Tissue clearing has been widely used for fluorescence imaging of fixed tissues, but its application to live tissues has been limited by toxicity. Here we develop minimally invasive optical clearing media for fluorescence imaging of live mammalian tissues. Light scattering is minimized by adding spherical polymers with low osmolarity to the extracellular medium. A clearing medium containing bovine serum albumin (SeeDB-Live) is compatible with live cells, enabling structural and functional imaging of live tissues, such as spheroids, organoids, acute brain slices and the mouse brains in vivo. SeeDB-Live minimally affects neuronal electrophysiological properties and sensory responses in vivo, and facilitates fluorescence imaging of deep cortical layers in live animals without detectable toxicity to neurons or behavior. We further demonstrate its utility to epifluorescence voltage imaging in acute brain slices and in vivo preparations. Thus, SeeDB-Live expands both the depth and modality range of fluorescence imaging in live mammalian tissues.

Local dendritic computations are thought to critically influence neuronal signaling and plasticity yet remain largely unexplored in vivo due to challenges in stably imaging small structures at ultrafast timescales. We developed a 3D real-time motion correction platform for movement-stabilized, ultrafast two-photon voltage imaging. By co-labeling CA1 pyramidal neurons with voltage and calcium indicators, we simultaneously measured somato-dendritic and electro-calcium coupling at multiple dendritic sites. We characterized isolated dendritic spikes and distance-dependent backpropagation of naturally occurring and photostimulation-evoked bursts and single spikes. We found that bursts backpropagated more reliably than single spikes, validated that somato-dendritic coupling decreases with distance from soma, and showed that electro-calcium coupling decreases with increasing branch order. These findings provide in vivo evidence for distance-dependent invasion of somatic signals into dendrites, highlight the prevalence of isolated dendritic events, and show that dendritic structure isolates voltage from calcium signaling, potentially enabling unique intracellular pathways in distal dendrites.

Understanding how behavior modulates neuronal integration is a fundamental goal in neuroscience. We combined voltage imaging with optogenetics to reveal how excitatory (E) and inhibitory (I) inputs modulate spiking output, subthreshold dynamics, and gain in genetically defined CA1 neurons. We imaged pyramidal cells (PCs), vasoactive intestinal peptide (VIP), somatostatin (SST), and parvalbumin (PV) interneurons (INs) and found that locomotion reduced firing in PCs and VIP INs while increasing activity in SST and PV INs. Prolonged optical depolarization revealed that inhibitory inputs substantially contribute to intracellular theta oscillations in PCs and VIP cells. Firing rate-laser intensity (F-I) curves revealed distinct gain modulation across cell types, with a divisive gain reduction in PC bursting during locomotion, while simple spikes are unaffected. A two-compartment model suggested that this effect results from a balanced increase in E/I input to the soma and dendrite. These findings reveal how behavior coordinates E/I signaling to modulate hippocampal computations.

Recent advances in the field of Voltage Imaging, with a special focus on new constructs and novel implementations.

Work related to place tuning, spatial navigation, orientation and direction. Mainly includes articles on connectivity in the hippocampus, retrosplenial cortex, and related areas.

Basal Ganglia Advances is a collection highlighting research on the structure, function, and disorders of the basal ganglia. It features studies spanning neuroscience, clinical insights, and computational models, serving as a hub for advances in movement, cognition, and behavior.

Advances in optical techniques and two-photon (2P) sensitive genetic voltage indicators (GEVIs) enabled in-depth voltage imaging at single-spike and single-cell resolution. These results were achieved using ASAP-type sensors, while rhodopsin-based GEVIs were mainly used with one-photon (1P) illumination. Here, we demonstrate compatibility of rhodopsin-based GEVIs with 2P illumination. We rationally engineer a fully genetically encoded, rhodopsin-based GEVI, just another voltage indicating sensor (Jarvis), and demonstrate its utility under 1P and 2P illumination. We further show 2P usability of the fluorescence resonance energy transfer (FRET)-opsin GEVIs pAce and Voltron2. Comparing 2P scanless with fast 2P scanning illumination revealed that responses are resolved with both approaches, but FRET-opsin GEVIs show improved signal-to-noise ratio (SNR) with low irradiance, inherent to scanless illumination. Utilizing Jarvis and pAce, we establish high-SNR action potential detection at kilohertz imaging rates in mouse hippocampal slices, zebrafish larvae, and the cortex of awake mice, demonstrating high-contrast action potential detection under 2P illumination with rhodopsin-based GEVIs in vitro and in vivo.

Skin graft expansion techniques have demonstrated efficacy in treating large burns when the donor skin supply is insufficient. Currently, the pursuit of skin expansion extends beyond merely covering a large area; it also aims to achieve a large perimeter gain, a smaller interpatch distance, and a shorter healing period. However, clinicians and surgeons appear to overlook the significance of inter-patch distance and perimeter gain on expansion ratio and healing period. Moreover, the interrelationships among these critical parameters remain unknown to this day. This study revisits the fundamental principles of various graft expansion techniques (meshing, micrografting, and punching) to describe the interrelationship between these parameters. The analysis indicates that increasing the expansion ratio always delays the wound closure, regardless of the graft expansion technique. The recommendation provided for clinicians/surgeons to select the best surgical parameters or commercially available skin graft expansion device to improve wound healing. Furthermore, a criterion was presented to surgeons to objectively compare the two different skin graft expansion methods without bias. Furthermore, a comprehensive understanding of the interrelationships among inter-patch distance, perimeter gain, wound-healing period, and expansion ratio will ultimately lead to the development of novel therapeutic methods to promote large wound coverage and rapid wound healing.