Imagerie spectroscopique proche infrarouge

L'imagerie spectroscopique proche infrarouge fonctionnelle (ISPIf, en anglais Near Infrared Spectroscopic Imaging, NIRSI ou functional near-infrared imaging, fNIR) ou spectroscopie proche infrarouge fonctionnelle (SPIRf) est l'application à l' de la spectroscopie proche infrarouge. Cette technique consiste à mesurer de l'oxygénation d'une zone du cerveau afin d'en déduire son activité. Principe Les tissus humains sont relativement transparents à la lumière dans la gamme du proche infrarouge (entre 700 et ) qui peut donc les traverser sur plusieurs centimètres, on parle de fenêtre optique du spectre. Toutefois la molécule d'hémoglobine est un chromophore qui réfléchit la lumière dans cette gamme et son spectre d'absorption est différent selon qu'elle transporte une molécule de dioxygène (oxyhémoglobine) ou non (désoxyhémoglobine). Or, l'augmentation d'activité neuronale induit une augmentation du débit sanguin local baptisée réponse hémodynamique et donc une modification de

Carbon nanotube uptake in cyanobacteria for near-infrared imaging and enhanced bioelectricity generation in living photovoltaics

Alessandra Antonucci, Ardemis Anoush Boghossian, Alice Judith Gillen, Benjamin Paul Johanès Gabriel Lambert, Mohammed Mouhib, Melania Reggente, Charlotte Elisabeth Marie Roullier, Nils Schürgers, Vitalijs Zubkovs

Single-walled carbon nanotubes (SWCNTs) have unique optoelectronic properties that make them suitable for applications ranging from phototherapy to imaging and sensing, but their uptake has mainly been explored in eukaryotic cells. Here the authors explore the interaction of SWCNTs with cyanobacteria, showing that they are spontaneously taken up by cells only when coated with positive charges, opening the possibility of prokaryotic-based biotechnology applications. The distinctive properties of single-walled carbon nanotubes (SWCNTs) have inspired the development of many novel applications in the field of cell nanobiotechnology. However, studies thus far have not explored the effect of SWCNT functionalization on transport across the cell walls of prokaryotes. We explore the uptake of SWCNTs in Gram-negative cyanobacteria and demonstrate a passive length-dependent and selective internalization of SWCNTs decorated with positively charged biomolecules. We show that lysozyme-coated SWCNTs spontaneously penetrate the cell walls of a unicellular strain and a multicellular strain. A custom-built spinning-disc confocal microscope was used to image the distinct near-infrared SWCNT fluorescence within the autofluorescent cells, revealing a highly inhomogeneous distribution of SWCNTs. Real-time near-infrared monitoring of cell growth and division reveal that the SWCNTs are inherited by daughter cells. Moreover, these nanobionic living cells retained photosynthetic activity and showed an improved photo-exoelectrogenicity when incorporated into bioelectrochemical devices.

2022

Exploring MEG brain fingerprints: Evaluation, pitfalls, and interpretations

Enrico Amico, Alessandra Griffa, Ekansh Sareen, Dimitri Nestor Alice Van De Ville, Sélima Zahar

Individual characterization of subjects based on their functional connectome (FC), termed “FC fingerprinting”, has become a highly sought-after goal in contemporary neuroscience research. Recent functional magnetic resonance imaging (fMRI) studies have demonstrated unique characterization and accurate identification of individuals as an accomplished task. However, FC fingerprinting in magnetoencephalography (MEG) data is still widely unexplored. Here, we study resting-state MEG data from the Human Connectome Project to assess the MEG FC fingerprinting and its relationship with several factors including amplitude- and phase-coupling functional connectivity measures, spatial leakage correction, frequency bands, and behavioral significance. To this end, we first employ two identification scoring methods, differential identifiability and success rate, to provide quantitative fingerprint scores for each FC measurement. Secondly, we explore the edgewise and nodal MEG fingerprinting patterns across the different frequency bands (delta, theta, alpha, beta, and gamma). Finally, we investigate the cross-modality fingerprinting patterns obtained from MEG and fMRI recordings from the same subjects. We assess the behavioral significance of FC across connectivity measures and imaging modalities using partial least square correlation analyses. Our results suggest that fingerprinting performance is heavily dependent on the functional connectivity measure, frequency band, identification scoring method, and spatial leakage correction. We report higher MEG fingerprinting performances in phase-coupling methods, central frequency bands (alpha and beta), and in the visual, frontoparietal, dorsal-attention, and default-mode networks. Furthermore, cross-modality comparisons reveal a certain degree of spatial concordance in fingerprinting patterns between the MEG and fMRI data, especially in the visual system. Finally, the multivariate correlation analyses show that MEG connectomes have strong behavioral significance, which however depends on the considered connectivity measure and temporal scale. This comprehensive, albeit preliminary investigation of MEG connectome test-retest identifiability offers a first characterization of MEG fingerprinting in relation to different methodological and electrophysiological factors and contributes to the understanding of fingerprinting cross-modal relationships. We hope that this first investigation will contribute to setting the grounds for MEG connectome identification.

2021

Exploring MEG brain fingerprints: Evaluation, pitfalls, and interpretations

Enrico Amico, Alessandra Griffa, Ekansh Sareen, Dimitri Nestor Alice Van De Ville, Sélima Zahar

2021

Imagerie spectroscopique proche infrarouge

Carbon nanotube uptake in cyanobacteria for near-infrared imaging and enhanced bioelectricity generation in living photovoltaics

In Vivo Local Determination of Tissue Optical Properties: Applications to Human Brain

Exploring MEG brain fingerprints: Evaluation, pitfalls, and interpretations

Carbon nanotube uptake in cyanobacteria for near-infrared imaging and enhanced bioelectricity generation in living photovoltaics

In Vivo Local Determination of Tissue Optical Properties: Applications to Human Brain

Exploring MEG brain fingerprints: Evaluation, pitfalls, and interpretations