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.

Striatal dopamine (DA) release regulates reward-related learning and motivation and is believed to consist of a short-lived and continuous component. Here, we build a large-scale three-dimensional model of extracellular DA dynamics in dorsal (DS) and ventral striatum (VS). The model predicts rapid dynamics in DS with little to no basal DA and slower dynamics in the VS enabling build-up of DA levels. These regional differences do not reflect release-related phenomena but rather differential dopamine transporter (DAT) activity. Interestingly, our simulations posit DAT nanoclustering as a possible regulator of this activity. Receptor binding simulations show that D1 receptor occupancy follows extracellular DA concentration with milliseconds delay, while D2 receptors do not respond to brief pauses in firing but rather integrate DA signal over seconds. Summarised, our model distills recent experimental observations into a computational framework that challenges prevailing paradigms of striatal DA signalling.

Polyamide thin-film composite membranes are critically important in combating global water scarcity. However, simultaneously achieving ultrafast water permeation and high solute rejection remains challenging due to their thick, dense separation layers. Herein, we demonstrate a simple yet versatile strategy to modulate the nanostructure of the polyamide separation layer, particularly the abundance and interconnectivity of free volume, by adopting well-designed aqueous monomers. The key is introducing methyl groups onto the conventional piperazine monomers, which accelerates trans-interfacial diffusion and decreases the ensuing amidation reaction rate. This leads to the formation of a thinner separation layer composed of more linear polyamide fragments, where the methyl groups, serving as "molecular pillar" sites, weaken the intra- and interchain interactions to prevent their dense stacking, thereby creating a more interconnected free volume network. One prepared membrane exhibits a very high water permeance of 57.8 ± 2.8 L m h bar along with a satisfactory per- and polyfluoroalkyl substance rejection over 90%, as well as superior resistance to compression. This molecular-level microstructural engineering provides a new route and fundamental insights into the scalable production of high-performance separation membranes for emerging contaminant removal.