High contrast, isotropic, and uniform 3D-imaging of centimeter-scale scattering samples using structured illumination light-sheet microscopy with axial sweeping

Light-sheet fluorescent microscopy (LSFM) has, in recent years, allowed for rapid 3D-imaging of cleared biomedical samples at larger and larger scale. However, even in cleared samples, multiple light scattering often degrades the imaging contrast and widens the optical sectioning. Accumulation of scattering intensifies these negative effects as light propagates inside the tissue, which accentuates the issues when imaging large samples. With axially swept light-sheet microscopy (ASLM), centimeter-scale samples can be scanned with a uniform micrometric optical sectioning. But to fully utilize these benefits for 3D-imaging in biomedical tissue samples, suppression of scattered light is needed. Here, we address this by merging ASLM with light-sheet based structured illumination into Structured Illumination Light-sheet Microscopy with Axial Sweeping (SILMAS). The SILMAS method thus enables high-contrast imaging, isotropic micrometric resolution and uniform optical sectioning in centimeter-scale scattering samples, creating isotropic 3D-volumes of e.g., whole mouse brains without the need for any computation-heavy post-processing. We demonstrate the effectiveness of the approach in agarose gel phantoms with fluorescent beads, and in an PFF injected alpha-synuclein transgenic mouse model tagged with a green fluorescent protein (SynGFP). SILMAS imaging is compared to standard ASLM imaging on the same samples and using the same optical setup, and is shown to increase contrast by as much as 370% and reduce widening of optical sectioning by 74%. With these results, we show that SILMAS improves upon the performance of current state-of-the-art light-sheet microscopes for large and imperfectly cleared tissue samples and is a valuable addition to the LSFM family

<b>FEEDING DEVELOPMENT IN THE CONTEXT OF INFANT VOCALIZATIONS & CAREGIVER FEEDING RESPONSIVENESS</b>

The development of feeding skills is essential for infant health, growth, and family well-being. Despite the importance of this skill, relatively little is known about the development of independent solid feeding skills relative to other body systems – like vocalizations – or external factors including caregivers or the feeding environment. The purpose of this preliminary study was to examine the relationship between feeding skills, vocalizations, and caregiver feeding responsiveness at the same point in 6-8-month-old infants. We conducted this study remotely in order to obtain the most accurate assessment of infant skills and include diverse infant feeding experiences within their own home environments. Twenty-five typically developing – low-risk – infants and a pilot group of ten infants at increased risk for feeding and communication disorders completed the study, along with their caregivers. Infants were categorized as “at-risk” if they spent time in the Neonatal Intensive Care Unit. We collected feeding data through caregiver-recorded videos of typical mealtimes, vocalization measures from daylong audio recordings, and responsiveness assessments from video-conferencing interviews with caregivers and the mealtime feeding videos. In our sample, it was feasible to use these remote data collection methods, and we obtained high inter- and intra-rater reliability for all measures (> 90%). In our preliminary study, we found that infants in the low- and at-risk groups demonstrated different oral motor feeding skills. In hierarchical regression models, the interaction between risk group and utterance duration was the most significant predictor of oral motor feeding skills, while neither vocalization measure was strongly related to eating efficiency. In the opposite direction, feeding skills were not predictive of either normalized child vocalization count or utterance duration. Relative to caregiver feeding responsiveness, we found that caregiver feeding responsivity alone did not predict feeding or vocalization measures. Responsivity in combination with weeks of feeding experience and medical risk group was related to oral motor feeding skill but not related to vocalization measures. Overall, this study provided initial evidence that feeding skills develop as a dynamic system, influenced by multiple within-child and external factors, and future research is warranted on the influence of these factors on feeding and communication skill development.</p