Extracting individual neural activity recorded through splayed optical microfibers

Abstract

Abstract.Previously introduced bundles of hundreds or thousands of microfibers have the potential to extend optical access to deep brain regions, sampling fluorescence activity throughout a three-dimensional volume. Each fiber has a small diameter (8 μm) and follows a path of least resistance, splaying during insertion. By superimposing the fiber sensitivity profile for each fiber, we model the interface properties for a simulated neural population. Our modeling results suggest that for small (<200) bundles of fibers, each fiber will collect fluorescence from a small number of nonoverlapping neurons near the fiber apertures. As the number of fibers increases, the bundle delivers more uniform excitation power to the region, moving to a regime where fibers collect fluorescence from more neurons and there is greater overlap between neighboring fibers. Under these conditions, it becomes feasible to apply source separation to extract individual neural contributions. In addition, we demonstrate a source separation technique particularly suited to the interface. Our modeling helps establish performance expectations for this interface and provides a framework for estimating neural contributions under a range of conditions.

Targeted micro-fiber arrays for measuring and manipulating localized multi-scale neural dynamics over large, deep brain volumes during behavior

“…Spontaneous Ca 2+ transients during locomotion were observed across locations which were clearly separable from noise and highly heterogeneous across locations (Figure 1C). These transients reflected spatially weighted Ca 2+ signals from neuron populations within a small volume around the fiber tips (Supplemental Figure 1A) 15,[26][27][28] . Transients were not observed with illumination at the 405nm isosbestic point, indicating minimal contribution from hemodynamic or motion artifacts (Figure 1C).…”

Neurophotonic Tools for Microscopic Measurements and Manipulation: Status Report

“…A number of recording channels can be increased using hundreds of splayed microfibers, each following a path of least resistance through tissue. 356 More recently, a proof-of-principle demonstration of deep brain imaging has been achieved by scanning the excitation beam through an implanted multimodal optical fiber to form an image (Sec. 4.4).…”