EFFECTS OF MOUTHING AND INTERLOCUTOR PRESENCE ON MOVEMENTS OF VISIBLE VS. NON-VISIBLE ARTICULATORS.

Speakers take into account what information a conversation partner requires in a given context in order to best understand an utterance. Despite growing evidence showing that movements of visible articulators such as the lips are augmented in mouthed speech relative to vocalized speech, little to date has been done comparing this effect in visible vs. non-visible articulators. In addition, no studies have examined whether interlocutor engagement differentially impacts these. Building on a basic present/not-present design, we investigated whether presence of audible speech information and/or an interlocutor affect the movements of the lips and the tongue. Participants were asked to a) speak or b) mouth three target syllables in interlocutor-present and interlocutor-not-present conditions, while lip and tongue movements were recorded using video and ultrasound imaging. Results show that lip protrusion was greater in mouthed conditions compared to vocalized ones and tongue movements were either attenuated (/wa/) or unaffected (/ri/, /ra/) by these same conditions, indicating differential effects for the visible and non-visible articulators in the absence of an auditory signal. A significant interaction between the social engagement and vocalizing conditions in reference to lip aperture showed that participants produced smaller lip apertures when vocalizing alone, as compared to when in the presence of an interlocutor. However, measures of lip protrusion failed to find an effect of social engagement. We conclude that speakers make use of both auditory and visual modalities in the presence of an interlocutor, and that when acoustic information is unavailable, compensatory increases are made in the visual domain. Our findings shed new light on the multimodal nature of speech, and pose new questions about differential adaptations made by visible and non-visible articulators in different speech conditions.

Les locuteurs prennent en compte l'information qu'un partenaire de conversation nécessite pour mieux comprendre une expression. Malgré l'évidence grandissante que les mouvements d'articulateurs visibles (comme les lèvres) sont augmentés dans l'articulation silencieuse par rapport à l'articulation vocalisée, peux d'études ont comparé cet effet dans les articulateurs visibles contre les articulateurs non visibles. De plus, aucune étude n'a examiné si l'engagement de l'interlocuteur changera ces résultats. En élaborant un conception d'expérience présent/non présent, nous avons testé si la présence d'information audible et/ou d'un interlocuteur affecte les mouvements des lèvres et de la langue. Les participants ont parlé trois syllabes, avec et sans production audible, dans chacune des conditions interlocuteur-présent et interlocuteur-non présent. Les mouvements des lèvres et de la langue étaient enregistrés avec la vidéo et l'échographie. Nos résultats montrent que la protubérance des lèvres était plus grande dans les conditions non audibles par rapport à ceux audibles et que les mouvements de la langue étaient atténués (/wa/) ou non affectés (/ri/, /ra/) par ces mêmes conditions, indiquant les effets différents pour les articulateurs visibles et non-visibles dans l'absence d'un signal auditif. Une interaction significative entre les conditions d'engagement sociale et d'audibilité de vocalisation avec référence à la fermeture orale a montré que les participants ont produit des fermetures plus étroites dans les conditions de vocalisation audible, interlocuteur-non présent (par rapport à la condition interlocuteur-présent). Cependant, les mesures de protubérance des lèvres n'étaient pas affectées par condition d'engagement sociale. Nous concluons que les locuteurs utilisent à la fois les modalités auditives et visuelles dans la présence d'un interlocuteur, et lorsque l'information acoustique n'est pas disponible, les augmentations compensatoires sont réalisés dans le domain visuel. Nos résultats soulignent encore le caractère multimodal de discours, et posent des nouvelles questions au sujet des adaptations différentielles faites par les articulateurs visibles et non visibles dans les différentes conditions de parole.

Activity-dependent changes in synaptic protein complex composition are consistent in different detergents despite differential solubility.

At the post-synaptic density (PSD), large protein complexes dynamically form and dissociate in response to synaptic activity, comprising the biophysical basis for learning and memory. The use of detergents to isolate the PSD and release its membrane-associated proteins complicates studies of these activity-dependent protein interaction networks, because detergents can simultaneously disrupt the very interactions under study. Despite widespread recognition that different detergents yield different experimental results, the effect of detergent on activity-dependent synaptic protein complexes has not been rigorously examined. Here, we characterize the effect of three detergents commonly used to study synaptic proteins on activity-dependent protein interactions. We first demonstrate that SynGAP-containing interactions are more abundant in 1% Deoxycholate (DOC), while Shank-, Homer- and mGluR5-containing interactions are more abundant in 1% NP-40 or Triton. All interactions were detected preferentially in high molecular weight complexes generated by size exclusion chromatography, although the detergent-specific abundance of proteins in high molecular weight fractions did not correlate with the abundance of detected interactions. Activity-dependent changes in protein complexes were consistent across detergent types, suggesting that detergents do not isolate distinct protein pools with unique behaviors. However, detection of activity-dependent changes is more or less feasible in different detergents due to baseline solubility. Collectively, our results demonstrate that detergents affect the solubility of individual proteins, but activity-dependent changes in protein interactions, when detectable, are consistent across detergent types.

Designer lipid-like peptides: a class of detergents for studying functional olfactory receptors using commercial cell-free systems.

A crucial bottleneck in membrane protein studies, particularly G-protein coupled receptors, is the notorious difficulty of finding an optimal detergent that can solubilize them and maintain their stability and function. Here we report rapid production of 12 unique mammalian olfactory receptors using short designer lipid-like peptides as detergents. The peptides were able to solubilize and stabilize each receptor. Circular dichroism showed that the purified olfactory receptors had alpha-helical secondary structures. Microscale thermophoresis suggested that the receptors were functional and bound their odorants. Blot intensity measurements indicated that milligram quantities of each olfactory receptor could be produced with at least one peptide detergent. The peptide detergents' capability was comparable to that of the detergent Brij-35. The ability of 10 peptide detergents to functionally solubilize 12 olfactory receptors demonstrates their usefulness as a new class of detergents for olfactory receptors, and possibly other G-protein coupled receptors and membrane proteins.