Biology subjects

Lyall, E. H.

Publications and source records attributed to Lyall, E. H..

2 recordsLinked to original sources

bioRxiv2022

Micropatterned Organoids Enable Modeling of the Earliest Stages of Human Cardiac Vascularization

Although model organisms have provided insight into the earliest stages of cardiac vascularization, we know very little about this process in humans. Here we show that spatially micropatterned human pluripotent stem cells (hPSCs) enable in vitro modeling of this process, corresponding to the first three weeks of in vivo human development. Using four hPSC fluorescent reporter lines, we create cardiac vascular organoids (cVOs) by identifying conditions that simultaneously give rise to spatially organized and branched vascular networks within endocardial, myocardial, and epicardial cells. Using single-cell transcriptomics, we show that the cellular composition of cVOs resembles that of a 6.5 post-conception week (PCW) human heart. We find that NOTCH and BMP pathways are upregulated in cVOs, and their inhibition disrupts vascularization. Finally, using the same vascular-inducing factors to create cVOs, we produce hepatic vascular organoids (hVOs). This suggests there is a conserved developmental program for creating vasculature within different organ systems. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=159 HEIGHT=200 SRC="FIGDIR/small/499233v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@17b265org.highwire.dtl.DTLVardef@1c1113eorg.highwire.dtl.DTLVardef@531c18org.highwire.dtl.DTLVardef@596bd2_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2020

Synthesis of higher order feature codes through stimulus-specific supra-linear summation

How cortical circuits build representations of complex objects is poorly understood. The massive dimensional expansion from the thalamus to the primary sensory cortex may enable sparse, comprehensive representations of higher order features to facilitate object identification. To generate such a code, cortical neurons must integrate broadly over space, yet simultaneously obtain sharp tuning to specific stimulus features. The logic of cortical integration that may synthesize such a sparse, high dimensional code for complex features is not known. To address this question, we probed the integration and population coding of higher order stimuli in the somatosensory and visual cortices of awake mice using two-photon calcium imaging across cortical layers. We found that somatosensory and visual cortical neurons sum highly specific combinations of sensory inputs supra-linearly, but integrate other inputs sub-linearly, leading to selective responses to higher order features. This integrative process generates a sparse, but comprehensive code for complex stimuli from the earliest stages of cortical processing. These results from multiple sensory modalities imply that input-specific supra-linear summation may represent a widespread cortical mechanism for the synthesis of higher order feature codes. This new mechanism may explain how the brain exploits the thalamocortical expansion of dimensionality to encode arbitrary complex features of sensory stimuli.

neuroscience↗