Simultaneous Electrophysiology and Fiber Photometry in Freely Behaving Mice

Abstract

In vivo electrophysiology is the gold standard technique used to investigate subsecond neural dynamics in freely behaving animals. However, monitoring celltype-specific population activity is not a trivial task. Over the last decade, fiber photometry based on genetically encoded calcium indicators (GECIs) has been widely adopted as a versatile tool to monitor cell-type-specific population activity in vivo. However, this approach suffers from low temporal resolution. Here, we combine these two approaches to monitor both sub-second field potentials and cell-type-specific population activity in freely behaving mice. By developing an economical custommade system and constructing a hybrid implant of an electrode and a fiber optic cannula, we simultaneously monitor artifact-free mesopontine field potentials and calcium transients in cholinergic neurons across the sleep-wake cycle. We find that mesopontine cholinergic activity co-occurs with sub-second pontine waves, called P-waves, during rapid eye movement sleep. Given the simplicity of our approach, simultaneous electrophysiological recording and cell-type-specific imaging provides a novel and valuable tool for interrogating state-dependent neural circuit dynamics in vivo.

Distinct Characteristics of Odor-evoked Calcium and Electrophysiological Signals in Mitral/Tufted Cells in the Mouse Olfactory Bulb

“…Since spikes perform well in discriminating odors but are not good at detecting odors, owing to their high variability, combining spike and population Ca 2+ recordings enables both odor detection and odor discrimination to be precisely monitored. A similar method to simultaneously monitor EEG signals and fiber photometry signals was described in a recent study [ 49 ]. Thus, simultaneous recording of neural activity by electrophysiology and fiber photometry, as in the present study, is a powerful technique for studying the functions of single cells and neural circuits underlying sensory processing, cognition, and specific behaviors.…”

Light-guided sectioning for precise in situ localization and tissue interface analysis for brain-implanted optical fibers and GRIN lenses

“…In the future, LiGS can be used in experiments that combine optical fibers with electrophysiological probes, such as FP in conjunction with local field potential recordings (Patel et al, 2020) or optogenetics in conjunction with extracellular recordings (optrodes) (Biran et al, 2008). Lately, slice-recorded electrophysiology data have been combined with information on cell morphology by injecting biocytin and then conducting high-resolution fixed-tissue imaging (Gouwens et al, 2019).…”

Population imaging discrepancies between a genetically-encoded calcium indicator (GECI) versus a genetically-encoded voltage indicator (GEVI)

“…Traditionally, researchers have used a number of terms: wide-field imaging, volumetric imaging, mesoscopic imaging, mesoscale imaging, population imaging, etc. Fiber photometry uses different kind of optic components than wide-field imaging, but often falls precisely into the category of population imaging techniques 40 , 47 , 48 . The current study is an example of a population imaging approach without single-cell information (Fig.…”