Biology subjects

Dumas, C.

Publications and source records attributed to Dumas, C..

3 recordsLinked to original sources

bioRxiv2024

Agency accounts for the effect of FB transparency onmotor imagery neurofeedback performance

ObjectiveNeurofeedback (NF) is a cognitive training procedure based on real-time feedback (FB) of a participants brain activity that they must learn to self-regulate. A classical visual FB delivered in a NF task is a filling gauge reflecting a measure of brain activity. This abstract visual FB is not transparently linked--from the subjects perspective--to the task performed (e.g., motor imagery). This may decrease the sense of agency, that is, the participants reported control over FB. Here, we assessed the influence of FB transparency on NF performance and the role of agency in this relationship. ApproachParticipants performed a NF task using motor imagery to regulate brain activity measured using electroencephalography. In separate blocks, participants experienced three different conditions designed to vary transparency: FB was presented as either 1) a swinging pendulum, 2) a clenching virtual hand, 3) a clenching virtual hand combined with a motor illusion induced by tendon vibration. We measured self-reported agency and user experience after each NF block. Main resultsWe found that FB transparency influences NF performance. Transparent visual FB provided by the virtual hand resulted in significantly better NF performance than the abstract FB of the pendulum. Surprisingly, adding a motor illusion to the virtual hand significantly decreased performance relative to the virtual hand alone. When introduced in incremental linear mixed effect models, self-reported agency was significantly associated with NF performance and it captured the variance related to the effect of FB transparency on NF performance. SignificanceOur results highlight the relevance of transparent FB in relation to the sense of agency. This is likely an important consideration in designing FB to improve NF performance and learning outcomes.

neuroscience↗

bioRxiv2022

Pump-less, recirculating organ-on-a-chip (rOoC) platform

Current organ-on-a-chip (OoC) systems mimic important aspects of specific organ and tissue functions, however, many commercial and academic devices are either too simple for advanced assays or require a complicated support set-up including external driving systems such as pumps and tubing that hamper scalability and robustness. We have developed a novel, pump-less directional flow recirculating organ-on-a-chip (rOoC) platform that creates continuous or pulsed directional gravity-driven flow by a combination of a 3D-tilting system and an optimized microfluidic layout. The rOoC platform allows growing and connecting tissue or organ representations on-chip with the possibility of incorporating barrier functions, gradients, and circulating cells. Using the rOoC platform we demonstrate simple and reproducible endothelialisation, hepatic organoid integration, and the first steps of vascularization of 3D organ representations on-chip.

bioengineering↗

bioRxiv2020

Synergy and allostery in ligand binding by HIV-1 Nef

The Nef protein of human and simian immunodeficiency viruses (HIV and SIV, respectively) boosts viral pathogenicity through its interactions with host cell proteins. Nef has a folded core domain and large flexible regions, each carrying several protein interaction sites. By combining the polyvalency intrinsic to unstructured regions with the binding selectivity and strength of a 3D folded domain, Nef can bind to many different host cell proteins, perturbing their cellular functions. For example, the combination of a linear proline-rich motif and a hydrophobic core domain surface allows Nef to increase affinity and selectivity for particular Src family SH3 domains. Here we investigated whether the interplay between Nefs flexible regions and its core domain can allosterically influence ligand selection. We found that the flexible regions can bind back to the core domain in different ways, producing distinct conformational states that alter the SH3 domain selectivity and availability of Nefs functional motifs. The resulting cross-talk might help synergising certain subsets of ligands while excluding others, promoting functionally coherent Nef-bound protein ensembles. Further, we combined proteomic and bioinformatic analyses to identify human proteins that select SH3 domains in the same way as does Nef. We found that only 2-3% of clones from a whole human fetal library displayed a Nef-like SH3 selectivity. However, in most cases this selectivity appears to be achieved by a canonical linear interaction rather than a Nef-like tertiary interaction. This analysis suggests that Nefs SH3 recognition surface has no (or marginally few) cellular counterparts, validating the Nef tertiary binding surface as a promising unique drug target.

biophysics↗