@article {69205, title = {Synchronous Ensembles of Hippocampal CA1 Pyramidal Neurons Associated with Theta but not Ripple Oscillations During Novel Exploration.}, journal = {eLife}, year = {2025}, month = {2025 Apr 1}, abstract = {

Synchronous neuronal ensembles play a pivotal role in the consolidation of long-term memory in the hippocampus. However, their organization during the acquisition of spatial memory remains less clear. In this study, we used neuronal population voltage imaging to investigate the synchronization patterns of CA1 pyramidal neuronal ensembles during the exploration of a new environment, a critical phase for spatial memory acquisition. We found synchronous ensembles comprising approximately 40\% of CA1 pyramidal neurons, firing simultaneously in brief windows (\~{}25ms) during immobility and locomotion in novel exploration. Notably, these synchronous ensembles were not associated with ripple oscillations but were instead phase-locked to local field potential theta waves. Specifically, the subthreshold membrane potentials of neurons exhibited coherent theta oscillations with a depolarizing peak at the moment of synchrony. Among newly formed place cells, pairs with more robust synchronization during locomotion displayed more distinct place-specific activities. These findings underscore the role of synchronous ensembles in coordinating place cells of different place fields.

}, doi = {10.7554/elife.96718.2}, url = {https://doi.org/10.7554/elife.96718.2}, author = {Bei-Jung Lin and Tsai-Wen Chen and En-Li Chen and Eric R. Schreiter} } @article {68967, title = {All-optical reporting of chloride ion driving force in the nervous system}, journal = {bioRxiv}, year = {2023}, month = {2023 Sep 01}, abstract = {

Ionic driving forces provide the net electromotive force for ion movement across membranes and are therefore a fundamental property of all cells. In the nervous system, chloride driving force (DFCl) determines inhibitory signaling, as fast synaptic inhibition is mediated by chloride-permeable GABAA\ and glycine receptors. Here we present a new tool for all-Optical Reporting of CHloride Ion Driving force (ORCHID). We demonstrate ORCHID{\textquoteright}s ability to provide accurate, high-throughput measurements of resting and dynamic DFCl\ from genetically targeted cell types over a range of timescales. ORCHID confirms theoretical predictions about the biophysical mechanisms that establish DFCl, reveals novel differences in DFCl\ between neurons and astrocytes under different network conditions, and affords the first\ in vivo\ measurements of intact DFCl\ in mouse cortical neurons. This work extends our understanding of chloride homeostasis and inhibitory synaptic transmission and establishes a precedent for utilizing all-optical methods to assess ionic driving force.

}, doi = {10.1101/2023.08.30.555464}, url = {https://doi.org/10.1101/2023.08.30.555464}, author = {Joshua S. Selfe and Teresa J. S. Steyn and Eran F. Shorer and Richard J. Burman and Kira M. D{\"u}sterwald and Ahmed S. Abdelfattah and Eric R. Schreiter and Sarah E. Newey and Colin J. Akerman and Joseph V. Raimondo} } @article {69090, title = {All-optical reporting of inhibitory receptor driving force in the nervous system.}, journal = {bioRxiv}, year = {2023}, month = {2023 Nov 20}, abstract = {

Ionic driving forces provide the net electromotive force for ion movement across receptors, channels, and transporters, and are a fundamental property of all cells. In the brain for example, fast synaptic inhibition is mediated by chloride permeable GABAA receptors, and single-cell intracellular recordings have been the only method for estimating driving forces across these receptors (DFGABAA). Here we present a new tool for quantifying inhibitory receptor driving force named ORCHID: all-Optical Reporting of CHloride Ion Driving force. We demonstrate ORCHID{\textquoteright}s ability to provide accurate, high-throughput measurements of resting and dynamic DFGABAA from genetically targeted cell types over multiple timescales. ORCHID confirms theoretical predictions about the biophysical mechanisms that establish DFGABAA, reveals novel differences in DFGABAA between neurons and astrocytes, and affords the first\ in vivo\ measurements of intact DFGABAA. This work extends our understanding of inhibitory synaptic transmission and establishes a precedent for all-optical methods to assess ionic driving forces.

}, doi = {10.1101/2023.08.30.555464}, url = {https://doi.org/10.1101/2023.08.30.555464}, author = {Joshua S. Selfe and Teresa J. S. Steyn and Eran F. Shorer and Richard J. Burman and Kira M. D{\"u}sterwald and Ahmed S. Abdelfattah and Eric R. Schreiter and Sarah E. Newey and Colin J. Akerman and Joseph V. Raimondo} }