Abstract
Dense microcircuit reconstruction techniques have begun to provide ultrafine insight into the architecture of small-scale networks. However, identifying the totality of cells belonging to such neuronal modules, the “inputs” and “outputs,” remains a major challenge. Here, we present the development of nanoengineered electroporation microelectrodes (NEMs) for comprehensive manipulation of a substantial volume of neuronal tissue. Combining finite element modeling and focused ion beam milling, NEMs permit substantially higher stimulation intensities compared to conventional glass capillaries, allowing for larger volumes configurable to the geometry of the target circuit. We apply NEMs to achieve near-complete labeling of the neuronal network associated with a genetically identified olfactory glomerulus. This allows us to detect sparse higher-order features of the wiring architecture that are inaccessible to statistical labeling approaches. Thus, NEM labeling provides crucial complementary information to dense circuit reconstruction techniques. Relying solely on targeting an electrode to the region of interest and passive biophysical properties largely common across cell types, this can easily be employed anywhere in the CNS.
Highlights
Dense microcircuit reconstruction techniques have begun to provide ultrafine insight into the architecture of small-scale networks
To provide a quantitative framework for neuronal network manipulation by electroporation, the volumetric range of effective electroporation was first calculated by finite element method (FEM) modeling; under standard conditions for a 1 μA electroporation current[10,14], the presumed electroporation threshold of 200 mV transmembrane potential[17] is already reached at approximately 0.3 μm distance from the tip, by far too low for an extended circuit (Fig. 1a, b)
Our modeling results were in excellent agreement with experimental measurements of the induced electric potential for a standard patch clamp setup (Supplementary Fig. 1)
Summary
Dense microcircuit reconstruction techniques have begun to provide ultrafine insight into the architecture of small-scale networks. Targeted electroporation as a versatile tool for the manipulation of cells was initially introduced as a single-cell approach[10], which was later proposed for delineating small neuronal ensembles using slightly increased stimulation currents[11] It still remains the state-of-the-art technique for specific, spatially restricted circuit labeling and loading[12,13]. A homogenous distribution of potential over the surface of the tip is created, leading to a larger effective electroporation volume with minimal damage We apply this technique to a defined exemplary microcircuit, the olfactory bulb glomerulus, thereby allowing us to identify sparse, long-range and higher-order anatomical features that have heretofore been inaccessible to statistical labeling approaches
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
