons (MSNs) and maturation of the incoming glutamatergic innervation. Our data demonstrate that functional GlyRs are highly expressed in MSNs of one-week-old mice, but they do not generate endogenous chloride-mediated tonic or phasic current. Despite of that, knocking out the Glra2 severely affects the shape of action potentials and impairs spontaneous activity and the frequency of miniature AMPA receptor-mediated currents in MSNs. This reduction in spontaneous activity and glutamatergic signaling can attribute to the observed changes in neonatal behavioral phenotypes as seen in ultrasonic vocalizations and righting reflex. In adult Glra2-knockout animals, the glutamatergic synapses in MSNs remain functionally underdeveloped. The number of glutamatergic synapses and release probability at presynaptic site remain unaffected, but the amount of postsynaptic AMPA receptors is decreased. This deficit is a consequence of impaired development of the neuronal circuitry since acute inhibition of GlyRs by strychnine in adult MSNs does not affect the properties of glutamatergic synapses. Altogether, these results demonstrate that GlyR-mediated signaling supports neonatal spontaneous MSN activity and, in consequence, promotes the functional maturation of glutamatergic synapses on MSNs. The described mechanism might shed light on the pathophysiological mechanisms in GLRA2-linked autism spectrum disorder cases

Identification of Protein Networks Involved in the Disease Course of Experimental Autoimmune Encephalomyelitis, an Animal Model of Multiple Sclerosis

A more detailed insight into disease mechanisms of multiple sclerosis (MS) is crucial for the development of new and more effective therapies. MS is a chronic inflammatory autoimmune disease of the central nervous system. The aim of this study is to identify novel disease associated proteins involved in the development of inflammatory brain lesions, to help unravel underlying disease processes. Brainstem proteins were obtained from rats with MBP induced acute experimental autoimmune encephalomyelitis (EAE), a well characterized disease model of MS. Samples were collected at different time points: just before onset of symptoms, at the top of the disease and following recovery. To analyze changes in the brainstem proteome during the disease course, a quantitative proteomics study was performed using two-dimensional difference in-gel electrophoresis (2D-DIGE) followed by mass spectrometry. We identified 75 unique proteins in 92 spots with a significant abundance difference between the experimental groups. To find disease-related networks, these regulated proteins were mapped to existing biological networks by Ingenuity Pathway Analysis (IPA). The analysis revealed that 70% of these proteins have been described to take part in neurological disease. Furthermore, some focus networks were created by IPA. These networks suggest an integrated regulation of the identified proteins with the addition of some putative regulators. Post-synaptic density protein 95 (DLG4), a key player in neuronal signalling and calcium-activated potassium channel alpha 1 (KCNMA1), involved in neurotransmitter release, are 2 putative regulators connecting 64% of the identified proteins. Functional blocking of the KCNMA1 in macrophages was able to alter myelin phagocytosis, a disease mechanism highly involved in EAE and MS pathology. Quantitative analysis of differentially expressed brainstem proteins in an animal model of MS is a first step to identify disease-associated proteins and networks that warrant further research to study their actual contribution to disease pathology

Context shapes interactive alignment: the role of cumulative priming

A growing body of evidence shows that dialogue involves a process of synchronisation across speakers at different semiotic levels. In this paper, we study which factors predict this synchronisation process at the lexical and gestural level. A multifactorial analysis based on a video corpus of dyadic interactions reveals that cumulative priming is the key factor at both levels. More than temporal or social factors, the number of preceding lexical or gestural references predicts which word or gesture participants will use. However, there is a crucial difference between the two modalities. At the lexical level cumulative priming by the interlocutor is crucial, whereas for gesture participants appear to draw on their own previous representations. A comparison with related studies shows that high-level, referential synchronisation and low-level, behavioural synchronisation seem to be governed by different rules. Models of human interaction that focus on synchronisation, should take both strands of research into account.status: publishe

Introduction: gaze, interaction and eye-tracking: A multidisciplinary endeavor

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Alignment sequences in multimodal interaction

This paper ties in with two recent developments in cognitive-functional approaches to language. First, there is a growing interest in explicitly incorporating dialogicity in cognitive discourse models (Langacker 2001, Verhagen 2005, Fried & Östman 2005, Du Bois 2011). Second, there is growing awareness that usage-based models in linguistics need to adopt a multimodal perspective (Mittelberg 2007, Sweetser 2007, Cienki & Müller 2008). Both strands serve as an empirical operationalization of the non-reductionist foundation of cognitive-functional linguistics, which holds that all aspects of the linguistic usage event that contribute to the meaning potential (including intonation, gesture, posture, etc.) should in principle be incorporated. In this paper we focus on the process of synchronization where interlocutors engaged in face-to-face interaction continuously and increasingly use and reuse each others’ linguistic and non-linguistic behaviour. This process has been approached from different theoretical perspectives (e.g. mechanistic processes vs. joint actions) and has alternatively been labelled interactive alignment (Pickering & Garrod 2004), conceptual pact (Brennan & Clark 1996), resonance (Du Bois 2011), and mimicry (Kimbara 2006). In the majority of studies, however, the perspective on this phenomenon has been largely monodimensional (focus on alignment behaviour in one semiotic channel or on one linguistic level) and restricted to minimal contexts (pairs of utterances rather than longer stretches of resonance). In order to arrive at a more fine-grained multimodal picture, we conducted a corpus study using the MIMIC-corpus (MultIModal Interaction Corpus, Brône & Oben 2011). This allowed us to incorporate various meaning-making cues, ranging from intonation in the acoustic channel, to gesture from the visual channel, and gaze generated by eye-trackers. The focus of this paper is on how multimodal alignment sequences emerge, persist and ‘die out’ in the interaction. First, we deal with the differences in distribution between the linguistic and non-linguistic channels in forming alignment sequences. We address questions such as “is non-linguistic alignment more restricted to simple pairs than linguistic alignment?” and “can linguistic alignment more easily cross the boundaries of one conversational sequence than non-linguistic alignment?”. Second, we look at distributional patterns within each of the semiotic channels, and the role of different levels of representation. For instance, for the language channel we address whether different levels of linguistic alignment (lexical, morphological, syntactic) behave differently, both in terms of frequency and persistence in and across conversational sequences. The results of the corpus-based study reveal both high degrees of interaction between channels/levels (what we label ‘clustered alignment’) and significant differences in sustainability.status: publishe

InSight Interaction: a multimodal and multifocal dialogue corpus

© 2014, Springer Science+Business Media Dordrecht. Research on the multimodal aspects of interactional language use requires high-quality multimodal resources. In contrast to the vast amount of available written language corpora and collections of transcribed spoken language, truly multimodal corpora including visual as well as auditory data are scarce. In this paper, we first discuss a few notable exceptions that do provide high-quality and multiple-angle video recordings of face-to-face conversations. We then present a new multimodal corpus design that adds two dimensions to the existing resources. First, the recording set-up was designed in such a way as to have a full view of the dialogue partners’ gestural behaviour, including hand gestures, facial expressions and body posture. Second, by recording the participant perspective and behaviour during conversation, using head-mounted scene cameras and eye-trackers, we obtained a 3D landscape of the conversation, with detailed production information (scene camera and sound) and indices of cognitive processing (eye movements for gaze analysis) for both participants. In its current form, the resulting InSight Interaction Corpus consists of 15 recorded face-to-face interactions of 20 min each, of which five have been transcribed and annotated for a range of linguistic and gestural features, using the ELAN multimodal annotation tool.status: publishe